Pub Date : 2021-07-03DOI: 10.1080/00063657.2022.2092067
C. Catoni, Roberto Aguilar-Pulido, Carlos B. Zavalaga, G. dell’Omo
ABSTRACT Capsule Grey Gulls Leucophaeus modestus breed in the Atacama Desert, Chile, and perform nocturnal commuting flights between their inland nesting sites and the coast in order to forage. Some aspects of the gullś flight patterns and routes remain unknown. Aim Determine the patterns and the routes of the commuting flights of Grey Gulls breeding in a remote colony in the Atacama Desert. Methods Using a modified marine radar we tracked the departure and arrival times, and direction of Grey Gulls. Furthermore, we managed to ground truth the information obtained from the radar by tracking two incubating gulls with GPS tags. Results Birds left the colony in two waves: first between 21:00 and 22:00 at the onset of nautical twilight, and a second, larger wave between 02:00 and 05:00 (peak at 03:15) before sunrise. Birds returned to the colony through the whole night with a major peak at 23:00, two hours after sunset. Tracking data confirmed the travel times and directions obtained from the radar. Conclusion Grey Gulls adjust their departure time from the colony and from the coast to fly only in the dark. Most birds left just after nautical twilight and flew at a constant speed to the coast. By knowing the arrival time, the peak of bird passage and their inbound flying direction, it is possible to infer the location of the departure place on the coast. By identifying consistent inbound flight patterns with radar it is possible to detect unknown colonies.
{"title":"Radar reveals the nocturnal flights of breeding Grey Gulls Leucophaeus modestus in the Atacama Desert, Chile","authors":"C. Catoni, Roberto Aguilar-Pulido, Carlos B. Zavalaga, G. dell’Omo","doi":"10.1080/00063657.2022.2092067","DOIUrl":"https://doi.org/10.1080/00063657.2022.2092067","url":null,"abstract":"ABSTRACT Capsule Grey Gulls Leucophaeus modestus breed in the Atacama Desert, Chile, and perform nocturnal commuting flights between their inland nesting sites and the coast in order to forage. Some aspects of the gullś flight patterns and routes remain unknown. Aim Determine the patterns and the routes of the commuting flights of Grey Gulls breeding in a remote colony in the Atacama Desert. Methods Using a modified marine radar we tracked the departure and arrival times, and direction of Grey Gulls. Furthermore, we managed to ground truth the information obtained from the radar by tracking two incubating gulls with GPS tags. Results Birds left the colony in two waves: first between 21:00 and 22:00 at the onset of nautical twilight, and a second, larger wave between 02:00 and 05:00 (peak at 03:15) before sunrise. Birds returned to the colony through the whole night with a major peak at 23:00, two hours after sunset. Tracking data confirmed the travel times and directions obtained from the radar. Conclusion Grey Gulls adjust their departure time from the colony and from the coast to fly only in the dark. Most birds left just after nautical twilight and flew at a constant speed to the coast. By knowing the arrival time, the peak of bird passage and their inbound flying direction, it is possible to infer the location of the departure place on the coast. By identifying consistent inbound flight patterns with radar it is possible to detect unknown colonies.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49306270","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 : 2021-07-03DOI: 10.1080/00063657.2022.2103096
J. Škrábal, I. Literák, Marek Dostál, R. Raab, D. Horal, H. Matušík, P. Spakovszky
ABSTRACT Capsule Some birds of the central European population of Red Kite Milvus milvus are non-migratory and winter within their natal area, whereas others migrate to southern Europe or even to northern Africa. Aims To determine what factors affect the area use and communal roost use by Red Kites wintering in their natal area. Methods We studied spatiotemporal activity and factors affecting area use by Red Kites wintering in their natal area in the tripoint border area of Austria, the Czech Republic, and Slovakia, using GPS/GSM telemetry devices. Results We characterized home ranges used by wintering Red Kites in natal areas. Birds wintered for an average of 146 days and spent 88% of the time within temporary settlement areas (TSAs). The number of TSAs used by one Red Kite during the winter varied from 1–4 (mean ± sd = 2 ± 1); the mean (± sd) size of the home range of TSAs was 190 ± 144 km2 as a 95% minimum convex polygon, 136 ± 82 km2 as a 95% kernel density estimate, and 41 ± 34 km2 as a 50% kernel density estimate (core activity area). Age, breeding status, and percentage of forest habitat were the main factors negatively related to home range size. Winter duration and the number of TSAs were positively related to the size of the home range. Young birds (before first breeding) and males explored larger areas and used more TSAs during winter. Conclusion Wintering of Red Kites in their natal area may relate to the social refuge–territory prospecting hypothesis, breeding site fidelity, wintering site fidelity, and/or mate loyalty, and this understanding could lead to better conservation of Red Kites in central Europe.
