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Tracking data highlight the importance of human-induced mortality for large migratory birds at a flyway scale

Human-induced direct mortality affects huge numbers of birds each year, threatening hundreds of species worldwide. Tracking technologies can be an important tool to investigate temporal and spatial patterns of bird mortality as well as their drivers. We compiled 1704 mortality records from tracking studies across the African-Eurasian flyway for 45 species, including raptors, storks, and cranes, covering the period from 2003 to 2021. Our results show a higher frequency of human-induced causes of mortality than natural causes across taxonomic groups, geographical areas, and age classes. Moreover, we found that the frequency of human-induced mortality remained stable over the study period. From the human-induced mortality events with a known cause (n = 637), three main causes were identified: electrocution (40.5 %), illegal killing (21.7 %), and poisoning (16.3 %). Additionally, combined energy infrastructure-related mortality (i.e., electrocution, power line collision, and wind-farm collision) represented 49 % of all human-induced mortality events. Using a random forest model, the main predictors of human-induced mortality were found to be taxonomic group, geographic location (latitude and longitude), and human footprint index value at the location of mortality. Despite conservation efforts, human drivers of bird mortality in the African-Eurasian flyway do not appear to have declined over the last 15 years for the studied group of species. Results suggest that stronger conservation actions to address these threats across the flyway can reduce their impacts on species. In particular, projected future development of energy infrastructure is a representative example where application of planning, operation, and mitigation measures can enhance bird conservation.

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Open Access
LIFE: A metric for quantitively mapping the impact of land-cover change on global extinctions

Tracking and preventing continued extinctions requires robust spatially explicit metrics quantifying the impacts of human activities on habitat extent. Existing metrics either fail to consider species identity or focus solely on recent habitat losses. The persistence score approach represented an important development by combining species ecologies and land-cover data whilst considering the cumulative and non-linear impact of past habitat loss on species’ probability of persistence. However, it is computationally demanding, limiting its global use and application. Here we couple the persistence score approach with high-performance computing to generate global maps of what we term the LIFE (Land-cover change Impacts on Future Extinctions) metric for 29153 species of terrestrial vertebrates at 1 arc-minute resolution (3.4km2 at the equator). These maps quantify, for the first time, the marginal changes in the expected number of extinctions caused by (1) converting remaining natural vegetation to agriculture, and (2) restoring farmland to natural habitat. We demonstrate statistically that this approach integrates information on species richness, endemism, and past habitat loss. Our resulting maps can reliably be used at scales from 0.5-1000km2, and offer unprecedented opportunities to estimate the impact on extinctions of diverse actions, from dietary choices right through to global protected area development.

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Open Access
Using citizen science data to assess the vulnerability of bottlenose dolphins to human impacts along England's South Coast

AbstractCoastal bottlenose dolphin populations are highly vulnerable due to their small population sizes and proximity to human activities. Long‐term studies in the UK have monitored populations protected within Special Areas of Conservation (SACs) since the 1990s, but a small community of bottlenose dolphins inhabiting the coastal waters of southern England has received much less attention. The English Channel is one of the most heavily impacted marine ecosystems worldwide and increasing anthropogenic pressures pose a severe threat to the long‐term viability of this population. Conservation measures to protect these animals have been hindered by a lack of knowledge of population size, distribution and ranging behaviour. This study aimed to fill these knowledge gaps. A citizen science sighting network yielded 7458 sighting reports of bottlenose dolphins between 2000 and 2020. Resightings of identified individuals were used to estimate abundance, distribution, and ranging behaviour. Social structure analysis revealed a discrete interconnected group of animals in shallow coastal waters, which did not appear to mix with conspecifics identified further offshore. A Bayesian multi‐site mark–recapture analysis estimated that this population comprises around 48 animals (CV = 0.18, 95% HPDI = 38–66). These dolphins ranged between North Cornwall and Sussex, with an average individual range of 530 km (68–760 km). Areas of high‐modelled habitat suitability were found to overlap with high levels of anthropogenic pressure, with pollution and boat traffic identified as the most pervasive threats. Although adult survival rates indicated that the population was relatively stable from 2008 to 2019 (0.945 (0.017 ± SE)), the small population size implies a significant risk to their long‐term viability and resilience to environmental change. By highlighting the most deleterious anthropogenic activities and regions of conservation significance, our results will be useful for developing management policies for threat mitigation and population conservation, to protect this vulnerable group of dolphins.

