Total Breeding Population Research Articles

Long-term changes in population size and distribution of Stercorarius maccormicki (Stercorariidae, Charadriiformes) on the Haswell Islands, East Antarctica

Long-term studies are crucial in ecology, environmental change assessment, resource management and biodiversity conservation. Stercorarius maccormicki (hereinafter – south polar skua) are predators that can threaten populations of bird species of the orders Sphenisciformes and Procellariiformes. At many places in Antarctica, abundance trends for the skua are not known or have not been updated. This study is an attempt to answer the question: how did a south polar skua population react to changes in environmental conditions during 1956–2013? The objectives of the study was (1) to establish the dynamics of the breeding skua population on the Haswell Islands, i.e. Haswell Island and the small islands of the Haswell Archipelago during 1956–2013, and (2) to explain the reasons of the changes in the studied population. A secondary research question was whether there were changes in the spatial distribution of the breeding skua population on the Haswell Archipelago during the study period? The studies have been carried out on the Haswell Archipelago (Davis Sea), mainly in Antarctic Specially Protected Area №127 «Haswell Island and adjacent emperor penguin rookery on fast ice». Ground count was the main method for determining the size of bird colonies. South polar skua bred on 3–8 islands of the Haswell Archipelago. In the study period, the population size of the south polar skua has changed on the Haswell Archipelago. A decrease in the number of individuals (-52%) was observed between 1956–1957 and 1966–1967 breeding seasons. Between 1966–1967 and 1999–2000 breeding seasons, the skua population declined by 30.7% and reached the lowest value of 18 pairs. Population growth (344.4%) was recorded between 1999–2000 and 2009–2010 breeding seasons, with an increase of 33.8% and reaching the maximum value (83 pairs) in 2010–2011 breeding season. By 2012–2013 breeding season, the south polar skua population has declined by 13.2%. On Haswell Island, between 1956–1957 and 2012–2013 breeding seasons, there was a change in skua abundance that was similar to the change in the total breeding population on Haswell Archipelago during the entire period. On the small islands of the Haswell Archipelago, the number of breeding south polar skuas declined (-80%) between 1956–1957 and 1962–1963 breeding seasons. The breeding seasons of 1962–1963, 1966–1967 and 1999–2000 were characterised by the lowest number of individuals. Between 1999–2000 and 2009–2010 breeding seasons, the number of south polar skuas increased by 400%. A decrease in abundance (-41.6%) occurred between 2009–2010 and 2010–2011, followed by the consequent increase (by 36.3%) by 2012–2013 breeding season. During the study period, changes in the abundance of south polar skuas on the Haswell Archipelago were independent of changes in average daily November temperatures between 1956–1957 and 2012–2013 breeding seasons (Mann-Whitney test U = 0, p = 0.0017, n = 7 (asymptotic (2-sided))), when they were laying eggs and heating them. The number of south polar skuas changed independently of changes in the number of individuals of their prey, represented by Aptenodytes forsteri, Pygoscelis adeliae, and Fulmarus glacialoides (respectively U = 49, p = 0.0006, n = 7; U = 16, p = 0.029, n = 4; U = 16, p = 0.029, n = 4 (asymptotic (2-sided))). The high mortality of eggs, chicks and local weather conditions could influence the breeding success of the south polar skua, which could have a delayed effect on their long-term dynamics. Human activities have influenced the skua population, but have not been studied quantitatively. On the Haswell Archipelago, the reasons for historical changes in abundance of the breeding skua population remain largely unclear.

Highly pathogenic avian influenza causes mass mortality in Sandwich TernThalasseus sandvicensisbreeding colonies across north-western Europe

SummaryIn 2022, highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b became enzootic and caused mass mortality in Sandwich TernThalasseus sandvicensisand other seabird species across north-western Europe. We present data on the characteristics of the spread of the virus between and within breeding colonies and the number of dead adult Sandwich Terns recorded at breeding sites throughout north-western Europe. Within two months of the first reported mortalities, 20,531 adult Sandwich Terns were found dead, which is >17% of the total north-western European breeding population. This is probably an under-representation of total mortality, as many carcasses are likely to have gone unnoticed and unreported. Within affected colonies, almost all chicks died. After the peak of the outbreak, in a colony established by late breeders, 25.7% of tested adults showed immunity to HPAI subtype H5. Removal of carcasses was associated with lower levels of mortality at affected colonies. More research on the sources and modes of transmission, incubation times, effective containment, and immunity is urgently needed to combat this major threat for colonial seabirds.

