Mammalian Biology最新文献

Information on the presence and abundance of a species is crucial for understanding key ecological processes but also for effective protection and population management. Collecting data on cryptic species, like small mustelids, is particularly challenging and often requires the use of non-invasive methods. Despite recent progress in the development of camera trap-based devices and statistical models to estimate the abundance of unmarked individuals, their application for studying this group of mammals is still very limited. We compared direct (live-trapping) and indirect (an enclosed camera-trapping approach—the Mostela system) survey methods to estimate the population size of weasels (Mustela nivalis) inhabiting open grasslands in Northeast Poland over a period of four years. We also live-trapped voles to determine prey availability. We used a Royle–Nichols model to estimate yearly (relative) abundance from the camera-trapping data in a Bayesian framework. The total number of live-captured weasels showed a similar change over time as the relative abundance of weasels estimated using camera-trap data. Moreover, estimates of weasel abundance increased with the availability of their main prey. Our study is part of a growing body of work showing that camera traps can provide a useful non-invasive method to estimate the relative abundance of small mustelids. Moreover, a combination of data from camera traps with statistical models allowed us to track the changes in weasel number over time. This information could be very useful for the conservation of small mustelids as well as their management in regions where they are invasive.

Abstract

Tropical forests and savannahs worldwide are yielding to agribusiness, impacting biodiversity. In the southern Amazon deforestation arc, deforestation progress and limited study of extensive areas result in knowledge gaps on the impacts on biodiversity. We examined patterns of small-bodied mammal species diversity along a gradient ranging from closed-canopy to open-area savannahs, in the Guaporé river basin, Brazil. During one temporal replica—between December 2011 and October 2012—we sampled small mammals using live-traps in seven sites along three 1 km transects each. We assessed and predicted species alpha-diversity (within site), beta-diversity (unshared between sites), and zeta-diversity (shared) across the gradient, relating each biodiversity facets to the sites habitat structure, including vegetation height and above-ground biomass. From 202 individuals recorded, we uncovered 18 species in the region, whereas alpha-diversity was similar between sites, the species composition discretely shifted from non-floodable terra firme to open-areas of the transition zone southwards. Sites located at the intermediary zones of the north–south axis had lower beta-diversity contributions in comparison with northern- and southernmost sites, suggesting mixed biome influences. Zeta-diversity declined rapidly from closer sites to the more distant ones. Along the middle Guaporé basin, small mammal distribution correspondingly reflected the influence of the Cerrado and Amazon. Species presence—and cryptic diversity in terms of species not recorded yet—highlights conserving extensive habitats to accommodate diverse regional-local diversity needs, whereas both beta- and zeta-diversity patterns reveal that sites distinctiveness and multiple assemblages are required to safeguard the regional-scale diversity.

Allosuckling, the suckling of milk from a non-biological mother, occurs in some species of mammals. Allosuckling has not been quantified in baleen whale calves; therefore, we examine allosuckling in southern right whales (SRWs; Eubalaena australis) off Australia. SRWs are listed as Endangered under the Australian Environment Protection and Biodiversity Conservation Act as their numbers remain below the estimated historical abundance. On a small aggregation area, where there were three mother–calf pairs present, we aimed to quantify the proportion of time that calves allosuckled relative to the time spent filial suckling. To achieve this, we conducted unmanned aerial vehicle focal follows on mother–calf pairs and video recorded all interactions among pairs (n = 22 interactions, 3 h total observation time). During interactions, allosuckling occurred in seven interactions, and filial nursing occurred in 11 interactions. One of the calves performed allosuckling, and it was the largest calf with the largest mother. The calf allosuckled from both of the non-biological mothers present. The average proportion of time allosuckling per interaction was 4% (95% CI = ± 0.01, range = 0–0.25), whilst filial nursing for the same calf was 8% (95% CI = ± 0.02, range = 0–0.37). It is important to understand the frequency of allosuckling, and to quantify the energetic benefits for allosuckling calves and the energetic cost incurred by targeted non-biological mothers. This is particularly pertinent for capital breeders who do not replenish lost energy reserves until they migrate to their feeding grounds.

This study provides the first comprehensive assessment of habitat connectivity for the Mongolian saiga, a species endemic to Western Mongolia. We utilized a resource selection function (RSF) to identify core habitats (CHs) throughout the saiga’s entire range. Additionally, the Circuitscape approach was employed to map the least-cost paths (LCPs) among these core habitats. The RSF models revealed a strong preference for high productivity areas, while avoiding disturbed regions. Through a spatially explicit model, 34 CHs covering an area of 12,480 km² (30.7% of the saiga’s range) were identified. The connectivity models identified 68 LCPs between various pairs of CHs, totaling 1700 km in length across the entire saiga range. The core habitat in the center of the saiga range displayed the highest centrality scores, highlighting their critical importance in maintaining their habitat interconnectedness. Furthermore, the presence of pinch points was observed in several CH pairs within the northwest region, suggesting potential bottlenecks that may hinder movement between these habitats. It is imperative to implement measures aimed at addressing these pinch points and establishing secure corridors to facilitate the saiga movement between the CHs. To ensure the survival of the saiga, it is also crucial to mitigate the impact of existing and planned linear infrastructures, as well as other human disturbances that have the potential to fragment habitats and disrupt connectivity. These findings serve as valuable insights for targeted conservation efforts and the formulation of effective management strategies geared toward safeguarding this iconic species in Western Mongolia.

