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Tiger Salamander
Ambystoma tigrinum
Status
No status assigned in Minnesota.
Description
This is a large Minnesota salamander with
specimens up to 13 3/4 inches long found here (Oldfield and
Moriarty, 1994). Adults are black to gray in ground color
with irregular yellow spots all over the body. These spots
vary intensively among individuals; there may be yellow spots
or the yellow pigment may take over so that the black is a
network of lines. Usually, adults have a yellow lower lip
and throat. They have 11 to 14 costal grooves and there are
four toes on the front and five on the back feet. Larvae have
bushy gills and are much paler in coloration than adults.
Subspecies
Two of the many subspecies of tiger salamander
occur in Minnesota: the Eastern Tiger Salamander (Ambystoma
tigrinum tigrinum) and the Gray Tiger Salamander (Ambystoma
tigrinum diaboli).
Range
The eastern subspecies is found throughout
the entire state of Minnesota, while A. t. diaboli has been
reported in extreme west-central Minnesota. To my knowledge,
no records of the latter subspecies have been secured in the
state and better documentation needs to be done.
Habitat
Everywhere. This species is found
in open fields, prairies, cultivated fields, pastures, forests,
and even towns. All they require is ponds, lakes, marshes
or other permanent bodies of water in which to breed.
Habits
Tiger Salamanders, although abundant, are
one of the most secretive salamanders in our state. Nearly
all of their time is spent underground in burrows of other
animals or burrows they have constructed themselves. Occasionally
they are found above ground on damp or humid nights. I did,
however, observe an adult hastily crossing a sandy road on
a hot summer day with no rainfall and one found under a rock
on a hillside while searching for milk snakes. They often
fall into window wells or are found in damp basements. The
only time they are found above ground in numbers are during
heavy spring and fall rains while they migrate to and from
overwintering sites. Tiger Salamanders breed in spring, often
before all the ice has melted from the ponds' surface. Females
may lay 100 eggs in loose masses. The larvae metamorphose
in August and September and may be smaller upon transformation
then when they were larvae. They overwinter underground in
burrows or other debris in October.
Food
Both adults and larvae alike are extremely
voracious feeders consuming anything that is smaller than
themselves. They snap quickly and sometimes use their tongue
to catch prey, but they are also very clumsy hunters. Some
larvae become cannibalistic. These have huge heads compared
to other larvae and also metamorphose faster. Some populations
of tiger salamanders are progenetic. The larvae become sexually
mature without transforming into a terrestrial adult. Adults
also secrete a milky toxin from glands on the back and tail
for defense.
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