Foraging Habitat and Its Effects on the Tricolored Blackbird’s Breeding Distribution and Abundance in the Sierra Nevada Foothills, California

The grassland-dominated eastern Central Valley and Sierra Nevada foothills of California, from Placer to Stanislaus counties, supported at least 43,000–55,000 breeding Tricolored Blackbirds (Agelaius tricolor) annually from 2014 to 2018—about 30% of the statewide population. We found that within 5 km of a colony, the extent of land cover used for foraging, grassland–herbaceous, and to a lesser extent annual crops and irrigated pasture, exceeded their proportions in this region as a whole, suggesting that nesting Tricolored Blackbirds select colony sites where these habitats are more abundant. Other land-cover types were underutilized for foraging, suggesting avoidance. The probability of Tricolored Blackbird occupancy of blocks of 100 km2 was strongly associated with the extent of the selected land-cover types. The relationship between average density of the breeding population and the extent of the selected land-cover types was significant but weaker, implying that other factors are important in determining density. From 2014 to 2018, development and mining eliminated or degraded 9 of 79 colony sites and made 4 others unsuitable by reducing the extent of nearby foraging habitat, although the total breeding population in the region did not decline. We recommend that conservation measures for the Tricolored Blackbird in federally and state-approved habitat-conservation plans in Placer and Sacramento counties, which support the largest breeding populations in the central Sierra foothills but where urban development is rapid, be reevaluated on the basis of recent colony locations and recognition of the critical role of grassland, annual crops, and irrigated pasture as foraging habitat.

Status of the common myna Acridotheres tristis Linnaeus, 1766 in Turkey

The common myna, a species native to central and southern Asia, has been introduced to many countries through the pet trade. The aim of this study was to determine the status of this myna in Turkey. We created a database of sightings of the species in Turkey. The total breeding population of myna birds is estimated to have reached 132–172 pairs. It was reported to have escaped from cages in 11 provinces and populations have become established in urban areas in three provinces. The pet trade has been the main pathway for the introduction of the species. The impact of the myna bird in Turkey remains unclear.

Counting Results of Great Bustard (Otis tarda, Linnaeus, 1758) Between 2013-2020 in Eskişehir, Kütahya and Afyonkarahisar provinces

The Great Bustard (Otis tarda, Linneaus 1758) is a bird species categorized as “Least Concern” in Europe and “Vulnerable” in the world by the IUCN and listed in both CITES and the Bern Convention Annex II. According to the latest estimates, Turkey’s population makes up only 1-2% of the global population, which is represented by 44.000-57.000 individuals. This population study was carried out in 7 different locations in Eskişehir, Kütahya, and Afyonkarahisar provinces between March 2013 and January 2020. In summary, the surveyed areas were recorded as having a total wintering population of 205 individuals, a total breeding population of 100 individuals, and a total summering population of 70 individuals. The surveyed areas represent an average of 17-29% of Turkey’s population in wintering period, an average of 8-14% of Turkey’s population in breeding period, and an average of 6-10% of Turkey’s population in summering period. Urgent implementation of protective measures is required to prevent the population decline of the Great Bustard within the study areas. Detailed ethological studies on the species are recommended as a means of creating new measures to not only stop population decline but to promote population growth to healthy levels.

