Matthew J. Bowers, Paula M. Orozco-Valor, Rebecca A. McCabe, J. Therrien
The American Kestrel (Falco sparverius) has been steadily declining throughout most of its eastern North American range, and the cause of this decline is still relatively unknown. As a cavity nesting species, the American Kestrel often competes with other cavity nesters such as the invasive and abundant European Starling (Sturnus vulgaris) over nest boxes. The relationship between European Starling presence at nesting sites and American Kestrel occupancy and nesting success is understudied. We analyzed data from nest boxes monitored in eastern Pennsylvania, USA, from 1992 to 2021 to identify changes in occupancy of American Kestrels and competitors, and to examine the relationship between competition at nest boxes and American Kestrel nesting parameters. We found that American Kestrel occupancy decreased while European Starling occupancy increased over the study period. All other species occupying nest boxes (small mammals, passerines, owls, and snakes) showed no significant occupancy trends. On average 21% of nest boxes remained unoccupied annually, and 7% of occupied nest boxes were used by both American Kestrels and competitors in the same breeding season. The presence of these competitors had negative associations with American Kestrel occupancy, clutch size, number of fledglings produced, and overall nesting success. Specifically, the rate of nesting success decreased by 26% when European Starlings used the same nest box within the same breeding season. In recent years, nesting productivity of American Kestrels has decreased, with the average number of nestlings, fledglings, and nesting success rate all declining, while the average clutch size remained constant. Our results suggest that American Kestrel nesting parameters in eastern Pennsylvania are negatively associated with competition for nest boxes during the breeding season. The opposing trends in occupancy for the European Starling and the American Kestrel in this study area coupled with the declining productivity of American Kestrel nests raise concerns over the future of this raptor species in eastern Pennsylvania.
{"title":"American Kestrels Compete with European Starlings over Nest Boxes in Eastern Pennsylvania","authors":"Matthew J. Bowers, Paula M. Orozco-Valor, Rebecca A. McCabe, J. Therrien","doi":"10.3356/jrr-22-88","DOIUrl":"https://doi.org/10.3356/jrr-22-88","url":null,"abstract":"\u0000 The American Kestrel (Falco sparverius) has been steadily declining throughout most of its eastern North American range, and the cause of this decline is still relatively unknown. As a cavity nesting species, the American Kestrel often competes with other cavity nesters such as the invasive and abundant European Starling (Sturnus vulgaris) over nest boxes. The relationship between European Starling presence at nesting sites and American Kestrel occupancy and nesting success is understudied. We analyzed data from nest boxes monitored in eastern Pennsylvania, USA, from 1992 to 2021 to identify changes in occupancy of American Kestrels and competitors, and to examine the relationship between competition at nest boxes and American Kestrel nesting parameters. We found that American Kestrel occupancy decreased while European Starling occupancy increased over the study period. All other species occupying nest boxes (small mammals, passerines, owls, and snakes) showed no significant occupancy trends. On average 21% of nest boxes remained unoccupied annually, and 7% of occupied nest boxes were used by both American Kestrels and competitors in the same breeding season. The presence of these competitors had negative associations with American Kestrel occupancy, clutch size, number of fledglings produced, and overall nesting success. Specifically, the rate of nesting success decreased by 26% when European Starlings used the same nest box within the same breeding season. In recent years, nesting productivity of American Kestrels has decreased, with the average number of nestlings, fledglings, and nesting success rate all declining, while the average clutch size remained constant. Our results suggest that American Kestrel nesting parameters in eastern Pennsylvania are negatively associated with competition for nest boxes during the breeding season. The opposing trends in occupancy for the European Starling and the American Kestrel in this study area coupled with the declining productivity of American Kestrel nests raise concerns over the future of this raptor species in eastern Pennsylvania.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86789697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marek Dostál, I. Literák, D. Horal, J. Svetlik, R. Raab, J. Hohenegger, H. Matušík
The Red Kite (Milvus milvus) is a common raptor in suitable areas of Austria, the Czech Republic, and Slovakia during the nonbreeding season. However, the exact number of birds wintering in these countries remains unknown. Through an integrated approach using satellite telemetry, direct field surveys at nocturnal roosts, and citizen science databases, we estimated the wintering population of Red Kites in this area during the winter of 2020/2021. Based on three surveys taking place at the beginning (28 November 2020), middle (9 January 2021), and end (5 February 2021) of winter, respectively, we counted 566, 558, and 536 Red Kites. The observations from online citizen science databases mostly appeared to correspond with the area of communal roost sites. Using our combined approach, the estimates of wintering Red Kites were determined as minimum numbers in the study area. A comparison of historical data (from the second half of the 20th and beginning of the 21st centuries, respectively) and our own results suggests that the wintering population of Red Kites in the study area has increased substantially. This dynamic could be caused by changes in climatic conditions, a shift of the birds' breeding range in Europe, changes in migration behavior and/or food availability, and/or conservation efforts.