{"title":"Red Kites Milvus milvus wintering in their natal area: demographic, environmental, and temporary factors affecting spatiotemporal behaviour patterns","authors":"J. Škrábal, I. Literák, Marek Dostál, R. Raab, D. Horal, H. Matušík, P. Spakovszky","doi":"10.1080/00063657.2022.2103096","DOIUrl":"https://doi.org/10.1080/00063657.2022.2103096","url":null,"abstract":"ABSTRACT Capsule Some birds of the central European population of Red Kite Milvus milvus are non-migratory and winter within their natal area, whereas others migrate to southern Europe or even to northern Africa. Aims To determine what factors affect the area use and communal roost use by Red Kites wintering in their natal area. Methods We studied spatiotemporal activity and factors affecting area use by Red Kites wintering in their natal area in the tripoint border area of Austria, the Czech Republic, and Slovakia, using GPS/GSM telemetry devices. Results We characterized home ranges used by wintering Red Kites in natal areas. Birds wintered for an average of 146 days and spent 88% of the time within temporary settlement areas (TSAs). The number of TSAs used by one Red Kite during the winter varied from 1–4 (mean ± sd = 2 ± 1); the mean (± sd) size of the home range of TSAs was 190 ± 144 km2 as a 95% minimum convex polygon, 136 ± 82 km2 as a 95% kernel density estimate, and 41 ± 34 km2 as a 50% kernel density estimate (core activity area). Age, breeding status, and percentage of forest habitat were the main factors negatively related to home range size. Winter duration and the number of TSAs were positively related to the size of the home range. Young birds (before first breeding) and males explored larger areas and used more TSAs during winter. Conclusion Wintering of Red Kites in their natal area may relate to the social refuge–territory prospecting hypothesis, breeding site fidelity, wintering site fidelity, and/or mate loyalty, and this understanding could lead to better conservation of Red Kites in central Europe.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46031531","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 : 2021-04-03DOI: 10.1080/00063657.2021.1977780
G. Chiatante
ABSTRACT Capsule A species distrubtion model shows that Masked Shrikes Lanius nubicus in the southern Balkans inhabit areas with shrubs and trees, as well as open areas. It also reveals areas that are suitable for expansion of the population. Aims To fill a data gap on the habitat requirements of the Masked Shrike in North Macedonia, Bulgaria, and Greece. Methods Species distribution modelling was used to investigate the effects of environmental variables, such as land cover, vegetation activity, and climate, on the occurrence of Masked Shrikes. The MaxEnt algorithm was used with data on species occurrences downloaded from the Global Biodiversity Information Facility database. A bias map was used to resolve problems related to inhomogeneous data sources. Results The spatial distribution of the Masked Shrike in the southern Balkans is shaped mainly by land cover, especially by transitional shrub/woodland areas. There was also a positive relationship with the Enhanced Vegetation Index (EVI) in April and negative relationships with the EVI in July and temperature seasonality. Conclusions In the southern Balkans, the Masked Shrike inhabits areas with shrubs and trees interspersed with open areas, such as natural grassland. The predicted spatial distribution matches the known distribution quite well. The potential distribution showed many sites where the species could be present, and those are worthy of investigation given that the species has been expanding in the region.
