Global shortfalls in documented actions to conserve biodiversity.

Threatened species are by definition species that are in need of assistance. In the absence of suitable conservation interventions, they are likely to disappear soon1. There is limited understanding of how and where conservation interventions are applied globally, or how well they work2,3. Here, using information from the International Union for Conservation of Nature Red List and other global databases, we find that for species at risk from three of the biggest drivers of biodiversity loss-habitat loss, overexploitation for international trade and invasive species4-many appear to lack the appropriate types of conservation interventions. Indeed, although there has been substantial recent expansion of the protected area network, we still find that 91% of threatened species have insufficient representation of their habitats within protected areas. Conservation interventions are not implemented uniformly across different taxa and regions and, even when present, have infrequently led to substantial improvements in the status of species. For 58% of the world's threatened terrestrial species, we find conservation interventions to be notably insufficient or absent. We cannot determine whether such species are truly neglected, or whether efforts to recover them are not included in major conservation databases. If they are indeed neglected, the outlook for many of the world's threatened species is grim without more and better targeted action.

Assessing the illegal hunting of native wildlife in China.

Illegal harvesting and trading of wildlife have become major threats to global biodiversity and public health1-3. Although China is widely recognized as an important destination for wildlife illegally obtained abroad4, little attention has been given to illegal hunting within its borders. Here we extracted 9,256 convictions for illegal hunting from a nationwide database of trial verdicts in China spanning January 2014 to March 2020. These convictions involved illegal hunting of 21% (n = 673) of China's amphibian, reptile, bird and mammal species, including 25% of imperilled species in these groups. Sample-based extrapolation indicates that many more species were taken illegally during this period. Larger body mass and range size (for all groups), and proximity to urban markets (for amphibians and birds) increase the probability of a species appearing in the convictions database. Convictions pertained overwhelmingly to illegal hunting for commercial purposes and involved all major habitats across China. A small number of convictions represented most of the animals taken, indicating the existence of large commercial poaching operations. Prefectures closer to urban markets show higher densities of convictions and more individual animals taken. Our results suggest that illegal hunting is a major, overlooked threat to biodiversity throughout China.

Autumn stopover hotspots and multiscale habitat associations of migratory landbirds in the eastern United States.

Halting the global decline of migratory birds requires a better understanding of migration ecology. Stopover sites are a crucial yet understudied aspect of bird conservation, mostly due to challenges associated with understanding broad-scale patterns of transient habitat use. Here, we use a national network of weather radar stations to identify stopover hotspots and assess multiscale habitat associations of migratory landbirds across the eastern United States during autumn migration. We mapped seasonal bird densities over 5 y (2015 to 2019) from 60 radar stations covering 63.2 million hectares. At a coarse scale, we found that landbirds migrate across a broad front with small differences in migrant density between radar domains. However, relatively more birds concentrate along the Mississippi River and Appalachian Mountains. At a finer scale, we identified radar pixels that consistently harbored high densities of migrants for all 5 y, which we classify as stopover hotspots. Hotspot probability increased with percent cover of all forest types and decreased with percent cover of pasture and cultivated crops. Moreover, we found strong concentrating effects of deciduous forest patches within deforested regions. We also found that the prairie biome in the Midwest (now mostly cropland) is likely a migration barrier, with large concentrations of migrants at the prairie-forest boundary after crossing the agricultural Midwest. Overall, the broad-front migration pattern highlights the importance of locally based conservation efforts to protect stopover habitats. Such efforts should target forests, especially deciduous forests in highly altered landscapes. These findings demonstrate the value of multiscale habitat assessments for the conservation of migratory landbirds.

Importance of habitat heterogeneity in tidal flats to the conservation of migratory shorebirds.

Understanding species distribution patterns and what determines them is critical for effective conservation planning and management. In the case of shorebirds migrating along the East Asian-Australasian Flyway (EAAF), the loss of stopover habitat in the Yellow Sea region is thought to be the primary reason for the precipitous population declines. However, the rates of decline vary considerably among species, and it remains unclear how such differences could arise within a group of closely related species using apparently similar habitats at the same locales. We mapped the spatial distributions of foraging shorebirds, as well as biotic (benthic invertebrates consumed by migrating shorebirds) and abiotic (sediment characteristics) environmental factors, at a key stopover site in eastern China. Five of the six sediment characteristics showed significant spatial variation with respect to distance along the shoreline or distance from the seawall in the same tidal flat. The biomasses of four of the six most abundant benthic invertebrates were concentrated in the upper or middle zones of the tidal flat. The distribution patterns of all three focal shorebird species on the tidal flat were best explained jointly by this heterogeneity of sediment characteristics and invertebrate prey. These results suggest that the loss of tidal flats along the Yellow Sea, which is typically concentrated at the upper and middle zones, may not only reduce the overall amount of staging habitat, but also disproportionately affect the most resource-rich portions for the birds. Effective conservation of shorebird staging areas along the EAAF and likely elsewhere must consider the subtle habitat heterogeneity that characterizes these tidal flats, prioritizing the protection of those portions richest in food resources, most frequently used by focal bird species, and most vulnerable to anthropogenic threats. Article impact statement: Heterogeneity of tidal flats with respect to biotic and abiotic factors must be considered in shorebird conservation planning.