{"title":"Integrated Approach Improves Monitoring of Wintering Red Kites in Central Europe","authors":"Marek Dostál, I. Literák, D. Horal, J. Svetlik, R. Raab, J. Hohenegger, H. Matušík","doi":"10.3356/jrr-22-97","DOIUrl":"https://doi.org/10.3356/jrr-22-97","url":null,"abstract":"\u0000 The Red Kite (Milvus milvus) is a common raptor in suitable areas of Austria, the Czech Republic, and Slovakia during the nonbreeding season. However, the exact number of birds wintering in these countries remains unknown. Through an integrated approach using satellite telemetry, direct field surveys at nocturnal roosts, and citizen science databases, we estimated the wintering population of Red Kites in this area during the winter of 2020/2021. Based on three surveys taking place at the beginning (28 November 2020), middle (9 January 2021), and end (5 February 2021) of winter, respectively, we counted 566, 558, and 536 Red Kites. The observations from online citizen science databases mostly appeared to correspond with the area of communal roost sites. Using our combined approach, the estimates of wintering Red Kites were determined as minimum numbers in the study area. A comparison of historical data (from the second half of the 20th and beginning of the 21st centuries, respectively) and our own results suggests that the wintering population of Red Kites in the study area has increased substantially. This dynamic could be caused by changes in climatic conditions, a shift of the birds' breeding range in Europe, changes in migration behavior and/or food availability, and/or conservation efforts.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77444454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Kolowski, Caylen Wolfer, Megan McDaniels, Alan Williams, J. Harris
Long-term monitoring data indicate a persistent decline in American Kestrel populations across North America. Loss or alteration of habitat have been listed as potential causal factors, but basic information on kestrel space use, including breeding home range size, is lacking. No study has provided robust estimates of the ranging behavior of breeding kestrels based on tracking data of any resolution. We fitted 19 adult female kestrels with solar-powered GPS transmitters during the incubation period in northern Virginia. High-resolution tracking began during the early nestling stage for 17 birds. We collected an average of 1710 locations per bird through the end of the breeding season (31 August), with 13 birds tracked through the fledging of their young. Autocorrelated kernel density home range estimation showed that female kestrels used breeding home ranges that were smaller (average: 0.32 km2) than most previously published range sizes. Home ranges did not vary significantly in size across breeding stages and demonstrated little overlap with the ranges of neighboring kestrels. Five females shifted their territories in the post-breeding stage (i.e., after disappearance or dispersal of fledglings) between 1.5 and 12.3 km from their nest box; they maintained these new ranges at least to the migration period. We also documented home range excursion forays (n = 128) by all 12 consistently tracked females. Mean (4.0 km) and maximum (127.7 km) foray distances were some of the largest reported among birds and mammals relative to home range size. Weekly foray rates were highest during the nestling stage, and for birds that ultimately shifted from their breeding home range. The existence of long-distance foray behavior and the use of multiple summer home ranges, both shown here for the first time for this species, has a direct impact on interpretation of kestrel nest-site and habitat selection data, and on the assessment of potential threats to this species in the breeding season.
{"title":"High-resolution GPS Tracking of American Kestrels Reveals Breeding and Post-breeding Ranging Behavior in Northern Virginia, USA","authors":"J. Kolowski, Caylen Wolfer, Megan McDaniels, Alan Williams, J. Harris","doi":"10.3356/jrr-22-106","DOIUrl":"https://doi.org/10.3356/jrr-22-106","url":null,"abstract":"\u0000 Long-term monitoring data indicate a persistent decline in American Kestrel populations across North America. Loss or alteration of habitat have been listed as potential causal factors, but basic information on kestrel space use, including breeding home range size, is lacking. No study has provided robust estimates of the ranging behavior of breeding kestrels based on tracking data of any resolution. We fitted 19 adult female kestrels with solar-powered GPS transmitters during the incubation period in northern Virginia. High-resolution tracking began during the early nestling stage for 17 birds. We collected an average of 1710 locations per bird through the end of the breeding season (31 August), with 13 birds tracked through the fledging of their young. Autocorrelated kernel density home range estimation showed that female kestrels used breeding home ranges that were smaller (average: 0.32 km2) than most previously published range sizes. Home ranges did not vary significantly in size across breeding stages and demonstrated little overlap with the ranges of neighboring kestrels. Five females shifted their territories in the post-breeding stage (i.e., after disappearance or dispersal of fledglings) between 1.5 and 12.3 km from their nest box; they maintained these new ranges at least to the migration period. We also documented home range excursion forays (n = 128) by all 12 consistently tracked females. Mean (4.0 km) and maximum (127.7 km) foray distances were some of the largest reported among birds and mammals relative to home range size. Weekly foray rates were highest during the nestling stage, and for birds that ultimately shifted from their breeding home range. The existence of long-distance foray behavior and the use of multiple summer home ranges, both shown here for the first time for this species, has a direct impact on interpretation of kestrel nest-site and habitat selection data, and on the assessment of potential threats to this species in the breeding season.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81713146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Trio of Aplomado Falcons Captures a Swallow-tailed Kite","authors":"Kennedy Borges, J. O. Coulson","doi":"10.3356/jrr-23-01","DOIUrl":"https://doi.org/10.3356/jrr-23-01","url":null,"abstract":"","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82646372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sandra Goded, Nathaniel N. D. Annorbah, O. Boissier, Kristen M. Rosamond, Samuel Boakye Yiadom, Zébigou Kolani, A. Mahama, N. Arcilla
Vultures are among the most threatened species in Africa, with several critically endangered species surviving mainly or only in protected areas. West African vulture declines are correlated with steep losses of natural habitat and mammalian wildlife. Major factors driving vulture extirpations include wildlife trade for traditional medicine, belief-based rituals, and bushmeat. Current data on vulture abundance and breeding ecology are crucial for conservation but lacking in many countries, including Ghana. Between 2020 and 2022, we conducted 761 km of surveys for critically endangered vultures in Mole National Park (Mole NP), a 4840 km2 protected savanna in northern Ghana. Using our count data, we estimated populations of 29–36 Hooded Vultures (Necrosyrtes monachus), 25–73 White-backed Vultures (Gyps africanus), and 3–4 White-headed Vultures (Trigonoceps occipitalis) in the southern region of Mole NP. We also documented 17 occupied vulture nests, including six Hooded Vulture nests, 10 White-backed Vulture nests, and one White-headed Vulture nest. Our findings include the first nest records for Hooded Vultures in Mole NP, the first nest description of White-backed Vultures in Ghana, and the first nest records for White-headed Vultures in Ghana, confirming the importance of Mole NP for conserving critically endangered vultures. Reducing poaching, preventing the killing of vultures for wildlife trade, and protecting vulture habitat and food resources will be paramount to the survival of critically endangered vultures in Ghana and West Africa.