{"title":"Habitat requirements of the Masked Shrike Lanius nubicus in the southern Balkans","authors":"G. Chiatante","doi":"10.1080/00063657.2021.1977780","DOIUrl":"https://doi.org/10.1080/00063657.2021.1977780","url":null,"abstract":"ABSTRACT Capsule A species distrubtion model shows that Masked Shrikes Lanius nubicus in the southern Balkans inhabit areas with shrubs and trees, as well as open areas. It also reveals areas that are suitable for expansion of the population. Aims To fill a data gap on the habitat requirements of the Masked Shrike in North Macedonia, Bulgaria, and Greece. Methods Species distribution modelling was used to investigate the effects of environmental variables, such as land cover, vegetation activity, and climate, on the occurrence of Masked Shrikes. The MaxEnt algorithm was used with data on species occurrences downloaded from the Global Biodiversity Information Facility database. A bias map was used to resolve problems related to inhomogeneous data sources. Results The spatial distribution of the Masked Shrike in the southern Balkans is shaped mainly by land cover, especially by transitional shrub/woodland areas. There was also a positive relationship with the Enhanced Vegetation Index (EVI) in April and negative relationships with the EVI in July and temperature seasonality. Conclusions In the southern Balkans, the Masked Shrike inhabits areas with shrubs and trees interspersed with open areas, such as natural grassland. The predicted spatial distribution matches the known distribution quite well. The potential distribution showed many sites where the species could be present, and those are worthy of investigation given that the species has been expanding in the region.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49289099","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 : 2021-04-03DOI: 10.1080/00063657.2021.1966740
Michael Thornton, C. Mitchell, L. Griffin, R. Briers, B. Minshull, Angus Maciver, Patrick J. C. White
ABSTRACT Capsule Our multi-scale habitat selection and spatial analysis of a threatened population of Taiga Bean Geese Anser fabalis highlights the importance of monitoring and review programmes to determine whether species conservation measures are being implemented at the correct spatio-temporal scales. Aims To undertake a habitat selection and spatial analysis of an internationally important population of Taiga Bean Geese, and quantify the extent to which their foraging range overlaps with a protected area classified to protect their roost sites and foraging areas. Methods A five-year field count dataset was used to quantify foraging habitat selection at the population range scale. In addition, global positioning system (GPS)/ultra high frequency loggers were attached to 12 birds and GPS location data were collected to quantify foraging habitat selection at an individual foraging range scale. Results Generalized linear models predicted that, at the population foraging range scale, Taiga Bean Geese selected agriculturally improved pasture, and this selection was more pronounced at greater distances from public roads. At an individual foraging range scale, compositional analysis revealed that agriculturally improved pasture was significantly selected over all other habitats. There was a substantial mismatch between their individual foraging ranges and the protected area, with less than 35% (median: 21%; range 9.5–31.9%) of their individual full foraging ranges overlapping with the protected area. Discussion Fixed protected areas may fail to fully accommodate the spatio-temporal foraging dynamics of geese, however a more appropriate conservation measure may be the use of flexible management schemes to maintain their foraging areas within and beyond protected area boundaries. This case study highlights the importance of developing dynamic conservation strategies for species liable to undergo range shifts.
