Diet of Culpeo fox (Lycalopex culpaeus, Molina 1782): the role of non-native prey in a strongly seasonal environment of south-central Chile

In this study, we establish the seasonal variation of the Culpeo fox’s diet in a seasonal ecosystem of south-central Chile. By scat analyses, 21 prey taxa were identified, 16 were animal and five were plant species. Mammals (88.47%) were the main biomass contribution with small seasonal fluctuations. Plants contributed the most to the differences observed in all seasons since they showed very marked changes. We determined that the Culpeo fox inhabiting the Andes of south-central Chile feeds mainly on small non-native mammals all year round, and supplements its diet opportunistically from items whose abundance oscillates seasonally.

A refined fish consumption model for lactating Cape fur seals (Arctocephalus pusillus pusillus), based on scat analyses

A refined fish consumption model for lactating Cape fur seals in Namibia during the eight-month lactation period, which allows for spatio-temporal variation in the diet as determined by scat analyses, has been developed. Previous estimates of prey consumption by Cape fur seals have been based mostly on coarse diet composition models. Sensitivity analyses showed that the energetic requirement and mass of lactating females (bioenergetic variables), as well as the energetic density of prey (diet variable), contributed most to the uncertainty in consumption estimates. Uncertainty in the remaining input variables had minimal effects on the estimates of food consumption. The consumption of commercial prey (horse mackerel, hake and pelagic fish) was greatest by the colony at Cape Cross. The model estimated that a female of average mass 55 kg ingested, on average, 11% of her body mass per day. This model is easily applied to other age/sex classes of the seal population. It permits improvement of the estimates of prey consumption by seals, which are useful for assessing levels of competitive interactions between seals and fisheries or other predators, or the impacts of seals on prey species.

Seed Dispersal by Brown Bears, Ursus arctos, in Southeastern Alaska

Mammals often consume fleshy fruits and disperse significant quantities of the enclosed seeds. In southeastern Alaska, Brown Bears (Ursus arctos) are among the most important dispersers of seeds for the numerous plant species producing fleshy fruits, because these bears are abundant, often eat large quantities of fruit, and commonly excrete seeds in germinable condition. Scat analyses showed that Brown Bears on Chichagof Island ate increasing quantities of fruit through summer and fall. Scats commonly contained several thousand seeds, often of two or more species. Four kinds of seeds of fleshyfruited plants that normally grow in forest understory germinated at similar levels when experimentally deposited (in bear scats) in the two most common habitats (forest and muskeg), suggesting that habitat distribution of these plants is not determined simply by germination patterns. Although seed passage through bear digestive tracts and the composition of scats are known to affect germination rates to some degree, the most important role of bears in seed dispersal is probably transport.

Coyote coexistence with wolves on the Kenai Peninsula, Alaska

Coyote food habits, home range, and interactions with wolves were examined on the Kenai Peninsula, Alaska (1976–1980), to determine mechanisms of competition between the two species. Scat analyses (percent frequency occurrence) indicated coyotes relied primarily on snowshoe hare, porcupine, and small mammals. Coyote home ranges overlapped those of wolves and averaged 104.0 ± 44.6 (SE) and 70.2 ± 10.4 km2 for males and females, respectively. The ratio of coyotes to wolves captured on public roads was 10:1, while the ratio on roads closed to vehicle access was 0.71:1. Eight instances of wolves killing coyotes are reported. Lack of or minimal exploitation competition appears to allow coexistence of wolves and coyotes, while interference competition is believed to account for the difference in canid abundance near the two road types.