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94 IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 APRILL

An effort to remove Butler’s Garter Snake (Thamnophis butleri) from the Wisconsin list of threatened wildlife has been thwarted for the
moment.

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After a contentious battle, a little garter snake has defeated
opposition to its protection in Wisconsin — for the time

being. The Butler’s Garter Snake (Thamnophis butleri) was listed
as a Threatened Species in 1997, based on an extremely limited
range in the state, and rapid and ongoing habitat loss within that
limited range. The snake lives in remnants of wetlands and grass-
lands (mesic prairies, marshes, roadside grassy areas, and vacant
city lots) in the Milwaukee area, where it is isolated from other
members of its species, the closest of which are in Michigan and
Indiana.

These medium-sized snakes (total length = 38–51 cm) have
a shorter, narrower head, a generally thicker body, and less of a
constriction behind the head than other Wisconsin garter
snakes. Dorsal ground color is brown, black, or olive with or
without a double row of black spots between the stripes. Distinct
lateral stripes are on scale row three and adjacent rows two and
four anteriorly and most of scale rows two and three posteriorly.
Stripes vary from light yellow to a rich orange-yellow color. The
venter is green to yellow-green with dark spots along the lateral
edges.

The principal food is earthworms, but leeches are some-
times eaten as well. In captivity, they may consume fish or frogs.
In Wisconsin, they are active from mid-March through early
November, and hibernate in underground retreats, especially

crayfish burrows. Males mature in their second spring, females
in their third. Mating occurs mostly from late March to late
April. In Wisconsin, an average of nine young are born between
July and mid-September.

Many of the populations of this species have been isolated
from each other due to wetland loss and habitat fragmentation.
These snakes already have a limited range, so habitat destruction
is especially detrimental to them. Another concern is genetic
swamping by the Plains Garter Snake (T. radix); this closely
related species moves into the range of T. butleri and breeds with
them. Only a handful of populations still exhibit only the char-
acteristics of T. butleri , and most of those populations occur in
Milwaukee County, the most urbanized county in the state.

Politics and Garter Snakes
On 18 July 2006, a majority Republican faction within the
Wisconsin Legislature’s Joint Committee for Review of
Administrative Rules (JCRAR) voted along party lines to remove

The Little Snake That Could: 
Butler’s Garter Snake in Wisconsin

Howard Aprill

Wehr Nature Center, Milwaukee County Parks

Photographs by Gary S. Casper except where noted.

IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 95BUTLER’S GARTER SNAKE

�

A female Butler’s Garter Snake slithers across an access road at a cen-
tral Ozaukee County research site. Co-occurring species at this site
were Eastern Garter Snakes (Thamnophis sirtalis sirtalis) and Eastern
Milksnakes (Lampropeltis triangulum triangulum).

Butler’s Garter Snakes are sometimes killed in urban areas; this one
along a trap line in a suburban neighborhood study site in north-cen-
tral Milwaukee County appears to have had its head stomped. Usually
this behavior is displayed by young boys, and is not likely to have sig-
nificant impact on snake populations, although, in one instance, such
indiscriminate killing persuaded a concerned citizen to capture approx-
imately 300 Butler’s Garter Snakes and move them “to a safe place”
approximately 30 miles away. Such translocations probably result in
the demise of the transported individuals, but also may be responsible
for unnatural gene flow between populations or even species or the
establishment of new colonies outside the natural range.



the species from the state’s list of threatened wildlife, a move
which ignored all available science and which was at odds with
recommendations from the state’s own Department of Natural
Resources (WDNR). Whereas no official reasons were given for
this move, opinions expressed were that the snake was impeding
economic development, cost too much to protect, and support-
ers of de-listing did not believe the species was actually threat-
ened. However, no economic analyses were presented to support
the first of these contentions, no evidence that the species was
secure to support the second, and no evidence or scientific opin-
ion that would refute the findings that had led to the 1997 list-
ing to support the third. The JCRAR attached conditions to their
ruling, specifying that the species would be removed from the
Threatened Species list on 1 October 2006, unless:

a. The Department of Natural Resources (DNR) lowers its
determination of the number of sites necessary to maintain
the viability of the Butler’s Garter Snake.

b. DNR formulates a plan to mitigate further the amount of
land affected by the conservation needs associated with the
Butler’s Garter Snake.

c. DNR specifies parameters for the orderly delisting of the
Butler’s Garter Snake from the state’s threatened species list.