{"title":"Abundance and Breeding Ecology of Critically Endangered Vultures in Mole National Park, Ghana","authors":"Sandra Goded, Nathaniel N. D. Annorbah, O. Boissier, Kristen M. Rosamond, Samuel Boakye Yiadom, Zébigou Kolani, A. Mahama, N. Arcilla","doi":"10.3356/jrr-22-54","DOIUrl":"https://doi.org/10.3356/jrr-22-54","url":null,"abstract":"\u0000 Vultures are among the most threatened species in Africa, with several critically endangered species surviving mainly or only in protected areas. West African vulture declines are correlated with steep losses of natural habitat and mammalian wildlife. Major factors driving vulture extirpations include wildlife trade for traditional medicine, belief-based rituals, and bushmeat. Current data on vulture abundance and breeding ecology are crucial for conservation but lacking in many countries, including Ghana. Between 2020 and 2022, we conducted 761 km of surveys for critically endangered vultures in Mole National Park (Mole NP), a 4840 km2 protected savanna in northern Ghana. Using our count data, we estimated populations of 29–36 Hooded Vultures (Necrosyrtes monachus), 25–73 White-backed Vultures (Gyps africanus), and 3–4 White-headed Vultures (Trigonoceps occipitalis) in the southern region of Mole NP. We also documented 17 occupied vulture nests, including six Hooded Vulture nests, 10 White-backed Vulture nests, and one White-headed Vulture nest. Our findings include the first nest records for Hooded Vultures in Mole NP, the first nest description of White-backed Vultures in Ghana, and the first nest records for White-headed Vultures in Ghana, confirming the importance of Mole NP for conserving critically endangered vultures. Reducing poaching, preventing the killing of vultures for wildlife trade, and protecting vulture habitat and food resources will be paramount to the survival of critically endangered vultures in Ghana and West Africa.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86950075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Bell, S. Snyder, Joseph E. Didonato, K. S. Smallwood
Assessing impacts of wind farms on volant animals requires conducting fatality monitoring studies that incorporate integrated carcass detection trials to account for searcher detection probability and carcass persistence and to reduce biases in the estimated number of fatalities (Smallwood et al. 2018). These trials involve placing a wide range of volant animal carcasses that mimic the expected species composition and actual spatial and temporal patterns of fatalities deposited by the wind turbines and measuring rates of carcass detection (Smallwood et al. 2018). When combined with remote cameras, carcass placement trials can reveal the suite of local scavengers that affect carcass persistence. We report here on an incident of conspecific carcass removal by a Great Horned Owl (Bubo virginianus) documented during a study designed to assess scavenger removal rates of avian carcasses at a wind energy project (Smallwood et al. 2009, 2010). We conducted the scavenger removal study from 12 December 2006 to 28 September 2007 on a 250ha parcel of land administered by the East Bay Regional Park District in the Altamont Pass Wind Resource Area, California, USA. The study area contained 52 functional wind turbines situated in rows along ridgelines within a landscape dominated by annual grasses. Sixty-three avian carcasses representing diverse avian species and body sizes, including two Great Horned Owls, were used for this study. Carcasses were obtained fresh-dead as either road kills or from animal rehabilitation hospitals and were kept frozen until used. To avoid scavenger swamping, from one to five carcasses were placed each week at randomly chosen locations within 60-m radii of wind turbine bases throughout the facility. Infrared, motion-activated cameras (Reconyxt, Holmen, WI, USA) were attached to metal posts approximately 1 m above the ground and 1.5 m away from each carcass. When activated, the cameras were set to take five pictures in rapid succession, with a recovery phase of approximately 1 sec between firings. All scavenging trial locations were monitored with cameras for 21 d after carcass placement or until a carcass was removed by scavengers, whichever came first. In some instances, camera removals were delayed beyond 21 d due to field conditions. After cameras were removed, all trial locations with either partial carcasses or feathers continued to be monitored weekly by biologists until the end of the study. For more details on this study, see Smallwood et al. (2009). A Great Horned Owl carcass was placed on 19 December 2006 at 1500 H in front of a remote camera set-up. On 13 January 2007, at 1843 H, a Great Horned Owl was photographed landing on
评估风电场对流浪动物的影响需要进行死亡率监测研究，其中包括综合尸体检测试验，以考虑搜索者发现概率和尸体持久性，并减少估计死亡人数的偏差(Smallwood et al. 2018)。这些试验包括放置各种挥发性动物尸体，模拟预期的物种组成和风力涡轮机沉积的实际死亡时空模式，并测量尸体检测率(Smallwood等人，2018)。当与远程摄像机相结合时，尸体放置试验可以揭示影响尸体持久性的当地食腐动物。我们在此报告了一项研究中记录的大角猫头鹰(Bubo virginianus)清除同种尸体的事件，该研究旨在评估风能项目中鸟类尸体的清除率(Smallwood et al. 2009, 2010)。我们于2006年12月12日至2007年9月28日在美国加利福尼亚州Altamont Pass风力资源区东湾地区公园区管理的一块250公顷的土地上进行了清除研究。研究区域包含52个功能风力涡轮机，沿山脊线排列，在一年生草为主的景观中。这项研究使用了63具鸟类尸体，代表了不同的鸟类种类和体型，其中包括两只大角猫头鹰。尸体是从新鲜的道路死亡或动物康复医院获得的，并冷冻保存直到使用。为了避免食腐动物淹没，每周将一到五具尸体随机放置在整个设施内风力涡轮机基地半径60米范围内的位置。红外运动激活摄像机(Reconyxt, Holmen, WI, USA)安装在距地面约1米，距每具尸体1.5米的金属柱子上。激活后，相机被设置为快速连续拍摄五张照片，每次拍摄之间的恢复阶段约为1秒。在屠体放置后或直至屠体被食腐动物移走之前，以先到者为准，用摄像机监测所有食腐动物试验地点21 d。在某些情况下，由于现场条件的原因，相机的移除被推迟到21天以后。在移除摄像机后，生物学家继续每周监测所有有部分尸体或羽毛的试验地点，直到研究结束。关于这项研究的更多细节，请参见Smallwood et al.(2009)。2006年12月19日下午15时，一只大角猫头鹰的尸体被放置在远程摄像机前。2007年1月13日，1843时，一只大角猫头鹰被拍到降落在
