Tamias striatus 345and the duration (the latter by more than 50%) of these peri-
ods of torpor. Such fats are critical for maintaining phospho-
lipid membranes and preventing the depletion of body fat at
low temperatures. Although eastern chipmunks also show a
reduction in their aboveground activity in summer, it is not
known whether this is due to physiological adaptations, be-
havioral adaptations, or a combination of the two. Regardless,
it appears that food supplementation during this period has
little eff ect on activity levels.
These chipmunks frequently vocalize, and they respond
to the alarm calls of neighbors by sitting on their hind legs
and engaging in vigilance behavior. Four diff erent calls (in
the frequency range of 1–11 kHz) are produced. Experimen-
tal playback of alarm calls results in increased vigilance and
a reduction in foraging effi ciency. There are two annual
mating periods: late February to early April, and again in
late June to July. The precise time of estrus is not clear, and
estimates range from less than 1 day up to 10 days. As many
as eight males will pursue a female in estrus. Dominant
males are usually successful at mating when competitors are
few, but when numerous males are pursuing a female, sub-
ordinates often successfully mate. One male may mate sev-
eral times, and one female may mate with several males.
Gestation is 31–32 days; litter sizes are usually four to fi ve
(but as high as 15); and the young are less than 5.0 g at birth.
Both males and females disperse, although males disperse
farther from the natal area and never establish home ranges
near the mother, whereas females often do. It is suggested
that this male-biased dispersal reduces both inbreeding and
mate competition. The lifespan of T. striatus is usually 2–3
years, but it can be as long as 6 years. The eastern chipmunk
is generally solitary, except when a mother is with her
young. This species usually defends an area with a small
radius (~ 15 m) around its burrow system. Most displays,
however, are stereotypic; chases are short; and agonistic
encounters are infrequent. The eastern chipmunk is diurnal
and concentrates much of its activity in the middle of the
day. Patterns of female and male activity may diff er. Home
ranges are relatively small, but they vary seasonally, geo-
graphically, and with habitat. Home range estimates are
anywhere from as low as 0.05 ha to 0.60 ha, yet animals will
frequently take longer forays (more than 100 m) to collect
food for their larders. Eastern chipmunks are most active
around the nest. T. striatus is capable of homing up to 500 m,
although the probability of a successful return drops off at
about 200 m. Experimental manipulation of food in one
study resulted in a temporary reduction in range size, which
then returned to normal when the food was depleted. How-
ever, in a similar study, no change was detected. There is
evidence that eastern chipmunks maintain larger home
ranges in association with a greater basal area of mast-pro-
ducing trees, suggesting the possibility of these animals an-
ticipating higher food supplies.
Few defi nitive measures of the densities and demograph-
ics of T. striatus are available. In one study, demographic mea-
sures (age classes, reproductive measures, and body mass)
showed no diff erences between fragmented and uncut for-
ests, further supporting the idea that T. striatus is highly re-
silient with regard to forest management and fragmenta-
tion. However, in another study, densities were negatively
correlated with the distance from sources and with wood-
lot size, suggesting that isolation, rather than patch size, is
most important in determining this species’ distribution in
fragmented landscapes. Numerous animals prey on east-
ern chipmunks, such as hawks, owls, snakes, and a variety of
carnivorous mammals, including house cats. A diverse array
of ectoparasites is reported from T. striatus. They include at
least 2 lice, 12 ticks and mites, and 13 species of fl eas. Experi-
mental studies on a sucking louse (Hoplopleura erratica) indi-
cate that the transfer of lice occurs primarily during the mat-
ing season and is usually from male chipmunks to females.
Probably because of its frequent consumption of intermedi-
ate hosts, the eastern chipmunk is itself host to a number of
endoparasites, including 4 protozoans, 5 cestodes, 2 trema-
todes, 5 nematodes, and 1 acanthocephalan. In late summer
and autumn throughout its range, T. striatus is also frequently
infected with larvae of the botfl y (Cuterebra). However, long-
term studies of botfl y infections on chipmunks fail to show
any eff ect on the reproduction and survival of chipmunks.
The eastern chipmunk may also serve as one of several mam-
malian reservoir hosts for the human pathogen Cryptosporid-
ium parvum, as well as a host for the larvae and nymphs of Ixo-
des scapularis (= I. dammini), the tick that transmits Borrelia
burgdorferi, the cause of Lyme disease. Laboratory studies
suggest that T. striatus may also be involved in the life cycle
and ecology of the West Nile virus. Numerous fossil records
of T. striatus are available; they indicate that during cooler
periods of the Quaternary, suitable forests and the eastern
chipmunk’s distribution extended up to 600 km farther to the
southwest than they do today.general references: J. F. Anderson et al. 1985; Baack and
Switzer 2000; Bertolino 2009; Bowers 1995; Bowers and Ad-
ams-Manson 1993; Bowers et al. 1993; Bowman and Fahrig
2002; Caire and Caddell 2006; Durden 1983; Ford and Fahrig
2008; French 2000; Graham 1983; Healey and Brooks 1988;
Heff ner et al. 2001; Jaff e et al. 2005; D. I. King et al. 1998;
Lacher and Mares 1996; Lacki et al. 1984a, 1984b; A. W. Linzey
and Hammerson 2008p; Loew 1999; Mahan and Yahner 1996,
1998, 1999; J. G. A. Martin and Réale 2008; Munro et al. 2005;
Perz and Le Blancq 2001; Platt et al. 2007; Reitsma et al. 1990;
Reunanen and Grubb 2005; Schnurr, Canham, et al. 2004;