familiar male castoreum than did adult females. Males re-
sponded at a greater distance, hissed for a longer period of
time, marked more frequently, and spent more time inves-
tigating the unfamiliar scent. The response by both adult
males and females was weaker to unfamiliar than to fa-
miliar female castoreum. The adult males also showed a
slightly stronger response than adult females to unfamiliar
anal gland secretion of both sexes, but the difference was
not significant (Hodgdon 1978).
The territorial function of scent mounds has been sup-
ported by data obtained from recent field experiments. In
North America, adult males had a higher response to non-
neighbor castoreum than to castoreum from neighbors or
to castoreum from their own offspring (Schulte 1998). A
similar study of the Eurasian beaver obtained similar re-
sults, as family members responded strongly to unfamiliar
scent and showed territorial behavior when confronted
with unfamiliar scent (Rosell et al. 2000). Numerous other
studies have been conducted in the past 20 years, often us-
ing field experimental techniques, to better understand the
functional role of scent marking in beavers (for reviews of
these studies see Schulte and Müller-Schwarze 1999; Rosell
and Pedersen 1999; Müller-Schwarze and Sun 2003). The
consensus from these studies is that beavers build and main-
tain scent mounds as a means of marking their territories
and that the adult male is actively involved in this activity.
Castoreum appears to be more important than anal gland
secretion in territorial marking, and castoreum from unfa-
miliar males elicits a stronger response. Whether adult male
scent marking behavior is a resource based territorial de-
fense or a mate-guarding strategy is difficult to determine
and it probably functions as both.
Alarm behaviors
Alarm behaviors are used for territorial defense and in re-
sponse to potential predators. Beavers patrol their ponds by
purposefully swimming along the perimeter, usually when
they first emerge in the evening. They actively sniff unfa-
miliar scent and slap their tails on the surface of the water
in response to unfamiliar stimuli (Wilsson 1971; Hodgdon
1978; Jenkins and Busher 1979). Tail-slapping behavior ap-
pears to be a direct response to a disturbance in the terri-
tory cued by sound, scent, or visual stimuli (fig. 24.5).
Hodgdon (1978) observed 896 tail-slapping incidents
and 1,617 individual slaps by marked beavers. Adult fe-
males were involved in 26.9% of the incidences and ac-
counted for 26.4% of the tail slaps. Adult males were in-
volved in 15.7% of incidences, but accounted for 23.5% of
the slaps. Hodgdon noted that older animals tended to slap
more than younger animals, and found that males of all age
classes slapped more per incident than females and that a
slap by either an adult male or an adult female elicited the
same response from other family members. Busher (1980)
found no difference in tail slapping between adult males
and females and reported that kits slapped more than any
other age class. Woodard (1994) also found no difference
between the adults in tail slapping and, although she did
not observe any kits involved in this behavior, she reported
that yearling and 2-year-old beavers slapped more than
adults. Buech (1987) does not separate tail slapping from
other alarm behaviors; however, he reported that adult
males allocated more time to these alarm behaviors than
adult females during all months of observation.
The behavior of patrolling a territory may be a function
of the specific habitat. Buech (1987), studying beavers liv-
ing on a large lake, did not record this as a separate behav-
ior, while Busher (1980) and Woodard (1994) did observe
it in beavers on a small stream. Adult males have been re-
ported to be more active in patrolling their territory than
adult females or any other age class, and patrolling activ-
ity generally increases with age (Busher 1980; Brady and
Svendsen 1981). Woodard (1994), while reporting that
adult males and females were similar in time allocated to
patrolling, found that yearlings and 2-year-olds were more
active in this behavior than adults. Adult males in pairs
of Eurasian beavers living on large rivers were significantly
different from adult females in the time they allocated to
travel (Sharpe and Rosell 2003). There appears to be varia-
tion in patrolling behavior, which is likely due to differences
among individual beavers, the composition of the family
group, the habitat, and the density of the population. How-
ever, adult males are at least as active as adult females in
this behavior.Other behavioral observations of male investment and care
Most data on beaver behavior are obtained while the ani-
mals are outside the rest sites during the activity period.286 Chapter Twenty-Four
Figure 24.5 An adult North American beaver (Castor canadensis), tail slapping
in response to an observer. Photograph by Peter Busher.