Human‐mediated habitat transformation is increasingly evident around the world. Yet, how this transformation influences species’ niche width and overlap remains unclear. On the one hand, ...human‐mediated habitat transformation promotes increased species similarity through trait‐based filtering, and an increased prevalence of generalist species with broad niches, resulting in functional homogenization. On the other hand, species that colonize transformed habitats could use empty niches, resulting in decreased species similarity and an expansion of assemblage‐level niche space. Here we explore these two alternatives in eight highly diverse passerine assembles in natural, rural and urban habitats in south and southwest China, a rapidly developing region of the world. Based on stable isotopes, we found that species’ niche width increased from natural to human‐made habitats, but there were no differences in niche overlap among habitats. Therefore, we found evidence for niche expansion, with generalists appearing to use empty niches created by human habitat modification, and with assemblages being comprised of complementary species. Further research is needed to determine whether increased between‐ or within‐individual niche variation is the main driver of niche expansion in transformed habitats.
What structures the organization of mixed‐species bird flocks, so that some ‘nuclear’ species lead the flocks, and others follow? Previous research has shown that species actively listen to each ...other, and that leaders are gregarious; such gregarious species tend to make contact calls and hence may be vocally conspicuous. Here we investigated whether vocal characteristics are associated with leadership, using a global dataset of mixed‐species flock studies and recordings from sound archives. We first asked whether leaders are different from following or occasional species in flocks in the proportion of the recordings that contain calls (n = 58 flock studies, 145 species), and especially alarm calls (n = 111 species). We found that leaders tended to have a higher proportion of their vocalizations that were classified as calls than occasional species, and both leaders and following species had a significantly higher proportion of their calls rated as alarms compared to occasional species. Next, we investigated the acoustic characteristics of flock participants’ calls, hypothesizing that leaders would make more calls, and have less silence on the recordings. We also hypothesized that leaders’ calls would be simple acoustically, as contact calls tend to be, and thus similar to each other, as well as being detectable, in being low frequency and with high frequence bandwidth. The analysis (n = 45 species, 169 recordings) found that only one of these predictions was supported: leading species were less often silent than following or occasional species. Unexpectedly, leaders’ calls were less similar to each other than occasional species. The greater amount of information available and the greater variety of that information support the hypothesis that leadership in flocks is related to vocal communication. We highlight the use of sound archives to ask questions about behavioral and community ecology, while acknowledging some limitations of such studies.
The pace‐of‐life hypothesis predicts no impact of urbanization on stress responses. Accordingly, several studies have been inconsistent in showing differences in breath rate (BR), a proxy of acute ...stress responses to handling in passerines, between rural and urban areas. However, this evidence is limited to a single bird species and a limited geographic region (SW Europe). No study addressed whether this pattern is also apparent in other species or regions, such as in tropical environments, or whether it is dependent on the level of diet specialization, given that diet restriction and change influence stress responses. Here, we tested whether there were differences in BR between habitats and diet groups using eight highly diverse passerine assemblages experiencing different levels of anthropogenic disturbance (i.e., natural, rural, and urban locations) in SW China. We predicted that insectivores and herbivores (frugivores, nectarivores, and seed‐eating species) would show higher BR than omnivores. We also predicted no differences in BR among habitat types. BR was a moderately repeatable trait, which showed a negative relationship with body mass and a positive relationship with the time of the day. We also recorded a relatively strong phylogenetic bias in the expression of this trait. Confirming our predictions, our results showed no differences in BR among natural, rural, and urban locations. Similarly, within species, there were no differences in BR between rural and urban locations. However, we also found that herbivores showed higher BR than omnivores. Overall, our results provide support to the pace‐of‐life hypothesis, but suggest acute stress responses can be diet‐mediated, which may help to explain the marked decline of specialized trophic guilds around the world in response to anthropogenic disturbance.
The pace‐of‐life hypothesis predicts no impact of urbanization on stress responses. Here, we found support to this idea using breath rate, an indicator of acute stress responses, on a broad area and using a large number of species. However, our results also support that stress responses are likely diet‐mediated, with herbivores displaying stronger stress responses than omnivores.
The
Kunming-Montreal Global Biodiversity Framework
puts forward a new conservation target to enhance urban biodiversity. Cities have a great potential for sustaining biodiversity and nurturing a ...healthy relationship between people and our nearest nature. It is especially important in developing countries such as China, which has a rich biodiversity and a rapidly growing urban population. Using citizen science data, we show that 48% of the national bird diversity and 42% of its threatened species have been recorded in the top-20 most avian-diverse cities of China. Urban bird diversity hotspots clustered along the eastern coast, indicating the importance of establishing an inter-city conservation network along the East Asian-Australasian Flyway. This urban conservation network would be a starting point to promote social recognition of biodiversity’s relational value in a country with a vast population and an increasingly important role in meeting UN’s Sustainable Development Goals.
