Bulletin ILLINOIS NATURAL HISTORY SURVEY M§'fX I £^L%Th Printfd by Authority of the State of Illinois Lead Poisoning as a Mortality Factor in Waterfowl Populations FRANK C. BELLROSE STATE OF ILLINOIS • William G. Stratton. Governor DEPARTMENT OF REGISTRATION AND EDUCATION • Vera M. Binm, Direefr NATURAL HISTORY SURVEY DIVISION • Harlow B. Mills, Chief .7^) ILLINOIS NATURAL HISTORY SURVEY Bulletin Volume 27, Article 3 Printed by Authority of May, 1959 the State of Illinois Lead Poisoning as a Mortality Factor in Waterfowl Populations FRANK C. BELLROSE STATE OF ILLINOIS • William G. Stratton, Governor DEPARTMENT OF REGISTRATION AND EDUCATION • Vera M. Binks, Director NATURAL HISTORY SURVEY DIVISION • Harlow B. Mills, Chief Urbana Illinois STATE OF ILLINOIS William G. Stratton, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Vera M. Binks, Director BOARD OF NATURAL RESOURCES AND CONSERVATION \'era M. Binks, Chairman; A. E. Emerson. Pli.D., Biology; Walter H. Newhouse, Ph.D., Geology. Roger Adams, Ph.D., D.Sc, Chemistry: Robert H. Anperson, B.S.C.E., Engineering: W. L. Everitt, E.E., Ph.D., Representing the President oj the University oj Illinois: Delyte W. Morris, Ph.D.. Piesitlent of Southern Illinois University NATURAL HISTORY SURVEY DIVISION, Urbano, Illinois SCIENTIFIC AND TECHNICAL STAFF Harlow B. Mills, Ph.D., Chief Bessie B. East, M.S., Assistant to the Chiel Section of Aquatic Biology—continued RuHAKD E. Bass, Field Assistant Robert D. Crompton, Field Assistant .Arnold W. Fritz, B.S., Field Assistant* David J. McGinty, Field Assistant* Section of Applied Botany and Plant Pathology I. Cedric Carter, Ph.D., Plant Pathologist and Head J. L. Forsberg, Ph.D., Plant Pathologist G. H. BoEWE, M.S., Associate Botanist RouERT A. EvERS, Ph.D., Associate Botanist Robert Da.n Neely, Ph.D., Associate Plant Pathologist E. B. Hi.MELicK, M.S., Assistant Plant Pathologist Walter Hartstirn, Ph.D., Assistant Plant Pathologist D. F. ScHOENEWEiss. Ph.D., Assistant Plant Pathologist Rovenia F. Fitz-Gerald, B.A., Technical Assistant Section of Wildlife Research Thomas G. Scott, Ph.D., Game Specialist and Head Ralph E. Yeatter, Ph.D., Game Specialist Carl O. Mohr, Ph.D.. Game Specialist F. C. Bellrose, B.S., Game Specialist H. C. Hanson, Ph.D., Associate Game Specialist Richard R. Graber, Ph.D., Associate Wildlife Specialist Ronald F. Labisky', M.S., Assistant Wildlije Specialist Frances D. Robbins, B.A., Technical Assistant Virginia A. Langdon. Technical Assistant Howard Crum, Jr., Field Assistant John L. Roseberry', B.S., Technical Assistant Rexford D. Lord, D.Sc, Project Leader* Frederick Greeley, Ph.D., Project Leader* Glen C. Sanderson, M.A., Project Leader* Iack A. Ellis, M.S., Assistant Project Leader* Thomas R. B. Barr, M.V.Sc, M.R.C.V.S.. Research Assistant* Bobbie Joe Verts. M.S., Field Mammalogist* Erwin W. Pearson, M.S., Field Mammalogist* Keith P. Dauphin, Assistant Laboratory Attendant* Gary P. I.mel, Assistant Laboratory Attendant* Section of Publications and Public Relations James S. Ayars, B.S.. Technical 'Editor and Head Blanche P. Young, B.A.. Assistant Technical Editor Diana R. Braverman, B.A., Assistant Technical Editor William E. Clark, Assistant Technical Photographer Marguerite Verley, Technical Assistant Technical Library Ruth R. Warrick, B.S., B.S.L.S., Technical Librarian NhLL Miles, M.S., B.S.L.S.. Assistant Technical Librarian CONSULTANTS: Herpetolocy, Hobart M. Smith, Ph.D., Professor oj Zoology, University oj Illinois: Parasitology, Norman D. Levine, V\\.1l)., Professor of Veterinary Parasitology and of Veterinary Research, University of Illinois: Wildlife Research, Willard D. Klimstra, Ph.D., Assistant Professor of Zoology and Director of Co-operative Wildlife Research, Southern Illinois University. Section of Economic Entomology George C. Decker, Ph.D., Principal Scientist and Head ]. H. Bigger, M.S., Entomologist L. L. English, Ph.D., Entomologist Willis N. Bruce, Ph.D., Associate Entomologist Norman Gannon, Ph.D., Associate Entomologist W. H. Luckmann, Ph.D., Associate Entomologist Ronald H. Meyer, M.S., Assistant Entomologist John D. Paschke, Ph.D., Assistant Entomologist John P. Kramer. Ph.D.. Assistant Entomologist Robert Snetsinger, M.S., Field Assistant Carol Morgan, B.S.. Laboratory Assistant Eugene M. Bravi, M.S.. Research Assistant Richard B. Dysart, B.S., Technical Assistant Reginald Roberis. A.B., Technical Assistant James W. Sanford. B.S., Technical Assistant Earl Stadelbacher. B.S., Technical Assistant Sue E. Watkins. Technical Assistant H. B. Petty-, Ph.D , Extension Specialist in Entomology* Stevenson Moore, III, Ph.D., Extension Specialist in Entomology* Zen AS B. Noon, Jr., M.S., Research Assistant* Clarence E. White, B.S., Research ,4ssistant* John Arthur Lowe, M.S.. Research Assistant* J. David Hoffman, B.S., Research Assistant* Carlos A. White, B.S., Research Assistant* Roy E. McLaughlin, B.S., Research Assistant* CosTAS KousKOLEKAS, M.S., Research .Assistant* Louise Zingrone, B.S., Research Assistant* Mary E. Mann, R.N., Research Assistant* Section of Faunistic Surveys and Insect Identification H. H. Ross, Ph.D., Systematic Entomologist and Head Milton W. Sanderson, Ph.D., Taxonomist Lewis J. Stannard, Jr., Ph.D., Associate Taxonomist Philip W. Smith, Ph.D., Associate Taxonomist Leonora K. Gloyd, M.S., Assistant Taxonomist H. B. Cunningham. M.S.. Assistant Taxonomist Edward L. Mockford, M.S., Technical Assistant Thelma H. Overstreet, Technical Assistant Section of Aquatic Biology George W. Bennett, Ph.D., Aquatic Biologist and Head William C. Starrett, Ph.D., Aquatic Biologist R. W. Larimore, Ph.D., Aquatic Biologist David H. Buck, Ph.D., Associate Aquatic Biologist Robert C. Hiltibran, Ph.D., Associate Biochemist Donald F. Hansen. Ph.D., Assistant Aquatic Biologist William F. Childers, M.S., Assistant Aquatic Biologist Marifran Martin, Technical Assistant John C. Cralley, B.S., Field Assistant Employed on co-operative projects with one of several agencies: University of Illinois, Illinois Agricultural Extension Service, Illinois Department of Conservation, United States Army Surgeon General's Office, United States Department of Agriculture, United States Fish and Wildlife Service, United States Public Health Service, and others. This paper is a contribution from the Section of Wildlife Research. f86180—5,500—10-58) CONTENTS Acknowledgments 236 Lead Poisoning Die-Offs 236 Early Die-Offs 238 Recent Die-Offs 239 Atlantic Flyway 239 Mississippi Flyway 242 Central Flyway 243 Pacific Flyway 244 Frequency of Die-Offs 245 Seasons of Die-Offs 246 Species Affected by Dic-Offs 247 Incidence of Lead Shot in Die-( )ffs 247 Availability of Lead 249 Ingested Lead Shot in Migrating Ducks 254 Shot in Live-Trapped Ducks 254 Shot in Ducks Bagged by Hunters 258 Variations in Shot Incidence Among Species 259 Regional Variations in Shot Incidence 261 Periodic Variations in Shot Incidence 265 Incidence of Various Shot Levels 268 Lead in Wild Mallards Dosed and Released 269 Effect of Lead on Vulnerability to Hunting 270 Effect of Lead on Migration Rate 272 Effect of Lead on Year-of-Banding Mortality Rate 274 Preventing Lead Poisoning 276 Discussion 279 Summary 283 Literature Cited 287 Photographs not otherivisr crrditrd arc by fVilliam E. (Uark or by Charles L. Scott. A few of the 2,000 wild mallards that were victims of a lead poisoning outbreak near Grafton, Illinois, in January, 1948. (Photograph from Western Cartridge Company.) Lead Poisoning as a Mortality Factor in Waterfowl Populations FRANK C. BELLROSE THE mortality resulting from lead poisoning in populations of wild waterfowl has been a cause of con- cern to conservationists for many years. This concern has grown out of the knowl- edge that lead poisoning is of common oc- currence among waterfowl, that this poi- soning results from the ingestion of lead by the birds in their feeding, and that large numbers of lead pellets fired from the guns of hunters lie in lakes and marshes visited by waterfowl. Phillips & Lincoln (1930:166), over two decades ago, stated : "From this ac- count it will be seen that lead poisoning due to eating shot is of common occur- rence, and it seems reasonable to presume that the disease will continue and even increase in the great ducking marshes of the country. The ultimate conclusions as to its effect upon the supply of waterfowl are hazardous to imagine," A few years later Dr. E. C. O'Roke of the Univer- sity of Michigan was quoted in Michigan Waterfowl Management (Pirnie 1935: 75-6) as follows: "Considering the enor- mous quantity of lead that there must be in the vicinity of blinds that have been shot over for decades, it is reasonable to conclude that the potential danger from lead poisoning is great and should be con- sidered in any waterfowl management program. In the writer's opinion lead poi- soning is the disease which takes the greatest toll of adult ducks in this section of the country." This theme was reiterated by Cottam (1949:339-40) who, in discussing fur- ther needs in wildlife research, suggested that "direct and indirect effects of lead shot in the digestive tracts of birds may be an exceedingly important stumbling block in the restoration of waterfowl. At the close of the hunting season live birds are carrying in their bodies an alarming amount of lead, and this condition may be much more widespread than we have realized. There is urgent need to ascer- tain the effects of the lead shot used in hunting." These remarks point up the generally recognized need for further appraisals of the problem, which was brought home to officials of the Illinois Natural History Survey and Western Cartridge Company (the latter now the Winchester-Western Cartridge Division of Olin Mathieson Chemical Corporation) at the time of a publicized die-off of wild ducks, frontis- piece, near Grafton, Illinois, in January of 1948 (Jordan & Bellrose 1951:10-1). As a result of a common interest in the problem of lead poisoning in waterfowl, the two groups supported a joint