Correcting for within-season demographic turnover to estimate the island-wide population of King Penguins (Aptenodytes patagonicus) on South Georgia

King Penguins (Aptenodytes patagonicus) live in remote locations, in large colonies with asynchronous breeding. These three factors hinder the design and conduct of King Penguin censuses, and assessments of trend often require piecing together mismatched surveys of different demographic components. This study introduces a new method to remotely census these populations year-round and correct population estimates for the King Penguin’s unique breeding phenology. We combined in situ ground counts with estimates based on high-resolution satellite imagery to catalog the distribution of breeding colonies and estimate population abundance across the island of South Georgia, in the south Atlantic. While most King Penguin populations are forecast to decline significantly over the next century, South Georgia is expected to experience more favorable conditions and represents an important refugium for the species, though the challenges of surveying King Penguins have precluded a comprehensive census. Due to the variable timing of both in situ and remote counts, we developed a discrete time, age- and stage-structured population model that provides stage- and day-specific correction factors for standardization of census counts. We estimate the current population of King Penguins on South Georgia as 405,425 (95% CI 102,624–2,375,061) breeding pairs and find that population trends that do not account for phenological biases persistently underestimate the population growth rate. Correction factors are highly sensitive to annual egg mortality and the total breeding population is best estimated using nest counts of early-breeding pairs. Future efforts to census King Penguin populations may minimize uncertainty by capturing more precise estimates of egg survival and optimizing the timing of ground and satellite censuses to occur during the settlement of early breeders. Accounting for the error associated with current uncertainty in model parameters, 18–32 years of census data would be required to accurately detect trends of a population with a 10% growth rate. While asynchronously breeding species present a unique challenge to population monitoring, careful accounting of within-season dynamics can be used to assemble a self-consistent time series from heterogeneous survey data.

Breeding abundance and population trend of the Peruvian Diving-petrel Pelecanoides garnotii in Chile: Recovery of an endangered seabird?

SummaryAs island ecosystems are among the most critical breeding habitats for seabirds, their protection should enhance population viability for many species. The Peruvian Diving-petrel Pelecanoides garnotii breeds only in Chile and Perú, is an endangered seabird with historically large populations of over 100,000 breeding pairs, but fewer than 1,000 remained in the 1980s and it became the first endangered seabird of the Humboldt Current System. In Chile, they breed on five islands, three of which are legally protected, but only two have a management plan. Between 2010 and 2014, we evaluated the density of nests, burrow occupancy, and colony patch sizes on the islands to estimate the breeding population. The population trend was assessed by compiling historical data available in the literature and several unpublished technical reports. The current breeding population size in Chile was ∼12,500 breeding pairs (95% CI: 10,613–14,676 pairs) that is ∼34% of the breeding pairs reported for Peru (∼36,450 pairs). Choros Island, the only island with adequate protection, accounted for ∼95% of the total breeding population of the Peruvian Diving-petrel in Chile. Historical population trends showed a significant increase in breeding pairs during recent years on Choros Island. It seems that the adequate legal protection of Choros Island is leading to the recovery of Peruvian Diving-petrels, demonstrating that protection of breeding colonies remains an essential strategy for the conservation of endemic seabirds.

Are Western European ospreys (Pandion haliaetus) shortening their migration distances? Evidence from trends of the wintering population in the Iberian Peninsula

Here, we provide evidence that the number of Western European ospreys wintering in the Iberian Peninsula has been increasing over nearly two decades due to a reduction of the migration distances. We compared trends in wintering and breeding populations of ospreys in the Iberian Peninsula and western Europe, respectively, and we provide a detailed description of the present distribution and the numbers of ospreys wintering in the Iberian Peninsula. Observations of the species were collected as a citizen science project in January 2017. Based on the long-term data series from the Andalusian region (2004–2016) and from the Bay of Cadiz site (2000–2016), we estimated temporal trends in the population size of the ospreys wintering in these areas. Trends in the western European breeding population were derived from counts of ospreys migrating over the Strait of Gibraltar conducted by volunteers (1999–2016). All the trends were estimated by fitting a linear regression to the logarithm of the annual counts. For quantifying the origin of ospreys wintering in the Iberian Peninsula, we collected 204 confirmed field sightings of wintering ospreys in Spain and 155 in Portugal. We showed that the number of wintering ospreys has been increasing in southern Spain over the last 16 years. The magnitude of this increase is similar to the rate of change observed in the ospreys breeding across Western Europe. Recoveries of ringed birds in the Iberian Peninsula during winter indicate a reduction in the migration distances of Central and Northern European ospreys, making these birds winter at higher latitudes more than before. According to our results, this reduction in the migration distance was fairly uniform among different breeding populations in western Europe, but it did not affect all age classes equally, with juvenile birds more prone to winter at higher latitudes compared to adult birds. Our results showed that the overall number of ospreys which are shortening their migration distance, now over 3% of the total breeding population estimated for western Europe, is on an upward trend.