{"title":"Multi-scale habitat selection and spatial analysis reveals a mismatch between the wintering distribution of a threatened population of Taiga Bean Geese Anser fabalis and its protected area","authors":"Michael Thornton, C. Mitchell, L. Griffin, R. Briers, B. Minshull, Angus Maciver, Patrick J. C. White","doi":"10.1080/00063657.2021.1966740","DOIUrl":"https://doi.org/10.1080/00063657.2021.1966740","url":null,"abstract":"ABSTRACT\u0000 Capsule Our multi-scale habitat selection and spatial analysis of a threatened population of Taiga Bean Geese Anser fabalis highlights the importance of monitoring and review programmes to determine whether species conservation measures are being implemented at the correct spatio-temporal scales. Aims To undertake a habitat selection and spatial analysis of an internationally important population of Taiga Bean Geese, and quantify the extent to which their foraging range overlaps with a protected area classified to protect their roost sites and foraging areas. Methods A five-year field count dataset was used to quantify foraging habitat selection at the population range scale. In addition, global positioning system (GPS)/ultra high frequency loggers were attached to 12 birds and GPS location data were collected to quantify foraging habitat selection at an individual foraging range scale. Results Generalized linear models predicted that, at the population foraging range scale, Taiga Bean Geese selected agriculturally improved pasture, and this selection was more pronounced at greater distances from public roads. At an individual foraging range scale, compositional analysis revealed that agriculturally improved pasture was significantly selected over all other habitats. There was a substantial mismatch between their individual foraging ranges and the protected area, with less than 35% (median: 21%; range 9.5–31.9%) of their individual full foraging ranges overlapping with the protected area. Discussion Fixed protected areas may fail to fully accommodate the spatio-temporal foraging dynamics of geese, however a more appropriate conservation measure may be the use of flexible management schemes to maintain their foraging areas within and beyond protected area boundaries. This case study highlights the importance of developing dynamic conservation strategies for species liable to undergo range shifts.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43535202","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 : 2021-04-03DOI: 10.1080/00063657.2022.2026877
Izabela Fedyń, E. Grzędzicka, D. Wiehle, Ł. Kajtoch
ABSTRACT Capsule Territories of the nocturnal Ural Owl Strix uralensis and diurnal Northern Goshawk Accipiter gentilis were spatially associated in fragmented forest but not in extensive forest. Aims To test the hypotheses that (i) the patterns of distribution of Ural Owl and Northern Goshawk territories are different in extensive and fragmented forests and (ii) the distribution of their territories do not depend on local forest structure and habitat variables. Methods The territories of Northern Goshawks and Ural Owls were identified in forests in southern Poland. Spatial analysis was used to examine the co-occurrence patterns of the two species, and multivariate analysis to examine the impact of environmental cues on territory selection. Results Most habitat parameters were not significantly related to the presence of territories of either species. For Northern Goshawk there was a positive association with the occurrence of old-growth patches and a negative association with clear-cut areas and proximity to forest edge in fragmented forests; for Ural Owl there was a significant effect of wood type in extensive forest. None of the habitat parameters distinguished the territories of the two species, suggesting similarity in the habitats used. The territories of the two species were spatially associated in fragmented forests, suggesting some positive interspecific relationship. In contrast, the distributions of the two species were not significantly associated in extensive forest. Conclusions To explain the spatial co-occurrence between Northern Goshawks and Ural Owls we suggest: (i) Ural Owls can occupy unused Northern Goshawk nests in managed extensive forest where there is a deficiency of large tree cavities; (ii) restricted availability of habitat in fragmented forests forces both species to nest in close proximity, and/or (iii) Ural Owls use social information from Northern Goshawks about habitat quality when selecting territories in some landscapes.