Importancia de la heterogeneidad de hábitat en las llanuras intermareales para la conservación de aves playeras migratorias Resumen Entender las pautas de distribución de las especies y los factores que las determinan es fundamental para planificar y gestionar eficazmente su conservación. En el caso de las aves playeras que migran a lo largo de la ruta migratoria Asia Oriental-Australasia (EAAF, en inglés), se cree que la pérdida de puntos de parada en la región del Mar Amarillo es la razón principal de la declinación poblacional precipitada. Sin embargo, las tasas de declinación varían considerablemente entre especies, y sigue sin estar claro cómo pueden surgir tales diferencias dentro de un grupo de especies emparentadas que utilizan hábitats aparentemente similares en los mismos lugares. Mapeamos las distribuciones espaciales de las aves playeras forrajeras, así como los factores ambientales bióticos (invertebrados bénticos consumidos por las aves playeras migratorias) y abióticos (características de los sedimentos), en un punto de parada clave en el este de China. Cinco de las seis características de los sedimentos mostraron una variación espacial significativa con respecto a los cambios lineales en la distancia a lo largo de la costa o la distancia desde el malecón en la misma llanura mareal. La biomasa de cuatro de los seis invertebrados bénticos más abundantes se concentró en las zonas superior o media de la llanura mareal. Esta heterogeneidad de las características de los sedimentos y de las presas invertebradas es la que mejor explica los patrones de distribución de las tres especies de aves playeras en la llanura mareal. Estos resultados sugieren que la pérdida de llanuras mareales a lo largo del Mar Amarillo, que suele concentrarse en las zonas superior y media, puede no sólo reducir la cantidad total de hábitat de parada, sino también afectar de manera desproporcionada a las partes más ricas en recursos para las aves. La conservación eficaz de los puntos de parada de las aves playeras a lo largo del EAAF, y probablemente en otros lugares, debe tener en cuenta la sutil heterogeneidad del hábitat que caracteriza a estas llanuras mareales, priorizando la protección de las partes más ricas en recursos alimenticios, más frecuentemente utilizadas por las especies de aves focales y más vulnerables a las amenazas antropogénicas.

Assessing shorebird mortalities due to razor clam aquaculture at key migratory stopover sites in southeastern China.

Aquaculture can provide foraging habitat for birds, but it can also result in intentional and accidental mortality. We examined an overlooked conflict between razor clam (Sinonovacula spp.) aquaculture and declining shorebirds in southeastern China's Fujian and Zhejiang provinces. We surveyed 6 out of 11 internationally important stopover sites for these shorebirds and monitored shorebird mortality in 2 sites (Xinghua Bay, Yueqing Bay) with razor clam aquaculture. We visited an additional 32 sites in these 2 provinces to determine if there was netting in other razor clam farms. Approximately 8-9 km2 of intertidal foraging habitat was covered by horizontal nets to prevent birds from feeding on young razor clams at Xinghua Bay and Yueqing Bay. We conservatively estimated that 13,676 (2.5th-97.5th percentile 8,330-21,285) individual shorebirds were entangled in the nets at the 2 monitored sites in April and May 2021, including 2 endangered and 7 near-threatened species. Mortality of 5 species for which we had sufficient data accounted for 0.76% (black-tailed godwit [Limosa limosa]) to 4.27% (terek sandpiper [Xenus cinereus]) of their total flyway populations. This level of mortality could strongly affect their populations. We found netting at 17 additional razor clam farms, indicating a widespread threat to shorebirds. Although razor clams are typically harvested in late March to early April, nets are left on the mudflats throughout the spring and summer, including when the bulk of shorebird migration takes place. Immediately removing these nets after the clam harvest could prevent most of the spring mortality of shorebirds, although this is unlikely to happen without government regulations or economic incentives. To better assess and mitigate the impacts of this conflict, future research should quantify shorebird mortality at other razor clam farms, including during winter, explore less harmful deterrence methods, and assess the socioeconomic factors driving the conflict.

