Causes and consequences of bird extinctions

Journal ArticleIncreased human domination of the planet has caused the declines and extinctions of countless species. Each species has not only intrinsic value, but ecological functions of organisms are also essential for the integrity of ecosystems that allow people to benefit from essential free ecosystem services, such as carcass disposal, pest control, pollination and seed dispersal. In order to retain global biodiversity and ecosystem services, we must study the factors behind species' declines, understand their consequences, improve capacity of human-dominated landscapes to maintain biodiversity, and persuade local human communities to preserve their natural heritage. With birds as my focal group, I take various approaches to addressing these issues, including an analysis of the world's bird species, modeling bird extinctions in the 21st century, field research on effects of habitat degradation on tropical forest bird communities, a radio telemetry study of forest birds that persist in deforested landscapes, and a review of birdwatching tourism. My research sheds light on the ecological consequences of species' declines, the long-term impacts of tropical forest degradation, the role of mobility for persistence of birds in deforested tropical landscapes, the conservation significance of integrating human-dominated and native habitats, and the importance of local human communities for biodiversity preservation. Analyzing a database of all the world's bird species, I found that certain functional groups, such as frugivores, herbivores, piscivores and scavengers, are more extinction-prone than average, and some areas, such as oceanic islands and forested landscapes, have significantly more species that are at risk. These patterns are likely to deteriorate in the 21st century, signaling the potential loss of crucial ecosystem services such as pest control, pollination, and seed dispersal. In Uganda, I found that beyond a certain intensity, one-time forestry practices can have long-term negative impacts on forest birds through changes in vegetation structure, whereas low intensity forestry can be compatible with the preservation of local biodiversity. The largest simultaneous study of forest understory insectivorous birds, their diets and prey base in the premontane forest fragments of southern Costa Rica showed that these area-sensitive species disappear from small forest fragments not due to lack of food, but because their limited mobility prevents movements between small habitat patches, making them vulnerable to stochastic, local extinctions. On the other hand, three forest bird species that were able to persist in agricultural countryside dominated by coffee plantations were able to do so either by being pre-adapted to disturbed habitats (Catharus aurantiirostris) or by being highly mobile and making efficient use of 11% of the landscape still covered by trees (Tangara icterocephala and Turdus assimilis). Results from radio telemetry also underlined the importance of remnant trees, riparian strips, and small forest patches for native forest species. An analysis of birdwatching tourism revealed that, just as human-dominated landscapes are often excluded from conservation initiatives, most local people in less-developed areas are also excluded from the income generated by birdwatching that is overwhelmingly conducted by wealthy citizens of developed countries. If the combination of large scale habitat clearance, exclusion of human-dominated landscapes from conservation policies, and alienation of local communities from ecotourism initiatives continues, consequent disappearance of species is likely to cause collapses in ecosystems and their services that are crucial for humanity

Ibis quest

Journal ArticleThe day I arrived in Ethiopia, researcher Yilma Dellelegn Abebe of the Ethiopia Wildlife and Natural History Society (EWNHS) was just leaving the capital city, Addis Ababa, to search for three Northern Bald Ibises in a remote, roadless area of the country. These critically endangered birds had been satellite-tagged earlier in Syria by a team of researchers from Britain's Royal Society for the Protection of Birds (RSPB), BirdLife Middle East, and Cambridge University. According to the satellite signals, they had crossed into Ethiopia the previous month and were frequenting an area only some 80 kilometers to the northeast of us. Also known as the Walldrap, the Northern Bald Ibis (Geronticus eremita) was once common in the Mediterranean area, but the birds now stand in imminent danger of extinction, with fewer than 300 individuals existing in the wild. Until 2002, the only known populations were in Morocco and Turkey, and these birds were nonmigratory

Forest fragmentation hits insectivorous birds hard

Journal ArticleHabitats around the world, especially in the tropics, are being fragmented at a rapid rate, causing a tremendous loss of biodiversity[1]. For example, 12% of the approximately 10,000 bird species are threatened with extinction in the next 10 to 100 years, and another 8% are near-threatened[2]. This loss of species is likely to result in the collapse of significant ecosystem processes and free ecosystem services to people[3], such as pest control by insectivorous birds. Tropical forest insectivorous birds, such as antbirds, woodcreepers, and wrens, present a good example of an important, species-rich group of small, noncharismatic organisms who do not get much public attention, but whose demise may have significant negative ecological and financial consequences. They are among the species most likely to go extinct as a result of forest fragmentation[4] and their loss may result in insect pest outbreaks in tropical forests and surrounding agricultural areas. Finding out the causes of the disappearance of understory insectivores may help explain the disappearance of the other small, short-lived, and specialized bird species that comprise the majority (65%) of threatened bird species in the world[5]. In a recent study of the factors behind the disappearance of insectivorous birds in Costa Rican forest fragments reported in the Proceedings of the National Academy of Sciences[6], we provide evidence that interfragment dispersal, rather than food limitation, may be the most critical factor for the persistence of understory insectivorous birds in forest fragments. As in previous studies[4,7], small forest fragments had significantly lower insectivore species diversity and abundance than more extensive forest. However, our initial hypothesis - that the decline of insectivorous birds in forest fragments is caused by an impoverished invertebrate prey base - was not supported by invertebrate counts and examination of bird diet samples. Instead, the inability of understory insectivores to use the nonforest matrix surrounding the fragments seemed to be the main reason for their decline

