Animal Conservation最新文献

Primates are declining worldwide and rapid infrastructure expansion, particularly roads, threatens their habitat. New roads fragment habitats allowing anthropogenic activities to occur in once pristine ecosystems; this is particularly impactful in tropical areas with high endemic biodiversity, as is occurring with primates in Colombia. However, temporal assessments of how roads impact local biodiversity are rare. We conducted a comprehensive assessment of the exposure of Colombian primates to roads from 1970 to 2015. Using a spatially explicit and species-specific approach, we estimated the critical road density and the critical patch size primate species can withstand before going locally extinct. Then, overlapping 15 primate species (~40% of the primate species present in Colombia) ranges with Colombia's road networks over time, we determined the road expansion scope within each habitat and consequent fragmentation. Comparing the species critical road density and patch size, we determined the degree of road exposure of each species over time and its vulnerability to local extinction. Our results show that between 1970 and 2015, there were nearly 40 000 km² where at least one species was at risk of local extinction, due to road expansion, principally in the Andean and Caribbean regions. Primates in these regions faced the greatest exposure to road impacts, with an average 16% increase in the amount of affected habitat during this period. Species in most need of conservation based on road exposure rankings are: Cebus versicolor, Aotus griseimembra, Ateles hybridus, Saguinus leucopus and Saguinus oedipus. Our study contributes to understanding road impacts on local biodiversity in one of the biodiversity hotspots across the tropics and highlights the need of infrastructure accounting for the necessary mitigation and conservation actions.

Predation and habitat deterioration are the main reasons for the strong decline of ground-nesting farmland birds such as the grey partridge Perdix perdix in Europe. Grey partridge nests and incubating females are especially vulnerable to predation. We have previously demonstrated that predator activity is much lower inside flower blocks (agri-environment schemes sown with a flower seed mix) than at their edges and that predator activity in flower blocks depends on the surrounding landscape. Here, we investigate whether these differences in predator activity translate into differences in grey partridge nest predation and assess predation patterns relative to landscape and nest site characteristics. We recorded the success of 56 nests of radio-tagged grey partridges between 2009 and 2017 in an agricultural landscape in Central Germany. We used Bayesian logistic regression to analyse the effects of nest site and landscape characteristics on nest predation on a subset of 46 nests (21 nests successful, 25 predated). Distance to the edge of the nesting habitat was the most important predictor, reducing predation probability from 66.8% at the edge to 18.5% at 85.5 m. Predation probability decreased with increasing length of habitat borders, habitat diversity and the area of permanent grasslands and fallows. Predation probability was higher further from settlements and increased with increasing woodland area in the agricultural matrix. When considering linear landscape structures, nest predation patterns matched the patterns of predator activity from our previous studies. Results suggest that the distance to the edge of the nesting habitat is most important and that nest predation may be reduced by providing sufficiently broad nesting habitats. Nest predation may further be minimized by increasing habitat diversity and coverage of extensive vegetation types and by establishing conservation measures for grey partridges further away from woodlands. These measures may also benefit other ground-nesting farmland birds.

Widely dispersed fragmented populations are a challenge to monitor because subpopulation sizes may be very small, difficult to access and time consuming to sample regularly. We use the coconut crab (Birgus latro) on Pemba, United Republic of Zanzibar as a case study for estimating highly fragmented populations and metapopulation sizes. The species is a very large terrestrial decapod threatened by exploitation and habitat alteration and now classified as vulnerable. We developed an integrated model to analyse capture-mark-recapture (CMR) data from five sites jointly with count data from 24 sites to estimate site-level densities and population sizes, predicted total population size across the Pemba archipelago, and investigated the effect of six predictors of human influence on density. We fitted separate models to test the effect of the same predictors on raw counts and individual body mass. We estimate the total population of coconut crabs on the Pemba archipelago to be c. 6700 terrestrial individuals. We show that government protection generally affects crabs positively, whereas presence of agriculture negatively affects their densities. This study highlights that time-consuming CMR data can be leveraged to estimate densities on less visited sites, and that fully protected islands are critical for maintaining relatively high population densities. Our overall population estimate suggests that Pemba still hosts a viable coconut crab population in a part of its range where the species is otherwise in steep decline.

Ex situ threatened species management has both conservation and welfare objectives and these objectives often align, but can diverge. Areas of agreement can present win-wins for achieving welfare and conservation objectives, while identifying areas of divergence is important to ensure management strategies achieve balance across objectives. We examined welfare and conservation objectives in the ex situ population of Extinct in the Wild sihek (Guam kingfisher, Todiramphus cinnamominus) by quantifying mortality rates, determining sex- and age-specific causes of mortality and identifying associated welfare domains, as well as quantifying sex- and age-specific differences in reproductive value and contributions to variation in population growth rate (λ). Females had significantly higher mortality rates than males, potentially impacting population viability and suggesting females may be more vulnerable to experiencing lower welfare than males. Mitigating causes of female mortality would therefore present a clear win-win for both welfare and conservation objectives. Both causes of mortality and contributions to variation in λ were found to differ across sex- and age-classes. In particular, nutritional and metabolic diseases tended to impact younger age-classes and these age-classes had large contributions to variation in λ. Mitigation of these diseases could therefore also present a win-win for welfare and conservation objectives. However, we also identified a potential divergence between objectives: a major cause of female mortality was reproductive disease with older aged females primarily affected, but older aged females contributed little to variation in λ and had low reproductive value. Developing mitigation strategies for reproductive disease could therefore aid welfare objectives but have little benefit for conservation objectives, suggesting careful balancing across objectives is required. Our results highlight the need to explicitly consider conservation and welfare objectives in threatened species management, in particular in the context of an increasing conservation need for ex situ population management, coupled with increasing social concern for animal welfare.

