Segregation in the African wintering ranges of English and Swiss Swallow Hirundo rustica populations: a stable isotope study

Capsule Stable isotope analysis of Swallow feathers, grown in Africa, revealed significant differences between populations breeding in Switzerland and England.

Aims To investigate the extent to which Swallow populations breeding in Switzerland and England are separated on their African wintering grounds.

Methods Swallows were caught at breeding colonies, biometric measurements were taken and feathers, grown in Africa, were collected. Feathers were combusted in a Carlo Erba C/N/S analyser and the δ¹³C and δ¹⁵N signatures were measured using a mass spectrometer.

Results The δ¹³C signatures of Swiss birds were significantly more depleted than those of birds from England. The δ¹⁵N signatures did not differ between the two populations.

Conclusion Birds from Switzerland and England probably winter in geographically distinct parts of Africa. The Swiss birds probably feed on prey that are more reliant on C₃ vegetation, from woodlands, than the prey of English birds, which are more reliant on C₄ vegetation, from grasslands.     

The Salton Sea as critical habitat to migratory and resident waterbirds

Concern about the Salton Sea ecosystem, based on potential impacts of increasing salinity, contaminants, disease outbreaks, and large die-offs of birds, is heightened because of tremendous prior loss and degradation of wetland habitat in western North America. In 1999, we used a variety of survey methods to describe patterns of abundance of birds at the Salton Sea and in adjacent habitats. Our results further documented the great importance of the Salton Sea within the Pacific Flyway to wintering, migratory, and breeding waterbirds. Exclusive of Eared Grebes, we estimated about 187000 individual waterbirds at the Salton Sea in January, 88000 in April, 170000 in August, and 261000 in November. Additional surveys of Eared Grebes in November and December suggested the total population of all waterbirds was about 434000 to 583000 in those months, respectively. We also documented breeding by about 14000 pairs of colonial waterbirds. Waterbirds were particularly concentrated along the northern, southwestern, southern, and southeastern shorelines and river deltas. By contrast, some species of wading birds (Cattle Egret, White-faced Ibis, Sandhill Crane) and shorebirds (Mountain Plover, Whimbrel, Long-billed Curlew) were much more numerous in agricultural fields of the Imperial Valley than in wetland habitats at the Sea. Various studies indicate the Salton Sea is of regional or national importance to pelicans and cormorants, wading birds, waterfowl, shorebirds, and gulls and terns. Important taxa are the Eared Grebe, American White Pelican, Double-crested Cormorant, Cattle Egret, White-faced Ibis, Ruddy Duck, Yuma Clapper Rail, Snowy Plover, Mountain Plover, Gull-billed, Caspian, and Black terns, and Black Skimmer. Proposed restoration projects should be carefully assessed to ensure they do not have unintended impacts and are not placed where large numbers of breeding, roosting, or foraging birds concentrate. Similarly, plans to enhance opportunities for recreation or commerce at the Sea should aim to avoid or minimize disturbance to birds. Future research should focus on filling gaps in knowledge needed to effectively conserve birds at the Salton Sea.     

The decline of Afro‐Palaearctic migrants and an assessment of potential causes

There is compelling evidence that Afro‐Palaearctic (A‐P) migrant bird populations have declined in Europe in recent decades, often to a greater degree than resident or short‐distance migrants. There appear to have been two phases of decline. The first in the 1960s–1970s, and in some cases into the early 1980s, largely affected species wintering predominantly in the arid Sahelian zone, and the second since the 1980s has mostly affected species wintering in the humid tropics and Guinea forest zone. Potential drivers of these declines are diverse and are spread across and interact within the migratory cycle. Our knowledge of declining species is generally better for the breeding than the non‐breeding parts of their life cycles, but there are significant gaps in both for many species. On the breeding grounds, degradation of breeding habitats is the factor affecting the demography of the largest number of species, particularly within agricultural systems and woodland and forests. In the non‐breeding areas, the interacting factors of anthropogenic habitat degradation and climatic conditions, particularly drought in the Sahel zone, appear to be the most important factors. Based on our synthesis of existing information, we suggest four priorities for further research: (1) use of new and emerging tracking technologies to identify migratory pathways and strategies, understand migratory connectivity and enable field research to be targeted more effectively; (2) undertake detailed field studies in sub‐Saharan Africa and at staging sites, where we understand little about distribution patterns, habitat use and foraging ecology; (3) make better use of the wealth of data from the European breeding grounds to explore spatial and temporal patterns in demographic parameters and relate these to migratory pathways and large‐scale patterns of habitat change and climatic factors; and (4) make better use of remote sensing to improve our understanding of how and where land cover is changing across these extensive areas and how this impacts A‐P migrants. This research needs to inform and underpin a flyway approach to conservation, evaluating a suite of drivers across the migratory cycle and combining this with an understanding of land management practices that integrate the needs of birds and people in these areas.     

