ALCES VOL. 44, 2008 KLASSEN AND REA – NOCTURNAL ACTIVITY OF MOOSE 101 WHAT DO WE KNOW ABOUT NOCTURNAL ACTIVITY OF MOOSE? Nicole A. Klassen and Roy V. Rea University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada, V2N 4Z9 ABSTRACT: Study of activity and behavior of moose (Alces alces) has generally been undertaken during daylight hours because research at night is logistically complicated. However, some believe that moose are as or more active at night than day, thus, the amount and content of research about moose activity could be considered diurnally-biased. We conducted a review of the literature to determine what is known regarding nocturnal activity of moose and found that only 2.2% of all articles published about moose activity and behavior refer to nocturnal activity. Studies designed specifically to document nocturnal activity were mostly related to moose-vehicle collisions and use of mineral licks. Recent and increased use of GPS radio-collars will provide more and easier opportunities to distinguish and analyze diurnal and nocturnal activity of moose. Such information is important to understand better a variety of aspects of moose behavior and activity including predator-prey interactions, influence of human disturbances, relationships among habitat use, thermal stress, and climate change. ALCES VOL. 44: 101-109 (2008) Key words: Activity patterns, Alces alces, behavior, crepuscular, dark, dawn, dusk, ecology, night, ungulate. There is extensive research and literature describing diurnal activity of moose (Alces alces) including foraging, movement, groom- ing, reproduction, and rearing (Franzmann & Schwartz 1998). Although certain studies have found that moose are most active during diurnal hours (Ericsson & Wallin 1996), it ap- pears little is known about the 24-h activity patterns of moose (Bubenik 1998) because few studies have been designed to evaluate nocturnal behavior. One important manage- ment concern associated with nocturnal ac- tivity of moose is vehicle collisions in North America and Scandinavia (Oosenbrug et al. 1986, Child et al. 1991, Lavsund & Sandegren 1991, Belant 1995). These authors found that moose-vehicle collisions occurred mostly at twilight and night; traffic volume does not wholly account for this pattern (Dussault et al. 2006). Although reduced visibility likely contributes to increased moose-vehicle col- lisions at night, much nocturnal activity is unrelated to moose-vehicle collisions (Best et al. 1978, Leblond et al. 2007). In New Hampshire, 3 times as many en- counters between people and moose occurred at night than in daytime at roadside salt licks (Silverberg et al. 2002). Over the course of several years, Leblond et al. (2007) found in- creased nocturnal activity by moose at roadside salt pools in Quebec. Tankersley & Gasaway (1983) also observed that moose activity at mineral licks occurred predominately around midnight with little activity occurring midday. In British Columbia, Peterson (1955) also found that there was much more nocturnal than diurnal activity at salt licks, and moose had a tendency to feed at night. As in deer (Odocoileus spp.), the nocturnal habits of moose can be implied because they possess an eye shine or tapetum lucidum, a reflective surface on the retina that helps to amplify light in dark conditions (Bubenik 1998, VerCauteren & Pipas 2003). Although certain aspects of nocturnal activity of moose have been addressed often, particularly moose-vehicle collisions that have important economic and human safety NOCTURNAL ACTIVITY OF MOOSE – KLASSEN AND REA ALCES VOL. 44, 2008 102 concerns, most studies have not considered nocturnal activity of moose specifically. How- ever, the importance of such is obvious when considering predation, thermal stress during summer (and in relation to climate change), and human influences on activity and security. In an effort to elucidate more clearly our current state of knowledge about nocturnal activity of moose, we reviewed the journal ALCES and conducted supplemental on-line searches of other peer-reviewed journals and monographs for articles pertaining to moose activity. Our primary objective was to identify the relative amount of research and knowledge concerning nocturnal activity of moose, and secondarily to identify and affirm the need for related behavioral studies. METHODS We searched the literature to determine the current state of understanding about nocturnal activity of moose. The primary sources of articles were hard copy volumes of ALCES to which we had access (Volumes 5, 8-41; 1968, 1971-2005); we manually scanned these articles. The exceptions were Volume 38 and Supplement 2 of ALCES that were available on-line (http://bolt.lakeheadu.ca/~alceswww/ alces.html); pdf articles