Suchergebnisse

Context One of the welfare and ethical challenges with tracking animals is ensuring that the tracking device is removed from the animal at the conclusion of the study. However, for animals that are not readily re-trapped, the impact of devices and alternatives for their retrieval are rarely examined. Aims We compared the retention time of two types of break-away mechanisms for tracking collars deployed on mainland quokkas (Setonix brachyurus). Methods We tested a cotton thread (CT) weak-link, where the collar was cut and then a looping stitch was made to link the cut ends of the collar. We compared collar retention time of this simple mechanism with a lightweight automatic micro timed-release device (mTRD, Sirtrack). Key results Of the 17 radio collars with CT, the fates of 15 collars contributed to retention time data. Seven collars released: six fell off and were recovered 148 ± 64 (s.d.) days after deployment and another collar fell off 136 days after deployment but could not be recovered. Eight quokkas were recaptured (161 ± 109 days after deployment) and collars removed. Two quokkas were each tracked for over a year but then disappeared. Of the 11 GPS collars fitted with a mTRD, the fates of nine collars contributed to retention time data. Two released early at 16 and 29 days and were recovered. Seven fell off around the scheduled release date. There were two unknown fates. Re-trapped collared quokkas did not show evidence of injuries from wearing collars or any significant change in body mass (P = 0.442). Conclusions The timing of release for the CT weak-link was unpredictable, with a third of the collars releasing within 1 year and 7/15 lasting only about 6 months. Over two-thirds (7/9) of the GPS collars fitted with timed-release device released on schedule while 2/9 released early. Implications Tracking devices equipped with break-away mechanisms are essential for safeguarding animal welfare outcomes for species where the chance of recapture is not certain. For both break-away types examined in this study, the release timing was unpredictable and poor collar recovery rates show the importance of adding camera traps to monitor the outcomes for collared animals.

Brushtail possums (Trichosurus vulpecula) were live-trapped for two years prior to and following depopulation in two ~6-ha areas of native forest in New Zealand. The populations had recovered to 55% of the original density at one site and 40% of the original density at the other site, two years after the depopulation. The post-removal populations responded to reduced density with a higher proportion of females breeding, higher survival rate of young, and less seasonal fluctuation in body condition. The initial recolonisation was probably mainly due to surrounding animals shifting their ranges into the depopulated area, rather than long-range dispersal, which resulted in an even sex ratio in the recovering populations. The greater proportion of adult males in the post-removal populations is likely to increase sexual contact rates for females. This would enhance the dissemination of a viral-vectored biological control agent through the population, when used as part of an integrated control program.

Context The Illinois Department of Natural Resources was mandated by legislation to develop management plans for American Black Bears and needed Illinois residents' preferences for bear management strategies. Aims The aim of this article was to examine how demographics, emotions and attitudes were related to support for three American black bear management strategies (active reintroduction, natural recolonisation, having breeding populations of black bears). Researchers have repeatedly suggested that these predictors are related to support for management actions. Methods Data were obtained from a mail survey sent to two populations of stakeholder groups. A total of 896 agricultural producers completed the questionnaire (response rate = 36%); 904 hunters completed the questionnaire (response rate = 36%). Five demographic variables were used in the analyses: (1) agricultural producer; (2) hunter; (3) age; (4) sex; and (5) residence growing up. Positive and negative emotional dispositions were operationalised with eight items. General attitude toward bears was measured with four items. All three management questions were asked for 'in Illinois' and 'in my county'. Reliability analyses supported combining the psychological variables into indices for each construct. Key results Findings indicated that demographic and psychological characteristics are related to support for bear management strategies, but that these relationships are complex for a number of reasons. First, the regression beta coefficients for the demographic regression models were 'minimal' (M = 0.13), whereas the coefficients for psychological variables were 'typical' (M = 0.30). Second, not all of the demographic and psychological variables affected support for agency actions in the same way. Third, the average R2 for the three demographic models was only 16%, whereas the average R2 for the three psychological characteristics models was 53%. Conclusions Given the weak relationships between demographics and support for bear management, managers may not need to always target specific groups based on their demographics. Implications Certain situations may warrant specific messages to target audiences; weak demographic relationships suggest that managers should be cautious when using these characteristics to target communication messages to specific groups.

Context Quantifying the space use and movement patterns of animals is important to understand other aspects of a species ecology, such as habitat use and social systems. However, basic data on space use and movement patterns, and how they are influenced by biotic or abiotic factors, are lacking for many species. Aims We identified the space use and movement patterns of the central bearded dragon (Pogona vitticeps), and assessed how external factors (environmental conditions) and internal factors (sex and morphology) shape these patterns. Methods We tracked 36 P. vitticeps individuals over three seasons from 2017 to 2018. Animals carried tags with a Global Positioning Systems (GPS) device to collect spatial data and an accelerometer to collect movement data in far western New South Wales, Australia. Measurements of body morphology were taken for each individual and ambient temperatures were recorded. Space use was analysed by calculating minimum convex polygons (MCPs) and kernel density estimates (KDEs) using the spatial data. Movement data were analysed to determine whether dragons had moved during 10-min periods. Results Twenty-three out of 36 individuals held defined activity areas. Males with wider tails were most likely to be floaters (i.e. not restricted to specific areas). Evidence of floater behaviour was shown by 45% of females and 20% of males, though both sexes often roamed over distances greater than 1 km. Air temperatures strongly influenced movement rates in both sexes. Movement rate was significantly higher for males than females during late-spring, but not mid-summer, and was inversely related to head sizes and body mass during mid-summer. Interestingly, although there was no correlation observed between daily movement rates and size of MCPs calculated, the movement rates of residents were significantly different from floaters for each season. Conclusions These results confirm that wild P. vitticeps movement patterns are driven by temperature, though space-use patterns vary from previously studied agamids, with high rates of nomadism, possibly due to drought conditions. Individuals varied widely in their space-use tactics, which seem unrelated to size, a potential proxy for social status or age. Implications Our study provides baseline information on a common arid zone agamid that is lacking research in the wild. More complex studies on the ecology of P. vitticeps can build on the findings of this study.