Quantifying the contribution of immigration to population dynamics: a review of methods, evidence and perspectives in birds and mammals.

The demography of a population is often reduced to the apparent (or local) survival of individuals and their realised fecundity within a study area defined according to logistical constraints rather than landscape features. Such demographics are then used to infer whether a local population contributes positively to population dynamics across a wider landscape context. Such a simplistic approach ignores a fundamental process underpinning population dynamics: dispersal. Indeed, it has long been accepted that immigration contributed by dispersers that emigrated from neighbouring populations may strongly influence the net growth of a local population. To date however, we lack a clear picture of how widely immigration rate varies both among and within populations, in relation to extrinsic and intrinsic ecological conditions, even for the best-studied avian and mammalian populations. This empirical knowledge gap precludes the emergence of a sound conceptual framework that ought to inform conservation and population ecology. This review, conducted on both birds and mammals, has thus three complementary objectives. First, we describe and evaluate the relative merits of methods used to quantify immigration and how they relate to widely applicable metrics. We identify two simple and unifying metrics to measure immigration: the immigration rate it defined as the ratio of the number of immigrants present in the population at time t+1 and the total breeding population in year t, and πt , the proportion of immigrants among new recruits (i.e. new breeders). Two recently developed methods are likely to provide the most valuable data on immigration in the near future: individual parentage (rather than population) assignments based on genetic sampling, and spatially explicit integrated population models combining multiple sources of demographic data (survival, fecundity and population counts). Second, we report on a systematic literature review of studies providing a quantitative measure of immigration. Although the diversity of methods employed precludes detailed analyses, it appears that the number of immigrants exceeds locally born individuals in recruitment for most avian populations (median πt =0.57, N=45 estimates from 37 studies), a figure twofold higher than estimated for mammalian populations (median πt =0.26, N=33 estimates from 11 studies). Third, recent quantitative studies reveal that immigration can be the main driver of temporal variation in population growth rates, across a wide array of demographic and spatial contexts. To what extent immigration acts as a regulatory process has however been considered only rarely to date and deserves more attention. Overall, it is likely that most populations benefit from immigrants without necessarily being sink populations. Furthermore, we suggest that quantitative estimates of immigration should be core to future demographic studies and plead for more empirical evidence about the ways in which immigration interacts with local demographic processes to shape population dynamics. Finally, we discuss how to tackle spatial population dynamics by exploring, beyond the classical source-sink framework, the extent to which populations exchange individuals according to spatial scale and type of population distribution throughout the landscape.

Colonies of Reddish Egret (Egretta rufescens) in Western Mexico

Very little is known about the numbers and distribution of the Reddish Egret (Egretta rufescens) in western Mexico. To estimate the size and distribution of Reddish Egret colonies along the coast of western Mexico, historical and potential Reddish Egret nesting sites were surveyed in 2008 and 2009. Forty-six colonies were found from Baja California to Chiapas. Mean colony size was 24 pairs/colony (95% CI ± 15; n = 46), but most (74%) colonies were < 20 pairs (Median = 7 pairs; n = 46). The largest colony (258 pairs) and the only two colonies with dark and white morphs were found in Oaxaca. The second largest colony (248 pairs) was found in Baja California Sur. The total breeding population was estimated at 1,108 breeding pairs; 788 pairs in 43 colonies were located in northwestern Mexico (Baja California peninsula, Sonora and Sinaloa, subspecies E. r. dickeyi) and 320 pairs in three colonies were in southern Mexico (Oaxaca and Chiapas, subspecies undetermined). This breeding population, although small, is three to four times larger than previously reported for the Pacific Coast of Mexico (225-300 pairs). Thirty-five (76%) Reddish Egret nesting sites were inside a natural protected area; however, the Oaxaca and Chiapas colonies were not.