The hearing was highly contentious. Peter McKeever, reporting
for the Milwaukee County Conservation Coalition, noted: “To
be generous, the science was ignored and ridiculed. It was an
astounding and extraordinary demonstration of ignorance, arro-
gance, partisanship, bias, and lack of concern for the environ-
ment. It is shameful that the question of whether to de-list a
species has become a partisan issue. The seven-hour hearing was
largely a staged performance designed to satisfy a select group of
political supporters. The politics were blatant: the committee
clerk was observed exchanging hand signals with the lobbyist for
the builders during the debate on the motion under considera-
tion, à la Nero giving the thumbs up or thumbs down to gladi-
ators in the lion pit.”

On 27 September 2006, the JCRAR again took up the
proposed de-listing. Again along strict party lines, the JCRAR
approved a motion to rescind its earlier motion, and to make the
rule suspension (i.e., de-listing) effective on 30 November 2006,
unless the DNR “... updates its conservation strategy so that its
policy relating to the Butler’s Garter Snake is less burdensome
on the private property owner.”

The vote followed some compromises from DNR on the
timing and cost of reviews and surveys, and a promise to reduce
the amount of protected area for the species. However, no guid-

96 IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 APRILL

Crayfish burrows are heavily utilized by Butler’s Garter Snakes as underground retreats. These, in northeastern Waukesha County, probably are
occupied by either Devil Crayfish (Cambarus diogenes) or Prairie Crayfish (Procambarus gracilis), the two most common burrowing species in south-
eastern Wisconsin. The burrows descend to the water table, and offer snakes hibernating retreats in winter and drought refugia in summer. Butler’s
Garter Snakes appear to be especially abundant in areas of high crayfish burrow density.



IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 97BUTLER’S GARTER SNAKE

High quality habitat is typified by this floodplain habitat along Poplar Creek in northeastern Waukesha County. Diverse grasses afford patchy sun
penetration to ground level, so that snakes may cryptically bask partially hidden in clumped grasses, where they are less obvious to avian predators.
The diverse wet meadows and grassland also provide variance in root densities, making it easier for burrowing crayfish to find places to dig. In con-
trast, thick monotypic stands of invasive plant species, such as Reed Canary Grass (Phalaris arundinacea), form tall (2 m) stands of uniform stem
and root density, which do not provide basking opportunities for snakes and make digging very difficult for crayfish. The scrape in the center of
the photo is periodically inundated during floods and spring snowmelt, and is riddled with crayfish burrows.

Labial scales (those forming the “lips”) of Butler’s Garter Snakes typically have little or no black edging, as shown in this individual.



ance was forthcoming from the JCRAR as to what might be
accepted as “less burdensome,” nor why this vague requirement
should trump biological issues in maintaining the species as
viable in Wisconsin. Members of the minority made efforts to
find a compromise, and all were rejected on party line votes. In
reference to the idea of basing species protections on “burden”
instead of science, minority member Rep. Spencer Black opined:
“We can change the laws of the State of Wisconsin, but we can-
not change the laws of nature.”

Representatives of the DNR consistently defended the
principle, which is also the law, that the only basis for de-listing
a species is sound science that shows that it is no longer threat-
ened. A strong majority of the public, including the Wisconsin
Wildlife Federation, came out against the de-listing. Many
expressed worry that de-listing without any regard for the sci-
ence would set a dangerous precedent for endangered species
recovery efforts, and would jeopardize Wisconsin’s eligibility for
federal wildlife funding. Even the Milwaukee Metropolitan
Builders Association, a hitherto strong critic of protecting the
snake (which affects many of their members’ building projects),
at this time opposed the de-listing, and supported the DNR
position to revise its conservation strategy — perhaps recogniz-
ing that the loss of state protection and the consequent further
decline of snakes might lead to even stricter state or federal reg-
ulations in the future. In the face of this overwhelming support
for the snake and the Endangered Species Law, the JCRAR

majority still voted to de-list. The postponement of the de-list-
ing date was widely viewed as politically motivated, with several
Republican members up for re-election on 4 November.