Evaluación de la mortalidad de aves costeras causada por la acuacultura de almejas navaja en sitios importantes de descanso migratorio en el sureste de China Resumen La acuacultura puede proporcionar hábitats de forrajeo para las aves, pero también puede derivar en muertes accidentales o intencionales. Analizamos un conflicto ignorado entre la acuacultura de almeja navaja (Sinonovacula spp.) y la declinación de aves costeras en las provincias de Fujian y Zhejiang del sureste de China. Censamos seis de los once sitios de descanso con importancia internacional para estas aves y monitoreamos su mortalidad en dos sitios en donde se cría la almeja navaja: la bahía de Xinghua y la de Yueqing. Además, visitamos 32 sitios en estas dos provincias para determinar si existían redes en otras granjas de almeja navaja. Unos 8 ­ 9 km2 del hábitat intermareal de forrajeo estaban cubiertos por redes horizontales para evitar que las aves se alimentaran de las almejas juveniles en ambas bahías. Estimamos moderadamente que 13,676 (2.5° ­ 97.5° percentil 8,330 ­ 21,285) individuos de aves costeras se enredaron en las redes en los dos sitios monitoreados durante abril y mayo de 2021, incluyendo a dos especies en peligro y siete casi amenazadas. La mortalidad de las cinco especies para las cuales tuvimos suficientes datos representó del 0.76% (Limosa limosa) al 4.27% (Xenus cinereus) del total de las poblaciones migratorias. Este nivel de mortalidad podría tener un gran efecto sobre las poblaciones de estas especies. Encontramos redes en 17 granjas más, lo que indica una amenaza extendida para las aves costeras. Aunque es típico que se colecte la almeja navaja a finales de marzo y principios de abril, las redes permanecen durante toda la primavera y el verano, incluso cuando ocurre la mayoría de los vuelos migratorios. La eliminación inmediata de estas redes después de la colecta de almejas podría prevenir la mayoría de las muertes primaverales de las aves costeras, aunque no es probable que esto suceda sin regulaciones gubernamentales o incentivos económicos. Para tener mejores evaluaciones y mitigaciones del impacto de este conflicto, una investigación más profunda debería cuantificar la mortalidad de las aves costeras en otras granjas, incluso durante el invierno, explorar métodos de disuasión menos dañinos y evaluar los factores socioeconómicos que causan el conflicto.

Cryptic species in a colorful genus: Integrative taxonomy of the bush robins (Aves, Muscicapidae, Tarsiger) suggests two overlooked species.

Several cryptic avian species have been validated by recent integrative taxonomic efforts in the Sino-Himalayan mountains, indicating that avian diversity in this global biodiversity hotspot may be underestimated. In the present study, we investigated species limits in the genus Tarsiger, the bush robins, a group of montane forest specialists with high species richness in the Sino-Himalayan region. Based on comprehensive sampling of all 11 subspecies of the six currently recognized species, we applied an integrative taxonomic approach by combining multilocus, acoustic, plumage and morphometric analyses. Our results reveal that the isolated north-central Chinese populations of Tarsiger cyanurus, described as the subspecies albocoeruleus but usually considered invalid, is distinctive in genetics and vocalisation, but only marginally differentiated in morphology. We also found the Taiwan endemic T. indicus formosanus to be distinctive in genetics, song and morphology from T. i. indicus and T. i. yunnanensis of the Sino-Himalayan mountains. Moreover, Bayesian species delimitation using BPP suggests that both albocoeruleus and formosanus merit full species status. We propose their treatment as 'Qilian Bluetail' T. albocoeruleus and 'Taiwan Bush Robin' T. formosanus, respectively.

Consequences of underexplored variation in biodiversity indices used for land-use prioritization.

For biodiversity protection to play a persuasive role in land-use planning, conservationists must be able to offer objective systems for ranking which natural areas to protect or convert. Representing biodiversity in spatially explicit indices is challenging because it entails numerous judgments regarding what variables to measure, how to measure them, and how to combine them. Surprisingly few studies have explored this variation. Here, we explore how this variation affects which areas are selected for agricultural conversion by a land-use prioritization model designed to reduce the biodiversity losses associated with agricultural expansion in Zambia. We first explore the similarity between model recommendations generated by three recently published composite indices and a commonly used rarity-weighted species richness metric. We then explore four underlying sources of ecological and methodological variation within these and other approaches, including different terrestrial vertebrate taxonomic groups, different species-richness metrics, different mathematical methods for combining layers, and different spatial resolutions of inputs. The results generated using different biodiversity approaches show very low spatial agreement regarding which areas to convert to agriculture. There is little overlap in areas identified for conversion using previously published indices (mean Jaccard similarity, Jw , between 0.3 and 3.7%), different taxonomic groups (5.0% < mean Jw  < 13.5%), or different measures of species richness (15.6% < mean Jw  < 33.7%). Even with shared conservation goals, different methods for combining layers and different input spatial resolutions still produce meaningful, though smaller, differences among areas selected for conversion (40.9% < mean Jw  < 67.5%). The choice of taxonomic group had the largest effect on conservation priorities, followed by the choice of species richness metric, the choice of combination method, and finally the choice of spatial resolution. These disagreements highlight the challenge of objectively representing biodiversity in land-use planning tools, and present a credibility challenge for conservation scientists seeking to inform policy making. Our results suggest an urgent need for a more consistent and transparent framework for designing the biodiversity indices used in land-use planning, which we propose here.