within were analyzed with keyword searches. Additionally, we searched literature in a variety of other rel- evant journals from an on-line source (i.e., ISI Web of Science). Finally, we reviewed the summary book “Ecology and Management of the North American Moose” (Franzmann & Schwartz 1998). Other monographs such as “The North American Moose” (Peterson 1955) were also checked and cross-referenced for reference to nocturnal activity. The on- line search and book reviews were done with keyword (Boolean) searches. We developed a list of keywords based on words that could be used to identify literature pertaining to moose activity. The 14 keywords were activity, night, dark, dusk, dawn, daily, time, social, behavio(u)r, pattern, diurnal, nocturnal, morning, and evening. Using these keywords, we searched the entire text of each article in Volume 38 and Supplement 2 of AL- CES with Adobe Reader 4.0 (Adobe Systems Incorporated, San Jose, CA). We recorded all relevant keyword hits. Each part of the article that contained the keyword was reviewed to determine if it related to nocturnal activity. A visual scan of articles was conducted in each hard copy volume of ALCES. Each article title was scanned first after which we determined if that article, based on its title, was relevant to our search. If the title appeared relevant, we subsequently read the abstract; if the abstract contained relevant information, the methods section was read. Finally, we read the entire article and recorded any relevant information in point form. We became more experienced as we scanned more articles; hence, if a general theme originally led us to believe that it contained relevant information, but it failed on numerous accounts, it was considered irrelevant. The logistical process we used to conduct our review is illustrated in Figure 1. The on-line search using the ISI Web of Science (http://isiknowledge.com; accessed November-December 2006, January 2007, and March 2007) consisted of using the previ- ously mentioned keywords in conjunction with moose, ungulate, or cervid. We recorded the number of successful hits and scanned each article title. If the title appeared relevant to nocturnal activity, the abstract was scanned and we recorded relevant information; the entire article was not read. The working assumption was that if the activity patterns of moose were discussed in any great detail, it would appear within the abstract of the article. The total number of moose articles found was estimated by first searching ‘moose’ in all of the fields, and then randomly selecting the top article from each results page (10 articles/page) to determine the percentage of articles that were specifically related to moose and not other ungulates. We then applied this percentage ALCES VOL. 44, 2008 KLASSEN AND REA – NOCTURNAL ACTIVITY OF MOOSE 103 as a correction factor to determine the total number of moose-related articles on the ISI Web of Science. We were unconcerned about overlap with our search in ALCES because the ISI Web of Science did not search ALCES. Finally, we reviewed “The Ecology and Management of the North American Moose” (Franzmann & Schwartz 1998) and “The North American Moose” (Peterson 1955). The indices of these books were searched us- ing the previously mentioned keywords. We scanned the chapter topics and read specific Fig. 1. Overview of the search strategy employed to identify articles documenting nocturnal activity of moose. Review Search Strategy Online Alces PDF Format Scan part of article containing keyword Enter Keywords into Search Contains info on moose activity patterns Contains no info on moose activity patterns (irrelevant) Scan Title of Article Title Irrelevant (disregard article) Title suggests relevance to moose and nocturnal activity Scan Abstract of Article Scan Title of Article General Online Search ISI web of science Alces Hard Cover Format Abstract Irrelevant (disregard) Abstract discusses moose and nocturnal activity Title suggests relevance to moose and night Scan Abstract of Article Abstract Irrelevant (disregard) Abstract suggests relevance to moose and nocturnal activity Methods discusses moose and nocturnal activity Scan Methods of Article Methods Irrelevant (disregard) Read Entire Article Article Relevant (discuss-in text) Article Irrelevant (disregard) Enter Keywords into Search Title Irrelevant (disregard article) NOCTURNAL ACTIVITY OF MOOSE – KLASSEN AND REA ALCES VOL. 44, 2008 104 chapters (i.e., Behavior, Ecology) based on their relationship to our objective. RESULTS In total, only 41 articles were identified that related to nocturnal activity of moose. We grouped the 41 articles into 5 general catego- ries; vehicle collisions, mineral lick use, daily activity, human disturbance, and reproduction (Table 1). Articles addressing vehicle colli- sions, daily activity, and human disturbance spanned the range of moose; articles about reproduction were from Eurasia and those about use of mineral licks were from North America. The 2 most common categories were daily activity (n = 17) and vehicle collisions (n = 11) (Table 1), although many “daily activity” articles referred to activity at dusk and dawn, not nocturnal activity specifically. The keyword search of the 47 pdf articles in ALCES yielded 4 relevant articles about nocturnal activity, an 8.5% rate of relevancy. Of 726 articles in the hard copy volumes of ALCES searched with the keywords, 20 were relevant to nocturnal/evening/morning moose activity, a 2.7% rate of relevancy. Using moose as the primary keyword was the most success- ful method of finding relevant articles in the ISI Web of Science search. The estimated number of moose-related articles was 1067 of which only 16 pertained to moose activity, a 1.5% rate of relevancy. Using the keyword list to search the index and table of contents of “The Ecology and Management of the North American Moose” yielded no relevant information about noc- turnal activity of moose. Scanning chapters considered relevant to moose activity also failed to identify any discussion about noc- turnal activity patterns of moose. The chapter "Incidental Mortality" (Child 1998) indicated that moose-vehicle collisions occurred most often in low light conditions, and the chapter "Behavior" (Bubenik 1998) stated that the po- sition of the sun in the sky influences activity patterns of moose. DISCUSSION Despite the evidence that moose are commonly active at night, and that nocturnal activity in winter is necessarily high due to the short diurnal period in far northern latitudes, the amount of literature we found delineating nocturnal and diurnal activity was limited. Specifically, the percentage of relevant articles about nocturnal activity in ALCES was <10%, and the Boolean search also uncovered few (16) relevant articles. When all data were averaged, the percentage of articles relevant to nocturnal activity of moose was very low, only 2.2% of all articles searched. Most assuredly, we did not identify all published information about nocturnal activity of moose because our search of ALCES ended with the 2005 volume, and not all relevant M. Sc. theses and Ph. D. dissertations were searched. However, the proportion of litera- ture delineating nocturnal activity within our search is likely representative of the broader body of literature on moose behavior and ac- tivity patterns, because we were just as likely to have missed articles on general activity as those on specific nocturnal activity. In the book “The Ecology and Manage- ment of the North American Moose” we found only limited information regarding nocturnal activity. Mention was made of moose being struck most often by vehicles at dusk and dawn (Child 1998), which appears to be a common occurrence (Fig. 2), and has received obvious attention because of the economic and hu- man safety concerns. For our purposes, we included articles outlining activity at dawn and dusk as nocturnal activity. Subsequently, the relative amount of information about true nocturnal activity of moose could be less than we report. Bubenik (1998) identified the need to understand better how endogenous rhythms of moose change seasonally. The recent, increased use of GPS radio-collars on moose should provide related information if research- ers analyze data to differentiate nocturnal ALCES VOL. 44, 2008 KLASSEN AND REA – NOCTURNAL ACTIVITY OF MOOSE 105 Category No. Articles Location Author Vehicle collisions 11 Sweden Eriksson et al. 1985 Newfoundland Oosenbrug et al. 1986 British Columbia Child et al. 1991 Alaska Del Frate and Spraker 1991 Sweden Lavsund and Sandegren 1991 Minnesota Belant 1995 New England Farrell et al. 1996 United States Hughes et al. 1996 Alaska Garrett and Conway 1999 Newfoundland Joyce and Mahoney 2001 Quebec Dussault et al. 2006 Mineral licks 6 Alaska Tankersley and Gasaway 1983 Quebec Couturier and Barrette 1988 New Hampshire Silverberg et al. 2002, 2003 British Columbia Rea et al. 2004 Quebec Leblond et al. 2007 Daily activity 17 Ontario deVos 1958 Ontario Simkin 1963 Ontario Cobus 1972 Quebec Joyal and Sherrer 1974 Alberta Best et al. 1978 Alaska Risenhoover 1986 Sweden Cederlund 1989 Alaska Gillingham and Klein 1992 Worldwide Timmerman 1992 British Columbia Demarchi and Bunnell 1995 Alaska Moen et al. 1996 Russia Roshchevsky et al. 1999 Minnesota Moen et al. 2001 Russia Zaitsev 2002 Sweden Dettki et al. 2004 Quebec Dussault et al. 2004 Norway Eriksen 2006 Human disturbance 5 Alberta Lynch 1978 Norway Anderson et al. 1996 Sweden Ericsson and Wallin 1996 Wyoming