research project embracing the following objec- tives : ( 1 ) evaluation of losses from lead poisoning in wild waterfowl, (2) in- vestigation of lead alloys and other metals as materials for possible use as nontoxic shot, and (3) determination of the phys- iological effects of lead poisoning in wa- terfowl. The present paper is devoted primarily to the evaluation of losses resulting from lead poisoning in wild waterfowl popula- tions. Two reports have been published which presented preliminary findings on this subject (Bellrose 1951; Jordan & Bellrose 1951). Efforts to develop a non- toxic shot were treated in a paper dealing with the value of various shot alloys in relation to lead poisoning (Jordan & Bellrose 1950) ; additional data on this subject are presented herein. Findings as to the physiological effects of lead poison- ing on captive waterfowl have been dis- cussed in a paper bv Tordan & Bellrose (1951). The approach toward evaluating the importance of lead poisoning in wild waterfowl was threefold : ( 1 ) appraisal of the incidence and magnitude of water- fowl die-offs resulting from lead poison- ing, (2) appraisal of the incidence of [235] 2.?6 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 ingested lead shot among waterfowl popu- lations in fall and early winter, and (3) appraisal of waterfowl losses resulting from the ingestion of various quantities of lead shot per bird. ACKNOWLEDGMENTS The writer is most grateful to the man\ persons in various parts of the North American continent who furnished material and data. W^ithout their aid, it would have been impossible to appraise the importance of lead poisoning on such an extensive basis. The sources of much of the informa- tion outside of Illinois are acknowledged in the text or tables. However, the sources of material and data related to the occurrence of lead shot in waterfowl gizzards have been so numerous as to make such acknowledgment cumbersome. Acknowledgment is made here to those persons who sent 100 or more waterfowl gizzards for examination: Harold M. Swope, Colorado; E. B. Chamberlain, Jr., Florida; William P. Baldwin, Jr., Georgia and South Carolina; Robert L. Salter, Idaho; James D. McCall and Russell E. Mumford, Indiana ; Rich- ard K. Yancey and Charles W. Bosch, Louisiana ; Howard L. Mendall, Maine ; Gordon T. Nightingale and Dave Grice, Massachusetts; Forrest B. Lee, Minne- sota; Harvey Miller, Nebraska; Fred E. Wright, Nevada; T. Stuart Critcher and Yates M. Barber, Jr., North Carolina; Brandt V. Hjelle, North Dakota; Wil- liam B. Morse, Oregon ; Ray Murdy and Clair T. Rollings, South Dakota; J. R. Singleton. Texas; Allen G, Smith. Utah. The following biologists contributed data on the incidence of ingested lead shot found in waterfowl gizzards examined primarily for food contents: Ian McT. Cowan, British Columbia; Carol M. Fer- rel and Howard R. Leach, California ; E. B. Chamberlain, Jr., Florida; Rich- ard K. Yancey, Louisiana; Howard L. Mendall, Maine ; Leroy J. Korschgen and Charles E. Shanks, Missouri ; Donald D. Foley, New York; T. Stuart Critcher, North Carolina ; Charles K. Rawls, Jr., Tennessee ; Allen G. Smith, Utah ; Rob- ert G. Jeffrey and Charles F. Yocom, Washington. Many persons provided information on waterfowl die-offs resulting from lead poisoning. I especially wish to thank Richard E. Griffith, John J. Lynch, John W. Perkins, and Edward B. Davis of the United States Fish and Wildlife Service, and Richard K. Yancey and Morton M. Smith of the Louisiana Wild Life and Fisheries Commission for their excellent co-operation. Edwin R. Kalmbach and Arnold L. Nelson of the United States Fish and Wildlife Service provided suggestions and unpublished reports on lead poisoning in waterfowl. Johnson A. Neff of the same agency submitted an unpublished report on band recoveries from experimental mallards, some untreated and some dosed with six No. 6 shot pellets each, near Denver, Colorado. Dr. Harlow B. Mills, Chief of the Illi- nois Natural History Survey, and the late Charles H. Hopkins and Ray Holmes, both of Olin Mathieson Chemi- cal Corporation, who initiated this study as a result of their interest in a die-off of wild ducks near Grafton, Illinois, in 1948, continued their interest and aid throughout the study. Dr. Thomas G. Scott, Head of the Survey's Wildlife Re- search Section, and Mrs. Frances Rob- bins, Dr. Ralph E. Yeatter, and Dr. Carl O. Mohr, all of that section, gave many helpful suggestions which improved both the study and the paper. John C. Dear and Charles E. Gillham of the Olin Mathieson Chemical Corporation helped many times in many ways. James S. Ayars of the Natural History Survey edited the manuscript. Without the financial assistance pro- vided by Olin Mathieson Chemical Cor- poration, much of this study would have been impossible. LEAD POISONING DIE-OFFS The most dramatic expressions of lead poisoning in waterfowl are die-offs in which large numbers of birds in relatively small areas perish in short periods of time. Most of those persons who are se- riously concerned about lead poisoning among waterfowl have been convinced of the importance of the malady through witnessing one or more die-offs. Because May, 1959 Bellrose: Lead Poisoning in Waterfowl 237 of its emotional impact on any person who sees it, a waterfowl die-off is an event that is remembered and chronicled for a number of years. Three approaches have been made by the author of this paper in evaluating the importance of die-offs among waterfowl in the United States: (1) a study of the Fig. 1.—Opened duck gizzards and the ingested lead shot they contained. Black spots on the horny linings of the gizzards mark areas of tissue destruction by lead salts. Fig. 2.—Two mallard stoiriachs: the lower one from a lead-free duck, the upper from a lead-poisoned duck. The glandular stomach attached to the gizzard of the lead-poisoned mallard shows impaction of small grains. The impaction of food resulting from malfunctioning of the gizzard is one of the symptoms of lead poisoning in waterfowl. 238 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 literature, (2) personal on-the-spot in- vestigations of die-offs in Illinois and Louisiana, and (3) a canvass of state and federal conservation agencies for recent records of lead poisoning outbreaks among waterfowl. In studying several large outbreaks of lead poisoning in Illinois, 1940-1954, and at Catahoula Lake, Louisiana, 1953, the author and his associates undertook a tally of all dead and dying ducks found nnd of feathers marking the demise of birds. Rough compensations were made for areas not covered and for the time of each sam- pling in relation to the period of the out- break. An estimate was made of the duck population in each area. Samples of dead and dying ducks were collected. These ducks were sexed, aged, weighed, and fluoroscoped. Fluoroscopic procedure was similar to that described by Jordan & Bellrose (1950:158) and by Bellrose (1953:341). Examinations were made of lead shot pellets in gizzards of a number of dead ducks and were found to agree closely with fluoroscopic findings. Gizzards from lead-poisoned ducks are shown in figs. 1 and 2. Early Die-OflFs Records of lead poisoning in North American waterfowl date back to the lat- ter half of the nineteenth century. From remarks made by Phillips & Lincoln (1930:164), it is assumed that lead poi- soning in waterfowl was known at least as early as 1874. According to them, the March, 1894, issue of the American Field carried a note reporting that two lots of ducks which were unfit for food (pre- sumably as a result of lead poisoning) were seized at Galveston, Texas. These ducks had been taken at Stephenson Lake, where the disease had been noted for 20 years. More than 60 vears ago, George Bird Grinnell (1894:112) and E. Hough (1894:117) reported in Forest and Stream on some of the effects of lead poi- soning on waterfowl as determined from observations made during the winter of 1893-94. A few years later, Grinnell (1901:598-601), in addition to review- ing his earlier account on the appearance and behavior of a sick goose and a sick swan at Currituck Sound, North Caro- lina, stated that lead poisoning occurred among waterfowl in Texas at Galveston, at Stephenson Lake, and on Lake Sur- prise. A half century ago, Bowles (1908: 312-3) recorded the loss of a number of mallards {Anas platyrhynchos) from lead poisoning on the "Misqually" (presumably Nisqually) Flats of Puget Sound, Wash- ington. McAtee (1908:472) in the same year gave an account of lead poisoning in canvasbacks (Aytliya valisineria) at Lake Surprise, Texas. Wetmore (1919:2) reported that sev- eral whistling swans {Olor columbianus) from Back Bay, Virginia, were examined by the U. S. Biological Survey in Janu- ary of 1915. Twenty-two to 45 shot pel- lets were found in the gizzard of each swan, indicating that the birds had been affected by lead poisoning. He reported also that during the summers of 1915 and 1916 in the Bear River marshes of Utah many mallards and pintails {Anas acuta) were affected by lead poisoning. These ducks were found in the period June- September, and, although many died, the total was insignificant as compared with losses from other causes in the Bear River marshes. In discussing lead poisoning, Phillips & Lincoln (1930:165-6) recorded an instance in which "thousands" of ducks were reported dying at Hovey Lake, In- diana, in February, 1922, from an un- known malady that was later diagnosed as lead poisoning. The report they found to be "much exaggerated." They ob- served that "Possibly the most serious con- dition exists in Louisiana, where duck mortality from this cause may sometimes be further complicated by internal para- sites and possibly at times by lack of food" ; that newspapers reported in Janu- ary of 1925 that "thousands" of ducks were dying in Louisiana, apparently from lead poisoning, for all the specimens ex- amined were found to have ingested lead shot; and that large numbers of ducks died from