Seasonal variation and sexual difference of home ranges by takins

Estimation of the maximum utilization area including home range and peripheral sites

There is increasing evidence that occasional utilization area (peripheral sites), in addition to typical utilization area (home range), is important for wildlife conservation and management. Here we estimated the maximum utilization area (MUA), including both typical and occasional utilization areas, based on asymptotic curves of utilization area plotted against sample size. In previous studies, these curves have conventionally been plots of cumulative utilization area versus sample size, but this cumulative method is sensitive to stochastic effects. We propose a new method based on simulation studies where outcomes of replicated simulations are averaged to reduce stochastic effects. In this averaged method, possible combinations of sample size with the same number of location data replicated from a dataset were averaged and applied to the curves of utilization area. The cumulative method resulted in a large variation of MUA estimates, depending on the start date as well as total sample size of the dataset. In the averaged method, MUA estimates were robust against changes in the start date and total sample size. The large variation of MUA estimates arose because location data on any day including the start date are affected by unpredictable effects associated with animal activity and environmental conditions. In the averaged method, replicates of sample size resulted in a reduction of temporal stochasticity, suggesting that the method stably provides reliable estimates for MUA.

Staying close to home: Ecological constraints on space use and range fidelity in a mountain ungulate

Understanding patterns of animal space use and range fidelity has important implications for species and habitat conservation. For species that live in highly seasonal environments, such as mountain goats (Oreamnos americanus), spatial use patterns are expected to vary in relation to seasonal changes in environmental conditions and sex- or age-specific selection pressures. To address hypotheses about sex, age, and seasonality influence on space-use ecology, we collected GPS location data from 263 radio-collared mountain goats (males, n = 140; females, n = 123) in coastal Alaska during 2005-2016. Location data were analyzed to derive seasonal and sex-specific fixed-kernel home range estimates and to quantify the degree of seasonal range and utilization distribution overlap. Overall, we determined that home range size was smallest during winter, expanded coincident with the onset of green-up and parturition, and was largest during summer. Home range size of males and females did not differ significantly during winter, but females had larger home ranges than males during summer, a relationship that was switched during the mating season. Pairwise comparisons involving individual females across subsequent years indicated home ranges were significantly smaller during years when they gave birth to offspring. Mountain goats exhibited a strong degree of range fidelity, and 99% (n = 138) of individual animals returned to their previous year's seasonal range with an average annual Bhattacharyya's affinity utilization distribution overlap index of 68%. Similarity of seasonal home range utilization distributions varied in relation to sex and season in some respects. Home range overlap was highest during the summer vegetation growing season, particularly among females. These findings advance our understanding about how environmental variation and sex- and age-related reproductive constraints influence space use and range fidelity among alpine ungulates. Documentation of the high degree of range fidelity among mountain goats has important conservation implications in landscapes increasingly altered by anthropogenic activities.

Locomotor activity patterns of takin (Budorcas taxicolor) in a temperate mountain region

Understanding locomotor activity patterns would reveal key information about an animal’s foraging strategy, energy budget and evolutionary adaptation. We studied the locomotor activity patterns of the takin (Budorcas taxicolor) in a temperate mountain region in China using GPS radio-collar technology from 1 July 2014 to 30 June 2015. Our research showed that takin had a bimodal crepuscular locomotor activity pattern, with an especially obvious movement peak at dusk. The takins showed significant seasonal differences in their movement rates, with the lowest movement rate in winter. The animals also showed sexual differences in their movement rates. In spring, the female movement rate was significantly higher than that of males during daytime, while during nighttime the movement rate of males was higher than that of females. The male movement rate was significantly higher than that of females in summer. The movement rate of the takins were correlated to microenvironment temperature and normalized difference vegetation index (NDVI) in each season. These findings suggest that takin could adjust locomotor activity levels adapt to reproductive requirements, temperature variation and forage variability.

Spatiotemporal occurrence of Mishmi takin Budorcas taxicolor in Dulongjiang Region, southwestern China

Here, we assessed the spatiotemporal distribution of the poorly studied Mishmi takin Budorcas taxicolor to gain a preliminary understanding of the spatiotemporal ecology of the species. We used presence data from line transects and camera-trap surveys combined with a presence-only species distribution model to identify the key factors relevant to takin distribution. Distance to residential site was the main contributing factor to the model predicting habitat suitability for takin. Mishmi takin appeared to prefer habitats far away from residential locations. Our predicted suitable habitats for takin were highly fragmented and were constrained in narrow ranges of remote mountain areas. A circular distribution curve fitted to camera events indicated that grouped takin were more active during the day and less active at night compared to solitary takin. Differences in activity patterns between takin in groups and solitaries might relate to sexual segregation and calve attendance. Our information on the distribution and habitat characteristics of the species will assist habitat management and our prediction map could guide future field surveys for locating a long-term monitoring program.