{"title":"Conspecific Carcass Removal from a Wind Project Study Plot by a Great Horned Owl (Bubo virginianus)","authors":"D. Bell, S. Snyder, Joseph E. Didonato, K. S. Smallwood","doi":"10.3356/JRR-21-65","DOIUrl":"https://doi.org/10.3356/JRR-21-65","url":null,"abstract":"Assessing impacts of wind farms on volant animals requires conducting fatality monitoring studies that incorporate integrated carcass detection trials to account for searcher detection probability and carcass persistence and to reduce biases in the estimated number of fatalities (Smallwood et al. 2018). These trials involve placing a wide range of volant animal carcasses that mimic the expected species composition and actual spatial and temporal patterns of fatalities deposited by the wind turbines and measuring rates of carcass detection (Smallwood et al. 2018). When combined with remote cameras, carcass placement trials can reveal the suite of local scavengers that affect carcass persistence. We report here on an incident of conspecific carcass removal by a Great Horned Owl (Bubo virginianus) documented during a study designed to assess scavenger removal rates of avian carcasses at a wind energy project (Smallwood et al. 2009, 2010). We conducted the scavenger removal study from 12 December 2006 to 28 September 2007 on a 250ha parcel of land administered by the East Bay Regional Park District in the Altamont Pass Wind Resource Area, California, USA. The study area contained 52 functional wind turbines situated in rows along ridgelines within a landscape dominated by annual grasses. Sixty-three avian carcasses representing diverse avian species and body sizes, including two Great Horned Owls, were used for this study. Carcasses were obtained fresh-dead as either road kills or from animal rehabilitation hospitals and were kept frozen until used. To avoid scavenger swamping, from one to five carcasses were placed each week at randomly chosen locations within 60-m radii of wind turbine bases throughout the facility. Infrared, motion-activated cameras (Reconyxt, Holmen, WI, USA) were attached to metal posts approximately 1 m above the ground and 1.5 m away from each carcass. When activated, the cameras were set to take five pictures in rapid succession, with a recovery phase of approximately 1 sec between firings. All scavenging trial locations were monitored with cameras for 21 d after carcass placement or until a carcass was removed by scavengers, whichever came first. In some instances, camera removals were delayed beyond 21 d due to field conditions. After cameras were removed, all trial locations with either partial carcasses or feathers continued to be monitored weekly by biologists until the end of the study. For more details on this study, see Smallwood et al. (2009). A Great Horned Owl carcass was placed on 19 December 2006 at 1500 H in front of a remote camera set-up. On 13 January 2007, at 1843 H, a Great Horned Owl was photographed landing on","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84866319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Subadult (immature) raptors of a variety of species are capable of holding breeding territories and even reproducing (Newton 1979, Steenhof et al. 1983). Robust populations, however, typically contain few, if any, pair members in pre-definitive plumage, and the general explanation is that adults tend to outcompete younger individuals for territory ownership where space is limiting. Their rarity as territory-holders can therefore be a useful indicator of breeding habitat saturation, whereas their increase has been considered ‘‘early warning’’ that vital rates (survival and reproduction) are insufficient to fill territorial space (Ferrer and Donazar 1996, Ferrer et al. 2003). Territory saturation also constitutes a threshold beyond which floaters (nonterritorial adults) can be expected to accumulate. The size of such a population and the ratio of floaters to territory-holders will stabilize if vital rates remain high enough to maintain saturation, a mode of population limitation known as Moffat’s equilibrium (Hunt 1998). The equilibrium floater-tobreeder ratio is useful in broadly indexing the durability of territory saturation as well as the degree of expected feedback of floater intrusions upon nest success (see Haller 1996). A stochastic population matrix model developed by Monzón and Friedenberg (2018) explored the floater dynamics of Moffat’s equilibrium (Hunt 1998, Hunt et al. 2017). Importantly, the rate of floater transition to the breeder stage was modeled dynamically so that transitions were determined by the availability of territories. Their model projected life-stage-structure and allowed computation of instantaneous floater-to-breeder ratios and rates of subadult nest occupancy in a hypothetical Golden Eagle (Aquila chrysaetos) population. The authors ran simulations of population decline and growth, habitat expansion and contraction, and valuably, the 10-yr cycling of a hypothetical prey population. Monzón and Friedenberg’s (2018) report emphasized that floater-to-breeder ratios and the incidence of subadult nest occupancy responded to these scenarios in ways indicating that neither, as a ‘‘snapshot metric,’’ can diagnose the status of a population in the absence of other information. For example, high instantaneous floater-to-breeder ratios characterized not only robust populations, but also those where territory occupancy was shrinking because of habitat loss. High rates of subadult occupancy manifested in both increasing and declining populations. In all, we found Monzón and Friedenberg’s (2018) modeling results consistent with Moffat’s equilibrium dynamics as described by Hunt (1998), Hunt and Law (2000), and Hunt et al. (2017). We believe that variations upon the authors’ algorithm can find useful application in studies of
