Mountain beavers

Mountain beaver, Aplodontia rufa, a primitive rodent from northwestern North America, fed less from food bowls if the rim was scented with mink anal gland secretion, or urine from mink, bobcat, coyote, or dog. The control odors butyric acid or guinea pig urine had no effect (Epple et fl/., 1993). Mountain beaver did not respond significantly to mustelid sulfur compounds though, yet these deter other small mammals (Epple etal, 1993). 

Campbell, D. L. and Evans, J. (1989). Aversive conditioning with thiram to reduce mountain beaver damage to Douglas-fir seedlings. Northwest Science 63,70. 

Epple, G., Mason, J. R., Nolte, D. L., and Campbell, D. L. (1993). Effects of predator odors on feeding in the mountain beaver (Aplodontia rufa). Journal of Mammology 74, 715-711. 

Common beaver. Castor canadensis, 692 Mountain beaver, Aplodontia rufa, 268 Bison, Bison bison, 120 Boar, wild, Sus scrofa, 704 Buffalo, Indian, Bubalus sp., 737... 

Mountain beaver do not adapt well to food deprivation, but they can be trained to respond to a preferred food (e.g., apple). Therefore, mountain beaver can be accustomed to a feeding schedule that includes apples and then this highly preferred food is treated with stimuli or placed adjacent to test odors during test trials (Epple et al. 1993, 1995 Nolte et al. 1995a, 1995b). 

Response to food can be used as an indirect measure of prey response to predator scents. Stimuli can be placed either directly on the food or in close proximity to the food. For example, choice-tests were used to assess the avoidance of lion fecal odors by rabbits (Boag Mlotkiewicz 1994) and deer (Abbot et al. 1990). In both cases, subjects were offered a choice between treated and untreated pelleted food and relative intake was taken to reflect avoidance. Likewise, arena tests have been used to demonstrate that domestic livestock will investigate but reduce their ingestion of feed in the presence of predator odors (Pfister et al. 1990). Odors also can be applied to natural forage to assess whether target species avoid the treated plants (Sullivan et al. 1988 Calder Gorman 1991). Epple et al. (1995) monitored caching behavior to assess the response of mountain beaver to food resources associated with predator odors. 

The role of chemical communication in the social behavior of mountain beavers is mostly unknown (Brown 1985). The use of scent marks, however, was suspected because although solitary, mountain beavers often live close to conspecifics... 

Martin 1971). Further, nest sites are a valuable resource, rarely vacated voluntarily, and a vacated nest is quickly occupied by other mountain beavers (Campbell et al. 1988). 

Field observations of mountain beaver is difficult if not impossible because they are fossorial and predominately nocturnal. Therefore, Nolte et al. (1993a) created an artificial system to monitor mountain beaver activity. Each system consisted of an open cage (204 x 92 x 64 cm) with an assortment of tunnels and chambers below. Burrows were constructed of clear PVC pipe (15 cm diameter) and chambers consisted of polyethylene buckets (30 cm diameter x either 27 or 35 cm) with Plexiglas windows in the lids. Free access to food and water was provided in the open cage and aspen shavings covered the cage floor. 

Mountain beaver were introduced to the artificial burrow system by moving the nest bucket attached to their individual cage to the burrow system. Thus, each introduced mountain beaver had the option to retreat to its own nest. Introduced animals emerged into a small cage. Access between this and the larger enclosure was controlled by a sliding panel. 

Interactions between mountain beavers were observed in the morning at the beginning of the light period. Mountain beavers were introduced to the burrow system by attaching their nest buckets from individual cages as described above. Trials were concluded when animals returned to their respective nests and failed to emerge again for 15 min. Encounters were always between animals unfamiliar with each other. An intruder was never reintroduced to a system if it had previously encountered the resident animal. 

The first experiment assessed whether diet manipulations affect the repellency of a predator urine to several prey species. Four rodents served as subjects mountain beaver, house mice, deer mice and guinea pigs. Urine was collected from coyotes maintained on cantaloupe (CU) for 2 weeks and then from the same coyotes fed minced raw meat (MU) for two weeks. Test procedures were similar for all species, though food and deprivation schedules varied. On each of 2 pretreatment days, animals were given their respective foods in cups containing perforated containers with a piece of absorbent paper treated with 1 ml of tap water. On the 2 treatment days that followed, the animals were given the same foods, but the absorbent paper was treated with 1 ml of either CU or MU. Urine samples (1 ml) were pipetted onto pieces of absorbent paper placed inside small (38 mm diameter x 8 mm) perforated plastic containers. For all individuals of each species, the left-right position of CU urine samples was randomly determined on day 1, and then reversed on day 2. The data for each species was evaluated separately in a two-factor repeated measures ANOVA. In each case, urine type was the main effect, with the animals nested within urine type and the repeated measure was days. 

Diet manipulation experiments showed that the presence of meat in a donor coyote s diet increased the repellency of the urine. This result led us to hypothesize that byproducts of meat digestion in urine (e.g., sulfur compounds) might contribute to aversiveness. To test this hypothesis, we removed sulfur-containing substances from MU by precipitation with mercuric chloride. The responses of mountain beaver to urine stimuli with and without sulfur compounds were then... 

Campbell, D.L., J.D. Ocheltree M.G. Carey. 1988. Adaptation of mountain beaver (Aplodontia rufa) to removal of underground nests. Northw. Sci. 62 75. 

Epple, G., J.R. Mason, E. Aronov, D.L. Nolte, R.A. Hartz, R. Kaloostian, D.L. Campbell A.B. Smith. 1995. Foraging responses to natural and synthetic predator cues in Aplodontia rufa, the North American mountain beaver. Ecol. Appl. 5 1163-1170. 

Martin, P. 1971. Movements and activities of the mountain beaver Aplodontia rufa. J. Mammal. 52 717-723. 

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