Distribution and Abundance of Breeding Striated Caracaras in the Falkland Islands (Malvinas)

We conducted surveys of breeding pairs of the endemic and globally “Near Threatened” Striated Caracara (Phalcoboenus australis) on 79 outer islands in the Falklands archipelago (Islas Malvinas) during the austral-summer breeding seasons of 2013–2014 and 2014–2015. A total of 354 breeding pairs (defined as pairs with evidence of egg-laying), or an archipelago-wide adult breeding population of at least 0.05 birds/km2 was recorded. An additional 477 probable breeding pairs also were found. The distribution of breeding pairs remains similar to that found during surveys in the 1990s and 2000s. Grand Jason, Steeple Jason, New Island, Beauchene Island, and Bird Island, the five islands with the highest numbers of breeding pairs, accounted for half of the total breeding population. “Vegetationally pristine” islands with dense areas of tussac grass (Poa flabellata) and high densities of small burrowing seabirds—namely Bird Island, Saddle Island, and Beauchene Island—supported the highest densities of breeding pairs. Eighty percent of all pairs occurred on National Nature Reserves or on privately owned nature sanctuaries. Our surveys suggest that sustained protection of key breeding sites is critical for the long-term conservation of this species. We recommend that populations of Striated Caracaras at Tierra del Fuego also be surveyed and that the global population status of the species be reassessed.

Abundance, biomass and energy use of native and alien breeding birds in Britain

We quantify the contribution of alien species to the total breeding population numbers, biomass and energy use of an entire taxonomic assemblage at a large spatial scale, using data on British birds from 1997 and 2013. A total of 216 native and 16 alien bird species were recorded as breeding in Great Britain across the two census years. Only 2.8–3.7% of British breeding bird individuals were alien, but alien species co-opted 11.9–13.8% of the energy used by the assemblage, and contributed 19.1–21.1% of assemblage biomass. Neither the population sizes nor biomasses of native and alien species differed, on average, in either census, but alien species biomass is higher than native species biomass for a given population size. Species richness underestimates the potential effects of alien bird species in Britain, which have disproportionately high overall biomass and population energy use. The main driver of these effects is the ring-necked pheasant (Phasianus colchicus), which comprised 74–81% of alien biomass, yet the breeding population of this species is still only a small fraction of the estimated 35 million birds released in the UK in autumn. The biomass of this release exceeds that of the entire breeding avifauna, and suggests that the pheasant should have an important role in structuring the communities in which it is embedded.

Female turnover rate differs between two Northern GoshawkAccipiter gentilisnesting areas, as revealed by DNA analysis of moulted feathers

The turnover rate of breeding Northern Goshawk Accipiter gentilis females in two study areas in southern Norway, which are assumed to experience different levels of illegal human persecution, was estimated using DNA extracted from moulted feathers, along with other characteristics. Female turnover rate over a 4-year period for each nesting territory during 1990–2015 was significantly higher in Aust-Agder County (31.9%; 23 territories), where hunters have long shown antipathy to Goshawks, than in Telemark County (17.3%; 25 territories). Turnover rate was not related to territory quality. The proportion of successful nesting attempts was lower in Aust-Agder (70–75%) than in Telemark (82–84%), but for newly built nests, which are less likely to be known by hunters, the difference was not significant (77.4 vs 79.6%). The proportion of juvenile female Goshawks among recruits and in the total breeding population also did not differ between the two areas. Our findings support the notion that Goshawk persecution was higher in Aust-Agder than in Telemark. We found that the use of phenotypic characteristics for individual recognition was successful in 96.2% of 130 comparisons of female Goshawks from two consecutive nesting attempts, when assessed using genetic markers.

The distribution and abundance of Blue Petrels (Halobaena caerulea) breeding at subantarctic Marion Island

ABSTRACTBlue Petrels (Halobaena caerulea) are known to breed at seven locations in the Southern Ocean. Population estimates have been made recently for the two major breeding sites, but accurate estimates are lacking for the remaining locations. We used a systematic survey technique to estimate the size of the population breeding at Marion Island (290 km2), the larger of the two Prince Edward Islands. A combination of colony area and density estimates suggested there were 214 700 Blue Petrel burrows on Marion Island in 2012. Burrow occupancy rates at the mid-incubation stage averaged 82% (range 36–98%), suggesting a total breeding population of 145 000 pairs (95% confidence interval 110 000–180 000). There appeared to be some range expansion since the population was mapped in the mid-1980s. Predation of chicks and eggs by introduced house mice (Mus musculus) could be affecting the recovery of Blue Petrels since feral cats (Felis catus) were eradicated in 1991. Based on our count from Marion Island alone, the Prince Edward Islands support the third largest population of Blue Petrels globally, after Diego Ramirez Islands and the Kerguelen Islands.

