Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and invest...Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.展开更多
The Pallas’s Gull Ichthyaetus ichthyaetus is a piscivorous gull,some local populations of which are rare and vulnerable.The review presents data on the status and distribution of the Pallas’s Gull in the reservoirs ...The Pallas’s Gull Ichthyaetus ichthyaetus is a piscivorous gull,some local populations of which are rare and vulnerable.The review presents data on the status and distribution of the Pallas’s Gull in the reservoirs of the Palearctic-water bodies in which the water level is controlled by humans.The aim of the study was to assess the current state of the species in the reservoirs of the Palearctic.The review was based on 1080 publications found in the search engines Yandex,Google,Google Scholar,eLybrary.During the last 35 years,the Pallas’s Gull has been found in 63 reservoirs of the Palearctic.Breeding has been established in 11 reservoirs,breeding has not been established in 43 reservoirs,and birds were present in 9 reservoirs,but the status was not specified.Two-thirds of the reservoirs where the gull was recorded or bred were located in the European part and only 1/3 in Asia.It is assumed that up to 5000 adults(0.45%-4.0%of the global population of the species)breed annually in the reservoirs of the Palearctic,and the reservoirs are not the main habitats for maintaining and reproducing the population of the species.The majority of the breeding population reproduces in natural water bodies,and the reservoirs of the Palearctic are important for the maintenance of non-breeding individuals.Detection of presumed breeding and new breeding colonies in reservoirs north of the historical range of the species has been established on the Russian Plain,in the Urals and Trans-Urals.The reservoirs of Russia play a leading role in providing breeding sites for the species in water bodies of this type.An analysis of the data allows us to state the important and increased role of reservoirs in the modern distribution and expansion of the range of the Pallas’s Gull in the Palearctic.展开更多
With the continued development of tracking technology and increasing interest in animal movement,our understanding of migration behavior has become more comprehensive.However,there are still many species that have not...With the continued development of tracking technology and increasing interest in animal movement,our understanding of migration behavior has become more comprehensive.However,there are still many species that have not been well studied,particularly sea birds.Here,we present the first year-round Global Positioning System(GPS)tracking data of the Black-tailed Gull(Larus crassirostris)at the population level.We used solar-powered GPS-Global System for Mobile communication(GSM)loggers to successfully track 30 individuals breeding at Xingrentuo Islet,Liaoning Province,China,for 1-3 years.Except for one individual who roamed in the far north of the Yellow Sea during non-breeding period,all others did a directed southward migration.Migration routes and wintering sites differed among migrating gulls and between years for the birds tracked for two or more years.Additionally,during wintering,the migrating gulls were more likely to travel over a large body of water and shift sites,and some trajectories were quite complex,which was probably closely related to what we observed in the field about their boat-chasing behavior.Compared to wintering movements,the post-breeding movements ranged over a smaller area.Specifically,almost all of them had a long post-breeding period near the breeding islet(≥120days,<220 km from the breeding islet),and 80%of the gulls who were tracked more than one year had at least one faithful post-breeding site.Compared to the post-breeding period,only approximately half of the migrating gulls had a pre-breeding period that was shorter(3-20 days)and closer to the breeding islet(≤80 km).Migration distance varied among migrating gulls(range 209-2405 km)and the gulls moved least distance during postbreeding period.Furthermore,we found that the southward movement of the migrating gulls occurred when the temperature near the breeding islet dropped;specifically,the gulls directly migrated southward away from the post-breeding site.Our results suggest that the Black-tailed Gull has a long post-breeding period but a short prebreeding period near the breeding islet and high diversity of their migrating patterns(in especial migration routes and wintering sites).展开更多
The study was conducted in the Awbarre district of the Fafen zone of the Somali regional state of Ethiopia. The objective of the study was to assess the breeding practices and reproductive performance of Black-head So...The study was conducted in the Awbarre district of the Fafen zone of the Somali regional state of Ethiopia. The objective of the study was to assess the breeding practices and reproductive performance of Black-head Somali sheep under a traditional management system. Purposive and simple random sampling techniques were used to select targeted kebeles and households, respectively. A total of 120 households were selected from four kebeles, each of 30 households, based on the production system and sheep population. Semi-structured questionnaires, group discussions, key informants interviews and field observations were used to generate the required data. The primary purpose of keeping sheep was for income generation, followed by saving as a future asset. The majority (89.2%) of the respondents separated male and female animals during herding. The selection criteria for breeding rams were appearance, growth, pedigree, and color while for breeding ewes were appearance, adaptability, pedigree, color, and lamb growth. The overall weaning age of Black-head Somali sheep in the study area was 3.7 months for both males & females. The castration of male sheep was common for the purpose of fattening, fattening