Accurate maps of species ranges are essential to inform conservation, but time-consuming to produce and update. Given the pace of change of knowledge about species distributions and shifts in ranges under climate change and land use, a need exists for timely mapping approaches that enable batch processing employing widely available data. We develop a systematic approach of batch-processing range maps and derived Area of Habitat maps for terrestrial bird species with published ranges below 125,000 km2 in Central and South America. (Area of Habitat is the habitat available to a species within its range.) We combine existing range maps with the rapidly expanding crowd-sourced eBird data of presences and absences from frequently surveyed locations, plus readily accessible, high resolution satellite data on forest cover and elevation to map the Area of Habitat available to each species. Users can interrogate the maps produced to see details of the observations that contributed to the ranges. Previous estimates of Areas of Habitat were constrained within the published ranges and thus were, by definition, smaller—typically about 30%. This reflects how little habitat within suitable elevation ranges exists within the published ranges. Our results show that on average, Areas of Habitat are 12% larger than published ranges, reflecting the often-considerable extent that eBird records expand the known distributions of species. Interestingly, there are substantial differences between threatened and non-threatened species. Some 40% of Critically Endangered, 43% of Endangered, and 55% of Vulnerable species have Areas of Habitat larger than their published ranges, compared with 31% for Near Threatened and Least Concern species. The important finding for conservation is that threatened species are generally more widespread than previously estimated.
As a landscape becomes increasingly fragmented through habitat loss, the individual patches become smaller and more isolated and thus less likely to sustain a local population. Metapopulation theory is appropriate for analyzing fragmented landscapes because it combines empirical landscape features with speciesspecific information to produce direct information on population extinction risks. This approach contrasts with descriptions of habitat fragments, which provide only indirect information on risk. Combining a spatially explicit metapopulation model with empirical data on endemic species' ranges and maps of habitat cover, we calculated the metapopulation capacity-a measure of a landscape's ability to sustain a metapopulation. Mangroves provide an ideal model landscape because they are of conservation concern and their patch boundaries are easily delineated. For 2000-20015, we calculated global metapopulation capacity for 99 metapopulations of 32 different bird species endemic to mangroves. Northern Australia and Southeast Asia had the highest richness of mangrove endemic birds. The Caribbean, Pacific coast of Central America, Madagascar, Borneo, and isolated patches in Southeast Asia in Myanmar and Malaysia had the highest metapopulation losses. Regions with the highest loss of habitat area were not necessarily those with the highest loss of metapopulation capacity. Often, it was not a matter of how much, but how the habitat was lost. Our method can be used by managers to evaluate and prioritize a landscape for metapopulation persistence.Resumen: A medida que un paisaje se fragmenta cada vez más debido a la pérdida de hábitat, los parches se vuelven más pequeños y aislados y, por lo tanto, menos propensos a sostener a una población local. La teoría de metapoblaciones es adecuada para analizar paisajes fragmentados porque combina características empíricas del paisaje con información de cada especie para producir información directa sobre los riesgos de extinción de la población. Este enfoque contrasta con las descripciones de los fragmentos de hábitat que solo proporcionan información directa sobre el riesgo. Mediante la combinación de un modelo metapoblacional espacialmente explícito con datos empíricos de los rangos de distribución de especies endémicas y mapas de la cobertura del hábitat, calculamos la capacidad de la metapoblación -una medida de la capacidad del paisaje para sostener una metapoblación. Los manglares proporcionan un paisaje modelo ideal porque son de interés para la conservación y los límites de los parches son delineados fácilmente. Calculamos la capacidad de la metapoblación global para el período 2000-2015 de 99 metapoblaciones de 32 especies de aves endémicas de manglares. El norte de Australia y el sudeste de Asia tuvieron la mayor riqueza de aves endémicas de manglares. El Caribe, la costa del Pacífico de Centroamérica, Madagascar, Borneo y parches aislados en el sudeste de Asia en Myanmar y Malasia tuvieron las mayores pérdidas de metapoblaciones. Las regiones con mayor pérdida hábita...
The cause of deaths of 350 elephants in 2020 in a relatively small unprotected area of northern Botswana is unknown, and may never be known. Media speculations about it ignore ecological realities. Worse, they make conjectures that can be detrimental to wildlife and sometimes discredit conservation incentives. A broader understanding of the ecological and conservation issues speaks to elephant management across the Kavango–Zambezi Transfrontier Conservation Area that extends across Botswana, Namibia, Angola, Zambia, and Zimbabwe. Our communication addresses these. Malicious poisoning and poaching are unlikely to have played a role. Other species were unaffected, and elephant carcases had their tusks intact. Restriction of freshwater supplies that force elephants to use pans as a water source possibly polluted by blue-green algae blooms is a possible cause, but as yet not supported by evidence. No other species were involved. A contagious disease is the more probable one. Fences and a deep channel of water confine these elephants’ dispersal. These factors explain the elephants’ relatively high population growth rate despite a spell of increased poaching during 2014–2018. While the deaths represent only ~2% of the area’s elephants, the additive effects of poaching and stress induced by people protecting their crops cause alarm. Confinement and relatively high densities probably explain why the die-off occurred only here. It suggests a re-alignment or removal of fences that restrict elephant movements and limits year-round access to freshwater.
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Migratory seabirds face threats from climate change and a variety of anthropogenic disturbances. Although most seabird research has focused on the ecology of individuals at the colony, technological advances now allow researchers to track seabird movements at sea and during migration. We combined telemetry data on Onychoprion fuscatus (sooty terns) with a long-term capture-mark-recapture dataset from the Dry Tortugas National Park to map the movements at sea for this species, calculate estimates of mortality, and investigate the impact of hurricanes on a migratory seabird. Included in the latter analysis is information on the locations of recovered bands from deceased individuals wrecked by tropical storms. We present the first known map of sooty tern migration in the Atlantic Ocean. Our results indicate that the birds had minor overlaps with areas affected by the major 2010 oil spill and a major shrimp fishery. Indices of hurricane strength and occurrence are positively correlated with annual mortality and indices of numbers of wrecked birds. As climate change may lead to an increase in severity and frequency of major hurricanes, this may pose a long-term problem for this colony.
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