Animal Conservation最新文献

Reintroductions of threatened species is a conservation strategy utilised around the world. Unfortunately, many translocated individuals have poor rates of survival post-release. If released individuals are unable to socially integrate into wild populations, they might lose the safety of the group or fail to learn critical skills. We examined the effects of age and captivity on sociality and migration survival for the critically endangered orange-bellied parrot (Neophema chrysogaster). As part of recovery efforts, adult birds are released in spring to contribute to breeding and juveniles are released in autumn prior to migration. Historically, captive-bred adults have low rates of migration survival, whereas captive and wild juveniles survive at comparable rates. We investigated both the long-term impacts of captivity on sociality and how sociality impacted migration survival by constructing social networks and comparing captive and wild birds of different age classes. We found no differences between captive and wild birds, suggesting that released birds integrated into the population. However, juveniles were more strongly connected and demonstrated greater network stability than adults. While we found no impact of sociality on survival, our results provide evidence of different migration strategies previously described for juveniles and adults: adults depart in small groups and juveniles depart as a larger flock a few weeks later. We suggest that the low migration survival of captive-bred adults may be attributable to this cohort missing the juvenile flocking phase. These results suggest that a juvenile developmental phase may be impactful in this species for future survival.

Degradation of natural and semi-natural habitats is often initiated and facilitated by expansions in anthropogenic infrastructures. Identifying and reducing the impact of anthropogenic structures on the wildlife that these habitats support is vital for biodiversity conservation. In Iceland, the number of summer houses has increased over the past two decades, from ~10 000 to 15 000, and >7000 additional plots for summer house construction have been approved. Most of this housing infrastructure development is in the Icelandic lowlands, which support internationally important populations of several ground-nesting bird species. To explore the effects of summer house infrastructure on the distribution of ground-nesting birds, we conducted surveys at 292 points within 71 sites with varying density of houses and associated infrastructure (tracks, decking, etc). Significant reductions in abundance with increasing housing density occurred in five (Golden Plover (Pluvialis apricaria), Black-tailed Godwit (Limosa limosa), Redshank (Tringa totanus), Whimbrel (Numenius phaeopus) and Meadow pipit (Anthus pratensis)) of the seven study species, while one species (Snipe (Gallinago gallinago)) showed no change and one (Redwing (Turdus iliacus)) increased. The differences in abundance between plots with no houses and plots with high house densities (>0.5 houses ha⁻¹) ranged from 34 to 95%, despite the housing infrastructure covering only ~6% of the area of these plots. These findings suggest that even relatively low densities of anthropogenic structures in natural or semi-natural areas can have substantial impacts on wildlife in the surrounding areas and highlight the urgent need for effective planning regulations to limit the expansion of anthropogenic structures into currently undisturbed habitats, particularly in areas of high biodiversity value.

Blue whales (Balaenoptera musculus) are the largest living animal and, like other baleen whales, became endangered due to whaling. Here, we used population genomics to infer the number, distribution and other characteristics of subspecies and populations. We used the largest DNA dataset in blue whales, both in terms of genomic markers (16,661 SNPs and mtDNA) and geographic coverage (n = 276 for SNPs; n = 531 for mtDNA). We found greatest divergence among the eastern Pacific, Indo-western Pacific and Antarctic blue whales. There were indications that natural selection in different environments promoted divergence among these groupings. Within these regions, there was divergence between the eastern North and eastern South Pacific, and among the eastern Indian Ocean, the western South Pacific and the northern Indian Ocean. There was no divergence within the Antarctic. These findings are consistent with the current classification of Antarctic and Indo-western Pacific blue whales in the Southern Hemisphere as different subspecies but call into question the subspecies taxonomy of eastern Pacific blue whales. The study shows that opposite breeding seasons on either side of the equator do not necessarily inhibit connectivity across the equator, and reinforces that population structure needs to be well understood to conserve the diversity within species.