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Open Access
LIFE: A metric for quantitively mapping the impact of land-cover change on global extinctions

Tracking and preventing continued extinctions requires robust spatially explicit metrics quantifying the impacts of human activities on habitat extent. Existing metrics either fail to consider species identity or focus solely on recent habitat losses. The persistence score approach represented an important development by combining species ecologies and land-cover data whilst considering the cumulative and non-linear impact of past habitat loss on species’ probability of persistence. However, it is computationally demanding, limiting its global use and application. Here we couple the persistence score approach with high-performance computing to generate global maps of what we term the LIFE (Land-cover change Impacts on Future Extinctions) metric for 29153 species of terrestrial vertebrates at 1 arc-minute resolution (3.4km2 at the equator). These maps quantify, for the first time, the marginal changes in the expected number of extinctions caused by (1) converting remaining natural vegetation to agriculture, and (2) restoring farmland to natural habitat. We demonstrate statistically that this approach integrates information on species richness, endemism, and past habitat loss. Our resulting maps can reliably be used at scales from 0.5-1000km2, and offer unprecedented opportunities to estimate the impact on extinctions of diverse actions, from dietary choices right through to global protected area development.

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The road to recovery: conservation management for the Critically Endangered Bali myna shows signs of success

AbstractThe Bali myna Leucopsar rothschildi has long suffered heavy trapping, leading to its near extinction in the wild and categorization as Critically Endangered on the IUCN Red List. Decades of conservation breeding, release of birds and post-release management at Bali Barat National Park have, until recently, failed to secure a viable wild population. However, over the past decade, population increases, expansion into new areas of the National Park and beyond, and successful breeding in both artificial and natural nest sites have occurred. These recent successes are associated with a change in approach by the National Park authority from concentrating efforts on the last refugium of the species (an area protected from trapping but with potentially suboptimal habitat) and towards the human-dominated landscapes around the main road through the National Park. Bali mynas tended to favour areas with extensive shorter grass cover and open canopies and to shun denser woodland. Anthropogenic landscapes such as farmland and plantations presumably mimic the original savannah habitat of the species, but nestbox provision has probably been crucial in these areas in the absence of natural cavities. A potential further factor in the increases in myna numbers and range has been a scheme involving local people in commercial breeding of the species, thereby reducing its market price, and working with communities to reduce trapping pressure. We encourage continuing operation of this management strategy inside the National Park and its further extension into adjacent tourist areas, which appear to have myna-friendly socio-ecological conditions.

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Open Access
A novel, post-Soviet fire disturbance regime drives bird diversity and abundance on the Eurasian steppe.

Many grassland ecosystems and their associated biodiversity depend on the interactions between fire and land-use, both of which are shaped by socioeconomic conditions. The Eurasian steppe biome, much of it situated in Kazakhstan, contains 10% of the world's remaining grasslands. The break-up of the Soviet Union in 1991, widespread land abandonment and massive declines in wild and domestic ungulates led to biomass accumulation over millions of hectares. This rapid fuel increase made the steppes a global fire hotspot, with major changes in vegetation structure. Yet, the response of steppe biodiversity to these changes remains unexplored. We utilized a unique bird abundance dataset covering the entire Kazakh steppe and semi-desert regions together with the MODIS burned area product. We modeled the response of bird species richness and abundance as a function of fire disturbance variables-fire extent, cumulative burned area, fire frequency-at varying grazing intensity. Bird species richness was impacted negatively by large fire extent, cumulative burned area, and high fire frequency in moderately grazed and ungrazed steppe. Similarly, overall bird abundance was impacted negatively by large fire extent, cumulative burned area and higher fire frequency in the moderately grazed steppe, ungrazed steppe, and ungrazed semi-deserts. At the species level, the effect of high fire disturbance was negative for more species than positive. There were considerable fire legacy effects, detectable for at least 8 years. We conclude that the increase in fire disturbance across the post-Soviet Eurasian steppe has led to strong declines in bird abundance and pronounced changes in community assembly. To gain back control over wildfires and prevent further biodiversity loss, restoration of wild herbivore populations and traditional domestic ungulate grazing systems seems much needed.

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