{"title":"The co-occurrence of Ural Owls Strix uralensis and Northern Goshawks Accipiter gentilis differs between extensive and fragmented forests","authors":"Izabela Fedyń, E. Grzędzicka, D. Wiehle, Ł. Kajtoch","doi":"10.1080/00063657.2022.2026877","DOIUrl":"https://doi.org/10.1080/00063657.2022.2026877","url":null,"abstract":"ABSTRACT Capsule Territories of the nocturnal Ural Owl Strix uralensis and diurnal Northern Goshawk Accipiter gentilis were spatially associated in fragmented forest but not in extensive forest. Aims To test the hypotheses that (i) the patterns of distribution of Ural Owl and Northern Goshawk territories are different in extensive and fragmented forests and (ii) the distribution of their territories do not depend on local forest structure and habitat variables. Methods The territories of Northern Goshawks and Ural Owls were identified in forests in southern Poland. Spatial analysis was used to examine the co-occurrence patterns of the two species, and multivariate analysis to examine the impact of environmental cues on territory selection. Results Most habitat parameters were not significantly related to the presence of territories of either species. For Northern Goshawk there was a positive association with the occurrence of old-growth patches and a negative association with clear-cut areas and proximity to forest edge in fragmented forests; for Ural Owl there was a significant effect of wood type in extensive forest. None of the habitat parameters distinguished the territories of the two species, suggesting similarity in the habitats used. The territories of the two species were spatially associated in fragmented forests, suggesting some positive interspecific relationship. In contrast, the distributions of the two species were not significantly associated in extensive forest. Conclusions To explain the spatial co-occurrence between Northern Goshawks and Ural Owls we suggest: (i) Ural Owls can occupy unused Northern Goshawk nests in managed extensive forest where there is a deficiency of large tree cavities; (ii) restricted availability of habitat in fragmented forests forces both species to nest in close proximity, and/or (iii) Ural Owls use social information from Northern Goshawks about habitat quality when selecting territories in some landscapes.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47310666","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 : 2021-04-03DOI: 10.1080/00063657.2022.2026875
M. Matysek, R. Gwiazda, Tomasz Figarski, F. Zięba, M. Klimecki, Radosław Mateja, P. Krzan, G. Piątek
ABSTRACT Capsule Predation risk of artificial nests resembling Hazel Grouse Tetrastes bonasia nests was reduced in more diverse habitats and when roads and trails were closer. Aims To determine the importance of habitat structure and the presence of roads and hiking trails for the predation risk of artificial ground nests. Methods We investigated predation on artificial nests in mountain spruce forests with high tourist numbers in the Tatra Mountains, Southern Poland, in 2012–2014. Some 174 artificial ground nests resembling those of Hazel Grouse were set up and monitored. For 98 artificial nests, we compared environmental variables at two area scales, and the forest structure between predated and surviving nests. Results At the local scale (within 5 m) artificial nests were more likely to be predated at sites with lower occurrence of ferns and lying dead wood. At the wider spatial scale (within 100 m), nests were more likely to survive if near to roads and tourist trails. The occurrence of different tree species in the forest stand did not significantly influence predation rate of artificial nests. The mean daily nest predation rate was not high and varied between years (0.003–0.009). Conclusion Greater habitat diversity and the presence of roads and trails increased the survival of ground nests. These results are potentially important for conservation planning for threatened ground-nesting birds, such as the Tetraonidae.
{"title":"What habitat parameters are important for the survival of ground nests in mountain forests? Recommendations for protection of Hazel Grouse Tetrastes bonasia based on an experiment with artificial nests","authors":"M. Matysek, R. Gwiazda, Tomasz Figarski, F. Zięba, M. Klimecki, Radosław Mateja, P. Krzan, G. Piątek","doi":"10.1080/00063657.2022.2026875","DOIUrl":"https://doi.org/10.1080/00063657.2022.2026875","url":null,"abstract":"ABSTRACT Capsule Predation risk of artificial nests resembling Hazel Grouse Tetrastes bonasia nests was reduced in more diverse habitats and when roads and trails were closer. Aims To determine the importance of habitat structure and the presence of roads and hiking trails for the predation risk of artificial ground nests. Methods We investigated predation on artificial nests in mountain spruce forests with high tourist numbers in the Tatra Mountains, Southern Poland, in 2012–2014. Some 174 artificial ground nests resembling those of Hazel Grouse were set up and monitored. For 98 artificial nests, we compared environmental variables at two area scales, and the forest structure between predated and surviving nests. Results At the local scale (within 5 m) artificial nests were more likely to be predated at sites with lower occurrence of ferns and lying dead wood. At the wider spatial scale (within 100 m), nests were more likely to survive if near to roads and tourist trails. The occurrence of different tree species in the forest stand did not significantly influence predation rate of artificial nests. The mean daily nest predation rate was not high and varied between years (0.003–0.009). Conclusion Greater habitat diversity and the presence of roads and trails increased the survival of ground nests. These results are potentially important for conservation planning for threatened ground-nesting birds, such as the Tetraonidae.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46553155","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 : 2021-04-03DOI: 10.1080/00063657.2021.2021389
Alberto G. Gantz, Carlos E. Valdivia
ABSTRACT We evaluate, experimentally, the relative rate of artificial nest predation in hedgerows in southern Chile. Predation on artificial eggs was extremely high, with rodents being the main nest predators.