许多种类的亚成年(未成熟)猛禽都有能力守住繁殖领地，甚至进行繁殖(Newton 1979, Steenhof et al. 1983)。然而，健壮的种群中，通常只有很少(如果有的话)一对配偶拥有未确定的羽毛，一般的解释是，在空间有限的情况下，成年个体往往会在争夺领地所有权方面胜过年轻个体。因此，它们作为领地所有者的稀有性可以作为繁殖栖息地饱和的有用指标，而它们的增加被认为是生命率(生存和繁殖)不足以填补领土空间的“早期预警”(Ferrer and Donazar 1996, Ferrer et al. 2003)。领地饱和也构成了一个阈值，超过这个阈值，漂浮物(无领地的成虫)可能会聚集。如果生命率保持在足够高的水平以保持饱和，那么这种种群的规模和漂浮物与领地持有者的比例将趋于稳定，这是一种被称为莫法特均衡的种群限制模式(Hunt 1998)。平衡的漂浮物与繁殖者的比率在广泛地指示领地饱和的持久性以及漂浮物入侵对巢成功的预期反馈程度方面是有用的(见Haller 1996)。Monzón和Friedenberg(2018)开发的随机种群矩阵模型探索了Moffat均衡的浮动动力学(Hunt 1998, Hunt et al. 2017)。重要的是，漂浮物过渡到繁殖阶段的速度是动态建模的，因此过渡是由领土的可用性决定的。他们的模型预测了生命阶段的结构，并允许在一个假设的金鹰(Aquila chrysaetos)种群中计算瞬时的漂浮物与繁殖者的比率和亚成年巢占用率。作者模拟了人口的减少和增长，栖息地的扩张和收缩，以及有价值的假设猎物数量的10年周期。Monzón和Friedenberg(2018)的报告强调，浮游生物与繁殖者的比率和亚成虫巢占用率对这些情况的反应表明，作为“快照指标”，两者都不能在缺乏其他信息的情况下诊断种群的状态。例如，高瞬时的漂浮物与繁殖者的比率不仅是种群健壮的特征，而且是那些由于栖息地丧失而领土占用减少的种群的特征。在增加和减少的种群中，亚成年占用率都很高。总之，我们发现Monzón和Friedenberg(2018)的建模结果与Hunt(1998)、Hunt and Law(2000)以及Hunt et al.(2017)所描述的Moffat均衡动力学一致。我们相信作者算法的变体可以在研究中找到有用的应用
{"title":"Commentary: Subadult Nest Occupancy Rates and Floater-To-Breeder Ratios in Raptor Population Assessment","authors":"W. G. Hunt, P. Law","doi":"10.3356/JRR-22-87","DOIUrl":"https://doi.org/10.3356/JRR-22-87","url":null,"abstract":"Subadult (immature) raptors of a variety of species are capable of holding breeding territories and even reproducing (Newton 1979, Steenhof et al. 1983). Robust populations, however, typically contain few, if any, pair members in pre-definitive plumage, and the general explanation is that adults tend to outcompete younger individuals for territory ownership where space is limiting. Their rarity as territory-holders can therefore be a useful indicator of breeding habitat saturation, whereas their increase has been considered ‘‘early warning’’ that vital rates (survival and reproduction) are insufficient to fill territorial space (Ferrer and Donazar 1996, Ferrer et al. 2003). Territory saturation also constitutes a threshold beyond which floaters (nonterritorial adults) can be expected to accumulate. The size of such a population and the ratio of floaters to territory-holders will stabilize if vital rates remain high enough to maintain saturation, a mode of population limitation known as Moffat’s equilibrium (Hunt 1998). The equilibrium floater-tobreeder ratio is useful in broadly indexing the durability of territory saturation as well as the degree of expected feedback of floater intrusions upon nest success (see Haller 1996). A stochastic population matrix model developed by Monzón and Friedenberg (2018) explored the floater dynamics of Moffat’s equilibrium (Hunt 1998, Hunt et al. 2017). Importantly, the rate of floater transition to the breeder stage was modeled dynamically so that transitions were determined by the availability of territories. Their model projected life-stage-structure and allowed computation of instantaneous floater-to-breeder ratios and rates of subadult nest occupancy in a hypothetical Golden Eagle (Aquila chrysaetos) population. The authors ran simulations of population decline and growth, habitat expansion and contraction, and valuably, the 10-yr cycling of a hypothetical prey population. Monzón and Friedenberg’s (2018) report emphasized that floater-to-breeder ratios and the incidence of subadult nest occupancy responded to these scenarios in ways indicating that neither, as a ‘‘snapshot metric,’’ can diagnose the status of a population in the absence of other information. For example, high instantaneous floater-to-breeder ratios characterized not only robust populations, but also those where territory occupancy was shrinking because of habitat loss. High rates of subadult occupancy manifested in both increasing and declining populations. In all, we found Monzón and Friedenberg’s (2018) modeling results consistent with Moffat’s equilibrium dynamics as described by Hunt (1998), Hunt and Law (2000), and Hunt et al. (2017). We believe that variations upon the authors’ algorithm can find useful application in studies of","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78678491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-23DOI: 10.3356/JRR-57-3-Book-Review
Matías A. Juhant, Evan McWreath, J. Burnett
Vultures of the World: Essential Ecology and Conservation. By Keith L. Bildstein. 2022. Cornell University Press, Comstock Publishing Associates, Ithaca, New York, USA. ISBN: 978-1501761614. Hardcover, $25.29 and Kindle, $12.99. Dr. Keith Bildstein’s latest book, Vultures of the World: Essential Ecology and Conservation, provides an engaging look at vultures and condors, seeking to help us understand this widely recognized but underappreciated avian group. Bildstein is known to many Journal of Raptor Research (JRR) readers as a past Raptor Research Foundation Vice-President (1999–2002) and member of the Board of Directors (1988–1997). Bildstein is also a former Sarkis Acopian Director of Conservation Science at Hawk Mountain Sanctuary, Kempton, Pennsylvania, USA. His new book reflects the culmination of nearly two decades of personal experience observing and studying vultures worldwide, focusing on migration and movement behavior, physiology, and ecology of migratory and nonmigratory vulture species. We (MAJ, EM, and JB) appreciate the opportunity to review this book on vultures and condors, as the three of us study these full-time obligate scavengers in the western hemisphere. In his three-page preface, Bildstein makes two critical points that the new generation of vulture biologists should consider. The first point: Bildstein has broadened his perspectives over the decades by interacting with other research biologists, and without those interactions, this book could not have been written. Consequently, this