lead poisoning in the Jacobs and Pecan Lake region of Arkansas in January of 1925. Van' Tyne (1929:103-4) reported that at Houghton Lake, Michigan, in April of 1928, greater scaups {Aythya marila) died from lead poisoning. Of 10 May, 1959 Bellrose: Lead Poisoning in Waterfowl 239 stomachs examined by Van Tyne, most contained 40 to 60 pellets of lead, and one contained 80 pellets. Elsewhere in Michigan, Pirnie (1935:74—5) reported that the deaths of five Canada geese {Branta canadensis) in Barry County in the spring of 1933, and a similar loss in Cass County in April, 1935, apparently were the result of lead poisoning. Munroe (1925:160) recorded that one adult trumpeter swan {Olor buccinator) and six cygnets had died from lead poison- ing in British Columbia during the winter of 1925. E. R. Kalmbach (unpublished report, March 6, 1930, in files of U. S. Fish and Wildlife Service) observed a lead poison- ing die-off of ducks in the coastal marsh area south of Gueydan, Vermilion Par- ish, Louisiana, in February of 1930. In a 200-acre rice field he found 199 dead ducks: namely, 120 pintails, 71 mallards, and 8 lesser scaups {Aythya affinis). Kalmbach believed that the toll in the rice field was greater than that found in any other area of similar size, but that losses occurred throughout 300 or more square miles of marsh. Albert Bonin, a resident of that area, told Kalmbach that sick ducks had been observed in the Florence section for at least 30 years. In Benin's experience, the spring of 1921 marked the severest outbreak noted in that region. Shillinger & Cottam (1937:399) re- corded the following waterfowl losses from lead poisoning, all in the fall and early winter of 1936: 8 ducks from the coast of North Carolina; 5 mallards from the Pamlico Sound area of Virginia ; 14 ducks from Delaware Bay; 12 ducks from northern Ohio; and 100 ducks, most of them mallards, from Boyd Lake, Colorado. The same authors (1937:402) gave an account of a die-off of ducks at the Sand Lake National Wildlife Refuge, South Dakota, during November and De- cember of 1935. Of 113 mallards exam- ined there by John J. Lynch, 103 were deemed victims of lead poisoning. Deaths of 6 other individuals, representing four species of ducks, were attributed to this disease. Recent Die-Oflfs In this review of lead poisoning die- offs, it has been necessary to rely almost entirely upon unpublished accounts for information up to 1937. Since that time only a few reports have been published (Mohler 1945; Bellrose 1947; Ayars 1947; Yancey 1953) but, fortunately, outbreaks have been recorded in letters and reported by biologists of state conser- vation agencies and the U. S. Fish and Wildlife Service. Data on most of the known die-offs of waterfowl from lead poisoning for the period beginning with the winter of 1938- 39 and extending through the winter of 1956-57 are summarized in table 1. These data have been obtained by contacting all state conservation agencies in the United States, as well as those in Ontario and British Columbia, plus the following branches of the U. S. Fish and Wildlife Service: Wildlife Refuges, Game Man- agement, and Wildlife Research. Most of the information has been obtained from letters and file reports graciously made available by waterfowl biologists of these agencies. In addition to the information pre- sented in table 1, many details have been made available which could not readily be recorded in tabular form. Therefore, it seems advisable to give a flyway-by-flyway roundup of information on the occur- rence of waterfowl die-offs resulting from lead poisoning. Atlantic Flyway.—Lead poisoning in waterfowl apparently is not an im- portant mortality factor in the Atlantic Flyway. The largest reported losses, table 1, amount to about 600 Canada geese and whistling swans which were picked up over a 10-year period in North Carolina, The following comments, from letters by waterfowl biologists in that flyway, illustrate the paucity of reports of die- offs from this malady. Dr. C. H. D. Clarke (letter, April 4, 1955) of the On- tario Department of Lands and Forests reported: "I know of no die-off worthy of the name from lead poisoning in On- tario. From time to time we have picked up individual poisoned waterfowl at vari- ous places where they are concentrated." Of the situation in Maine, Howard E. Spencer, Jr. (letter, March 28, 1955), wrote: "I have no knowledge of any die- offs which could be associated in any way with lead poisoning." From Vermont, 240 Illinois Xatural History Survey Bulletin Vol. 27, Art. 3 , c/3 U- tr <:^ UJ3 1J c o •- c.-= " "^ re .- ^ I— ^ «j C/5 U • 2 OJ -c uj C c< 3-- ^ O A t: — o « X) o Ic lO (-0 CN O V/-1 — O vo O -^ OO — ffl S O + ++ + + "^ o o c o r^ o o o o .—I ^ lo ^^ o oo o O O On O O O OO CO — O * O O C: <*• CS (^ O O O f- -/ « z Sou; 5 2 S5^ a: o oo o «^ c O C'o o II o oo o o"c" oo o o o o o oo o o o o oO O O CN o o CI. UJ ^ CO ? u -13-T3-T3 4J U 5en tn 5 S S ^° "2 >., 5/J Ml Xp -. — '- r: rt en SSS uu^ T3 "O "^ Ui Ut k- c3 ri ci T3 "O T3 t3 %'%% SS SS S SuSu "O tS 'rt "O L. u r; u = = .E = R c« o. n ON T *^2 fo _" ON 'ON 0^ X, -yT .-1 *"• -. ^- '^ hf. -. f^ ON O OO ON O, , r—- C *- u <^ r-co On On S•? bf) « — P ..Si r: Qi < -£ *-•' SI is: i^-~'-5 0S gu n May, 1959 Bellrose: Lead Poisoning in Waterfowl 241 cU. X ^. ^CD ^^ -C (J 1/; Xt^ ^ .'^ oj rt O *• u u c -n: t^ c/) 3 c oj -a "^ ^— u ™^ a! u-i u *-' C c^. S o J. t- K .y 9 tlZOn rt :s:-r '^IB """^ o o 242 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 William R. Miller (letter, May 19, 1955) reported: "1 have on a few occa- sions seen what to my mind was a case of death due to lead poisoninjz;." James A. Lee (letter, March 29, 1955) reported: "As far as I can ascertain, we have never had a waterfowl die-off in New Hamp- shire attributable to lead poisoning." Charles L. McLaughlin (letter, May 23, 1955) reported: "I have no authentic rec- ords of ducks dying of lead poisoning in Massachusetts, and it is my opinion that this type of mortality is unimportant in the state. A few years ago reports of large scale mortality from lead poisoning in the coastal wintering black ducks was re- ported, but investigation revealed that the mortality was due to starvation rather than lead." Ruth S. Billard (letter, May 3, 1955) reported as follows for the Con- necticut State Board of Fisheries and Game : "We are not aware of any water- fowl succumbing from lead poisoning." Thomas J. Wright (letter, April 26, 1955) reported: "Rhode Island, to the best of my knowledge, has never had any waterfowl losses that could be attributed to lead poisoning." From New York, Donald D. Foley (letter. May 3, 1955) wrote: "There are without doubt many instances of such poi- soning in this state, particularly in late winter and early spring, of which we are not aware. However, we feel that the over-all picture is not too serious as to di- rect mortality." L. G. McNamara (let- ter, April 27, 1955) reported: "As far as we know, lead poisoning is not a problem in New Jersev." Robert E. Stewart (let- ter, May 21, 1955) of the U. S. Fish and Wildlife Service, in referring to the Maryland marshes, reported: "On sev- eral occasions, during the past years, div- ing ducks which appeared unable to fly were collected and found to contain worn lead pellets." In Delaware, Everett B. Chamberlain (letter, April 11, 1955) knew of only two duck deaths which were suspected to be from lead poisoning. In Virginia, C. P. Gilchrist, Jr. (let- ter, June 20, 1955), expressed his belief that some ducks are lost to lead poison- ing, but not in large enough numbers to be brought to the attention of the Com- mission of Game and Inland Fisheries. Farther south, T. Stuart Critcher (let- ter. May 13, 1955), reporting from North Carolina, remarked : "To my knowledge we have no records of losses in waterfowl populations as a result of lead poison. Un- doubtedly, such losses do occur from time to time." Dr. J. H. Jenkins (letter, May 12, 1955) of the University of Georgia wrote: "I don't know of a sin- gle case of lead poisoning of waterfowl in Georgia. For one thing, there is very lit- tle shooting over established marshes." E. B. Chamberlain, Jr. (letter, April 22, 1955), reported concerning lead poison- ing: "So far as we have been able to de- termine, there have never been any large scale losses of waterfowl in Florida due to this cause." Mississippi Flyway.—All but three states in the Mississippi Flyway have re- ported die-offs of waterfowl as a result of poisoning from ingested lead shot, table 1. Among the largest losses have been those reported from Louisiana. The largest die-offs in Louisiana have been at Cata- houla Lake in La Salle Parish, where 20,- 300 ducks are estimated to have died from lead poisoning in the period 1950- 1955. Lead poisoning among the water- fowl of Catahoula Lake probably dates back farther than 1930, for E. R. Kalm- bach in his 1930 report (on file, U. S. Fish and Wildlife Service) mentions a duck malady as occurring in previous years at that lake. The largest known single outbreak of lead poisoning occurred in the Claypool Reservoir area near Weiner, Arkansas, between mid-December of 1953 and mid- February of 1954. John W. Perkins (let- ter, February 12, 1954), game agent for the U. S. Fish and Wildlife Service, esti- mated that during that period 16,000 ducks, most of them mallards, succumbed to lead poisoning. A similar die-off of mallards had pre- viously occurred there in early February' of 1951. The die-off was investigated by John J. Lynch (letter, February 9, 1951) of the U. S. Fish and Wildlife Service, who reported seeing over 50 carcasses on less than 3 acres of the 1,300 acre reser- voir. He concluded that the casualties "numbered in the thousands." Further- more, Lynch stated that a die-off of simi- lar proportions occurred on the same res- ervoir in the winter of 1948-49. May, 1959 Bellrose: Lead Poisoning in Waterfowl 243 In Missouri, the largest reported die- off of ducks from lead poisoning took place at the