OCTOBER 1989 - City of Boulder

EASTERN COTTONTAIL
-Sy lvilaws f lor idanus
DistributionOnThe eastern cottontail is a species of the Great
Plains and eastward, and has a wider distribution than other s~ecies
of cottontails. It has a range from southern ~anida to ~enezuLla and
from the eastern seaboard of the United States to the base of the Rocky
Mountains. In Colorado, the species occurs in the northeastern comer of
the state. It has yet to be documented in Boulder County but doubtless
occurs here.
Description.--In Colorado, S. floridanus may be distinguished by
much darker pelage and larger size -ds.bonii, with which it is
sympatric. The animals are brownish to grayish on the upper parts and
white on the underside of the body and tail. mere is no redL pattern except
a distinct rusty patch on the nap of the neck.
External measurements of ten animals from Cherry County, Nebraska
were: total length, 420.3 (400-452); tail, 50-5 (41-7a hindfoot, 97.5
(83-104); ear, 55.9 (52-61); weight, 2 to 3 lbs. Greatest length of skull,
averages 72.6 (70.8-75.3); zygonmtic breadth is 36.0 (35.6-36).
Natural History.--Eastern cottontails prefer riparian communities
along major streams of the eastern plains or adjacent anricultural situations
where dense plant grovth provides good cok. his species feeds
upon a wide variety of plant species- Ln sunnner the diet is chiefly
herbaceous plants with a preference for legumes and grasses. They also
utilize stems and shoots of shrubs and woody vegetation, especially in
winter when preferred foods are dormant.
Females bear two to six litters per season with a litter size of four
to seven. Breeding periods are of one week duration separated by intervals
of about two weeks. Gestation Lase twenty six to twenty seven days and in
Missouri post-partum breeding was measured at almost one hundred percent.
As time of parturition approaches, the female digs an elliptical nest lined
with vegetation and wads of soft fur pulled from her shoulders, flanks, and
legs. The young are nursed at daM and dusk by the female who also defends
the nest from intruders. me yomg are dtricia but show rapid growth in
the first two weeks then leveling off . Mortality rate is extremely high
with seventy percent of the individuals dying before the age of five months.
Coyotes, foxes, 'weasels, hawks, owls, rattlesnakes, and numerous other
carnivores prey on these cottontails. Home ranges have been estimated in
Colorado to be from one to five acres for females although it may be as
large as fifteen. Adult males mag range as far as one hundred acres-
Eastern Cottontails are -runt game animals and it is not unconnnon
for the kill in the %I. S. to exceed one miflion animals, However,
general knowledge of the biology of this species in Colorado is poor.
Selected References.--Chagma~ et al. (1980) ; Jones -- et al. (hi press).
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