Yearling birds generally display duller colours than adults. This may be due to selection favouring birds with more intensely coloured plumage or to an increase in colour after the first complete ...moult. Most research to date on the topic has been carried out on species with structural plumage coloration or with carotenoid‐based coloration that is produced by the unmodified deposition of pigments. However, no study has been carried out on species whose carotenoids are metabolically modified before deposition. In this study, we assess age‐related changes in the carotenoid‐based coloration of European Serins, a species that metabolically processes carotenoids before they can be deposited into feathers. Birds were captured over consecutive years and we carried out both cross‐sectional and longitudinal analysis. Adults had significantly greater values of lightness and chroma than yearling birds. However, there were no changes in plumage colour when analysing the same individuals captured in subsequent seasons. Plumage lightness and chroma of adult males after moult were related to body mass, suggesting a role of body condition on plumage coloration. Our results suggest that changes in plumage coloration with age in European Serins are due to a selection process that favours more intensely coloured individuals.
Migratory shorebirds select stopover sites to fuel their migration across heterogeneous coastal landscapes with abundant prey resources. Quantifying the degree of dietary specialization between ...closely-related species and how they partition resources across different coastal habitat types during both spring and autumn migration could identify some interesting possibilities for conservation management given the extent of anthropogenic habitat degradation at critical stopover sites. Here we used a comparative approach to examine diet specialization and feeding rates of two migratory Numenius curlew species, Far Eastern Curlew Numenius madagascariensis and Eurasian Curlew N. arquata populations, at an important stopover site in the Yellow Sea, China, and to assess the influence of habitat type, presence of human disturbance (activities related to aquaculture and oil production), and migratory season on their feeding behavior. Far Eastern Curlews were more dependent on tidal crabs and exhibited less dietary flexibility than its closely-related congener. Feeding rates on crabs by Far Eastern Curlews were not significantly different between mudflat and Suaeda salsa saltmarsh habitat but were negatively influenced by human disturbance and were higher during spring migration. In contrast, these effects were not apparent for Eurasian Curlew which fed predominantly on ragworms in saltmarsh habitat. The differences in prey type and feeding rates between adjacent habitats and migration seasons could explain how these two congeners fit syntopically along coastal wetland resource gradients. The extensive utilization of S. salsa habitat by both species suggests that saltmarshes represent an important feeding habitat for these species and that further conservation efforts aimed at reducing human disturbance would benefit both species and may lead to improved feeding rates for Far Eastern Curlews.
•Far Eastern Curlews exhibited greater feeding specialization on crabs and less dietary flexibility than Eurasian Curlews.•Differences in feeding rates on crabs by Eurasian Curlews were significant between habitats but were not for Far Eastern Curlews.•Feeding rates on crabs by Far Eastern Curlews were negatively influenced by human disturbance, but not for Eurasian Curlew.•Differential prey resource use and feeding rates may explain how both curlews fit syntopically along coastal wetland resource•Lower dietary flexibility might be a reason for the surprisingly rapid population decline of the Far Eastern Curlew.
Resolving trade‐offs between economic development and biodiversity conservation needs is crucial in currently developing countries and in particularly sensitive systems harboring high biodiversity. ...Yet, such a task is challenging because human activities have complex effects on biodiversity. We assessed the effects of intense economic development on Hainan Island (southern China) on different components of biodiversity. This highly biodiverse tropical island has undergone extensive economic development and conversion of forest to agriculture and urban area. We identified 3 main transformation areas (low, medium, and high transformation) based on land‐use, local‐climate, and economic changes across 145 grids (10 × 10 km), and estimated changes in avian biodive6rsity from 1998 to 2013. We recorded ongoing taxonomic biotic homogenization throughout the island. Differences between traditional and directional alpha diversity decreased by 5%. Phylogenetically clustering increased by 0.5 points (W = 7928, p < 0.01), and functional overdispersion increased by 1 point (W = 16,411, p < 0.01). Initial taxonomic, phylogenetic, and functional scores correlated negatively with changes in these scores across all transformation areas (all ps < 0.01). At the local scale, economic and environmental indicators showed complex and divergent effects across transformation areas and biodiversity components. These effects were only partially ameliorated in an ecological function conservation area in the mountainous central part of the island. We found complex effects of economic development on different biodiversity dimensions in different areas with different land uses and protection regimes and between local and regional spatial scales. Profound ecosystem damage associated with economic development was partially averted, probably due to enhanced biodiversity conservation policies and law enforcement, but not without regional‐scale biotic homogenization and local‐scale biodiversity loss.