{"title":"A high rate of rodent-mediated predation on artificial nests in hedgerows of an agricultural landscape in southern Chile","authors":"Alberto G. Gantz, Carlos E. Valdivia","doi":"10.1080/00063657.2021.2021389","DOIUrl":"https://doi.org/10.1080/00063657.2021.2021389","url":null,"abstract":"ABSTRACT We evaluate, experimentally, the relative rate of artificial nest predation in hedgerows in southern Chile. Predation on artificial eggs was extremely high, with rodents being the main nest predators.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46568609","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 : 2021-04-03DOI: 10.1080/00063657.2021.1974339
Ivana Novčič, Z. Vidović
ABSTRACT Capsule The total flock size and number of nearby neighbours did not affect vigilance behaviour in the Black-headed Gull Chroicocephalus ridibundus, but an increase in the nearest neighbour distance had a positive effect on measures of vigilance. Aims Vigilance allows animals to detect environmental stimuli, such as the presence of predators or competitors. Vigilance entails costs, however, because individuals may devote less time to other biologically important activities. We examined the trade-off between preening and vigilance in wintering Black-headed Gulls, while simultaneously considering the role of several confounding variables. Methods Using multivariate regression models we examined the effect of several predictors on three common measures of vigilance: scan frequency, average scan duration, and the percentage of time allocated to scanning. Results We did not detect a group-size effect on vigilance, but an increase in the nearest-neighbour distance had a positive effect on scanning frequency and the proportion of time focal gulls allocated to scanning. In addition, individuals at the periphery of flocks scanned their environment more frequently compared to centrally positioned gulls. Other variables that had significant effects on vigilance were location of roosting flocks, ambient temperature and wind speed. Conclusions In general, this study indicates that antipredator vigilance played an important role in overall vigilance in preening gulls in an urban environment.
{"title":"Nearest-neighbour distance, rather than group size, affects vigilance in urban flocks of preening Black-headed Gulls Chroicocephalus ridibundus","authors":"Ivana Novčič, Z. Vidović","doi":"10.1080/00063657.2021.1974339","DOIUrl":"https://doi.org/10.1080/00063657.2021.1974339","url":null,"abstract":"ABSTRACT Capsule The total flock size and number of nearby neighbours did not affect vigilance behaviour in the Black-headed Gull Chroicocephalus ridibundus, but an increase in the nearest neighbour distance had a positive effect on measures of vigilance. Aims Vigilance allows animals to detect environmental stimuli, such as the presence of predators or competitors. Vigilance entails costs, however, because individuals may devote less time to other biologically important activities. We examined the trade-off between preening and vigilance in wintering Black-headed Gulls, while simultaneously considering the role of several confounding variables. Methods Using multivariate regression models we examined the effect of several predictors on three common measures of vigilance: scan frequency, average scan duration, and the percentage of time allocated to scanning. Results We did not detect a group-size effect on vigilance, but an increase in the nearest-neighbour distance had a positive effect on scanning frequency and the proportion of time focal gulls allocated to scanning. In addition, individuals at the periphery of flocks scanned their environment more frequently compared to centrally positioned gulls. Other variables that had significant effects on vigilance were location of roosting flocks, ambient temperature and wind speed. Conclusions In general, this study indicates that antipredator vigilance played an important role in overall vigilance in preening gulls in an urban environment.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47003826","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 : 2021-04-03DOI: 10.1080/00063657.2021.2019187
S. Gillings, D. Balmer, S. Harris, D. Massimino, J. Pearce‐Higgins