Impacts of birdwatching on human and avian communities

Journal ArticleEcotourism can be a vehicle for community-based conservation if it is conducted with an emphasis on the well-being of local ecosystems and human communities. Birdwatchers form the largest group of ecotourists, and are, on average, well-educated, wealthy and committed. This makes them ideal ecotourists for community-based conservation. Therefore, there is a need for a comprehensive review of birdwatching from a conservation biology perspective. Specific objectives here are: (1) to review the economic potential of non-residential birdwatching for community-based conservation; (2) to outline the potential benefits and problems associated with this activity; and (3) to provide suggestions for improving the conservation value of birdwatching. Birdwatching tourism has a high potential to improve the financial and environmental well-being of local communities, educate locals about the value of biodiversity and create local and national incentives for successful protection and preservation of natural areas. However, there needs to be more research on the economical and environmental impacts of this hobby, birdwatchingrelated disturbance needs to be reduced, and much has to be done to increase the financial contribution of birdwatching to local communities

Promoting community-based bird monitoring in the tropics: conservation, research, environmental education, capacity-building, and local incomes

ManuscriptLong-term, locally-based biodiversity monitoring programs are essential for understanding and mitigating the effects of global change on tropical biodiversity while providing capacity-building, environmental education, and public outreach. However, these programs are lacking in most tropical countries. Birds are the best-known major group of organism, comprise excellent environmental indicators, are relatively easy to monitor, and are met with enthusiasm and interest by people worldwide. Bird monitoring programs using mist nets and bird banding (ringing) are especially valuable, as these well-established techniques enable the use of capture-mark-recapture (CMR) models to measure population change and other demographic parameters. Equally important for conservation, the ability to capture and release birds makes it possible to provide hands-on ornithological training and educational activities to students, conservationists, villagers, decision-makers, journalists, and other local people. Bird banding programs provide local jobs for research assistants, who often go on to productive careers in conservation, education, research, or ecotourism. Long-term bird banding stations also provide the nuclei, infrastructure, and staff for monitoring, education, and conservation programs focused on other taxa. As successful examples from Costa Rica and Ethiopia show, bird monitoring programs that integrate conservation, ecological research, environmental education, capacity-building, and income generation are cost-effective tools to achieve the goals of community-based biodiversity conservation and poverty reduction in the developing world. Therefore, locally-based and long-term bird monitoring programs should be encouraged, established, and funded throughout the tropics

People skills for the conservation professional

Journal ArticleConservation scientists are increasingly becoming aware of the importance of the human aspects of conservation, and in conservation circles, ‘‘social science'' is the word of the day. There is a rapidly growing social science working group in the Society for Conservation Biology and it is hard to imagine a conservation project that does not have a strong emphasis on the importance of working effectively with local people. In fact, most of the challenges in conservation biology are not scientific, but diplomatic-in persuading people to follow the advice of conservation science

Habitat use and movements of native forest birds in southern Costa Rican agricultural countryside

Journal ArticleWe used radio telemetry to study the habitat use, activity budgets, and movements of three bird species that are found in native forest and coffee plantations of southern Costa Rica. We obtained 7522 locations from Turdus assimilis (n=27), Tangara icterocephala (n=53), and Catharus aurantiirostris (n=42), the species ranked from most to least forest-dependent. We caught birds in coffee and radiotracked them to understand their dependence on remnant native vegetation patches. Home range size and frequency of long-distance movement was positively correlated with the species' forest dependence. T. assimilis and T. icterocephala preferred forest fragments, riparian strips and remnant forest trees, mostly avoided coffee plantations, and moved frequently between suitable habitat patches. Even though remnant forest trees and riparian strips covered 3.7% and 4.8% of the land area, respectively, they made up 9%-49% of T. assimilis and T. icterocephala home ranges, and were especially important in the dry season (25%-49%). C. aurantiirostris, an edge/second growth species, was highly sedentary, opportunistic in its habitat preference in the wet season, and preferred second growth in the dry season. Home range size for C. aurantiirostris and T. icterocephala decreased significantly in the dry season, concentrating around food resources in secondary growth and fruiting trees, respectively. Native habitat patches were cooler, more humid, had reduced microclimatic fluctuations, and increased in importance during the dry season. Remnant patches of native vegetation in Costa Rican agricultural countryside provide crucial resources for these bird species that evolved in forest, but now have to live in an increasingly deforested landscape. Active management of tropical humandominated ecosystems can significantly increase their capacity to support native bird species