with breeding control and breeding control as well. The castration is mainly performed during the summer and autumn and the methods of castration were both traditional and modern methods, the traditional castration method being the most important one in pastoral areas. The age of sexual maturity was 7.64 months for rams and 8.97 months for ewe’s male and female lambs in the pastoral area and 8.42 & 8.38 for rams & ewes in agro-pastoral and overall lambing interval was 11 months. On average, the ewe of Black-head Somali sheep in pastoral & agro-pastoral could produce 9.49 & 9.57 lambs, respectively in their lifetime. As the pastoralists and agro-pastoralists indicated the source of the breeding ram was their own, so the exchange of breeding ram is recommended to minimize the risk of inbreeding and further studies of on-farm performance investigation would be necessary to be carried out so as to understand the uniqueness of the breed better.展开更多
Unsteady aerodynamic characteristics of a seagull wing in level flight are investigated using a boundary element method.A new no-penetration boundary condition is imposed on the surface of the wing by considering its ...Unsteady aerodynamic characteristics of a seagull wing in level flight are investigated using a boundary element method.A new no-penetration boundary condition is imposed on the surface of the wing by considering its deformation.The geometry and kinematics of the seagull wing are reproduced using the functions and data in the previously published literature.The proposed method is validated by comparing the computed results with the published data in the literature.The unsteady aerodynamics characteristics of the seagull wing are investigated by changing flapping frequency and advance ratio.It is found that the peak values of aerodynamic coefficients increase with the flapping frequency.The thrust and drag generations are complicated functions of frequency and wing stroke motions.The lift is inversely proportional to the advance ratio.The effects of several flapping modes on the lift and induced drag(or thrust)generation are also investigated.Among three single modes(flapping, folding and lead & lag),flapping generates the largest lift and can produce thrust alone.For three combined modes,both flapping/folding and flapping/lead & lag can produce lift and thrust larger than the flapping-alone mode can.Folding is shown to increase thrust when combined with flapping,whereas lead & lag has an effect of increasing the lift when also combined with flapping.When three modes are combined together,the bird can obtain the largest lift among the investigated modes.Even though the proposed method is limited to the inviscid flow assumption,it is believed that this method can be used to the design of flapping micro aerial vehicle.展开更多
Information on the migratory pathways for birds is essential to the future citing of wind power facilities, particularly in off-shore waters. Yet, relatively little is known about the coastal or offshore migratory beh...Information on the migratory pathways for birds is essential to the future citing of wind power facilities, particularly in off-shore waters. Yet, relatively little is known about the coastal or offshore migratory behavior of most birds, including Franklin’s gulls (Larus pipixcan), a long-distant migrant. We report observations along the coast of Peru made in November 2008 to determine where birds concentrated. Wind facilities can not avoid regions of high avian activity without knowing where that activity occurs. Migrant flocks of 250 to 50,000 were observed on coastal farmfields, dumps and estuaries, on beaches and mudflats, and up to 45 km offshore. Bathing and foraging flocks ranged in size from 20 to 500 birds, and most flocks were monospecific, with occasional grey-headed (Larus cirrocephalus) and band-tailed (L. belcheri) on the periphery. While previous notes report Franklin’s gulls foraging coastally, we found flocks feeding up to 45 km offshore by diving for prey or feeding on the water. The relative percentage of birds of the year varied in migrant flocks from zero to 14%, with lower numbers of young foraging aerially on insects (only 1%). The percentage of young feeding over the ocean decreased with increasing distance from shore;no young of the year were recorded at 36-44 km offshore. While there were large flocks of Franklin’s gulls resting on the water inshore, the number of gulls foraging offshore did not decline up to 45 km offshore. The presence of foraging flocks of Franklin’s gulls out to 45 km offshore, and occupying space from 0 to 20 m above the water, suggests that they would be vulnerable to offshore anthropogenic activities, such as offshore drilling and wind facilities.展开更多
The Relict Gull(Larus relictus) is recognized as a vulnerable species,with a worldwide population of about 6,000 individuals.Always inhabiting the extreme arid regions of Central Asia,their migratory routes and winter...The Relict Gull(Larus relictus) is recognized as a vulnerable species,with a worldwide population of about 6,000 individuals.Always inhabiting the extreme arid regions of Central Asia,their migratory routes and winter grounds are unclear.This research focused on distribution sites,habitat,behavior,population size and seasonal changes of Relict Gull.Line transects and point counts in every month were used to investigate the gulls around the Ebinur Lake.The result showed Relict Gull was summer visitor to Xinjiang,Western China.Population curve with a single peak was obtained.This gull appeared in early April and was 63 individuals(1% of the global population).The number remained stable from May to July in 2009.The discovery of fledglings indi-cates that Relict Gull may breed here.They left Ebinur Lake in August.Relict Gull in Ebinur Lake should belong to the Central Asian subpopulation,which was the most westerly record in China.展开更多
文摘Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.