Squaw Creek National Wild- life Refuge, where 10,000 out of 150,000- 205,000 mallards died during the winter of 1956-57. In the previous winter, 5,000 mallards out of the 200,000 on the ref- uge died from lead poisoning. Other die- offs occurred there every winter at least as far back as 1945; reported mortality varied from 50 to 300 victims per year. Additional die-offs of mallards occurred at Dalton Cut-off in Chariton County in 1949 and at the Swan Lake National Wildlife Refuge in 1939, 1952, 1953, and 1954. Hovey Lake, Posey County, Indiana, has been a trouble spot for many years. As mentioned earlier, Phillips & Lin- coln (1930:165) reported ducks dying there from lead poisoning as far back as 1922. The largest die-off there in recent years, an estimated 1,000 ducks, took place during the winter of 1947-48 (James D. McCall, letter, February 5, 1955). Reported losses since then have been sporadic and rather small, except for the death of 219 Canada geese in 1953 and 120 in 1955-56 (Martin 1957:114). Small die-offs, aggregating 678 birds, are reported to have occurred at Hovey Lake, the Kankakee State Game Preserve area (Starke County), and the Willow Slough State Game Preserve (Newton County) during January and February, 1955. Since 1947, wherever large numbers of mallards have wintered in central Illinois, there have been some outbreaks of lead poisoning. Most of the reported die-offs have occurred on, or in the vicinity of, the Chautauqua National Wildlife Ref- uge, near Havana, where 13,000 ducks are estimated to have died from lead poi- soning in the period 1941-1957, table 1. The largest single outbreak of lead poison- ing among waterfowl of Illinois occurred there in January and February of 1957, when an estimated 5,000 succumbed. The second largest die-off occurred at Stump Lake, north of Grafton, where 3,000 mal- lards were victims of lead poisoning in January, 1948. In Iowa, sporadic outbreaks of lead poi- soning among ducks have been noted since 1936, according to Everett B. Speaker (letter, February 23, 1955), but only one die-off amounted to over 1,000 birds, ta- ble 1. That one took place at Forney Slough, in Fremont County, during the winter of 1948. Reported losses from lead poisoning among waterfowl in the lake states of Minnesota, Wisconsin, and Michigan have been minor, table 1. In Wisconsin, small losses of whistling swans occurred in the Green Bay area in the springs of 1948-1954. L. R. Jahn (letter, February 16, 1955) reported that, although ducks were victims of lead poisoning in both spring and fall, their losses had been spo- radic. H. J. Miller (letter, February 23, 1955) wrote that Michigan had not known an appreciable die-off of ducks from lead poisoning since the taking of waterfowl records was begun in 1940. In the spring of 1942, 16 whistling swans were found dead from lead poisoning on widely separated marshes of southeastern Michigan. In the winter of 1953-54, 100 whistling swans and 75 mallards were reported as dying from lead poisoning at the Shiawassee National Wildlife Refuge, near Saginaw (Richard E. Griffith, letter, April 1, 1955). After studying the mortality in large populations of ducks wintering, 1949- 1952, on the Detroit River in Michigan. Hunt & Ewing (1953:362, 367) con- sidered lead poisoning to be of little im- portance as a mortality factor. In Ohio, lead poisoning has evidently been a minor problem, for Delmar Hand- ley (letter, April 28, 1955) stated that only a few ducks and geese had been found afflicted by this disease. A suspected case of lead poisoning in Tennessee waterfowl was reported by Parker Smith (letter, May 5, 1955) as affecting 40 or 50 mal- lards along the Obion River in Februarv, 1954. In three states of the Mississippi Fly- way, Kentucky, Mississippi, and Alabama, lead poisoning losses have not been re- ported (letters: Frank Dibble, April 12, 1955; W. Walter Beshears, Jr., May 9, 1955; and Alec Bumsted, March 1, 1955), but some losses undoubtedly oc- cur in those states. Central Flyway.—Although die-offs of waterfowl from lead poisoning have occurred at several places in the Central Flyway, they have not been so large as 244 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 those in the Mississippi Flyway, table 1. Largest losses in the Central Flyway have been reported from the Sand Lake Na- tional Wildlife Refuge area of South Da- kota, where more than 10,700 mallards succumbed to lead poisoning over a span of 10 winters. A large die-off of ducks reported in Lubbock County, Texas, during the win- ter of 1944 was a most unusual one. De- tails were reported in a letter (June 18, 1945) from Oscar L. Chapman, then As- sistant Secretary of the Department of the Interior, to the Secretary of War, Henry L. Stimson. Excerpts are as follows: "During the past winter approximately 800 wild ducks were found dead at two small lakes on the grounds of the Lub- bock Army Air Field, Texas. Field studies conducted by the Fish and Wild- life Service of this Department revealed that these losses were due primarily to lead poisoning resulting from ingestion of lead shot which drop into one of these lakes during skeet practices. Studies con- ducted by Army personnel indicated that 80 per cent of the dead ducks examined contained lead pellets in their gizzards. ... It is estimated that the annual loss from the two lakes is between 5,000-10,- 000 ducks, many of which perish on their northward migration. This estimate is substantiated by numerous reports of ema- ciated dead and live ducks being found or seen in areas north of Lubbock." In Nebraska, George V. Schildman (letter, March 5, 1955) reported siz- able die-offs of blue geese (Chen caeru- lescens) and lesser snow geese {Chen hy- perborea) from lead poisoning, table 1. In regard to loss of ducks, he stated: "The numerous rainwater basins in Clay, Fillmore, and York counties provide some losses each spring. . . .The losses are com- monplace, but—to my knowledge — haven't been conspicuous and concen- trated. However, these basins cover an extensive area, and the total loss may be considerable." According to Richard E. Griffith (let- ter, April 1, 1955) : "Minor losses have been reported from the Salt Plains Ref- uge (Oklahoma), usually in single iso- lated cases. An occasional bird with lead poisoning is picked up on other refuges throughout the Southwest, but in most in- stances it is felt the shot was ingested prior to arrival." Griffith reported some fatalities among mallards at the Fort Peck Game Range in Montana, where 5,000 to 17,000 winter. Elsewhere in Montana, Wynn G. Freeman (letter, April 23, 1955) reported he had found no water- fowl suffering from lead poisoning. Other waterfowl biologists in the Cen- tral Flyway who have yet to find mor- tality in waterfowl from lead poisoning are B. A. Fashingbauer (letter, February 17, 1955), North Dakota; Robert L. Patterson (letter, February 8, 1955), Wy- oming; and Levon Lee (letter, February 19, 1955), New Mexico. Pacific Flyway.—The largest out- breaks of lead poisoning among waterfowl of the Pacific Flyway have been reported from California, table 1. In 1939, ducks estimated at 9,500 died from lead poi- soning in the Central Valley, San Fran- cisco Bay, and Suisun Bay areas of Cali- fornia, table 1, but it is not known to what extent die-offs approach this number every year, for the problem was investi- gated in detail in only that j^ear by the California Department of Fish and Game. In the winters beginning in 1944 and end- ing in 1954, 4,000 ducks were estimated to have become victims of lead poisoning at the Salton Sea National Wildlife Ref- uge in southern California. Both the Tule Lake and the Lower Klamath National Wildlife refuges in northern California, according to Rich- ard E. Griffith (letter, May 17, 1955), have sections heavily shot over, and yet reported losses from lead poisoning have been surprisingly low. From Utah, Noland F. Nelson (letter, February 19, 1955) reported regarding lead poisoning: "During the past 10 years of waterfowl management work on Utah's marshlands, I have observed no large die- offs of waterfowl resulting from lead poi- soning. However, a few lead poisoning losses have been recorded every year. These recorded losses were almost always during the winter and early spring months on some of the areas of heavy shooting around Great Salt Lake. . . . A few emaciated mallard, pintail, shov- eler, and whistling swan have been exam- ined almost every winter and a large per cent have contained ino;ested lead shot. I May, 1959 Bellrose: Lead Poisoning in Waterfowl 245 The keeper of a local aviary rescued 33 sick whistling swans one winter and 28 died from lead poisoning." In discussing losses of waterfowl from lead poisoning at the Bear River Migra- tory Bird Refuge, Utah, Richard E. Grif- fith (letter, April 1, 1955) emphasized that the loss cited, table 1, was a mini- mum one and should not be construed as a reliable indicator of total mortality. He reported that outbreaks of lead poisoning occurred when ice restricted the birds to a limited feeding area. The development of this situation was most apparent among the 10,000-12,000 whistling swans win- tering at the refuge, for they began to die from lead poisoning as soon as the feed- ing areas became restricted by ice. Thirteen trumpeter swans affected by lead poisoning were found by Dr. Ian McT. Cowan (Tener 1948:12) in Feb- ruary of 1943 on Vancouver Island, Brit- ish Columbia. However, only a very few ducks have been found ill from lead poi- soning in that province (E. W. Taylor, letter, March 22, 1954). In regard to lead poisoning in Wash- ington, Henry A. Hansen (letter, Febru- ary 26, 1955) wrote: "It has been a rare and isolated case that weak or dead ducks have been found to have lead shot in their gizzards in this state since we organized the waterfowl research project in 1947. In no instance have we found a trouble spot that might require remedial action." Chester E. Kebbe (letter, April 21, 1955) reported