Compensaciones entre el Desarrollo Económico y la Conservación de la Biodiversidad en una Isla Tropical
Resumen
Es muy importante resolver las compensaciones entre el desarrollo económico y la conservación de la biodiversidad en los países que actualmente se encuentran en desarrollo y en los sistemas particularmente sensibles que albergan una gran biodiversidad. Sin embargo, dicha labor es un reto porque las actividades humanas tienen efectos complejos sobre la biodiversidad. Analizamos los efectos del desarrollo económico intenso en la isla de Hainan (sur de China) sobre diferentes elementos de la biodiversidad. Esta isla tropical con una gran biodiversidad ha sufrido un desarrollo económico extenso y la conversión forestal a campos agrícolas y áreas urbanas. Identificamos tres áreas principales de transformación (baja, media y alta) con base en cambios en el uso de suelo, clima local y en la economía a lo largo de 145 cuadrantes (10 × 10 km) y estimamos los cambios en la diversidad de aves desde 1998 hasta 2013. Registramos la homogenización biótica continua de los taxones en la isla. La diferencia entre la diversidad alfa tradicional y direccional disminuyó 5%. Las agrupaciones filogenéticas incrementaron 0.5 puntos (W = 7928, p < 0.01) y la sobredispersión funcional incrementó un punto (W = 16411, p < 0.01). Los puntajes taxonómicos, filogenéticos y funcionales iniciales estuvieron correlacionados negativamente con los cambios en estos puntajes en todas las áreas de transformación (todas p< 0.01). En la escala local, los indicadores económicos y ambientales mostraron efectos complejos y divergentes en las áreas de transformación y los elementos de la biodiversidad. Estos efectos sólo mejoraron parcialmente en un área de conservación con función ecológica en la parte montañosa al centro de la isla. Descubrimos que el desarrollo económico tiene efectos complejos sobre diferentes dimensiones de la biodiversidad en diferentes áreas con usos de suelo y sistemas de protección diferentes y entre las escales espaciales local y regional. El daño profundo al ecosistema asociado con el desarrollo económico pudo evitarse parcialmente, probablemente debido a la mejora en las políticas de conservación de la biodiversidad y la aplicación de la ley, pero no sin sufrir pérdidas de la biodiversidad a escala local y una homogenización biótica a escala regional.
Article impact statement: Economic development may have detrimental effects for biodiversity conservation even in a context of enhanced environmental protection.
摘要
权衡经济发展和生物多样性保护之间的关系是发展中国家目前面临的重要问题, 尤其是对那些生物多样性丰富、生态系统敏感的发展中国家而言。然而, 由于人类活动对生物多样性的影响十分复杂, 这样的任务非常具有挑战性。本研究中, 我们在中国的海南岛探讨了经济的快速发展是如何影响生物多样性不同组分的。作为生物多样性极高的热带岛屿, 海南岛在过去几十年经济快速发展, 土地利用剧烈改变(如, 大面积的森林变成农田, 并城市化)。我们基于 145 个10 × 10公里网格的土地利用、气候和经济变化将海南岛分为3种主要的栖息地变化模式, 并分析了这3类模式中鸟类多样性在1998~2013年的变化。结果显示, 鸟类群落在传统和定向的α多样性之间的差异下降了5%, 反映了海南岛正处于物种分类上的同质化过程。鸟类群落的谱系聚集程度上升了0.5 (W = 7928, p < 0.01), 功能性状发散上升了1 (W = 16411, p < 0.01)。在所有的栖息地变化模式中, 群落的物种分类、系统发育和功能结构的变化程度均与它们的初始状态呈负相关 (P < 0.01)。在局域尺度, 经济发展和环境因素对不同栖息地变化模式和生物多样性组分具有复杂且不同的影响。这些影响仅在海南岛中部山区新建的生态功能保护区内得到部分优化。我们的研究发现了经济发展对热带岛屿不同区域、不同土地利用和保护策略以及不同生物多样性维度在局域和区域尺度上的复杂影响。生物多样性保护政策和执法的强化, 似乎可以避免经济发展导致的部分生态系统退化, 但仍难以避免区域尺度上的生物同质化和局域尺度上的生态多样性丧失。
权衡热带岛屿的经济发展与生物多样性保护
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