Investigating illegal activities that affect biodiversity: the case of wildlife consumption in the Brazilian Amazon.

The illegal use of natural resources, manifested in activities like illegal logging, poaching, and illegal wildlife trade, poses a global threat to biodiversity. Addressing them will require an understanding of the magnitude of and factors influencing these activities. However, assessing such behaviors is challenging because of their illegal nature, making participants less willing to admit engaging in them. We compared how indirect (randomized response technique) and direct questioning techniques performed when assessing non-sensitive (fish consumption, used as negative control) and sensitive (illegal consumption of wild animals) behaviors across an urban gradient (small towns, large towns, and the large city of Manaus) in the Brazilian Amazon. We conducted 1,366 surveys of randomly selected households to assess the magnitude of consumption of meat from wild animals (i.e., wild meat) and its socioeconomic drivers, which included years the head of household lived in urban areas, age of the head of household, household size, presence of children, and poverty. The indirect method revealed higher rates of wildlife consumption in larger towns than did the direct method. Results for small towns were similar between the two methods. The indirect method also revealed socioeconomic factors influencing wild meat consumption that were not detected with direct methods. For instance, the indirect method showed that wild meat consumption increased with age of the head of household, and decreased with poverty and years the head of household lived in urban areas. Simultaneously, when responding to direct questioning, households with characteristics associated with higher wild meat consumption, as estimated from indirect questioning, tended to underreport consumption to a larger degree than households with lower wild meat consumption. Results for fish consumption, used as negative control, were similar for both methods. Our findings suggest that people edit their answers to varying degrees when responding to direct questioning, potentially biasing conclusions, and indirect methods can improve researchers' ability to identify patterns of illegal activities when the sensitivity of such activities varies across spatial (e.g., urban gradient) or social (e.g., as a function of age) contexts. This work is broadly applicable to other geographical regions and disciplines that deal with sensitive human behaviors.

Impacts of rural to urban migration, urbanization, and generational change on consumption of wild animals in the Amazon.

For the first time in history, more people live in urban areas than in rural areas. This trend is likely to continue, driven largely by rural-to-urban migration. We investigated how rural-to-urban migration, urbanization, and generational change affect the consumption of wild animals. We used chelonian (tortoises and freshwater turtles), one of the most hunted taxa in the Amazon, as a model. We surveyed 1356 households and 2776 school children across 10 urban areas of the Brazilian Amazon (6 small towns, 3 large towns, and Manaus, the largest city in the Amazon Basin) with a randomized response technique and anonymous questionnaires. Urban demand for wild meat (i.e., meat from wild animals) was alarmingly high. Approximately 1.7 million turtles and tortoises were consumed in urban areas of Amazonas during 2018. Consumption rates declined as size of the urban area increased and were greater for adults than children. Furthermore, the longer rural-to-urban migrants lived in urban areas, the lower their consumption rates. These results suggest that wild meat consumption is a rural-related tradition that decreases as urbanization increases and over time after people move to urban areas. However, it is unclear whether the observed decline will be fast enough to conserve hunted species, or whether children's consumption rate will remain the same as they become adults. Thus, conservation actions in urban areas are still needed. Current conservation efforts in the Amazon do not address urban demand for wildlife and may be insufficient to ensure the survival of traded species in the face of urbanization and human population growth. Our results suggest that conservation interventions must target the urban demand for wildlife, especially by focusing on young people and recent rural to urban migrants. Article impact statement: Amazon urbanite consumption of wildlife is high but decreases with urbanization, over time for rural to urban migrants, and between generations. Impactos de la Migración del Campo a la Ciudad, la Urbanización y del Cambio Generacional sobre el Consumo de Animales Silvestres en el Amazonas.