that, although an out- break of lead poisoning had not been no- ticed in Oregon, he believed that research would reveal large numbers of waterfowl dying each vear from ingested shot. Rich- ard E. Griffith (letter, May 17, 1955) reported that records at the Malheur Na- tional Wildlife Refuge in southwestern Oregon indicated that there had been no losses from this malady in the previous 7 years. A few waterfowl, mostly diving ducks, were victims of lead poisoning at that refuge in 1942. C. Vic Oglesby (letter, March 31, 1955) reported: "There have been no major die-of¥s nor any approaching even moderate die-offs in Nevada within the past 10 years. A very few birds, primarily shovelers, fall victim to lead poisoning each fall on the Stillwater Wildlife Man- agement Area located near Fallon, Ne- vada. This is our largest public hunting area and bears the bulk of the waterfowl shooters within the state." In Arizona, no losses of waterfowl from lead poisoning have been reported during the past 10 years, according to Wesley B. Fleming (letter, February 8, 1955). Undoubtedly not all the outbreaks of lead poisoning among waterfowl during the past decade have been reported. How- ever, it is believed that outbreaks dis- cussed in this paper include the most im- portant die-offs from lead poisoning, and that these outbreaks represent a cross sec- tion of such conditions in the United States. Today there are only a few places in this country where 1,000 or more ducks might succumb from lead poisoning and not be noticed. Past experience shows that the public becomes alarmed when large numbers of dead ducks are observed and that it reports such events to conser- vation authorities or the press. Moreover, waterfowl are prone to con- centrate in and around refuges; refuge personnel would be among the first to be- come aware of and report any unusual waterfowl mortality. Since the early 1930's, there have been numerous federal refuges, manned with technically trained personnel, well distributed throughout the four flyways. In addition to the waterfowl die-o£fs that attract public attention, there are the scattered day-to-day losses that pass unnoticed. These day-to-day losses are ex- tensive ; their magnitude is explored later in this paper on the basis of the incidence of ingested shot in waterfowl populations and the toxicity of various doses of lead shot. Lead poisoning outbreaks have occurred more commonly in the Mississippi Flyway than in all the other flyways combined. In both the Mississippi and Central fly- ways, mallards have been the principal victims in all but a few die-ofFs. A rough estimation of the annual rate of loss of mallards in outbreaks of lead poisoning in the Mississippi Flyway is 1 per cent. Frequency of Die-OflFs Some areas have outbreaks of lead poi- soning in waterfowl rarely, some occa- 246 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 sionally, and others with rather consistent frequency. For example, in Illinois there has been but one outbreak of lead poison- ing, near Henry in 18 years; near Grafton there have been two outbreaks in 12 years; at the Chautauqua National Wildlife Refuge there have been outbreaks in 10 of the last 13 years. The frequency and magnitude of lead poisoning outbreaks in a particular area are influenced largely by the following fac- tors: the size of late fall and winter popu- lations of mallards and other species of ducks with similar feeding habits ; the kind and amount of food available; the amount of lead shot present as a result of shooting pressure; the availability of shot, determined by bottom conditions, water levels, and ice cover. One reason that the Chautauqua Na- tional Wildlife Refuge area has been the scene of many outbreaks of lead poisoning in waterfowl is that generally 100,000 to 400,000 mallards winter there, making it usually the area of largest winter concen- tration in Illinois. Another reason is that nearby Quiver Creek, which remains partly open during the coldest weather, at- tracts a large proportion of the wintering population to its shot-laden stream bed. Water levels, food, and a lack of ice cover combined to cause the exceptionally large die-off of 5,000 mallards in the Chautauqua area during the winter of 1956-57. A rise in water resulted in the flooding of millet and smartweed beds adjacent to the refuge shortly after the hunting season closed. This area had been heavily shot over, and mallards congre- gated there for a week before a freeze-up forced them to leave. Most of them moved to Quiver Creek. Two to 3 weeks later, mallards in the Quiver Creek area com- menced dying by the hundreds. Other areas in the Mississippi Flj'way where there have been consistently fre- quent outbreaks of lead poisoning include Catahoula Lake, Louisiana, 4 out of 6 years; Claypool Reservoir, Arkansas, 3 out of 8 years; and Squaw Creek Na- tional Wildlife Refuge, Missouri, 8 out of 13 years. Seasons of Die-OflFs As shown by data in table 1, most wa- terfowl die-offs from lead poisoning have occurred during the late fall and early winter months, after the close of the hunting season. Only a very few die-ofts have been noted during the hunting sea- son, even though in the southern zone the season has usually extended to Janu- ary 10 or 15. Two large outbreaks have been reported during the hunting season: One of these occurred at Catahoula Lake, Louisiana, during the last two weeks of November and the first week of Decem- ber in 1950; the other took place in the Claypool Reservoir area of Arkansas be- tween mid-December of 1953 and early February of 1954. Outbreaks of lead poisoning are un- usual during the early fall months. Hunter activity keeps ducks out of heavily gunned areas where shot pellets are most heavily deposited, and, as shown later, a sizable number of the ducks suffering from the effects of lead poisoning are shot by hunters. Outbreaks of lead poisoning seldom have been noted among waterfowl during the spring. Principal losses at this season have been among swans and geese. Whis- tling swans have been recorded as dying during the spring at Green Bay, Wiscon- sin, and on the Shiawassee National Wild- life Refuge, Michigan, table 1. A die-olif of Canada geese took place in April, 1954, at Lake Puckaway, Wisconsin. In Nebras- ka, losses of blue geese and snow geese have occurred for a number of years dur- ing March and April. Greater scaups were reported by Van Tyne (1929:103- 4) as dying at Houghton Lake, Michigan, during April, 1928. In the spring of 1921 near Florence, Louisiana, many ducks died from lead poisoning, according to Albert Bonin, quoted in an unpub- lished report by E. R. Kalmbach. There are no records to indicate that in recent years wild waterfowl have died from lead poisoning during the summer months. However, Wetmore (1919:2) stated that during the summers of 1915 and 1916 he handled many ducks af- fected by lead poisoning in the Bear River Delta of Great Salt Lake, Utah. In spite of numerous and intensive investigations on botulism and other waterfowl problems at the Bear River Migratory Bird Refuge, lead poisoning losses have not been re- corded there during the summer since May, 1959 Bellrose: Lead Poisoning in Waterfowl 247 Wetmore (1919) reported on his field work of 1915 and 1916. Species AflFected by Die-Offs Individuals of most species of water- fowl have been recorded at one time or another as victims of lead poisoning. In addition to those species listed in table 1, the following species have been reported as victims: trumpeter swan, white-fronted goose {Jtiser albifrons) , gadwall {Anas strepera) , baldpate {Mareca americana) , blue-winged teal {Anas discors) , cinna- mon teal {Anas cyanoptera) , shoveler {Spatula clypeata), canvasback, greater scaup, common goldeneye {Bucephala clangula) , and ruddy duck {Oxyura ja- maicensis) . The largest number of spe- cies reported from any one area was found by Donald D. McLean (unpublished re- port, California Department of Fish and Game) in the San Francisco and Suisun Bay areas of California. He reported 257 pintails, 45 shovelers, 15 baldpates, 13 green-winged teals {Anas carolinensis) , 7 mallards, 2 lesser Canada geese, 1 cin- namon teal, and 1 canvasback in a group of waterfowl which had succumbed from lead poisoning. Although individuals of many species have died from lead poisoning, it is evi- dent that the mallard has been the prin- cipal victim in outbreaks of lead poison- ing across the nation, table 1. In the Pa- cific Flyway the pintail has made up the largest number of victims. In the Missis- sippi Flj'way, however, where mallards and pintails have frequented the same areas, mallard losses have been propor- tionately greater, table 1. Die-offs of the Canada goose, blue goose, and snow goose have been reported for several places, table 1, but losses in these die-offs have been comparatively small. An investigation of a lead poisoning outbreak at L atahoula Lake, Louisiana, in January of 1953 pointed up important differences in the mortality rates of spe- cies. During the period of the outbreak, the waterfowl population was composed of 30,000 pintails, 25,000 mallards, 5,000 green-winged teals, and small numbers of a few other species. Although pintails outnumbered mallards in the population, 5,500 mallards and 1,000 pintails were estimated to have died from lead poison- ing. In a 3-day period, 243 mallards and only 26 pintails were picked up. Not a single dead or incapacitated green-winged teal was found. From these observations, it was de- duced that the habits of the several species of ducks were such as to account for the different mortality rates. Observations of tile feeding ducks plus unpublished food habits studies of ducks at Catahoula Lake by Richard K. Yancey of the Louisiana Wild Life and Fisheries Commission sug- gested that both feeding traits and food preferences were involved. Ducks of all three species, mallard, pintail, and green- winged teal, were feeding extensively in flooded beds of chufa {Cyperus escnlen- tus), but mallards were puddling more commonly into the bottom for tubers of this plant than were pintails, which were probably feeding more commonly on the floating seeds. Green-winged teals ap- peared to be feeding almost entirely on floating seeds. Apparently, in puddling into the bot- tom mud, mallards came into contact with the lead shot more frequently than did pintails, and pintails more frequently than did green-winged teals. The form of the food they consumed undoubtedly influ- enced mortality among those ducks ingest- ing shot. Jordan & Bellrose (1951:18) reported that ducks that fed on small seeds were less affected by ingested lead than were those that fed on corn. The tubers of chufa and the kernels of corn appear to have similar physical proper- ties and they may be expected to have similar effects. Incidence of Lead Shot in Die-Offs Biologists investigating outbreaks of lead poisoning among waterfowl in the Mississippi Flyway, 1938-1955, exam- ined samples of dead and dying mallards for ingested shot, tables 2 and 3. Al- though 10.4 per cent of the drakes, table 2, and 13.0 per cent of the hens, table 3, found in the outbreaks carried no shot in their gizzards, most, if not all, of these were lead-poisoned victims. James S. Jordan (unpublished report) found in controlled experiments with captive mal- lards that 21 per cent of those dosed with one to four No. 6 shot pellets had no pel- lets in their gizzards at time of dearh. 