Population Status of American Oystercatchers (Haematopus palliatus frazari) Breeding in Northwest Mexico

Abstract. The western race of the American Oystercatcher (Haematopus palliatus frazari) is a resident and endangered shorebird of western Mexico. Its breeding population and conservation concerns are poorly known, but recent information indicates extremely low numbers and a discrete breeding distribution. Because of loss and degradation of sandy beaches by coastal development and disturbance from human recreational activities, the American Oystercatcher is a priority species in the Shorebird Conservation Plans of the United States and Mexico. Research on its distribution and abundance during the 2009 breeding season resulted in the identification of 2,286 adults in northwest Mexico. Although the population is higher than previous estimates, its distribution is more restricted than expected. It is distributed almost exclusively in northwest Mexico, and 80% of the total breeding population is found on the islands of Sinaloa and Baja California Sur. Based on these results, this species was officially federal...

Population size, dynamics and reproduction success of the lesser spotted eagle (Aquila pomarina) in Latvia

Abstract We analysed the population size, population dynamics and reproduction success of the lesser spotted eagle in Latvia from 1988 to 2014. While the overall population did not show a statistically significant trend during any of the periods analysed (long, medium and short term), the populations in the individual study areas changed differently: of five research plots, populations were stable in two, increased in one, and decreased in two research plots. Using the existing research plots as samples of breeding numbers in areas of different breeding density classes based on forest management units, the total breeding population in Latvia was estimated. The overall number of breeding pairs in 2012-2014 was between 3700-4000. During the period 1988-2014, 65.62% of all pairs recorded as present on their home range, made a breeding attempt and laid eggs. The reproductive success ratio was 0.49 young per occupied territory with an adult pair of birds and 0.74 young per breeding pair which laid eggs. Overall, during the 21 -year research period there was a stable long-term trend in reproductive success (young per pair present on home range). Rarely, indeed only in 1 .89% of all cases did two young fledge. The total number of young (young per 100 km2) shows stable long-, medium- and short-term trends with an average value of 5.1 young per 100 km2.

Comparison of breeding population survey methods for the Auckland Island shag (Phalacrocorax colensoi)

The Auckland Island shag (Phalacrocorax colensoi) is endemic to New Zealand and restricted to the subantarctic Auckland Islands. The species is classified as “Vulnerable” under the New Zealand threat classification systems. The total breeding population is estimated at <1000 pairs, with Enderby Island considered to be the stronghold for the species. The trend of the population is unknown, and it has been recommended a census of the entire adult population be conducted once a suitable methodology has been developed. The objective of this research was to examine census methods to estimate population size for the Auckland Island shag. Three census methods were trialled on Enderby Island during the 2011/2012 breeding season: (a) boat-based counts; (b) aerial photography using a helicopter and; (c) direct counts from the ground. The aerial photographic survey recorded 1889 pairs of Auckland Island shags breeding on Enderby Island during the 2011/2012 breeding season. In comparison, boat-based and ground count surveys recorded lower population sizes by 27 and 26 %, respectively. This research provides the first comparable methodology and baseline population estimate for the breeding stronghold of this threatened seabird and forms the basis for long-term population monitoring. All methodologies examined here could be used for other cliff-nesting seabird species; however, these results indicate a level of bias may be present for any survey method.

Population survey and conservation assessment of the globally threatened cheer pheasant (Catreus wallichi) in Jhelum Valley, Azad Kashmir, Pakistan.