Por primera vez en la historia, la población urbana es mayor que la rural. Es muy probable que esta tendencia continúe debido a la migración del campo a la ciudad. Investigamos el efecto de la migración del campo a la ciudad, la urbanización y el cambio generacional sobre el consumo de animales silvestres. Utilizamos como modelo a los quelonios (tortugas acuáticas y terrestres), uno de los taxa más cazados en el Amazonas. Aplicamos encuestas en 1,356 casas y a 2,776 niños en edad escolar en 10 áreas urbanas de la Amazonía brasileña (6 poblados pequeños, 3 poblados grandes y Manaos, la mayor ciudad en la Cuenca del Amazonas) mediante una técnica de respuesta aleatoria y cuestionarios anónimos. La demanda urbana de carne silvestre (i.e., carne de animales silvestres) fue alarmantemente alta. Aproximadamente 1.7 millones de tortugas acuáticas y terrestres fueron consumidas en áreas urbanas del Amazonas durante 2018. Las tasas de consumo declinaron a medida que incrementó la superficie urbana y fueron mayores en adultos que en niños. Más aun, entre más tiempo viviendo en áreas urbanas, las tasas de consumo fueron menores en los migrantes del campo a la ciudad. Estos resultados sugieren que el consumo de carne silvestre es una tradición rural que disminuye a medida que aumenta la urbanización y el tiempo desde que los habitantes se mueven a la ciudad. Sin embargo, no es claro si la declinación observada será lo suficientemente rápida para conservar a las especies cazadas, o si la tasa de consumo de los niños permanecerá igual cuando sean adultos. Por lo tanto, aun se requieren acciones de conservación en áreas urbanas. Los actuales esfuerzos de conservación en el Amazonas no abordan la demanda urbana de carne de monte y pueden ser insuficientes para asegurar la supervivencia de especies comercializadas ante la urbanización y el crecimiento de la población humana. Nuestros resultados sugieren que las intervenciones de conservación deben atender la demanda de fauna silvestre, con énfasis en los jóvenes y los migrantes recientes.

Upper tidal flats are disproportionately important for the conservation of migratory shorebirds.

Migratory animals play vital ecological roles in ecosystems worldwide, yet many species are threatened by human activities. Understanding the detailed patterns of habitat use throughout the migration cycle is critical to developing effective conservation strategies for these species. Migratory shorebirds undertake some of the longest known migrations, but they are also declining precipitously worldwide. To better understand the dynamics of shorebird declines along the East Asian-Australasian Flyway, we quantified the spatiotemporal foraging distribution of 17 migratory shorebirds at two critical stopover sites. We found that shorebirds exhibit substantial interspecific and site-specific differences in their foraging distributions. Notwithstanding these differences, however, the upper tidal flats appear to be especially important to most shorebirds by providing more than 70% of the birds' cumulative foraging time, twofold greater than their proportional area. Because the upper tidal flats are also more prone to coastal development, our findings may help to explain why shorebird populations along the flyway have declined much faster than the overall rate of tidal flat loss. Our work highlights the importance of protecting upper tidal flats to conserve migratory shorebirds and demonstrates the value of a detailed ecological understanding of habitat usage by migratory animals for conservation planning.

Forest-type specialization strongly predicts avian responses to tropical agriculture.

Species' traits influence how populations respond to land-use change. However, even in well-characterized groups such as birds, widely studied traits explain only a modest proportion of the variance in response across species. Here, we show that associations with particular forest types strongly predict the sensitivity of forest-dwelling Amazonian birds to agriculture. Incorporating these fine-scale habitat associations into models of population response dramatically improves predictive performance and markedly outperforms the functional traits that commonly appear in similar analyses. Moreover, by identifying habitat features that support assemblages of unusually sensitive habitat-specialist species, our model furnishes straightforward conservation recommendations. In Amazonia, species that specialize on forests along a soil-nutrient gradient (i.e. both rich-soil specialists and poor-soil specialists) are exceptionally sensitive to agriculture, whereas species that specialize on floodplain forests are unusually insensitive. Thus, habitat specialization per se does not predict disturbance sensitivity, but particular habitat associations do. A focus on conserving specific habitats that harbour highly sensitive avifaunas (e.g. poor-soil forest) would protect a critically threatened component of regional biodiversity. We present a conceptual model to explain the divergent responses of habitat specialists in the different habitats, and we suggest that similar patterns and conservation opportunities probably exist for other taxa and regions.

Overlooked biodiversity loss in tropical smallholder agriculture.