248 Illinois Natural History Survey Bulletin Vol. 27, Art. ^ Table 2.—Incidence of various ingested shot levels found among drake mallards picked up level is meant the number of ingested lead shot pellets found in a gizzard.) For each state are Mav, 1959 Bellrose: Lead Poisoning in Waterfowl 249 in a dead or moribund condition in lead poisoning die-offs in six states, 1938-1955. (By shot given the number and per cent of drakes represented at each shot level. 6 Pellets 250 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 bagged is five; if every shell were of 12 gauge and contained No. 6 shot, then about 1,400 shot pellets would be depos- ited for every duck bagged. In Illinois, the annual kill at some pub- lic shooting grounds has been as high as six ducks per acre, but for all Illinois duck hunting areas over a period of years the kill has averaged about one and one- half ducks per acre per year. The amount of lead shot deposited in Illinois River valley lakes is calculated to be approxi- mately 2,100 pellets per acre per year. Because of the scattered distribution of blinds, many acres of waterfowl habitat are untouched by spent shot, while small areas near blinds have an annual deposi- tion of shot many times as great as the calculated average for the larger acreage of which they are a part. Most blinds are located on or adjacent to the best water- fowl feeding grounds. In such situations, waterfowl are more likely to pick up shot in their feeding activities than if the blinds, and therefore the pellets, were more evenly distributed. LU O cr UJ CL NUMBER OF SHOT PELLETS Fig. 3.—Incidence of various levels of ingested lead shot found in gizzards of drake mallards picked up in a dead or moribund condition in each of four areas in which lead poisoning die-offs occurred, 1941-1954. Data, except those for Illinois, are from table 2. May, 1959 Bellrose: Lead Poisoning in Waterfowl 251 A number of surveys have been made of lake and marsh bottoms in an effort to ascertain the availability of lead shot to waterfowl. Wetmore (1919:9-10), in his pioneering investigation of lead poi- soning, examined mud from two areas at the mouth of the Bear River in Utah, in one area he found no shot pellets within 30 to 70 yards of a blind, but he found pellets at sampled 20-yard intervals from 70 yards to as far as 210 yards from the shooting point. He found most pellets at a distance of 130 yards, where he recov- ered 1 to 12 in each sieve filled with mud. In the other area, Wetmore found 1 to 13 pellets at each sampling point; most of the pellets had penetrated through 10 to 12 inches of a soft upper layer of mud to a lower layer of hardened clay. More recent studies, table 4, show the concentrations of lead pellets in bottom samples, most of them taken without spe- cific orientation to shooting blinds. The bottom material sampled varied in thick- ness from 2 to 10 inches. The greatest concentration of lead shot that has been reported was at Lake Puck- away, Wisconsin, table 4. Hartmeister Si Hansen (1949:18-22), after investigat- ing three Wisconsin shooting areas, re- Table 4.—Number of lead shot pellets per square foot and per acre found in samples of the bottom soils of various lakes and marshes used extensively by waterfowl in North America. The bottom samples varied from approximately one-half inch to 10 inches in thickness.* State California. Minnesota. Wisconsin. Manitoba. Michigan. Indiana. . . Illinois. Area Sacramento Valley North Bay, San Francisco. Suisun Bay Delta . . South Bay, San Francisco . San Joaquin Valley South Coast Lakes on Carlos Avery Refuge Lakes adjacent to Carlos Avery Refuge Rice Lake Rush Lake Heron Lake 24 Lakes Lake Puckaway. Clam Lake Horicon Marsh. Portage Creek, Delta Marsh Cadham Point, Delta Marsh Saginaw Bay Maumee Bay Willow Slough Quiver Lake Moscow Bay 1939, 1940 Springs 1939-1940 Winter 252 Illinois Natural History Survey Bulletin Vol. 27. Art. ^ ported 2.71 pellets per square foot (equiv- alent to 118,048 pellets per acre) at Lake Puckaway, less than half as many pellets per square foot at Clam Lake, and a "neg- ligible amount of lead shot available to waterfowl" on Horicon Marsh. Lake Puckaway, they reported, has a bottom of sand and gravel covered by a thin layer of vegetable matter 1 to 6 inches in depth. Clam Lake has a similar bottom. The dif- ference between the areas in number of pellets per square foot may reflect differ- ences in hunting pressure. Hartmeister & Hansen (1949:19) con- cluded: "Sampling on Horicon marsh re- vealed a practically negligible amount of lead shot available to waterfowl, in spite of the fact that this area is probably as heavily hunted as any lake or marsh in the state of Wisconsin. Obviously, lead shot are soon made unavailable to water- fowl where deep layers of muck and peat are present." Bottom samples were taken at the Car- los Avery Refuge in Minnesota 5 years after it had been closed to shooting; yet shot pellets were about as numerous there as in adjacent lakes that were hunted dur- ing the 5-year period (unpublished Min- nesota report cited in table 4 footnote). At Rush Lake, a mud-bottomed water area, no lead shot was found in samples taken 15 years after it had been closed to hunting. The highest concentration of lead shot found in the Minnesota lakes sampled was at Heron Lake, which has a hard clay bottom and had been heavily shot over, table 4. Bottom samples taken at Willow Slough in Indiana by Dale N. Martin (1957:113) revealed about the same con- centration of lead shot pellets on October 17, 1956, as on April 26, 1956, table 4. Apparently, during the 6-month period the shot had not settled deeper into the bottom. The bottom area sampled was composed of one-half to 1.5 inches of silt and plant debris over firm sand. In California waterfowl areas, Donald D. McLean (unpublished report cited in table 4 footnote) took bottom samples at levels of 0-2 inches, 4-6 inches, and 8-10 inches below the surface of the bottom. At these three levels he found 61 per cent of the shot in the top layer, 30 per cent in the middle layer, and 9 per cent in the lowest layer. There was a noticeable dif- ference between places; areas with hard bottoms had most of the shot pellets at depths of less than 6 inches while areas with soft bottoms had a greater propor- tion of shot deeper in the soil. McLean reported that at the Bolsa Chica Club, in southern California, there was a heavy concentration of shot lying on hardpan under 5.5 inches of soft mud. Both Portage Creek and Cadham Point in the Delta Marsh of Manitoba are tra- ditional shooting sites. Portage Creek re- ceives much heavier shooting pressure than does Cadham Point, and shot pellets were more numerous there, table 4. In view of the soft mud bottoms of both areas, the amount of shot found was sur- prisingly high. George K. Brakhage stated in an unpublished report cited in a table 4 footnote that the highest concen- trations of shot in the Cadham Point area were along those transects nearest the de- coy placement. In Michigan, Herbert J. Miller stated in an unpublished report cited in a table 4 footnote that at Mau- mee Bay shot pellets were twice as nu- merous in areas protected from severe wave action as in the exposed areas. Part of this difference may have resulted from differences in shooting pressure, but Miller believed that the wave action and cur- rents were largely responsible in that they covered much of the lead with sediment. Bottom samples taken during the sum- mer of 1950 from two heavily shot-over lakes in the Illinois River valley showed few lead shot pellets, table 4 ; samples were taken from the top 2 inches of the bottoms of these lakes. Undoubtedly only a small amount of lead shot was found because the expended shot sank in the soft mud and during spring floods was covered by a laj^er of silt. A study on the silting of Lake Chautauqua (Stall & Mel- sted 1951:10), an Illinois River valley lake, showed an average annual silt accu- mulation of no acre-feet in a basin of 3,562 acres. In water areas with silt or peat bot- J toms, there is, apparently, only a slight i carry-over of lead shot (within the soil depths at which most ducks search for food) from one season to the next. Lead shot is, therefore, most readily available to waterfowl in the fall and winter, dur- May, 1959 Bellrose: Lead Poisoning in Waterfowl 253 ing and immediately following the hunt- ing season. High water levels during the spring over much of the fall waterfowl habitat, which includes most shooting grounds, greatly diminish the availabil- ity of lead shot. Most breeding grounds are lightly hunted ; therefore, waterfowl are only slightly exposed to lead shot dur- ing the breeding season. As part of a study on lead shot in mud- bottomed lakes, an experiment was con- ducted by the writer at Quiver Lake, in The data in table 5 show that the smaller the shot size, the smaller the amount of recovered lead. Evidently wave action dislodged quantities of shot pel- lets, especially 7i/2's, and scattered them outside the pipes. From the distribution of the remaining pellets, there was, with the exception of 7'/2's on the moderately firm bottom, evidence that the larger the size, the more prone the pellets were to sink in the bottom soil. In the soft bot- tom soil, most of the shot had settled to Table 5.