Context Studies of distribution and habitat utilisation of sympatric animals, especially those experiencing population increases, are useful for understanding their specialised habitat niches and interspecies relationships, in addition to developing effective protection strategies. Aims As a species that lives within the range of the giant panda, the sambar population has been increasing in the past few decades in Southwest China. In this paper, we aimed to analyse the overlap in habitat area and habitat suitability between giant panda and sambar in Wolong National Nature Reserve to examine potential sympatric species competition in the context of wildlife conservation. Methods We ran MaxEnt models based on giant panda occurrence sign locations (n = 316) and sambar presence locations (n = 598). In addition, we predicted the core and secondary habitat for the two species to assess the degree of competition across a gradient of habitat conditions. Key results Our analysis detected significant habitat overlap between the two species – up to 75.96% in their potential habitat, with suitability overlap indices reaching 0.74. Conclusions These results indicate that the similarity of habitat requirements of the two species is high in our study area. In addition, the competition over space utilisation between the two species' populations could intensify in the future as the sambar population increases. Implications Our results suggest that habitat restoration and corridor construction could be recommended as conservation strategies for future wildlife conservation in China's Giant Panda National Park. Moreover, future wildlife conservation should pay greater attention to the niche overlap and interspecific competition among sympatric species. We suggest strengthening habitat restoration and corridors for all key species in the region, not just giant pandas, to alleviate the increased competition associated with niche overlap among sympatric species.

Context The lack of documentation and detailed assessment of previous sun bear (Helarctos malayanus) release programs raises concerns about bears' capacity to adapt to their new habitats and key elements of release success. Aims We evaluated the influence of the sun bears' individual profiles and environmental factors on their adaptability, and investigated their habitat use and movements in the wild. Methods We released 13 rescued sun bears (four wild-caught and nine rehabilitated) to natural habitats between December 2015 and August 2017, and inferred adaptability process by analysing their pre- and post-release data. Key results Post-release monitoring showed that sun bears required at least a month to acclimatise to their release area. No nuisance cases were reported, and bears were observed avoiding monitoring teams in a series of encounters. Principal-component analysis identified a previous history of ill health (e.g. malnutrition), low avoidance of humans prior to release and low potential of release sites as significant factors associated with poor adaptability of released bears. Rehabilitated bears also showed lower adaptability to hilly topography with an average elevation of more than 500 m. Individual profiles of adult physically fit wild-caught bears with high avoidance of humans prior to release were associated with high adaptability. Binary logistic regression indicated that habitat type was the main factor influencing bear movement. Bears had a high affinity for oil palm plantations adjacent to the forest edge. Most habitat use of released bears was close to the forest edge. Conclusions In terms of competition, predation, food availability, and adaptability, the selection of forest edges adjacent to other favourable habitats is perceived as a more opportunistic survival strategy, as long as the bears do not rely on humans to survive and endure with the natural interactions in the wild. Implications This study emphasises the importance of improving the likelihood of survival of rehabilitated bears, especially in the early release phase. Reducing human–bear interaction in rehabilitation centres by practising a buddy system and minimal human contact in captivity considerably enhances release effectiveness.

Context People and wildlife are coming into greater contact worldwide because of the increasing human footprint. Although some species tolerate certain levels of human activities, others are vulnerable to human disturbance, potentially altering their spatial or temporal patterns of activity in response to disturbance by humans. Aims We evaluated the influence of human activity on burrow activity of the Chinese pangolin, a Critically Endangered species that is heavily persecuted for subsistence and illegal trade. Methods We deployed remotely triggered camera traps at pangolin burrows located at four sites with contrasting levels of human density and infrastructure in Nepal, and estimated burrow-activity patterns of pangolins by using a kernel-density estimator based on the time stamp of camera trap observations. Key results Our findings did not suggest that anthropogenic disturbance affected pangolin burrow activity, but we acknowledge that these findings were based on a limited number of observations. Peak pangolin burrow activity was observed after midnight in three of the study sites, including those with highest and lowest levels of human activity. The fourth area, which had intermediate levels of human activity, had an earlier peak in burrow activity, possibly caused by prey deficiency owing to intense agriculture. Conclusions We suggest that pangolins may tolerate human activity because of their strictly nocturnal temporal niche, but that this tolerance has made them vulnerable to poaching because it allows them to co-exist spatially with humans. Implications Nocturnal species may be particularly prone to non-conflict-related persecution, because they may be easily accessible targets for illegal hunting activities.