Mapping functional traits: comparing bundance and presence-absence estimates at large spatial scales

journal articleEfforts to quantify the composition of biological communities increasingly focus on functional traits. The composition of communities in terms of traits can be summarized in several ways. Ecologists are beginning to map the geographic distribution of trait-based metrics from various sources of data, but the maps have not been tested against independent data. Using data for birds of the Western Hemisphere, we test for the first time the most commonly used method for mapping community trait composition - overlaying range maps, which assumes that the local abundance of a given species is unrelated to the traits in question - and three new methods that as well as the range maps include varying degrees of information about interspecific and geographic variation in abundance. For each method, and for four traits (body mass, generation length, migratory behaviour, diet) we calculated community-weighted mean of trait values, functional richness and functional divergence. The maps based on species ranges and limited abundance data were compared with independent data on community species composition from the American Christmas Bird Count (CBC) scheme coupled with data on traits. The correspondence with observed community composition at the CBC sites was mostly positive (62/73 correlations) but varied widely depending on the metric of community composition and method used (R2: 5.661027 to 0.82, with a median of 0.12). Importantly, the commonly-used range-overlap method resulted in the best fit (21/22 correlations positive; R2: 0.004 to 0.8, with a median of 0.33). Given the paucity of data on the local abundance of species, overlaying range maps appears to be the best available method for estimating patterns of community composition, but the poor fit for some metrics suggests that local abundance data are urgently needed to allow more accurate estimates of the composition of communities

Landscape constraints on functional diversity of birds and insects in tropical agroecosystems

Journal ArticleIn this paper, we analyze databases on bird and insects to assess patterns of functional diversity in human-dominated landscapes in the tropics. Perspective from developed landscapes is essential for understanding remnant natural ecosystems, because most species experience their surroundings at spatial scales beyond the plot level, and spillover between natural and managed ecosystems is common. Agricultural bird species have greater habitat and diet breadth than forest species. Based on a global data base, bird assemblages in tropical agroforest ecosystems were comprised of disproportionately more frugivorous and nectarivorous, but fewer insectivorous bird species compared with forest. Similarly, insect predators of plant-feeding arthropods were more diverse in Ecuadorian agroforest and forest compared with rice and pasture, while, in Indonesia, bee diversity was also higher in forested habitats. Hence, diversity of insectivorous birds and insect predators as well as bee pollinators declined with agricultural transformation. In contrast, with increasing agricultural intensification, avian pollinators and seed dispersers initially increase then decrease in proportion. It is well established that the proximity of agricultural habitats to forests has a strong influence on the functional diversity of agroecosystems. Community similarity is higher among agricultural systems than natural habitats and higher in simple than complex landscapes for both birds and insects, so natural communities, low-intensity agriculture and heterogeneous landscapes appear to be critical in the preservation of beta diversity. We require a better understanding of the relative role of landscape composition and the spatial configuration of landscape elements in affecting spillover of functionally important species across managed and natural habitats. This is important for data-based management of tropical human-dominated landscapes sustaining the capacity of communities to reorganize after disturbance and to ensure ecological functioning

Chewing lice (phthiraptera) found on songbirds (Passeriformes) in Turkey

Journal ArticleObjective: This study was performed to detect chewing lice species found on the songbirds at Lake Kuyucuk bird ringing station in the Kars province located in eastern Turkey. Methods: Chewing lice were collected from songbirds captured between September and October 2009. Fifty-one birds belonging to 22 species and 16 genera from 10 families were examined for the louse. Results: Eleven of 51 birds (21.57%) belonging to 7 species; were infested with at least one chewing louse species. The collected lice were identified as Menacanthus chrysophaeus (Kellogg, 1896) on Reed Bunting, Menacanthus pusillus (Nitzsch,1866) on Water Pipits, Calandra Lark and Yellow Wagtail, Myrsidea rustica (Giebel,1874) on Swallow, Brueelia cruciata (Burmeister,1838) on Red-backed Shrike, and Penenirmus rarus (Zlotorzycka,1976) on Chiffchaff. All four Reed Bunting specimens were infested with Menacanthus chrysophaeus. The rate of infestation was 100% in Reed Bunting, Red-backed Shrike and Swallow; 66.7% in Yellow Wagtail; 50% in Calandra Lark and Chiffchaff and 11.1% in Water Pipits. No louse infestation was found in the birds belonging to Paridae, Passeridae, Sylviidae, and Muscipapidae families. Conclusion: Menacanthus chrysophaeus on Reed Bunting and Menacanthus pusillus on Calandra Lark are new hosts for these lice species. All the louse species determined in the present study are fi rst records for Turkey. (Turkiye Parazitol Derg 2011; 35: 34-9)