—Data indicating the penetration of lead shot pellets into bottom soil of two different types at Quiver Lake, near Havana, Illinois. Figures show for each of five pipes, 8 inches in diameter, placed with upper mouth flush with lake bottom, the number of grams of shot pellets recovered at various soil depths, September 3, 1953, and the percentage of the recovered shot that was recovered at each depth. At the upper mouth of each pipe, 150 grams of shot pellets. No. 7'/2 or No. 6, had been deposited on August 13, 1952. 254 Illinois Natlral History Survey Bulletin Vol. 27, Art. 3 deep, but, in deeper water, they are prone to puddle out pockets several inches in depth. Mallards, in Illinois at least, dig deeper pockets than do pintails, but these are seldom more than 6 inches in depth. According to W^etmore (1919:3), mal- lards and pintails dig away mud to a depth of 6 to 18 inches and over an area 1 to 15 feet in diameter as they search for food. Such extensive digging on the part of ducks has been observed by the present writer only around trap sites where large numbers of birds have sifted through bot- tom soil day after day for bait. Under such circumstances, mallards have created holes as large as 2 feet in depth, 25 feet in length, and 10 feet in width. Field observations and food habits stud- ies indicate that, where underwater leafy aquatics occur, baldpates and gadwalls feed almost entirely upon these plants, seldom, if ever, sifting through bottom soils for food. Not only does the depth at which lead shot occurs in bottom soils determine its availability to different species of ducks; the depth of water above the bottom is also a factor. Species of ducks differ to some extent in preferred feeding depths. Dabbling ducks usually utilize waters less than 15 inches in depth, and diving ducks feed at depths of many feet. Among the diving ducks, redheads {Aythya atneri- cana) and ring-necked ducks {Aythya collaris) are prone to feed in shallower water than are lesser scaups and golden- eyes. When, in late fall or winter, ice fails to cover waterfowl feeding grounds that have been heavily shot over, the stage may be set for a large die-off of ducks. Ice almost invariably forms first on the shoal water of ponds, marshes, and lake mar- gins such as are commonly used by ducks for feeding and hunters for shooting. The sealing of these waters by ice makes the large quantities of shot on such areas un- available to waterfowl. At the same time it may cause the ducks to congregate in spring holes and spring-fed streams not covered by ice. If such areas have been heavily hunted, they are potential sources of large die-offs caused by lead poisoning. The extent to which the various spe- cies of waterfowl are exposed to shot pel- lets on the bottoms of marshes and lakes is influenced by the feeding habits of the birds and by the kinds of foods available, as well as by the numbers of shot pellets available. INGESTED LEAD SHOT IN MIGRATING DUCKS The incidence of ingested lead shot in migrating waterfowl populations (the percentages of ducks that carried ingested lead at the time gizzards were collected) was determined by ( 1 ) fluoroscopic ex- amination of live-trapped ducks, (2) com- pilation of data obtained from other in- vestigators who had examined waterfowl gizzards for food content, and (3) fluoro- scopic and direct examination (Bellrose 1951 : 126-7 ) of gizzards numbering many thousands that co-operating biologists had collected, especially for this study, from ducks in hunters' bags. Most of the data were from ducks migrating southward in fall and early winter. Shot in Live-Trapped Ducks During the fall months of 1948, 1949, 1950, and 1953, 5,148 mallards were live- trapped and fluoroscoped at the Chautau- qua National Wildlife Refuge, near Ha- vana, Illinois, fig. 4. Ingested lead shot was found in the gizzards of 10.14 per cent of these birds, but more than two- thirds of the gizzards with shot contained only one pellet each, table 6. Because the refuge has been closed to hunting since 1944, it is doubtful if much, or any, of the lead was picked up at the trapping site. Almost twice as many juvenile as adult male mallards carried ingested shot, table 6. The data indicate that more hens than drakes carried ingested shot, but the sam- ple on which the data are based is believed biased by an unduly large proportion of hens fluoroscoped late in the season, when the incidence of birds carrying shot was at its highest. Pintails, blue-winged teals, and wood ducks {Aix sponsa) were caught in baited traps during September at Moscow Bay, 10 miles south of Havana. Examination of these birds by fluoroscopy revealed an incidence of ingested lead that was un- usually high for these species, table 7. The high incidence may have occurred be- cause the traps were on a heavily shot- May, 1959 Bellrose: Lead Poisoning in Waterfowl 255 over area, which, combined with intensive feeding by the ducks, resulted in exposure of the birds to unusually large quantities of lead. At the trapping site, lead shot was avail- able equally to the three species, and, in September, it was unlikely that the birds were obtaining shot elsewhere. Yet, among the species, there were differences in incidence of ingested shot, table 7. Pro- portionally more pintails than wood ducks and proportionally more woodies than blue-winged teals carried ingested shot. Apparently, there is a relationship between the weight of a duck and its intake of food and lead. Perhaps under similar condi- tions of food and feeding, the duck spe- cies with the largest individuals have the highest percentages of individuals with in- gested lead shot, table 7. In two of the three species, table 7, an appreciably greater percentage of juveniles than of adults carried ingested lead shot; in the pintail there was little difference in shot incidence between age groups. In the pintail, blue-winged teal, and wood duck, there were only slight dififerences between the sexes with respect to inci- dence of shot, but, in the lesser scaup, pro- portionally twice as many drakes as hens carried ingested shot, table 7. The lesser scaups represented in table 7 were trapped on another area near Havana in April, 1953. The seasonal incidence of ingested lead shot among mallards trapped at the Chau- tauqua National Wildlife Refuge during the fall months of 1949 and 1950 is shown in table 8. Most of the mallard groups fluoroscoped early in the season had a Fig. 4.—An X-ray head and fluoroscopic screen used at the Havana laboratory of the Illinois Natural History Survey to determine the incidence of ingested lead shot in wild water- fowl trapped alive as well as in dead and moribund birds picked up in the field. Each bird was placed in the cone, which was rotated in front of the fluoroscopic screen. This procedure presented to view more than one plane of the bird's body and thereby resulted in more precise location of pellets than was possible in a single plane view. (Photograph from the Journal-Star, Peoria, Illinois.) 256 Illinois Natural History Survhy Bulletin Vol. 27, Art. ?, G It; o ^JS •- o •o >Saw a— *j I S-a V * « « w c « Qi S «> o e V o *" w o 22 w o *' 3 « <« « C "^ C St3 « B 1-1 '° «- s. £•— O a > •on CB SI'Sb*j: C8 O HE'S May, 1959 Bellrose: Lead Poisoning in Waterfowl 257 lower percentage of individuals with in- gested shot than had groups fluoroscoped later in the season. The decline in the in- cidence of ingested shot among birds fluoroscoped in the December 20—24 pe- riod may have occurred as a result of the freeze-up of the lakes a week or two be- fore, or as a result of a rapid die-of^ of lead-poisoned birds in a period of cold weather. Erratic changes in incidence of ingested shot from period to period were evidence of population changes brought about by the arrival and departure of migrating mallards that varied greatly from flight to flight in the amounts of ingested lead they carried. A few waterfowl in Illinois have been fluoroscoped in late winter or spring for evidence of ingested lead shot. Ingested shot was found in a moderate percentage of the lesser scaups examined, table 7, It was found in a very small percentage of the birds in one group of pintails; it was not found in another group of pintails nor in a sample of Canada geese, table 9. Many ducks in other states have been fluoroscoped for evidence of ingested lead shot, table 10. In Michigan, small per- centages of mallards and black ducks {Anas rubripes) were found to carry in- gested lead during the winter and spring months. Lesser scaups that were fluoro- scoped during the spring months contained no ingested shot. Examination of winter- ing ducks (most of them black ducks, can- vasbacks, lesser scaups, and redheads) by Hunt & Ewing ( 1953 :362) along the De- troit River disclosed that less than 4 per cent of 7,700 ducks fluoroscoped had lead in their gizzards. Of more than 1,000 ducks, most of them black ducks, that were fluoroscoped during the fall, winter, and spring months in New York, only a very small propor- tion carried ingested lead, table 10. Only a small proportion of mallards trapped during the winter months in South Da- kota had lead in their gizzards. Of six species of ducks fluoroscoped during the summer months in the Great Salt Lake Basin of Utah, the mallard was the only species in which a moderately large proportion of individuals carried in- gested lead, table 10. An astoundingly large proportion of the mallards, pintails, and redheads, and a smaller proportion of the blue-winged teals fluoroscoped during the summer at Delta Marsh, Manitoba, carried ingested lead shot, table 10. All of the redheads and most of the blue-winged teals and pin- tails were juveniles. The findings of Elder (1950:501) agree with Illinois data in indicating that juvenile ducks are more likely to ingest lead shot than are adults ; at Delta, over twice as large a percentage of juveniles as of adult mal- Table 8.