American Woodcock Fall Migration Using Central Region Band-Recovery and Wing-Collection Survey Data

ABSTRACT Band-recovery and wing-collection survey data have the potential to provide information on American woodcock (Scolopax minor) fall migration ecology in the Central Region of the United States, yet researchers have not recently analyzed these extensive data sets. We analyzed all direct recoveries of woodcock banded in Michigan, Minnesota, and Wisconsin, USA, as well as wing-collection survey data, to determine the progression of fall migration, the migration direction, and the final destination of woodcock migrating from these states. We did not observe migration initiation based on band recoveries until late October and early November, with most migration occurring during November. Wing-receipt data showed a similar trend, with most change in mean receipt latitude occurring from 1 November to 5 December. During November, wing receipts were spread through the entire Central Region. By 15–31 December, 92% (n = 26) of band recoveries were on the wintering grounds (south of latitude 33°N). Most banded woodcock from Michigan, Minnesota, and Wisconsin wintered in Louisiana, USA. Woodcock banded in these states will be exposed to harvest for most of the hunting season because they remain in these states through November. If the population status of local birds is a concern, managers should consider this migration pattern when setting season dates.     

北京十渡自然保护区越冬黑鹳的种群生态调查

为了解黑鹳在北京地区越冬的生态特点,于2004年1月至2007年3月采用直接观察法对北京市拒马河自然保护区越冬黑鹳的数量、栖息地选择和取食规律进行了观察。结果表明拒马河流域已成为北京地区越冬黑鹳稳定的栖息地,种群数量超过20只。越冬聚群从11月开始,分群时间为次年2月。取食地相对集中,取食活动在越冬初期以上午和中午为主,中期以下午为主,末期则分为早晚两个时段。干旱和人为活动导致的适宜取食地减少是影响黑鹳生存的主要因素。     

Confirmation of a wintering ground of Ross's Gull Rhodostethia rosea in the northern Labrador Sea

Ross's Gull Rhodostethia rosea is one of the world's least known seabirds; < 1% of the estimated global population can be accounted for at known breeding sites, and its wintering range has never been determined. Anecdotal reports over the last two centuries have prompted extensive speculation as to possible wintering areas used by this species in the north Pacific/Bering Sea region, but none has ever been confirmed. Using satellite and geolocator telemetry, we show that some Ross's Gulls from a colony in the Canadian Arctic winter in a restricted area of the northern Labrador Sea. Our discovery of a wintering area in the northwest Atlantic indicates that Ross's Gulls breeding in the Nearctic may be part of a disjunct population, or that birds breeding in the Palaearctic may winter off the east coast of North America.     

Seasonal abundance of nonbreeding Piping Plovers on a Georgia barrier island

ABSTRACT.   Although breeding populations of Piping Plovers are well studied, their winter distribution is less clear. We studied the seasonal abundance of nonbreeding Piping Plovers ( Charadrius melodus ) during the winters of 2003–2004 and 2004–2005 on Little St. Simons Island (LSSI), Georgia. Our objectives were to determine the relative abundance of individuals from three breeding populations at LSSI, and identify possible differences among populations in arrival time, winter movements, or departure time. We observed up to 100 Piping Plovers during peak migration, and approximately 40 plovers wintered at LSSI. From July 2004 to May 2005, approximately 20% of the Great Lakes breeding population used LSSI. Plovers were not present at LSSI during June. All breeding populations of Piping Plovers had similar patterns of temporal occurrence on LSSI, suggesting no need for population-specific management plans at this site. Our results suggest that LSSI is among the most important wintering sites on the Atlantic coast for Piping Plovers, especially for individuals from the endangered Great Lakes population.     

白冠长尾雉越冬期栖息地选择的多尺度分析

2000年至2002年冬季,在河南董寨国家级自然保护区对我国特有珍稀雉类白冠长尾雉（Syrmaticus reevesii）越冬期栖息地进行了调查,并结合RS和GIS在多个尺度上对其栖息地选择进行了分析.结果表明,不同尺度上影响白冠长尾雉越冬期栖息地选择的因素存在差异,影响因子之间还存在相互作用.在微生境上,影响因子主要是坡度、乔木盖度以及坡向余弦值与灌木高度的相互作用;在115 m尺度上,关键因子是灌木林、阔叶林和针叶林的面积;250m尺度上,主要因子是针叶林和阔叶林的面积及针叶林与阔叶林面积的相互作用;对于距离因素,到河漫滩和到农田的距离是影响白冠长尾雉越冬期栖息地选择的关键因子.根据回归分析和AIC及AICc值,115 m尺度上栖息地变量对白冠长尾雉越冬期的栖息地选择影响最大.综合分析发现,在较大的尺度上,影响白冠长尾雉越冬期栖息地选择的关键因子有针叶林面积、阔叶林面积、针叶林和灌丛面积的相互作用、到河漫滩的距离以及到农田的距离.