The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradua...The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradually increase their mobility, leave their parents, disperse from their natal site, and respond to the challenges of new environments. Characterizing these post-fledging movements and space use is essential for understanding juvenile survival strategies and devising targeted conservation measures. The Crested Ibis (Nipponia nippon), an endangered species and a highly protected animals at the national level in China, has seen limited research on its post-fledging movements and space use. From 2015 to 2023, we utilized biologgers, combined with field surveys, to study the movement and space use characteristics of 37 fledglings in Hanzhong City, Shaanxi Province, China, over a two-month post-fledging period. We quantified changes in activity levels (based on overall dynamic body acceleration), independence timing, onset of post-fledging dispersal, habitat selection, and daily activity rhythms after independence. Our results revealed individuals began independent living 26.23 ± 2.34 days post-fledging and onset of dispersal at 25.58 ± 2.33 days, with a range area at the natal of 2.08 ± 0.56 km^(2). The initial 30 days post-fledging are characterized as an ontogenetic phase marked by a rapid increase in body activity level. Fledglings preferred paddy fields during the independent period rather than the forests they relied on before independence. Interestingly, the daily activity rhythm, particularly foraging behavior, peaked at noon—contrasting with the expected morning and evening activity peaks—likely as an adaptation to avoid periods of peak human activity. Additionally, drowning, collisions, and predation in paddy fields are noteworthy causes of fledgling mortality. Consequently, we recommend protecting a 2-km^(2) area around the nest site for at least two-month post-fledging, implementing safety measures around power lines and cesspools. Additionally, reducing human disturbances near foraging habitats and expanding space within paddy fields would help mitigate survival pressures on fledglings.展开更多
Background: Knowledge of dispersal movement of birds and their habitat preference during the post-fledging period is fundamental to the understanding of their ecological and evolutionary processes. The Crested Ibis is...Background: Knowledge of dispersal movement of birds and their habitat preference during the post-fledging period is fundamental to the understanding of their ecological and evolutionary processes. The Crested Ibis is now being reintroduced to protected sites within its historical range, with the goal of establishing a self-sustaining population that may eventually qualify the species for delisting.Methods: We carried out an ecological study of post-fledging dispersal and habitat use of a reintroduced population of the Crested Ibis(Nipponia nippon) from 2008 to 2012 in Ningshan County, China, by using banding and radio-telemetry methods.Results: In about two weeks(an average of 14.3 days) after fledging, the activities of the fledglings were concentrated in a range of about 100 m around their natal sites, such as the oak-pine forest patches at the edge of open habitats.During this period, fledglings were still partially dependent upon parental care and fed typically on a daily basis.Siblings increasingly became independent by mid-August and then gradually moved away from their natal sites to post-fledging dispersal locations. During the period of the post-fledging dispersal process, most juveniles moving southwest were concentrated at the mean direction(μ = 254.6°, ? = 70.5°) with a mean dispersal distance of 5.1 km.It took an average of 56.4 days to disperse from the natal territory to the first wintering area. Also, forging habitats for juvenile ibis varied with time and local conditions. For example, paddy fields were used most frequently among all habitat types, while shallow rivers just from August to October. Masson pine(Pinus massoniana) was often regarded as the roosting tree species preferred by the Crested Ibis, with the highest utilization rate among all the roosting habitat types. The juveniles of the wild population dispersed four times as far as that of the reintroduced population, but the overall pattern of post-fledging dispersal is similar for the reintroduced and wild populations.Conclusions: Our results are very useful for us to predict the distance and direction of dispersal under various landscape conditions in other released sites. The project is a good example for reintroducing endangered species to their former ranges, and will be valuable for the protection of reintroduced populations of this critically and other endangered species.展开更多