The cheer pheasant Catreus wallichi is a globally threatened species that inhabits the western Himalayas. Though it is well established that the species is threatened and its numbers declining, updated definitive estimates are lacking, so in 2011, we conducted a survey to assess the density, population size, and threats to the species in Jhelum valley, Azad Kashmir, which holds the largest known population of cheer pheasants in Pakistan. We conducted dawn call count surveys at 17 points clustered in three survey zones of the valley, 11 of which had earlier been used for a 2002-2003 survey of the birds. Over the course of our survey, 113 birds were recorded. Mean density of cheer pheasant in the valley was estimated at 11.8 ± 6.47 pairs per km², with significant differences in terms of both counts and estimated density of cheer were significantly different across the three survey zones, with the highest in the Chinari region and the lowest, that is the area with no recorded sightings of the pheasants, in Gari Doppata. The total breeding population of cheer pheasants is estimated to be some 2 490 pairs, though this does not consider the actual area of occupancy in the study area. On the whole, more cheer pheasants were recorded in this survey than from the same points in 2002-2003, indicating some success in population growth. Unfortunately, increasing human settlement, fires, livestock grazing, hunting, and the collection of non-timber forest products continue to threaten the population of cheer in the Jhelum valley. To mitigate these potential impacts, some degree of site protection should be required for the conservation of cheer pheasants in Pakistan, and more effective monitoring of the species is clearly needed.

Current status of the threatened Olrog’s GullLarus atlanticus: global population, breeding distribution and threats

SummaryOlrog’s GullLarus atlanticusbreeds only in Argentina and is currently categorized as “Vulnerable”. Knowledge of the location of colonies and an updated understanding of human activities that may impact their breeding populations are crucial to the development of adequate conservation and management actions. In this paper we update the breeding distribution and abundance of Olrog’s Gull, using information from three aerial surveys (2004, 2007 and 2009) in its main breeding area, Buenos Aires Province, complemented by additional nest counts in southern Chubut Province, covering its entire breeding range. We also provide an updated and more detailed account of threats faced by Olrog’s Gulls at their nesting grounds, and summarise progress made towards their protection. The number of breeding sites was 7–12 per year, with locations differing among years. Five previously unrecorded breeding locations were identified. Colony size ranged from 5 to 3,540 breeding pairs, with the total breeding population 4,860–7,790 pairs, 98% of which nest in southern Buenos Aires Province. The main threats faced by breeding Olrog’s Gulls include coastal development, pollution, sport fishing and unregulated tourism and recreational activities. Recent strengthening of the protected area system in Argentina has resulted in all known breeding sites, with the exception of Isla Brightman, falling within protected areas. We need comprehensive, simultaneous surveys to track global population trends. Despite enhanced protection of Olrog’s Gull breeding populations, efforts are still needed to ensure that guidelines for their protection are included in management plans and that these are implemented effectively.

Breeding biology and conservation strategy of the Himalayan swiftlet (Aerodramus brevirostris innominata) in southern China

From April 1994 to November 2007, we studied the breeding biology of the Himalayan swiftlet (Aerodramus brevirostris innominata) based on field investigations, behavior observations, and bird bandings in the Shenjing Cave of Hupingshan National Nature Reserve, Hunan Province. Overall, we found a total breeding population of 2,000 swiftlets in the cave. The Himilayan swiftlet is a summer migrant in the area which arrives in early April and departs in early November. This species is monogamous with a sex ratio of about 1:1, and reaches sexual maturity at one year of age. Birds nested in dark caves, with nests primarily composed of saliva and mosses. Birds took 60 days to finish nest construction, and old nests from previous years were fully reused. We found that egg laying began after nest construction and peaked in June. In most cases, two eggs were found in each nest, while occasionally one egg. Both males and females were involved in incubation, but females invested relatively more time. The incubating temperature, duration, and hatching success were 37.3 ± 1.0 , 27.9 ± 3.4 days, and 71.4%, respectively. Nestlings were altr °C icial, and were fed mainly by males for about 27 days with insects, which were the same as adults’ diet. They spent another 3 or 4 days to learn to fly in the cave before fledgling the nest. Fledglings gained substantial weight, which tended to be greater total weight than the parents, before leaving the nest. We observed a concordant decrease in weight upon reaching sexual maturity. Primary threats to Himalayan swiftlets in China include disturbance to breeding activities resulting from tourism development and illegal nest-collection. We suggest that authorities 第 1期 王斌等: 短嘴金丝燕繁殖生物学特征与保护对策 55 halt development of caves and surrounding areas and ban the illegal nests collection.