ABSTRACT Capsule COVID-19 restrictions significantly biased BTO/JNCC/RSPB Breeding Bird Survey coverage across the UK allowing indicative trends to be produced for approximately one-third of species in England only. Aims To investigate the effect that COVID-19 restrictions had on participation in and coverage of the Breeding Bird Survey (BBS), and to quantify the likely impacts on population change reporting based on 2020 data. Methods We determined geographic, seasonal, and habitat coverage for the BBS in 2020 and compared this to previous years, and quantified the scale of biases and reductions in sample size for target species. We degraded existing BBS data (1994–2019) to simulate 2020 coverage and produced population change estimates using three methods applied to the complete and degraded data to assess the impacts of 2020 coverage on emergent trends. Results In 2020, 49% fewer survey squares were visited compared to 2019. Reductions were greatest in Wales, Scotland, and Northern Ireland, and in the early breeding season, when 90% fewer visits were made. The few early visits completed were on atypical dates and showed marked habitat biases. Individual species were detected in 23–96% fewer squares than normal. Population change estimates derived using routine trend models were negatively biased in up to 96% of species, with errors greatest for species normally detected on early visits. Alternative trend models using visit-specific parameterization or focussing only on late season visits overcame coverage biases for some species. Conclusions Lockdown restrictions associated with the COVID-19 outbreak meant it was not possible to produce population trend information for UK, Wales, Scotland, or Northern Ireland in 2020. Indicative long-term trends could be produced in England only for a subset of about 40 species. We recommend managers of citizen science schemes undertake similar analyses to assess the scale of coverage biases when unforeseen events cause temporary, but substantial changes, in sampling effort.
{"title":"Impacts of COVID-19 restrictions on capacity to monitor bird populations: a case study using the UK Breeding Bird Survey","authors":"S. Gillings, D. Balmer, S. Harris, D. Massimino, J. Pearce‐Higgins","doi":"10.1080/00063657.2021.2019187","DOIUrl":"https://doi.org/10.1080/00063657.2021.2019187","url":null,"abstract":"ABSTRACT Capsule COVID-19 restrictions significantly biased BTO/JNCC/RSPB Breeding Bird Survey coverage across the UK allowing indicative trends to be produced for approximately one-third of species in England only. Aims To investigate the effect that COVID-19 restrictions had on participation in and coverage of the Breeding Bird Survey (BBS), and to quantify the likely impacts on population change reporting based on 2020 data. Methods We determined geographic, seasonal, and habitat coverage for the BBS in 2020 and compared this to previous years, and quantified the scale of biases and reductions in sample size for target species. We degraded existing BBS data (1994–2019) to simulate 2020 coverage and produced population change estimates using three methods applied to the complete and degraded data to assess the impacts of 2020 coverage on emergent trends. Results In 2020, 49% fewer survey squares were visited compared to 2019. Reductions were greatest in Wales, Scotland, and Northern Ireland, and in the early breeding season, when 90% fewer visits were made. The few early visits completed were on atypical dates and showed marked habitat biases. Individual species were detected in 23–96% fewer squares than normal. Population change estimates derived using routine trend models were negatively biased in up to 96% of species, with errors greatest for species normally detected on early visits. Alternative trend models using visit-specific parameterization or focussing only on late season visits overcame coverage biases for some species. Conclusions Lockdown restrictions associated with the COVID-19 outbreak meant it was not possible to produce population trend information for UK, Wales, Scotland, or Northern Ireland in 2020. Indicative long-term trends could be produced in England only for a subset of about 40 species. We recommend managers of citizen science schemes undertake similar analyses to assess the scale of coverage biases when unforeseen events cause temporary, but substantial changes, in sampling effort.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45243212","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 : 2021-04-03DOI: 10.1080/00063657.2022.2028718