Golden jackal (Canis aureus) is one of the most common canid in Iran and can be found in habitats from Southeast Asia to Europe. Its rapid range expansion into Europe is indicated by the single haplotype (H1) of the mtDNA control region. H1 is the pioneer haplotype that expanded its range to Europe. Haplotypes from Turkey to Europe (western dispersal) and India (eastern dispersal) were identified before, while Iranian haplotypes are not known. Here, we completed its haplotype distribution from India to Europe by collecting samples from Iran. Results show that H1 is the most frequent Iranian haplotype compared to the five other haplotypes, and its most eastern distribution is in northeastern Iran. The phylogenetic tree and median-joining network indicate that all haplotypes are monophyletic, but Indian and Eurasian haplotypes are almost exclusive. We considered Oriental (Indian haplotypes + H13 from southeastern Iran) and Palearctic (others) haplogroups to explain haplotype distribution based on a median-joining network. The Oriental haplogroup is probably adapted to India towards southeastern Iran, while the Palearctic haplogroup is responsible for the current range expansion from Iran to Europe. The distribution and frequency of haplotypes indicate the rapid large-scale expansion, and unique haplotypes for specific geographic regions might be related to local adaptation.

Forage selection by mammalian herbivores has shown to be influenced by plant nutritional content, but the role of plant secondary compounds (PSCs) on forage selection is less well understood. Here, we studied the role of PSCs in giant panda (Ailuropoda melanoleuca) foraging strategies; examined seasonal and age class variation in PSC composition in the panda’s principal food resource, bamboo (Bashania fargesii); evaluated anti-oxidant and antibacterial effects of bamboo extract; and determined how panda’s seasonal movements and foraging patch selection which were determined by GPS collars related to patterns of PSC concentrations in bamboo. Panda’s selection of foraging sites indicated positive selection for several PSCs, including flavonoids, alkaloids, and tannins. Pandas primarily ingested bamboo leaves, as opposed other parts of the bamboo, during the time of year when many PSC concentrations were at their highest. Further, pandas prefer to forage on younger bamboo, which contains higher concentrations of alkaloids and antibacterial activity than older bamboo. As might be expected for compounds that can have positive or negative biological effects depending on dose, pandas appeared to select both for and against some PSCs depending on context. Ex situ experiments showed that flavonoids and alkaloids were influential antioxidants and tannins and alkaloids had high levels of antibacterial activity. Panda foraging sites were characterized by high anti-oxidant activity. Variation in PSC content of bamboo on the landscape may have profound effects on pandas, including parasite control, protecting against cancer, improved cardiovascular health, and disease prevention. These potential roles of PSCs should receive greater attention in ecology and conservation.

Abstract

Tiger and lion bones are valued highly on the wildlife black market. The skeletons of the two species are very similar, but the level of protection and the laws applicable to them differ. When detecting crime in the field, it can be crucial to recognize the skeletons of these two species by their morphological features. A distinguishing feature neglected in practice is the foramen ovale at the base of the skull. A total of 112 skulls were evaluated (55 tigers and 57 lions). The orientation and appearance of the foramina ovalia were analyzed on skull photographs. Significant differences were found between tigers and lions. In lions, the foramina ovalia faced laterally and their outlets were usually at least partially hidden behind the straight edge of the os basisphenoidale from the ventral view of the skull. In most adult tigers, the foramina ovalia faced more rostrally with their outlets visible and bounded by a semi-circular edge of the os basisphenoidale. However, tiger skulls exhibited higher variability in foramina ovalia orientation than lion skulls. Like other identifying features on tiger and lion skulls, the foramen ovale was unable to distinguish all skulls with 100% confidence. Nevertheless, knowledge of this structure can help considerably in species identification.

Antipredator responses could affect nutrient intake, which could lead to nutritional deficits. However, little is known about the antipredator response of small herbivores because most are nocturnal or crepuscular and therefore very difficult to study in the field. Therefore, we experimentally assessed the effect of a reactive response to predation risk on the nutrient (i.e., phosphorous) intake of the European hare (Lepus europaeus) using three different playback sounds. Additionally, we studied the time spent being costly vigilant, the time spent foraging, and the vegetation height in which the hares were present using accelerometers and GPS. Our results showed that elevated predation risk from our playback experiment did not affect the (1) phosphorus intake, (2) time spent being costly vigilant, and (3) time spent in tall vegetation. However, elevated predation risk did increase the time spent foraging. Possibly hares spent more time foraging with an increased predation risk because hares cannot seek refuge from predators. Additionally, the effect on phosphorus intake could be weak because phosphorous intake does not benefit a flight escape, while the reactive response acts late in the predation sequence limiting the effect on hare ecology. Prey anti-predator responses seem strongly related to the escape tactics of prey species that can differ between different habitats and the time of the day. More detailed field studies are necessary to get a better insight into species’ anti-predator-food tactics.