The conservation of threatened and rare species in remote areas often presents two challenges: there may be unknown populations that have not yet been documented and there is a need to identify suitable habitat to translocate individuals and help populations recover. This is the case of the reticulated giraffe (Giraffa reticulata), a species of high conservation priority for which: (a) there may be unknown populations in remote areas, and (b) detailed maps of suitable habitat available within its range are lacking. We implemented a species distribution modeling (SDM) workflow in Google Earth Engine, combining GPS telemetry data of 31 reticulated giraffe with Landsat 8 OLI, Advanced Land Observing Satellite Phased Arrayed L-band Synthetic Aperture Radar, and surface ruggedness layers to predict suitable habitat at 30-m spatial resolution across the potential range of the species. Models had high predictive power, with a mean AUC-PR of 0.88 (SD: 0.02; range: 0.86–0.91), mean sensitivity of 0.85 (SD: 0.04; range: 0.80–0.91), and mean precision was 0.81 (SD: 0.02; range: 0.79–0.83). Model predictions were also consistent with two independent validation datasets, with higher predicted suitable habitat values at known occurrence locations than at a random set of locations (P < 0.01). Our model predicted a total of 5519 km² of potentially suitable habitat in Kenya, 963 km² in Ethiopia, and 147 km² in Somalia. Our results indicate that is possible to combine moderate spatial resolution imagery with telemetry data to guide conservation programs of threatened terrestrial species. We provide a free web app where managers can visualize and interact with the 30 m resolution map to help guide future surveys to search for existing populations and to inform future reintroduction assessments. We present all analysis code as a framework that could be adapted for other species across the globe.

Translocation programmes for endangered species typically focus on a single species, but in areas where little native habitat remains, it may be necessary to translocate multiple species to the same sites. Interactions between translocated species, such as predation and competition, are among the factors that need to be considered when planning multispecies translocations. Translocation sites for aquatic species are particularly scarce in southern California, where a limited number of sites exist for historically co-occurring endangered mountain yellow-legged frogs Rana muscosa and unarmoured three-spine sticklebacks Gasterosteus aculeatus williamsoni. To determine how these species would interact if translocated to the same sites, we carried out experiments ex situ with R. muscosa tadpoles and a surrogate subspecies of stickleback (G. a. microcephalus). We found that (1) adult sticklebacks preyed on hatchling tadpoles but did not consume R. muscosa eggs or large tadpoles; (2) tadpoles did not consume stickleback eggs or disturb sticklebacks nests; and (3) both species' microhabitat use shifted slightly when the other was present. Our results suggest that these species can likely be co-managed successfully, if measures are taken to curb stickleback predation on tadpoles until the R. muscosa population is well established. Using ex situ studies to evaluate species interactions prior to translocation is an approach that could prove useful in other species recovery programmes. Multispecies translocations could make better use of available resources when habitat is limited and promote ecosystem recovery by re-establishing interactions among native species.

The Iberian lynx has shown a favourable demographic trajectory in the last decade as a result of the conservation measures adopted which are still ongoing. However, the viability of the species is still compromised by genetic factors. Here, we used the GESP software that predicts the effective population size (Ne) and inbreeding accumulation (∆f) over time in metapopulations, to find realistic scenarios that guarantee the genetic viability of this species. We proposed as genetic targets that Ne of the metapopulation (Ne_Meta) should exceed 500 in 20 generations (long term), whereas ∆f of the subpopulations (∆f_x) should not exceed 0.05 in five generations (short term). The current Iberian lynx metapopulation configuration, with the expected subpopulations sizes at carrying capacity (5 subpops.; Ne₁ = 100, Ne_2,3,4,5 = 25), does not reach the long-term goal, with a Ne_Meta ~ 150 in 20 generations. The results indicate that the long-term genetic viability of the metapopulation requires an increase in the subpopulation size of 50–200%, the creation of at least 8 new subpopulations, and migration rates close to 0.1 between neighbouring subpopulations, comprising 2165 effective individuals (ca. 1100 breeding females). In addition, a minimum migration rate of 0.05 into the smallest subpopulations of Ne = 25 (i.e. 1.25 migrants/generation) is needed to avoid excessive inbreeding accumulation (short-term goal). Larger subpopulations are preferable to several smaller subpopulations with the same number of effective individuals, even when the latter are well connected. Although these requirements seem challenging to achieve in the short-medium term, the study provides key information for informed decision making by environmental managers and policymakers. The conclusions drawn here apply to other carnivores in need of conservation.