T. Wesol̸owski
ABSTRACT Capsule European Starlings Sturnus vulgaris nested mostly in natural holes with strong walls (in live trees), typically excavated by medium-sized woodpeckers (small entrances, deep cavities), and high above the ground. Co-occurrence of these safety-enhancing features suggests that predation avoidance has been the main force shaping patterns of Starling nest site selection. Aims To describe patterns of nest site use by Starlings in a primeval forest and to assess the adaptive value of nest site choice. Methods Observations were made of Starlings breeding in undisturbed conditions in a strictly protected part of the Białowieża National Park, Poland. Intensive searches were made for nests (n = 2039) in permanent observation plots during 46 breeding seasons (1975–2020), coupled with measurements of hole attributes and observations of fate and re-use of nest sites. Results Starlings bred along forest edges in holes located in several species of deciduous tree; tree species used differed among habitats and hole location differed across tree species. The birds bred mostly in holes excavated by woodpeckers (70.3%), in trunks (77.4%) of living trees (84.5%). The median girth at breast height of these trees amounted to approximately 170 cm and median height of holes above the ground was 13 m. Starlings used holes excavated by the medium-sized woodpeckers roughly in proportion to their availability in the forest (tree species, stature, height above the ground). About 39% of holes were re-used in the consecutive years, with some holes being used over several decades. Conclusion The features of Starling nest holes (strong walls, narrow entrances, deep cavities) probably constitute adaptations to the need to evade predators. Their body size allows them to nest in excavated holes without threat of their broods being destroyed by woodpeckers.
{"title":"Natural nest sites of the European Starling Sturnus vulgaris in a primeval temperate forest","authors":"T. Wesol̸owski","doi":"10.1080/00063657.2022.2028718","DOIUrl":"https://doi.org/10.1080/00063657.2022.2028718","url":null,"abstract":"ABSTRACT\u0000 Capsule European Starlings Sturnus vulgaris nested mostly in natural holes with strong walls (in live trees), typically excavated by medium-sized woodpeckers (small entrances, deep cavities), and high above the ground. Co-occurrence of these safety-enhancing features suggests that predation avoidance has been the main force shaping patterns of Starling nest site selection. Aims To describe patterns of nest site use by Starlings in a primeval forest and to assess the adaptive value of nest site choice. Methods Observations were made of Starlings breeding in undisturbed conditions in a strictly protected part of the Białowieża National Park, Poland. Intensive searches were made for nests (n = 2039) in permanent observation plots during 46 breeding seasons (1975–2020), coupled with measurements of hole attributes and observations of fate and re-use of nest sites. Results Starlings bred along forest edges in holes located in several species of deciduous tree; tree species used differed among habitats and hole location differed across tree species. The birds bred mostly in holes excavated by woodpeckers (70.3%), in trunks (77.4%) of living trees (84.5%). The median girth at breast height of these trees amounted to approximately 170 cm and median height of holes above the ground was 13 m. Starlings used holes excavated by the medium-sized woodpeckers roughly in proportion to their availability in the forest (tree species, stature, height above the ground). About 39% of holes were re-used in the consecutive years, with some holes being used over several decades. Conclusion The features of Starling nest holes (strong walls, narrow entrances, deep cavities) probably constitute adaptations to the need to evade predators. Their body size allows them to nest in excavated holes without threat of their broods being destroyed by woodpeckers.","PeriodicalId":55353,"journal":{"name":"Bird Study","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2021-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43156376","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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