Smallholder agriculture is the main driver of deforestation in the western Amazon, where terrestrial biodiversity reaches its global maximum. Understanding the biodiversity value of the resulting mosaics of cultivated and secondary forest is therefore crucial for conservation planning. However, Amazonian communities are organized across multiple forest types that support distinct species assemblages, and little is known about smallholder impacts across the range of forest types that are essential for sustaining biodiversity. We addressed this issue with a large-scale field inventory of birds (point counts) and trees (transects) in primary forest and smallholder agriculture in northern Peru across 3 forest types that are key for Amazonian biodiversity. For birds smallholder agriculture supported species richness comparable to primary forest within each forest type, but biotic homogenization across forest types resulted in substantial losses of biodiversity overall. These overall losses are invisible to studies that focus solely on upland (terra firma) forest. For trees biodiversity losses in upland forests dominated the signal across all habitats combined and homogenization across habitats did not exacerbate biodiversity loss. Proximity to forest strongly predicted the persistence of forest-associated bird and tree species in the smallholder mosaic, and because intact forest is ubiquitous in our study area, our results probably represent a best-case scenario for biodiversity in Amazonian agriculture. Land-use planning inside and outside protected areas should recognize that tropical smallholder agriculture has pervasive biodiversity impacts that are not apparent in typical studies that cover a single forest type. The full range of forest types must be surveyed to accurately assess biodiversity losses, and primary forests must be protected to prevent landscape-scale biodiversity loss.

Pérdida de Biodiversidad Pasada por Alto en la Agricultura de Pequeños Propietarios Resumen La agricultura de pequeños propietarios es la principal causa de la deforestación en la Amazonía occidental, donde la biodiversidad terrestre alcanza su máximo global. Por lo tanto, comprender el valor de la biodiversidad de los mosaicos resultantes de bosques cultivados y secundarios es crucial para para la planificación de la conservación. Sin embargo, las comunidades amazónicas están organizadas a través de múltiples tipos de bosques que soportan ensambles de especies distintas, y poco se sabe sobre los impactos de los pequeños agricultores en toda la gama de tipos de bosques que son esenciales para mantener la biodiversidad. Abordamos este problema con un inventario de campo a gran escala de aves (puntos de conteo) y árboles (transectos) en bosques primarios y agricultura de pequeños productores en el norte de Perú en 3 tipos de bosques que son clave para la biodiversidad amazónica. Para aves, la agricultura de pequeños productores soportó una riqueza de especies comparable a la de los bosques primarios dentro de cada tipo de bosque, pero la homogeneización biótica entre los tipos de bosques dio lugar a pérdidas sustanciales de biodiversidad en general. Estas pérdidas globales son invisibles para los estudios que se centran únicamente en los bosques de tierra firme. En el caso de árboles, las pérdidas de biodiversidad en bosques de tierra firme fueron dominantes en todos los hábitats combinados y la homogeneización en todos los hábitats no agravó la pérdida de biodiversidad. La proximidad a los bosques predijo robustamente la persistencia de especies de aves y árboles asociadas a bosques en el mosaico de pequeños productores, y debido a la omnipresencia de bosque intacto en el área de estudio, nuestros resultados probablemente representan el mejor escenario para la biodiversidad en la agricultura amazónica. La planificación del uso de suelo dentro y fuera de las áreas protegidas debe reconocer que la agricultura tiene impactos generalizados sobre la biodiversidad que no son evidentes en estudios que solo abarcan un solo tipo de bosque. Se debe examinar toda la gama de tipos de bosque para evaluar con precisión las pérdidas de biodiversidad, y los bosques primarios deben ser protegidos para prevenir la pérdida de biodiversidad a escala de paisaje.

Temperature and competition interact to structure Himalayan bird communities.

Longstanding theory predicts that competitive interactions set species' range limits in relatively aseasonal, species-rich regions, while temperature limits distributions in more seasonal, species-poor areas. More recent theory holds that species evolve narrow physiological tolerances in aseasonal regions, with temperature being an important determining factor in such zones. We tested how abiotic (temperature) and biotic (competition) factors set range limits and structure bird communities along strong, opposing, temperature-seasonality and species-richness gradients in the Himalayas, in two regions separated by 1500 km. By examining the degree to which seasonal elevational migration conserves year-round thermal niches across species, we show that species in the relatively aseasonal and speciose east are more constrained by temperature compared with species in the highly seasonal west. We further show that seasonality has a profound effect on the strength of competition between congeneric species. Competition appears to be stronger in winter, a period of resource scarcity in the Himalayas, in both the east and the west, with similarly sized eastern species more likely to segregate in thermal niche space in winter. Our results indicate that rather than acting in isolation, abiotic and biotic factors mediate each other to structure ecological communities.

Conserving Himalayan birds in highly seasonal forested and agricultural landscapes.