Assessing individual differences and variability in animal movement patterns is essential to improve our understanding of the evolution and ontogeny of migratory strategies.In long-distance migratory species,fledged j...Assessing individual differences and variability in animal movement patterns is essential to improve our understanding of the evolution and ontogeny of migratory strategies.In long-distance migratory species,fledged juveniles often rely on an extremely restricted time span to learn the essential skills for survival and to prepare for migration,possibly the most risky phase of their lives.Collecting detailed information on the dynamics of the movements during the crucial pre-migratory phase is hence essential to understand the solutions developed by migratory species in different environmental contexts.Here,we used high-resolution GPS/GSM transmitters to collect information on the movement ecology of seven juvenile Montagu's Harriers(Circus pygargus)born in central Italy,investigating their early life stages,namely the post-fledging dependence period(PFDP)and the pre-migratory phase(PMP),until autumn migration.After fledging,individuals showed high variability(both in space and time)in home range size,daily distances covered(6.88±11.44 km/day),distance from the nest(1.45±2.8 km)and PFDP length(23.3±5.3 days).Residence time at the natal site significantly decreased,while time interval between revists in the natal area significantly increased,as the PFDP progressed.During the PMP,explored areas and distance from the nest(max value up to 320.8 km)varied among individuals,despite daily distances covered(27±40 km/day)and time allocation between traveling(60.7%)and foraging(39.3%)were similar across individuals.The PMP lasted 38±14 days.Land cover composition of foraging locations was mostly represented by agricultural lands(~78.2%),though habitat use differed among individuals.More than 76%of such locations were outside protected areas.This individual-based tracking study represents a novel approach that improves previous knowledge based on field studies on the early life stages of the Montagu's Harrier.High inter-individual variability in movement patterns,broad-range exploratory movements and foraging locations outside the protected area network make the application of standard conservation measures difficult,raising concerns about the long-term preservation of this vulnerable migratory species in Italy.展开更多
Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile developmen...Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile development continue,therefore,to attract scientific attention.In most species of birds,including raptors,the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent.Among raptors,post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months.By contrast,young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging,that is,at a time when the adults are expected to breed again.We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors.We found that the behavioral development of grey falcon young is extremely delayed,and that they even depend nutritionally on their parents for up to 12 months after fledging.We suggest that these 2 distinctive features are,ultimately,adaptations of the grey falcon to its extreme environment,Australia’s arid and semi-arid zone,one of the hottest environments in the world.展开更多
基金funded by the National Natural Science Foundation of China(No.32270554,32400400).
文摘The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradually increase their mobility, leave their parents, disperse from their natal site, and respond to the challenges of new environments. Characterizing these post-fledging movements and space use is essential for understanding juvenile survival strategies and devising targeted conservation measures. The Crested Ibis (Nipponia nippon), an endangered species and a highly protected animals at the national level in China, has seen limited research on its post-fledging movements and space use. From 2015 to 2023, we utilized biologgers, combined with field surveys, to study the movement and space use characteristics of 37 fledglings in Hanzhong City, Shaanxi Province, China, over a two-month post-fledging period. We quantified changes in activity levels (based on overall dynamic body acceleration), independence timing, onset of post-fledging dispersal, habitat selection, and daily activity rhythms after independence. Our results revealed individuals began independent living 26.23 ± 2.34 days post-fledging and onset of dispersal at 25.58 ± 2.33 days, with a range area at the natal of 2.08 ± 0.56 km^(2). The initial 30 days post-fledging are characterized as an ontogenetic phase marked by a rapid increase in body activity level. Fledglings preferred paddy fields during the independent period rather than the forests they relied on before independence. Interestingly, the daily activity rhythm, particularly foraging behavior, peaked at noon—contrasting with the expected morning and evening activity peaks—likely as an adaptation to avoid periods of peak human activity. Additionally, drowning, collisions, and predation in paddy fields are noteworthy causes of fledgling mortality. Consequently, we recommend protecting a 2-km^(2) area around the nest site for at least two-month post-fledging, implementing safety measures around power lines and cesspools. Additionally, reducing human disturbances near foraging habitats and expanding space within paddy fields would help mitigate survival pressures on fledglings.