Colescott and Gillingham 1998 Manitoba Crichton 2002 Reproduction 2 Northern Asia Zheleznov and Fox 2001 Russia Bogomolova and Kurochkin 2002 Table 1. Summary of research category, location, and authors of articles identified in a general literature search of the nocturnal activity of moose. NOCTURNAL ACTIVITY OF MOOSE – KLASSEN AND REA ALCES VOL. 44, 2008 106 activity. Cederlund (1989) and Ericksen (2006) have used GPS data to illustrate quite clearly that moose are active at night. Noctur- nal activity changed seasonally, with change probably attributable to seasonal shifts in foraging strategies and rumination require- ments (Cederlund 1989). The 2 specific research topics related directly to nocturnal activity that were most prevalent in the literature were moose-vehicle collisions and use of mineral licks (Table 1, Fig. 2 and 3). Peaks in nocturnal collisions are presumably related to moose being more difficult to see at night, but also reflect that nocturnal activity is common and relatively high (Oosenbrug et al. 1986, Child et al. 1991, Lavsund and Sandgren 1991, Belant 1995, Dussault et al. 2006, Leblond et al. 2007). The high frequency of nocturnal visits to mineral licks could indicate a general activity pattern unrelated to human interactions. Further, there is a relationship between moose-vehicle col- lisions and use of roadside salt licks in many areas (e.g., New Hampshire, Silverberg et al. 2002, 2003). Presumably, the inconvenience and dif- ficulty of studying moose at night is partly responsible for the paucity of studies about nocturnal activity in the literature. Despite these logistical constraints, it is evident that an important segment of moose ecology and behavior is not well researched or understood. However, it is also evident that certain noc- turnal activity and behavior is similar across moose range. For example, use of mineral licks in North America and moose-vehicle collisions in both North America and Scan- dinavia peak around midnight (Fig. 2 and 3), but is this similar activity and behavior due to similar influences? There is much basic information related to nocturnal activity that has important con- sequences in moose management. For ex- ample, does thermal stress in summer increase nocturnal activity of moose (Dussault et al. 2004), and does proximity of thermal cover and foraging areas affect energy budgets and productivity? Will climate change and global warming influence diurnal and nocturnal activity patterns of moose? Does human hunting alter moose behavior and increase their nocturnal movements and activity (An- dersen et al. 1996, Eriksen 2006)? Do moose populations affected by large predators (e.g., Alaska) have different activity patterns than populations without large predators (e.g., northeastern United States)? Will newly ar- rived predators affect daily activity patterns of previously non-predated moose populations (e.g., Norway; Eriksen 2006)? Does darkness 00-03 03-06 06-09 09-12 12-15 15-18 18-21 21-24 Time of Day (hr) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 N um be r o f M oo se C ol lis io ns Eriksson et al. 1985 Hughes et al. 1996 (Michigan) Hughes et al. 1996 (Illinois) Maine Department of Transportation 2003 Fig. 2. Distribution of moose-vehicle collisions by 3-h intervals over a 24-h period using data reported in Scandinavia and North America (modified from Eriksson et al. 1985, Hughes et al. 1996, and Maine Department of Transportation 2003). The number of collisions indicated on the Y axis for Eriksson et al. (1985) is x 1, for the Maine Department of Transportation (2003) is x 100, and for Hughes et al. (1996) is x 1000. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time of Day (hr) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 V is its / H ou r 1980 1979 Fig. 3. The diel pattern of mineral lick visits per observation hour (reproduced from Tankersley & Gasaway 1983). ALCES VOL. 44, 2008 KLASSEN AND REA – NOCTURNAL ACTIVITY OF MOOSE 107 serve the function of protective cover against such predators (Mysterud and Ostbye 1999)? Finally, do lunar cycles, seasonal changes in daylength, and latitude influence behaviour of moose populations? We recommend that more emphasis be placed on elucidating nocturnal activity and behavior of moose. The recent use of GPS technology in radio-collars should provide the opportunity to analyze data from varied locations and moose populations. Fine-tuning GPS radio-collars to record detailed temporal and activity patterns, and observing moose with infrared technologies should aid in gath- ering such information. Monitoring captive moose in zoos, wildlife rehabilitation centers, and research facilities could also provide useful insights. 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