The Himalayas are a global biodiversity hotspot threatened by widespread agriculture and pasture expansion. To determine the impact of these threats on biodiversity and to formulate appropriate conservation strategies, we surveyed birds along elevational gradients in primary forest and in human-dominated lands spanning a gradient of habitat alteration, including forest-agriculture mosaics, mixed agriculture mosaics, and pasture. We surveyed birds during the breeding season and in winter to account for pronounced seasonal migrations. Bird abundance and richness in forest-agriculture and mixed agriculture mosaics were equal to or greater than in primary forest and greater than in pasture at local and landscape scales during both seasons. Pasture had greater abundance and richness of birds in winter than primary forest, but richness was greater in primary forest at the landscape scale during the breeding season. All 4 land-use types held unique species, suggesting that all must be retained in the landscape to conserve the entire avifauna. Our results suggest forest-agriculture and mixed agriculture mosaics are particularly important for sustaining Himalayan bird communities during winter and primary forests are vital for sustaining Himalayan bird communities during the breeding season. Further conversion of forest-agriculture and mixed agriculture mosaics to pasture would likely result in significant biodiversity losses that would disproportionately affect breeding species. To ensure comprehensive conservation, strategies in the western Himalayas must balance the protection of intact primary forest with the minimization of pasture expansion.

The role of competition, ecotones, and temperature in the elevational distribution of Himalayan birds.

There is clear evidence that species' ranges along environmental gradients are constrained by both biotic and abiotic factors, yet their relative importance in structuring realized distributions remains uncertain. We surveyed breeding bird communities while collecting in situ temperature and vegetation data along five elevational transects in the Himalayas differing in temperature variability, habitat zonation, and bird richness in order to disentangle temperature, habitat, and congeneric competition as mechanisms structuring elevational ranges. Our results from species' abundance models representing these three mechanisms differed markedly from previous, foundational research in the tropics. Contrary to general expectations, we found little evidence for competition as a major determinant of range boundaries, with congeneric species limiting only 12% of ranges. Instead, temperature and habitat were found to structure the majority of species' distributions, limiting 48 and 40% of ranges, respectively. Our results suggest that different mechanisms may structure species ranges in the temperate Himalayas compared to tropical systems. Despite recent evidence suggesting temperate species have broader thermal tolerances than tropical species, our findings reinforce the notion that the abiotic environment has significant control over the distributions of temperate species.

The importance of agricultural lands for Himalayan birds in winter.

The impacts of land-use change on biodiversity in the Himalayas are poorly known, notwithstanding widespread deforestation and agricultural intensification in this highly biodiverse region. Although intact primary forests harbor many Himalayan birds during breeding, a large number of bird species use agricultural lands during winter. We assessed how Himalayan bird species richness, abundance, and composition during winter are affected by forest loss stemming from agriculture and grazing. Bird surveys along 12 elevational transects within primary forest, low-intensity agriculture, mixed subsistence agriculture, and intensively grazed pastures in winter revealed that bird species richness and abundance were greatest in low-intensity and mixed agriculture, intermediate in grazed pastures, and lowest in primary forest at both local and landscape scales; over twice as many species and individuals were recorded in low-intensity agriculture than in primary forest. Bird communities in primary forests were distinct from those in all other land-use classes, but only 4 species were unique to primary forests. Low-, medium-, and high-intensity agriculture harbored 32 unique species. Of the species observed in primary forest, 80% had equal or greater abundance in low-intensity agricultural lands, underscoring the value of these lands in retaining diverse community assemblages at high densities in winter. Among disturbed landscapes, bird species richness and abundance declined as land-use intensity increased, especially in high-intensity pastures. Our results suggest that agricultural landscapes are important for most Himalayan bird species in winter. But agricultural intensification-especially increased grazing-will likely result in biodiversity losses. Given that forest reserves alone may inadequately conserve Himalayan birds in winter, comprehensive conservation strategies in the region must go beyond protecting intact primary forests and ensure that low-intensity agricultural lands are not extensively converted to high-intensity pastures.

Measuring the impact of the pet trade on Indonesian birds.