基金the support and help from the Life Science College of Shaanxi Normal UniversityFinancial support was provided by National Nature Science Foundation of China (31172103)
文摘Background: Knowledge of dispersal movement of birds and their habitat preference during the post-fledging period is fundamental to the understanding of their ecological and evolutionary processes. The Crested Ibis is now being reintroduced to protected sites within its historical range, with the goal of establishing a self-sustaining population that may eventually qualify the species for delisting.Methods: We carried out an ecological study of post-fledging dispersal and habitat use of a reintroduced population of the Crested Ibis(Nipponia nippon) from 2008 to 2012 in Ningshan County, China, by using banding and radio-telemetry methods.Results: In about two weeks(an average of 14.3 days) after fledging, the activities of the fledglings were concentrated in a range of about 100 m around their natal sites, such as the oak-pine forest patches at the edge of open habitats.During this period, fledglings were still partially dependent upon parental care and fed typically on a daily basis.Siblings increasingly became independent by mid-August and then gradually moved away from their natal sites to post-fledging dispersal locations. During the period of the post-fledging dispersal process, most juveniles moving southwest were concentrated at the mean direction(μ = 254.6°, ? = 70.5°) with a mean dispersal distance of 5.1 km.It took an average of 56.4 days to disperse from the natal territory to the first wintering area. Also, forging habitats for juvenile ibis varied with time and local conditions. For example, paddy fields were used most frequently among all habitat types, while shallow rivers just from August to October. Masson pine(Pinus massoniana) was often regarded as the roosting tree species preferred by the Crested Ibis, with the highest utilization rate among all the roosting habitat types. The juveniles of the wild population dispersed four times as far as that of the reintroduced population, but the overall pattern of post-fledging dispersal is similar for the reintroduced and wild populations.Conclusions: Our results are very useful for us to predict the distance and direction of dispersal under various landscape conditions in other released sites. The project is a good example for reintroducing endangered species to their former ranges, and will be valuable for the protection of reintroduced populations of this critically and other endangered species.
文摘Assessing individual differences and variability in animal movement patterns is essential to improve our understanding of the evolution and ontogeny of migratory strategies.In long-distance migratory species,fledged juveniles often rely on an extremely restricted time span to learn the essential skills for survival and to prepare for migration,possibly the most risky phase of their lives.Collecting detailed information on the dynamics of the movements during the crucial pre-migratory phase is hence essential to understand the solutions developed by migratory species in different environmental contexts.Here,we used high-resolution GPS/GSM transmitters to collect information on the movement ecology of seven juvenile Montagu's Harriers(Circus pygargus)born in central Italy,investigating their early life stages,namely the post-fledging dependence period(PFDP)and the pre-migratory phase(PMP),until autumn migration.After fledging,individuals showed high variability(both in space and time)in home range size,daily distances covered(6.88±11.44 km/day),distance from the nest(1.45±2.8 km)and PFDP length(23.3±5.3 days).Residence time at the natal site significantly decreased,while time interval between revists in the natal area significantly increased,as the PFDP progressed.During the PMP,explored areas and distance from the nest(max value up to 320.8 km)varied among individuals,despite daily distances covered(27±40 km/day)and time allocation between traveling(60.7%)and foraging(39.3%)were similar across individuals.The PMP lasted 38±14 days.Land cover composition of foraging locations was mostly represented by agricultural lands(~78.2%),though habitat use differed among individuals.More than 76%of such locations were outside protected areas.This individual-based tracking study represents a novel approach that improves previous knowledge based on field studies on the early life stages of the Montagu's Harrier.High inter-individual variability in movement patterns,broad-range exploratory movements and foraging locations outside the protected area network make the application of standard conservation measures difficult,raising concerns about the long-term preservation of this vulnerable migratory species in Italy.
基金This work was supported by the Dampier Bunbury Pipeline,Perth,Western AustraliaThe Peregrine Fund,Boise IDthe Department of Biodiversity,Conservation and Attractions,Western Australia.J.S.was supported by the Australian Government Research Training Program Scholarship.
文摘Rapid learning in the young of most endothermic animals can be expected to be favored by natural selection because early independence reduces the period of vulnerability.Cases of comparatively slow juvenile development continue,therefore,to attract scientific attention.In most species of birds,including raptors,the young depend on their parents for some time after fledging for the provisioning of food and for protection while they learn to become nutritionally and otherwise independent.Among raptors,post-fledging dependence periods that exceed 6 months are exclusive to the largest species and these have reproductive cycles that exceed 12 months.By contrast,young of the medium-sized grey falcon Falco hypoleucos have been reported in close company with their parents up to 12 months after fledging,that is,at a time when the adults are expected to breed again.We investigated the occurrence and characteristics of prolonged adult–juvenile association relative to other falcons and similar-sized raptors.We found that the behavioral development of grey falcon young is extremely delayed,and that they even depend nutritionally on their parents for up to 12 months after fledging.We suggest that these 2 distinctive features are,ultimately,adaptations of the grey falcon to its extreme environment,Australia’s arid and semi-arid zone,one of the hottest environments in the world.