文摘The Pallas’s Gull Ichthyaetus ichthyaetus is a piscivorous gull,some local populations of which are rare and vulnerable.The review presents data on the status and distribution of the Pallas’s Gull in the reservoirs of the Palearctic-water bodies in which the water level is controlled by humans.The aim of the study was to assess the current state of the species in the reservoirs of the Palearctic.The review was based on 1080 publications found in the search engines Yandex,Google,Google Scholar,eLybrary.During the last 35 years,the Pallas’s Gull has been found in 63 reservoirs of the Palearctic.Breeding has been established in 11 reservoirs,breeding has not been established in 43 reservoirs,and birds were present in 9 reservoirs,but the status was not specified.Two-thirds of the reservoirs where the gull was recorded or bred were located in the European part and only 1/3 in Asia.It is assumed that up to 5000 adults(0.45%-4.0%of the global population of the species)breed annually in the reservoirs of the Palearctic,and the reservoirs are not the main habitats for maintaining and reproducing the population of the species.The majority of the breeding population reproduces in natural water bodies,and the reservoirs of the Palearctic are important for the maintenance of non-breeding individuals.Detection of presumed breeding and new breeding colonies in reservoirs north of the historical range of the species has been established on the Russian Plain,in the Urals and Trans-Urals.The reservoirs of Russia play a leading role in providing breeding sites for the species in water bodies of this type.An analysis of the data allows us to state the important and increased role of reservoirs in the modern distribution and expansion of the range of the Pallas’s Gull in the Palearctic.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFC2601601)the National Natural Science Foundation of China(Grant No.31727901)the China Scholarship Council(No.2019-13045 to H.X.)。
文摘With the continued development of tracking technology and increasing interest in animal movement,our understanding of migration behavior has become more comprehensive.However,there are still many species that have not been well studied,particularly sea birds.Here,we present the first year-round Global Positioning System(GPS)tracking data of the Black-tailed Gull(Larus crassirostris)at the population level.We used solar-powered GPS-Global System for Mobile communication(GSM)loggers to successfully track 30 individuals breeding at Xingrentuo Islet,Liaoning Province,China,for 1-3 years.Except for one individual who roamed in the far north of the Yellow Sea during non-breeding period,all others did a directed southward migration.Migration routes and wintering sites differed among migrating gulls and between years for the birds tracked for two or more years.Additionally,during wintering,the migrating gulls were more likely to travel over a large body of water and shift sites,and some trajectories were quite complex,which was probably closely related to what we observed in the field about their boat-chasing behavior.Compared to wintering movements,the post-breeding movements ranged over a smaller area.Specifically,almost all of them had a long post-breeding period near the breeding islet(≥120days,<220 km from the breeding islet),and 80%of the gulls who were tracked more than one year had at least one faithful post-breeding site.Compared to the post-breeding period,only approximately half of the migrating gulls had a pre-breeding period that was shorter(3-20 days)and closer to the breeding islet(≤80 km).Migration distance varied among migrating gulls(range 209-2405 km)and the gulls moved least distance during postbreeding period.Furthermore,we found that the southward movement of the migrating gulls occurred when the temperature near the breeding islet dropped;specifically,the gulls directly migrated southward away from the post-breeding site.Our results suggest that the Black-tailed Gull has a long post-breeding period but a short prebreeding period near the breeding islet and high diversity of their migrating patterns(in especial migration routes and wintering sites).
文摘The study was conducted in the Awbarre district of the Fafen zone of the Somali regional state of Ethiopia. The objective of the study was to assess the breeding practices and reproductive performance of Black-head Somali sheep under a traditional management system. Purposive and simple random sampling techniques were used to select targeted kebeles and households, respectively. A total of 120 households were selected from four kebeles, each of 30 households, based on the production system and sheep population. Semi-structured questionnaires, group discussions, key informants interviews and field observations were used to generate the required data. The primary purpose of keeping sheep was for income generation, followed by saving as a future asset. The majority (89.2%) of the respondents separated male and female animals during herding. The selection criteria for breeding rams were appearance, growth, pedigree, and color while for breeding ewes were appearance, adaptability, pedigree, color, and lamb growth. The overall weaning age of Black-head Somali sheep in the study area was 3.7 months for both males & females. The castration of male sheep was common for the purpose of fattening, fattening with breeding control and breeding control as well. The castration is mainly performed during the summer and autumn and the methods of castration were both traditional and modern methods, the traditional castration method being the most important one in pastoral areas. The age of sexual maturity was 7.64 months for rams and 8.97 months for ewe’s male and female lambs in the pastoral area and 8.42 & 8.38 for rams & ewes in agro-pastoral and overall lambing interval was 11 months. On average, the ewe of Black-head Somali sheep in pastoral & agro-pastoral could produce 9.49 & 9.57 lambs, respectively in their lifetime. As the pastoralists and agro-pastoralists indicated the source of the breeding ram was their own, so the exchange of breeding ram is recommended to minimize the risk of inbreeding and further studies of on-farm performance investigation would be necessary to be carried out so as to understand the uniqueness of the breed better.