—Periodic incidence of ingested lead shot among mallards trapped at the Chautauqua National Wildlife Refuge near Havana, Illinois, during the fall months of 1949 and 1950. Period 258 Illinois Natural History Survey Bulletin Vol. 27, Art. 3 lards were found with lead in their giz- zards, and over three times as large a per- centage of juvenile as of adult pintails carried ingested lead. On other breeding ground areas — Whitewater Lake, Manitoba, and Eye- brow Lake, Saskatchew^in—Elder (1950: 501) examined 3,300 ducks during the .summer months of 1948 and 1949 and found that less than 1 per cent of the in- dividuals of any species carried ingested lead. Undoubtedly, most breeding ground areas would show a low incidence of in- gested shot among waterfowl. The Delta ALirsh, which is one of the most heavily shot-over areas in Canada, is an excep- tion. Shot in Ducks Bagged by Hunters With the help of wildlife biologists in almost every state of the Union and some Canadian provinces, the Illinois Natural History Survey obtained data on the in- gested lead shot found in the gizzards of more than 40,000 waterfowl bagged by hunters in the autumn and earlv winter Table 9.—Incidence of ingested lead among pintails and Canada geese trapped and fluoro- scoped in Union County and pintails trapped and fluoroscoped in Henderson County, Illinois, 1952 and 1953. Species May, 1959 Bellrose: Lead Poisoning in Waterfowl 259 Fig. 5.—Shot pellets from the gizzards of wild ducks bagged by hunters. Pellets A and B were from the same gizzard. Pellet A entered the gizzard lumen from the charge that killed the bird. Pellet B had been ingested previously. Pellet A exhibits craters caused by the strik- ing of this pellet against others in passage through the shotgun barrel. Pellet B has been some- what smoothed by abrasion in the gizzard ; under magnification, the surface of this pellet shows pitting and flaking. Pellet C, another ingested pellet from another gizzard, shows surface erosion resulting from the action of digestive juices in the gizzard. months of the period 1938-1953. Lead pellets, two ingested and one not ingested, are shown somewhat magnified in fig. 5. The number of shot pellets and the spe- cies of ducks represented were known for each of 36,145 gizzards; data from these gizzards were used in an analysis of the incidence of shot among each of the prin- cipal kinds of waterfowl of North Amer- ica, table 11. Variations in Shot Incidence Among Species.—The incidence of ingested lead shot was about seven times as great among ducks as among geese, ta- ble 11. Less than 1 per cent of the (\an- ada geese and less than 3 per cent of the blues and snows were found to have lead in their gizzards; the numbers of shot pel- lets per gizzard were exceedingly low. There was a wide range in incidence of ingested shot among the different kinds of ducks, table 11. Kinds in which less than 2 per cent of the gizzards contained lead were bufflehead {Bucephala albeola) , green-winged teal, mergansers {Mergus spp.), wood duck, shoveler, and gadwall. Kinds in which lead was found in more than 2 and less than 5 per cent of the giz- zards were blue-winged teal, baldpate, and common goldeneye ; in more than 5 and less than 10 per cent, ruddy duck, mallard, black duck, and pintail ; in more than 10 per cent, canvasback, lesser scaup, redhead, and ring-necked duck. It is apparent that, with the exception of the last-named group, all of which be- long to the genus Aythya, there is no re- lationship between the incidence of shot and the phylogeny of the birds. Shillinger & Cottam (1937:402) be- lieved that ingestion of lead shot was re- lated to the availability, or lack of availa- bility, of grit, for they stated : "While lead poisoning is widely distributed throughout all sections of this country, evidence seems to indicate that it is more severe in those sections where there is a deficiency of available gravel that may serve as grit in the gizzard of the birds." Tener (1948:38) believed grit prefer- ences to be a factor influencing shot inges- tion by waterfowl. He noted that only fine sand appeared in baldpate and green- winged teal gizzards, and that a large proportion of the gizzards of these species contained no shot. He speculated that lead pellets were too large to be selected as grit by these species. If waterfowl were prone to pick up lead shot for grit, then it would seem reason- able to expect many species which pick up large-sized grit particles to have ingested more shot pellets than the numbers re- corded for them in table 11. Ducks that commonly pick up grit particles that are larger than a No. 6 shot and that show a low incidence of shot are wood duck, buf- flehead, and common goldeneye. The giz- zards of geese contain quantities of large grit particles, but the incidence of shot among geese is lower than among ducks, table 11. 260 Ii.MNOis Natural History Survey Bulletin Vol. 27, Art. 3 'U \C OO .— 1 CO OO -H CN — co-^ — coroO — "^ oo ^ ;^ vo r^ O O vC o c d 04 vnoor^irioc^-^ts ocs; 'U OOOO — OOOO^—'fO-^COOO iOoo--TfTtJ5,i Some Recent Publications of the Ilunois Natural History Survey BULLETIN Volume 26, Article 3.—Natural Availability of Oak Wilt Inocula. By E. A. Curl. June, 1955. 48 pp., frontis., 22 figs., bibliog. Volume 26, Article 4.—Efficiency and Selec- tivity of Commercial Fishing Oevicet Uaed on the Mississippi River. By William C. Starrett and Paul G. Baroickol. July, 1955. 42 pp., frontis., 17 figs., bibliog. Volume 26, Article 5.—Hill Prairies of Illi- nois. By Robert A. Evers. August, 1955. 80 pp., frontis., 28 figs., bibliog. Volume 26, Article 6.—Fusarium Disease of Gladiolus: Its Causal Agent. By Junius L. Forsberg. September, 19S5. 57 pp., frontis., 22 figs., bibliog. Volume 27, Article 1.—Ecological Life History of the Warmouth. By R. Weldon Larimore. August, 1957. 84 pp., color frontis., 27 figs., bibliog. Volume 27, Article 2.—A Century of Biological Research. By Harlow B. Mills, George C. Decker, Herbert H. Ross, J. Cedric Carter, George W. Bennett, Thomas G. Scott, James S. Ayars, Ruth R. Warrick, and Bessie B. East. December, 1958. 150 pp., 2 frontis., illus., bibliog. $1.00. CIRCULAR 32.—Pleasure With Plants. By L. R. Tehon. July, 1958. (Fifth printing, with revisions.) 32 pp., frontis., 8 figs. 42.—Bird Dogs in Sport and Conservation. By Ralph E. Yeatter. December, 1948. 64 pp., frontis., 40 figs. 45.—Housing for Wood Ducks. By Frank C. Bellrose. February, 1955. (Second print- ing, with revisions.) 47 pp., illus., bibUog. 46.—Illinois Trees: Their Diseases. By J. Cedric Carter. August, 1955. 99 pp., frontis., 93 figs. Single copies free to Illi- nois residents; 25 cents to others. 47.—Illinois Trees and Shrubs: Their Insect Enemies. By L. L. English. May, 1958. 92 pp., frontis., 59 figs., index. Single copies free to Illinois residents; 25 cents to others. BIOLOGICAL NOTES 29.—An Inventory of the Fishes of Jordan Creek, Vermilion County, Illinois. By R. Weldon Larimore, Quentin H. Pickering, and Leonard Durham. August, 1952. 26 pp., 25 figs., bibliog. 30.---Sport Fishing at Lake Chautauqua, near Havana, Illinois, in 1950 and 1951. By William C. Starrett and Perl L. McNeil, Jr. August, 1952. 31 pp., 22 figs., bibliog. 31.—Some Conservation Problems of the Great Lakes. By Harlow B. Mills. Octo- ber, 1953. (Second printing.) 14 pp., illus., bibliog. 33.—A New Technique in Control of tlkC House Fly. By Willis N. Bruce. Decem- ber, 1953. 8 pp., S figs. 34.—White-Tailed Deer Populations in Illi- nois. By Lysle R. Pietscb. June, 1954. 24 pp., 17 figs., bibliog. 35.—An Evaluation of the Red Fox. By Thomas G. Scott. July, 1955. (Second printing.) 16 pp., illus., bibliog. 36.—A Spectacular Waterfowl Migration Through Central North America. By Frank C. Bellrose. April, 1957. 24 pp., 9 figs. 37.—Continuous Mass Rearing of the Euro- pean Corn Borer in the Laboratory. By Paul Surany. May, 1957. 12 pp., 7 figs., bibliog. 38.—Ectoparasites of the Cottontail Rabbit in Lee County, Northern Illinois. By Lewis J. Stannard, Jr., and Lysle R. Pietsch. June, 1958. 20 pp., 14 figs., bibliog. 39.—A Guide to Aging of Pheasant Embryos, By Ronald F. Labisky and James F. Opsahl. 4 pp., illus., bibliog. MANUAL 3.—Fieldbook of Native Illinois Shrubs. By Leo R. Tehon. December, 1942. 307 pp., 4 color pis., 72 figs., glossary, index. $1.75. 4.—Fieldbook of Illinois Manunals. By Donald F. Hoffmeister and Carl O. Mohr. June, 1957. 233 pp., color frontis., 119 figs., glos- sary, bibliog., index. $1.75. Li*t of available publleotiona mailmd on rsquaat. Single copies of Illinois Natural History Survey publications for which no price is listed will be furnished free of charge to individuals until the supply becomes low, after which a nominal charge may be made. More than one copy of any free publication may be obtained without cost by educational institutions and official organizations within the State of Illinois; prices to others on quantity orders of these publications will be quoted upon request. Address orders and correspondence to the Chief Illinois Natural History Survey Natural Resources Building, Urbana, Illinois Payment in the form of money order or check made out to State Treasurer of Illinois, Springfield, Illinois, must accompany requests for those publications on which a price is set