Understanding factors that influence population-level responses to emerging threats in declining species is crucial for informed conservation action. In amphibian species impacted by the chytrid fungus (Batrachochytrium dendrobatidis), a pathogen that has caused amphibian declines globally, a commonly reported pattern is that more severe population declines tend to occur at higher elevations. Previous research has suggested that this pattern could be driven by reduced environmental suitability for chytrid fungus at lower elevations. However, delayed amphibian maturation, which is common in cold, high elevation populations, could also increase vulnerability to population decline. Here, we tackle this key knowledge gap, focusing on the critically endangered corroboree frogs (Pseudophryne corroboree and P. pengilleyi), which have experienced a pattern of extirpation at higher elevations, with remnant populations persisting at lower elevations. First, we quantify the age structure of two extant low elevation P. pengilleyi populations and museum specimens (both species) collected before the emergence of chytrid fungus in Australia. Male age to maturation varied from 1 to 3 years, with the extant population with higher chytrid prevalence displaying severe age structure truncation. Second, we use population simulations to calculate elasticity values under a range of scenarios with varying ages to maturation and chytrid-associated mortality. When the population growth rate was fixed at 1, adult survival became increasingly important as age to maturation increases, particularly under a scenario of high chytrid-associated mortality. Our simulation results indicate that delayed maturation could be a previously underappreciated factor associated with an increased risk of amphibian population decline and that earlier maturation could contribute to population persistence. Our study highlights the importance of examining variation in life history traits to better understand population-level responses to novel threats and guide the development of appropriate conservation actions.

Enhancing habitat connectivity is a key strategy for conserving endangered species in anthropogenic landscapes. However, connectivity planning often overlooks the crucial energetic costs to animals of traversing complex terrains. We applied a novel approach for estimating energy costs of movement for tigers – a globally endangered species. We used those estimates to calculate landscape connectivity for these animals across the extreme altitudinal gradient of Nepal, where recent sightings of tigers at higher elevations (~3200 m) suggest an upward range expansion from the tiger-rich lowlands. To evaluate our estimates, we simulated tiger routes to higher-elevation locations and compared modeled energy costs of those ascents to those derived from a previous model calibrated with data from GPS-collared tigers in Russia. In areas below 3200 m, we found about 7.5 times greater land areas with high connectivity outside protected areas (~51 000 km²) than inside (~6800 km²). However, most of the highly connected areas below 3200 m consist of croplands (56%). Importantly, community-managed forests, which spanned the altitudinal gradient, tended to include areas with moderate levels of connectivity. Our estimates of energy costs and those from Russia showed a strong consensus (ρ = 0.70, P < 0.05), with ours better capturing the higher energy costs of traversing mountains and of very large total ascents. Our results show that while barriers to tiger movement across Nepal are ubiquitous, other effective area-based conservation measures (OECMs), like community-managed forests, can play prominent roles in promoting tiger habitat connectivity while minimizing human–tiger conflict across anthropogenic landscapes. Our results also underscore the utility of integrating first principles of energy efficiency into connectivity analyses and planning.

Personality studies are increasingly relevant and applicable to a broad range of conservation issues, including a role for selecting compatible mates in conservation breeding programs (CBPs). Choosing compatible breeding pairs is essential for maximizing reproductive success in CBPs, which provide assurance populations for species facing extinction and candidates for translocation to support wild populations. We investigated the value of caretaker-assessed personality ratings of the critically endangered ‘Alalā (Hawaiian Crow, Corvus hawaiiensis) in predicting reproductive outcomes: nest quality, fertile egg production, and hatchability in the ‘Alalā CBP. Caretakers used well-defined operational definitions to rate 22 personality traits for 69 male and 59 female ‘Alalā, achieving high inter-rater agreement (ICC ≥ 0.85) for 8 traits – aggressive, bold/fearless, fearful, imprinted/abnormal, inept, submissive, territorial, and tendency to feather pluck (a stereotypic behavior) – used in a principal components analysis to distill intercorrelated variables into three principal components. While we did not find that personality influences nest quality or hatchability (based on limiting inferences to fixed effects with high relative importance scores; ≥0.8), we found some evidence that pairs with males that were more territorial/aggressive and fearful than their mates had a higher probability of egg fertilization, but there was substantial variability in this relationship, with confidence intervals overlapping zero. These personality traits may influence pair dynamics, enhancing compatibility, may predict better pair coordination on the nest, or both. Our results highlight the ability of caretakers to successfully identify ‘Alalā personality traits and provide some support for integrating personality into the pairing process; however, further research is needed to understand the value of ‘Alalā personality as a mate selection tool. The application of similar approaches to enhance CBP performance in other taxa is promising, but will require overcoming methodological challenges surrounding the complexity of data collection and interpretation of consistency among raters.