The trade in wild animals involves one-third of the world's bird species and thousands of other vertebrate species. Although a few species are imperiled as a result of the wildlife trade, the lack of field studies makes it difficult to gauge how serious a threat it is to biodiversity. We used data on changes in bird abundances across space and time and information from trapper interviews to evaluate the effects of trapping wild birds for the pet trade in Sumatra, Indonesia. To analyze changes in bird abundance over time, we used data gathered over 14 years of repeated bird surveys in a 900-ha forest in southern Sumatra. In northern Sumatra, we surveyed birds along a gradient of trapping accessibility, from the edge of roads to 5 km into the forest interior. We interviewed 49 bird trappers in northern Sumatra to learn which species they targeted and how far they went into the forest to trap. We used prices from Sumatran bird markets as a proxy for demand and, therefore, trapping pressure. Market price was a significant predictor of species declines over time in southern Sumatra (e.g., given a market price increase of approximately $50, the log change in abundance per year decreased by 0.06 on average). This result indicates a link between the market-based pet trade and community-wide species declines. In northern Sumatra, price and change in abundance were not related to remoteness (distance from the nearest road). However, based on our field surveys, high-value species were rare or absent across this region. The median maximum distance trappers went into the forest each day was 5.0 km. This suggests that trapping has depleted bird populations across our remoteness gradient. We found that less than half of Sumatra's remaining forests are >5 km from a major road. Our results suggest that trapping for the pet trade threatens birds in Sumatra. Given the popularity of pet birds across Southeast Asia, additional studies are urgently needed to determine the extent and magnitude of the threat posed by the pet trade.

The impact of logging roads on dung beetle assemblages in a tropical rainforest reserve.

The demand for timber products is facilitating the degradation and opening up of large areas of intact habitats rich in biodiversity. Logging creates an extensive network of access roads within the forest, yet these are commonly ignored or excluded when assessing impacts of logging on forest biodiversity. Here we determine the impact of these roads on the overall condition of selectively logged forests in Borneo, Southeast Asia. Focusing on dung beetles along > 40 km logging roads we determine: (i) the magnitude and extent of edge effects alongside logging roads; (ii) whether vegetation characteristics can explain patterns in dung beetle communities, and; (iii) how the inclusion of road edge forest impacts dung beetle assemblages within the overall logged landscape. We found that while vegetation structure was significantly affected up to 34 m from the road edge, impacts on dung beetle communities penetrated much further and were discernible up to 170 m into the forest interior. We found larger species and particularly tunnelling species responded more than other functional groups which were also influenced by micro-habitat variation. We provide important new insights into the long-term ecological impacts of tropical logging. We also support calls for improved logging road design both during and after timber extraction to conserve more effectively biodiversity in production forests, for instance, by considering the minimum volume of timber, per unit length of logging road needed to justify road construction. In particular, we suggest that governments and certification bodies need to highlight more clearly the biodiversity and environmental impacts of logging roads.

The pleasure of pursuit: recreational hunters in rural Southwest China exhibit low exit rates in response to declining catch.

Hunting is one of the greatest threats to tropical vertebrates. Examining why people hunt is crucial to identifying policy levers to prevent excessive hunting. Overhunting is particularly relevant in Southeast Asia, where a high proportion of mammals and birds are globally threatened. We interviewed hunters in Southwest China to examine their social behavior, motivations, and responses to changes in wildlife abundance. Respondents viewed hunting as a form of recreation, not as an economic livelihood, and reported that they would not stop hunting in response to marked declines in expected catch. Even in scenarios where the expected catch was limited to minimal quantities of small, low-price songbirds, up to 36.7% of respondents said they would still continue to hunt. Recreational hunting may be a prominent driver for continued hunting in increasingly defaunated landscapes; this motivation for hunting and its implications for the ecological consequences of hunting have been understudied relative to subsistence and profit hunting. The combination of a preference for larger over smaller game, reluctance to quit hunting, and weak enforcement of laws may lead to hunting-down-the-web outcomes in Southwest China.

Avian responses to selective logging shaped by species traits and logging practices.

Selective logging is one of the most common forms of forest use in the tropics. Although the effects of selective logging on biodiversity have been widely studied, there is little agreement on the relationship between life-history traits and tolerance to logging. In this study, we assessed how species traits and logging practices combine to determine species responses to selective logging, based on over 4000 observations of the responses of nearly 1000 bird species to selective logging across the tropics. Our analysis shows that species traits, such as feeding group and body mass, and logging practices, such as time since logging and logging intensity, interact to influence a species' response to logging. Frugivores and insectivores were most adversely affected by logging and declined further with increasing logging intensity. Nectarivores and granivores responded positively to selective logging for the first two decades, after which their abundances decrease below pre-logging levels. Larger species of omnivores and granivores responded more positively to selective logging than smaller species from either feeding group, whereas this effect of body size was reversed for carnivores, herbivores, frugivores and insectivores. Most importantly, species most negatively impacted by selective logging had not recovered approximately 40 years after logging cessation. We conclude that selective timber harvest has the potential to cause large and long-lasting changes in avian biodiversity. However, our results suggest that the impacts can be mitigated to a certain extent through specific forest management strategies such as lengthening the rotation cycle and implementing reduced impact logging.