point emphasizes the importance of humility and having or developing social abilities necessary to discuss the subjects of study with your peers. The second point: two monumental monographs by Brown and Amadon (1968) and Mundy et al. (1992) have provided an effective model to describe the essential ecology of these full-time obligate scavengers, facilitating Bildstein’s work on vultures at a global scale. The takehome message here is that regardless of the age of the reference, older literature can provide critical insight into the current knowledge of the subject of study. Vultures of the World provides thoughtful explanations to simple questions such as ‘‘Why are vultures the only full-time obligate scavengers in the vertebrate group? What physical and behavioral adaptations have evolved that allow them to inhabit a diverse set of habitats? How do vultures find and feast on rotting flesh?’’ Moreover, it provides helpful background on New World (family Cathartidae) and Old World (family Accipitridae) vultures. JRR readers may remember these terms refer only to the current species distributions and not their geographical origins, which is an important distinction, as Old World vultures may have evolved in the New World, and those we call New World vultures most likely evolved in the Old World. The scavenging habits of these two families are thought to have evolved independently, leading to adaptations such as large bodies, broad wings, power
世界秃鹫:基本生态学与保护。Keith L. Bildstein, 2022。康奈尔大学出版社，康斯托克出版协会，美国纽约州伊萨卡。ISBN: 978 - 1501761614。精装版25.29美元，Kindle版12.99美元。基思·比尔德斯坦博士的最新著作《世界秃鹫:基本生态与保护》，对秃鹫和秃鹰进行了引人入胜的观察，试图帮助我们了解这一被广泛认可但未得到充分重视的鸟类群体。Bildstein是《猛禽研究杂志》(JRR)的读者所熟知的，他曾担任猛禽研究基金会副主席(1999-2002)和董事会成员(1988-1997)。Bildstein也是美国宾夕法尼亚州肯普顿霍克山保护区的前Sarkis Acopian保护科学主任。他的新书反映了近二十年来在世界范围内观察和研究秃鹫的个人经验的高潮，重点是迁徙和运动行为，迁徙和非迁徙秃鹫物种的生理学和生态学。我们(MAJ, EM和JB)很高兴有机会回顾这本关于秃鹫和秃鹫的书，因为我们三个人在西半球研究这些全职的义务食腐动物。在他长达三页的序言中，Bildstein提出了新一代秃鹫生物学家应该考虑的两个关键点。第一点:几十年来，比尔德斯坦通过与其他从事研究的生物学家互动，拓宽了自己的视野，没有这些互动，就不可能写出这本书。因此，这一点强调了谦逊和拥有或发展与同龄人讨论学习主题所必需的社交能力的重要性。第二点:Brown和Amadon(1968)以及Mundy等人(1992)的两本重要的专著提供了一个有效的模型来描述这些全职义务食腐动物的基本生态，促进了Bildstein在全球范围内对秃鹫的研究。这里的关键信息是，无论参考文献的年龄如何，旧文献都可以为研究主题的当前知识提供关键的见解。《世界秃鹫》对一些简单的问题提供了深思熟虑的解释，比如“为什么秃鹫是脊椎动物群体中唯一的全职义务食腐动物?”它们进化出了什么样的身体和行为适应能力，使它们能够栖息在各种各样的栖息地?秃鹫是如何找到并享用腐肉的?此外，它还提供了有关新大陆(秃鹰科)和旧大陆(秃鹰科)秃鹫的有益背景。JRR的读者可能记得，这些术语只指当前的物种分布，而不是它们的地理起源，这是一个重要的区别，因为旧大陆秃鹫可能是在新世界进化的，而那些我们称之为新世界秃鹫的很可能是在旧大陆进化的。这两个家族的食腐习惯被认为是独立进化的，导致了诸如大身体、宽翅膀、有力的喙和无羽毛的头部等适应，这是自然史上趋同进化的最好例子之一。《世界上的秃鹫》以一篇个人的、写得很好的关于秃鹫的起源和演变的概述开篇，接着是七个章节。引言部分评估了导致食腐迅猛龙全球多样性的进化过程，以及一个框架
{"title":"Book Review: Vultures of the World: Essential Ecology and Conservation","authors":"Matías A. Juhant, Evan McWreath, J. Burnett","doi":"10.3356/JRR-57-3-Book-Review","DOIUrl":"https://doi.org/10.3356/JRR-57-3-Book-Review","url":null,"abstract":"Vultures of the World: Essential Ecology and Conservation. By Keith L. Bildstein. 2022. Cornell University Press, Comstock Publishing Associates, Ithaca, New York, USA. ISBN: 978-1501761614. Hardcover, $25.29 and Kindle, $12.99. Dr. Keith Bildstein’s latest book, Vultures of the World: Essential Ecology and Conservation, provides an engaging look at vultures and condors, seeking to help us understand this widely recognized but underappreciated avian group. Bildstein is known to many Journal of Raptor Research (JRR) readers as a past Raptor Research Foundation Vice-President (1999–2002) and member of the Board of Directors (1988–1997). Bildstein is also a former Sarkis Acopian Director of Conservation Science at Hawk Mountain Sanctuary, Kempton, Pennsylvania, USA. His new book reflects the culmination of nearly two decades of personal experience observing and studying vultures worldwide, focusing on migration and movement behavior, physiology, and ecology of migratory and nonmigratory vulture species. We (MAJ, EM, and JB) appreciate the opportunity to review this book on vultures and condors, as the three of us study these full-time obligate scavengers in the western hemisphere. In his three-page preface, Bildstein makes two critical points that the new generation of vulture biologists should consider. The first point: Bildstein has broadened his perspectives over the decades by interacting with other research biologists, and without those interactions, this book could not have been written. Consequently, this point emphasizes the importance of humility and having or developing social abilities necessary to discuss the subjects of study with your peers. The second point: two monumental monographs by Brown and Amadon (1968) and Mundy et al. (1992) have provided an effective model to describe the essential ecology of these full-time obligate scavengers, facilitating Bildstein’s work on vultures at a global scale. The takehome message here is that regardless of the age of the reference, older literature can provide critical insight into the current knowledge of the subject of study. Vultures of the World provides thoughtful explanations to simple questions such as ‘‘Why are vultures the only full-time obligate scavengers in the vertebrate group? What physical and behavioral adaptations have evolved that allow them to inhabit a diverse set of habitats? How do vultures find and feast on rotting flesh?’’ Moreover, it provides helpful background on New World (family Cathartidae) and Old World (family Accipitridae) vultures. JRR readers may remember these terms refer only to the current species distributions and not their geographical origins, which is an important distinction, as Old World vultures may have evolved in the New World, and those we call New World vultures most likely evolved in the Old World. The scavenging habits of these two families are thought to have evolved independently, leading to adaptations such as large bodies, broad wings, power","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87556222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many raptors exhibit life history characteristics that simultaneously place them at conservation risk and make them difficult to study, including delayed reproduction, long life spans, low annual fecundity, and large seasonal movements. Developing effective methods for rapid assessment of raptor populations will improve the feasibility and timeliness of adaptive management. To this end, we used a stage-structured demographic model to evaluate the insight into population decline risk provided by two population structure measurements: subadult nest occupancy and the ratio of non-territorial ‘‘floater’’ adults to territorial breeders (Monzón and Friedenberg 2018). Here, we respond to a commentary by Hunt and Law (2023) that addresses our study’s premises. There is no disagreement that the metrics require further context to be diagnostic; however, Hunt and Law (2023) offer three specific criticisms of our study, calling them strawmen. Although we did not intend them as such, discussing each criticism here offers an opportunity to clarify how these demographic metrics are and should be interpreted. First, Hunt and Law (2023) assert that we proposed, as a strawman, that subadult nest occupancy has only one possible explanation. They are referring to our summary of previously published work suggesting ‘‘a high incidence of subadults on nests might characterize a population in decline or at high risk of decline because it may be depleted of adult breeders and floaters’’ (Monzón and Friedenberg 2018, citing Balbontı́n et al. 2003 and Ferrer et al. 2003). Our summary reflects the preponderance of studies on the subject. Even Hunt and Law (2023), shortly after pointing out the narrowness of our summary, establish the general rarity of subadult nesting among raptors and assert that it should be regarded as a meaningful warning sign even if observed at a low level. With this premise as a hypothesis, we explored various ecological scenarios that can yield high rates of subadult nest occupancy and then assessed the value of this snapshot metric for indicating risk of population decline. The metric on its own was useful for identifying scenarios of moderate decline risk but failed to discern cases of low and high risk (Monzón and Friedenberg 2018). The examples presented by Hunt and Law (2023) all provide additional ecological context with which to interpret the metric properly and share the theme of high adult mortality being an important factor—the exact conclusion we reached in our original study (Monzón and Friedenberg 2018). In the example of Golden Eagles (Aquila chrysaetos) in the Altamont Pass Wind Resource Area in California, a high rate of subadult nest occupancy is interpreted in the context of high adult mortality from collisions with wind turbines (Wiens and Kolar 2021). Similarly, the
许多迅猛龙表现出的生活史特征，包括繁殖迟缓、寿命长、年繁殖力低和季节性活动大，同时使它们面临保护风险，也使它们难以研究。开发快速评估猛禽种群的有效方法将提高适应性管理的可行性和及时性。为此，我们使用了一个阶段结构的人口统计学模型来评估两种人口结构测量方法提供的人口下降风险洞察:亚成虫巢穴占用率和非领土“漂浮”成虫与领土繁殖者的比例(Monzón和Friedenberg 2018)。在这里，我们回应亨特和劳(2023)的一篇评论，该评论涉及我们的研究前提。毫无疑问，这些指标需要进一步的背景来进行诊断;然而，亨特和劳(2023)对我们的研究提出了三个具体的批评，称他们为稻草人。虽然我们并不打算这样做，但在这里讨论每一个批评都提供了一个机会来澄清这些人口统计指标是如何解释的。首先，Hunt和Law(2023)断言，我们提出，作为一个稻草人，亚成虫的巢穴占用只有一种可能的解释。他们指的是我们对先前发表的工作的总结，这些工作表明“巢穴中亚成虫的高发生率可能是种群数量下降或下降的高风险特征，因为它可能耗尽了成年繁殖者和飞蚊”(Monzón和Friedenberg 2018，引用balbontturn等人2003和Ferrer等人2003)。我们的摘要反映了这方面研究的优势。即使是亨特和劳(2023)，在指出我们的总结的狭隘性之后不久，也确定了猛禽中亚成虫筑巢的普遍罕见性，并断言即使在低水平上观察到，也应将其视为有意义的警告信号。以这一假设为前提，我们探索了各种可能产生高亚成虫巢占用率的生态情景，然后评估了这一快照指标在指示种群下降风险方面的价值。该指标本身对于识别中度下降风险的情景有用，但无法识别低风险和高风险的情况(Monzón和Friedenberg 2018)。Hunt和Law(2023)提出的例子都提供了额外的生态背景，可以适当地解释这一指标，并分享成人高死亡率是一个重要因素的主题——这是我们在原始研究中得出的确切结论(Monzón和Friedenberg 2018)。在加州Altamont Pass风力资源区的金鹰(Aquila chrysaetos)的例子中，亚成虫巢穴的高比例被解释为与风力涡轮机碰撞导致的高成虫死亡率(Wiens and Kolar 2021)。类似地,
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Virtually all species compete for resources, which can lead to aggressive intraand interspecific interactions between individuals (Scott and Fredericson 1951). These interactions may take the form of displays, aggressive chases, and physical contacts (Jamieson and Seymour 1983, Bildstein and Collopy 1985, Boal 2001). Among conspecifics, these interactions may be agonistic, which is an escalation of behaviors from threat displays (often ritualized) to aggression, ultimately resulting in the submission or death of one combatant (McGlone 1986). For example, territorial Harris’s Hawks (Parabuteo unicinctus) engage in posturing, display, and eventual attack if an intruding conspecific does not leave (Dawson and Mannan 1991). In more extreme cases, individuals may kill and cannibalize conspecifics (Allen et al. 2020). The Mississippi Kite (Ictinia mississippiensis) is a highly social, quasi-colonial species (Skipper 2018, Parker 2020). For example, in 2022 I monitored 52 nests among 20 urban parks (one to eight nests/ park) in Lubbock, Texas, USA, and documented a mean density of one nesting pair per 2.7 ha (62.46 SD). Additionally, large nonbreeding groups may communally roost in trees near occupied nests. Despite such close proximities, aggressive interactions between Mississippi Kites appear to be exceedingly rare, with only a few documented events that usually consist of adults chasing subadults away from nests (Shaw 1985, Parker 2020). In summer 2020, I banded a nesting female Mississippi Kite with a US Geological Survey Bird Banding Lab aluminum leg band and a plastic green-colored band with the white letters ME (hereafter G-ME). I did not band the male of the breeding pair. The pair’s 2020 nesting