基金supported by a grant from the Academic Research Program of Chungju National University,2006supported by the Korea Research Foundation Grant funded by the korean Govemment through the Ministry of Education and Human Resources Development,Basic Research Promotion Fund(KRF-2007-331-D00081)
文摘Unsteady aerodynamic characteristics of a seagull wing in level flight are investigated using a boundary element method.A new no-penetration boundary condition is imposed on the surface of the wing by considering its deformation.The geometry and kinematics of the seagull wing are reproduced using the functions and data in the previously published literature.The proposed method is validated by comparing the computed results with the published data in the literature.The unsteady aerodynamics characteristics of the seagull wing are investigated by changing flapping frequency and advance ratio.It is found that the peak values of aerodynamic coefficients increase with the flapping frequency.The thrust and drag generations are complicated functions of frequency and wing stroke motions.The lift is inversely proportional to the advance ratio.The effects of several flapping modes on the lift and induced drag(or thrust)generation are also investigated.Among three single modes(flapping, folding and lead & lag),flapping generates the largest lift and can produce thrust alone.For three combined modes,both flapping/folding and flapping/lead & lag can produce lift and thrust larger than the flapping-alone mode can.Folding is shown to increase thrust when combined with flapping,whereas lead & lag has an effect of increasing the lift when also combined with flapping.When three modes are combined together,the bird can obtain the largest lift among the investigated modes.Even though the proposed method is limited to the inviscid flow assumption,it is believed that this method can be used to the design of flapping micro aerial vehicle.
文摘Information on the migratory pathways for birds is essential to the future citing of wind power facilities, particularly in off-shore waters. Yet, relatively little is known about the coastal or offshore migratory behavior of most birds, including Franklin’s gulls (Larus pipixcan), a long-distant migrant. We report observations along the coast of Peru made in November 2008 to determine where birds concentrated. Wind facilities can not avoid regions of high avian activity without knowing where that activity occurs. Migrant flocks of 250 to 50,000 were observed on coastal farmfields, dumps and estuaries, on beaches and mudflats, and up to 45 km offshore. Bathing and foraging flocks ranged in size from 20 to 500 birds, and most flocks were monospecific, with occasional grey-headed (Larus cirrocephalus) and band-tailed (L. belcheri) on the periphery. While previous notes report Franklin’s gulls foraging coastally, we found flocks feeding up to 45 km offshore by diving for prey or feeding on the water. The relative percentage of birds of the year varied in migrant flocks from zero to 14%, with lower numbers of young foraging aerially on insects (only 1%). The percentage of young feeding over the ocean decreased with increasing distance from shore;no young of the year were recorded at 36-44 km offshore. While there were large flocks of Franklin’s gulls resting on the water inshore, the number of gulls foraging offshore did not decline up to 45 km offshore. The presence of foraging flocks of Franklin’s gulls out to 45 km offshore, and occupying space from 0 to 20 m above the water, suggests that they would be vulnerable to offshore anthropogenic activities, such as offshore drilling and wind facilities.
基金supported by Science Supporting Project of National Ministry of Science and Technology (2008BAC39B04)National Natural Science Foundation of China (30470262,30970340)
文摘The Relict Gull(Larus relictus) is recognized as a vulnerable species,with a worldwide population of about 6,000 individuals.Always inhabiting the extreme arid regions of Central Asia,their migratory routes and winter grounds are unclear.This research focused on distribution sites,habitat,behavior,population size and seasonal changes of Relict Gull.Line transects and point counts in every month were used to investigate the gulls around the Ebinur Lake.The result showed Relict Gull was summer visitor to Xinjiang,Western China.Population curve with a single peak was obtained.This gull appeared in early April and was 63 individuals(1% of the global population).The number remained stable from May to July in 2009.The discovery of fledglings indi-cates that Relict Gull may breed here.They left Ebinur Lake in August.Relict Gull in Ebinur Lake should belong to the Central Asian subpopulation,which was the most westerly record in China.
