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In human-dominated landscapes throughout the world, wildlife seek out anthropogenic foods because they are high in nutritional value and are consistently available. To investigate this mode of foraging, some researchers use stable isotope analysis to detect these animals in populations and estimate their individual diets. In this study, we develop an integrative approach to measure the proportion of corn, a C4plant, in the diets of free-ranging mammalian omnivores in C3-dominated ecosystems. We fed captive mice corn, C3plants, and meat until carbon stable isotopes (δ 13C) from each diet equilibrated in their hair. We then used carbon discrimination factors (Δ 13C; offsets between stable isotope values of consumer tissues and their foods) for mice from these feeding trials and a simple carbon stable isotope mixing model to estimate the corn-based diets of free-ranging American black bears in Wisconsin and brown bears in Slovenia. We used Δ 13C factors for mice to estimate the diets of bears because mouse models are used commonly to study mammalian diet and health, including humans and bears, and body mass has no effect on carbon discrimination factors in monogastric mammalian omnivores. In this study, we found that mice grew fastest, largest, and δ 13C values equilibrated quickest in the hair of mice fed meat versus plant-based diets, suggesting protein quantity (quality was the same) has an effect on Δ 13C. Evidence also suggests that Δ 13C did not increase with animal growth rate as all mice grew throughout the 109-day feeding trials, but isotopic equilibration occurred early while mice still were subadults and was maintained throughout their adult lives. We also found that Δ 13C was highest and most variable in the hair, serum, and liver, of mice fed a mixed diet of C3plants, supporting our mixed diet hypothesis that states that Δ 13C varies more among tissues of animals fed mixed diets than animals fed nonmixed diets because the former are composed of multiple foods, each with different macromolecular and isotopic compositions. Lastly, we found that corn may have been a more important component of bear diets in Wisconsin than previously thought (adults: x¯= 29%; x¯= 33%; subadults: x¯= 22%; x¯= 28%), and male brown bears may have fed on 50% more corn (x¯= 47% versus 31%) in autumn during a year when beechnut availability was low. In a world that is rapidly changing, it is more important than ever to develop the appropriate quantitative tools to measure the impact people have on wildlife. Here, we provide such a tool for monogastric mammalian omnivores and encourage other researchers to do the same for other taxa of interest.

Sensory enrichment has been used to improve the welfare of nocturnal and diurnal primates in captivity. This study looked at whether nocturnal and diurnal primate species would respond differently to four sensory enrichment conditions based on the differences in their natural history. Subjects were two nocturnal primates, pygmy slow lorises and douroucouli monkeys, and two diurnal primates, golden lion tamarin and black and white ruffed lemur. In general, diurnal primates were found to respond more to the olfactory, auditory, and tactile enrichment than nocturnal primates. The nocturnal primates were found to be more responsive to visual enrichment. These results may be used to suggest what types of sensory enrichment could be most effective for these species. [ABSTRACT FROM AUTHOR]

The article discusses the training of degus, rodents native to Chile, for their management in animal care programs in Unity College, Maine. Topics include natural history of degus, their dominance behaviors, their maintenance, challenges in the training such as injury to care taker and escapes, stages of training,

Most species of bears exhibit a reproductive strategy that includes a highly defined breeding season, delayed implantation, pseudopregnancy, and no postpartum estrus. Sun bears (Helarctos malayanus), a tropical lowland species, represent a potential departure from the typical ursid reproductive pattern. We studied reproductive timing in captive sun bears by examining fecal hormones and behavior of 13 female and 5 male sun bears, the entire North American population of H. m. euryspilus at the time of the study. Fecal estrogens and progestins in females did not vary by season or month, nor did fecal androgens in males. Estrus occurred in 11 of 12 months; breeding and births occurred year-round. However, birth rates were lower in the spring and higher in the fall and winter. Our study documented 1 complete pregnancy, in which delayed implantation did not occur; the delay between estrus and the progesterone rise (i.e., implantation) in the pregnant bear was similar to that seen in nonpregnant bears. All bears, whether nonpregnant or pregnant, exhibited a prolonged period of high progesterone after estrus, indicating obligate pseudopregnancy. Studbook records show that estrus can occur within 6 months after parturition; these cases were typically associated with loss of the previous cub. Our findings suggest that sun bears are unique among ursids, being polyestrous, nonseasonal breeders that do not appear to exhibit delayed implantation and that are capable of initiating estrus in the event of early loss of a cub.