98 IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 APRILL

A Butler’s Garter Snake-occupied development site in New Berlin, Wisconsin, where snakes were removed from the construction footprint. A for-
mer peat bog, adjacent habitat is being restored and managed for Butler’s Garter Snakes as part of the development agreement.

At this development site in South Milwaukee, snakes were confined to
a wetland while most of the upland habitat was developed. Here, heavy
rains have raised water levels beyond the limits of the snake fencing.
Under the existing regulations, the state has the authority to allow sites
of less than 20 acres of suitable existing Butler’s Garter Snake habitat
to be completely developed, with only voluntary snake conservation
measures. These smaller sites are considered to be less important to the
species’ long-term conservation and survival.



IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 99BUTLER’S GARTER SNAKE

Finally, on 28 November 2006, the JCRAR reconvened
and voted 7–2 to not remove the snake from the protected list.
What changed? The Republicans lost their majority in the state
Senate in the 4 November election, and therefore their majority
and co-chairmanship of the JCRAR. Any de-listing presumably
would have been swiftly reversed when the new Senate convened
in 2007.

Many landowners are hostile toward both the snake and
those who work with it, whereas others place high value on its
conservation, especially parents whose children routinely play
with this harmless urban species. Some of the stories are comi-
cal, and illustrate some of the human tensions involved with
achieving conservation in areas where land values are high. A
herpetologist I know was retained to perform snake surveys by
a private couple wanting to develop their property. The consult-
ant set up his survey traps and the landowners, distrustful of all
scientists, followed the consultant and his assistant each day,
watching their every move. One day, the consultant received a
call from his assistant, who was checking the traps that day. She
said several traps smelled strongly of mothballs, but she could-
n’t investigate too closely because the landowner was watching
like a hawk. Intrigued, the consultant sniffed the traps the next
day, and also smelled mothballs. He then ordered some com-
mercial “snake repellant,” and when it arrived — it too smelled
strongly of mothballs! Nevertheless, several Butler’s Garter
Snakes were eventually trapped on this site, and the landowners
have since attended public meetings and legislative hearings
where they accused the consultant of “planting” the snakes on
their property. Snake repellants are never mentioned.

Although the snake remains protected, the fact that the
threat of de-listing was used to force a compromise in favor of
development is troubling. The Wisconsin DNR continues to
work toward revising its protection plan, having promised to
reduce protection for the snake to favor private landowners.
They have retained the Conservation Breeding Specialist Group
(Apple Valley, Minnesota) to assist them with population viabil-
ity analyses and plan revisions.

Web Resources:
http://www.fortwayne.com/mld/newssentinel/news/local/16116112.htm
http://www.dnr.state.wi.us/org/land/er/herps/snakes/butlersgrt.htm

Butler’s Garter Snakes are still found in vacant lots in industrial and
commercial areas. In this approximately 9-acre site in west-central
Milwaukee County, 64 Butler’s Garter Snakes were trapped in two days
in early October.

To avoid and minimize “take” (a legal term meaning killing individual
snakes), construction projects may use silt fencing to prevent snakes
from moving into work areas. The fences must be placed between the
upland and wetland portions of the habitat, while snakes are hibernat-
ing in the wetlands. When snakes emerge in the spring, they are pre-
vented from dispersing into the upland habitat being developed. In this
photo, a snake exclusion fence is in the foreground, a snake survey
fence in the center, and another exclusion fence in the background,
beyond which a new storm water retention pond has been graded and
seeded. The storm water facility is designed as a “dry pond,” which will
have standing water only for brief periods and be naturally vegetated.
It therefore will continue to provide snake habitat after construction.
Currently a “no-net-loss” of snake habitat policy is in place, so many
development projects may proceed by altering and then restoring snake
habitat in this manner.

A typical adult Butler’s Garter Snake from Pewaukee, Wisconsin.