attempt was successful in fledging one young. On 4 June 2021, I confirmed the female G-ME had returned to the 2020 nest area. The 2020 nest had blown out, but the kites had constructed a new nest and I observed multiple copulations between an unbanded male and G-ME. On 23 June 2021 at approximately 1020 H CST, I approached the G-ME nest to assess breeding status. At this date, all the monitored kite nests in my study were in the incubation stage. Upon my arrival I observed G-ME standing on the north side of the nest and facing an unbanded adult female Mississippi Kite perched in the cup of the nest (Fig. 1). The two kites posed with gaped beaks, nape feathers erected, and wings flared out as they faced each other. An unbanded adult male was perched on a branch approximately 1 m above and to the side of the nest. Although I did not know when the interaction was initiated, I watched for more than 10 min as the two female kites commenced to fight on the nest. They began making pecking strikes at each other, progressing to breast to breast contact and batting at each other with their wings and making pecking strikes toward each other’s faces (Supplemental Material 1). When one bird struck out with its beak, the other would retract its head backward to avoi
几乎所有物种都在争夺资源，这可能导致个体之间具有侵略性的种内和种间相互作用(Scott和Fredericson, 1951)。这些互动可能以展示、攻击性追逐和身体接触的形式出现(Jamieson and Seymour 1983, Bildstein and Collopy 1985, Boal 2001)。在同种个体中，这些相互作用可能是敌对的，这是一种从威胁表现(通常是仪式化的)到攻击的行为升级，最终导致一个战斗员的屈服或死亡(McGlone 1986)。例如，具有领土意识的哈里斯鹰(Parabuteo unicinctus)会在入侵的同种动物不离开的情况下做出姿态、展示，并最终发起攻击(Dawson and Mannan 1991)。在更极端的情况下，个体可能会杀死并同类相食(Allen et al. 2020)。密西西比风筝(Ictinia密西西比)是一种高度社会化的准殖民地物种(Skipper 2018, Parker 2020)。例如，在2022年，我监测了美国德克萨斯州拉伯克市20个城市公园(1至8个鸟巢/公园)中的52个鸟巢，并记录了每2.7公顷(62.46 SD)一对鸟巢的平均密度。此外，大型非繁殖群体可能在被占领的巢穴附近的树上共同栖息。尽管距离如此之近，但密西西比鸢之间的攻击性互动似乎非常罕见，只有少数记录在案的事件通常是成虫将亚成虫从巢穴中赶走(Shaw 1985, Parker 2020)。在2020年夏天，我用美国地质调查局鸟类绑带实验室的铝腿带和带有白色字母ME(以下简称G-ME)的绿色塑料带捆绑了一只筑巢的雌性密西西比风筝。我没有给交配对中的雄性戴上手铐。这对夫妇在2020年的筑巢尝试成功地孵出了一只幼崽。2021年6月4日，我确认雌性G-ME已经回到2020年的巢穴区域。2020年的鸟巢已经被吹灭了，但风筝已经建造了一个新的鸟巢，我观察到一只没有绑带的雄性和G-ME之间进行了多次交配。2021年6月23日大约1020时，我走近G-ME巢穴，评估繁殖状况。此时，我所监测的所有风筝巢都处于孵化阶段。当我到达时，我观察到G-ME站在鸟巢的北侧，面对着一只未带的成年雌性密西西比风筝，它栖息在鸟巢的杯子里(图1)。两只风筝张开嘴，竖起后羽，翅膀张开，面对着对方。一只没有系带的成年雄性栖息在鸟巢上方约1米的树枝上。虽然我不知道互动是什么时候开始的，但我看了十多分钟，两只雌风筝开始在鸟巢里打架。它们开始互相啄击，发展到胸对胸接触，用翅膀互相拍打，对着对方的脸进行啄击(补充材料1)。当一只鸟用喙击打对方时，另一只鸟会缩回头以躲避攻击。这种来回的争吵持续了几分钟，直到
{"title":"Nest Usurpation by a Female Mississippi Kite (Ictinia mississippiensis)","authors":"C. Boal","doi":"10.3356/JRR-22-103","DOIUrl":"https://doi.org/10.3356/JRR-22-103","url":null,"abstract":"Virtually all species compete for resources, which can lead to aggressive intraand interspecific interactions between individuals (Scott and Fredericson 1951). These interactions may take the form of displays, aggressive chases, and physical contacts (Jamieson and Seymour 1983, Bildstein and Collopy 1985, Boal 2001). Among conspecifics, these interactions may be agonistic, which is an escalation of behaviors from threat displays (often ritualized) to aggression, ultimately resulting in the submission or death of one combatant (McGlone 1986). For example, territorial Harris’s Hawks (Parabuteo unicinctus) engage in posturing, display, and eventual attack if an intruding conspecific does not leave (Dawson and Mannan 1991). In more extreme cases, individuals may kill and cannibalize conspecifics (Allen et al. 2020). The Mississippi Kite (Ictinia mississippiensis) is a highly social, quasi-colonial species (Skipper 2018, Parker 2020). For example, in 2022 I monitored 52 nests among 20 urban parks (one to eight nests/ park) in Lubbock, Texas, USA, and documented a mean density of one nesting pair per 2.7 ha (62.46 SD). Additionally, large nonbreeding groups may communally roost in trees near occupied nests. Despite such close proximities, aggressive interactions between Mississippi Kites appear to be exceedingly rare, with only a few documented events that usually consist of adults chasing subadults away from nests (Shaw 1985, Parker 2020). In summer 2020, I banded a nesting female Mississippi Kite with a US Geological Survey Bird Banding Lab aluminum leg band and a plastic green-colored band with the white letters ME (hereafter G-ME). I did not band the male of the breeding pair. The pair’s 2020 nesting attempt was successful in fledging one young. On 4 June 2021, I confirmed the female G-ME had returned to the 2020 nest area. The 2020 nest had blown out, but the kites had constructed a new nest and I observed multiple copulations between an unbanded male and G-ME. On 23 June 2021 at approximately 1020 H CST, I approached the G-ME nest to assess breeding status. At this date, all the monitored kite nests in my study were in the incubation stage. Upon my arrival I observed G-ME standing on the north side of the nest and facing an unbanded adult female Mississippi Kite perched in the cup of the nest (Fig. 1). The two kites posed with gaped beaks, nape feathers erected, and wings flared out as they faced each other. An unbanded adult male was perched on a branch approximately 1 m above and to the side of the nest. Although I did not know when the interaction was initiated, I watched for more than 10 min as the two female kites commenced to fight on the nest. They began making pecking strikes at each other, progressing to breast to breast contact and batting at each other with their wings and making pecking strikes toward each other’s faces (Supplemental Material 1). When one bird struck out with its beak, the other would retract its head backward to avoi","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87306140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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