Young birds switch but old birds lead : how barnacle geese adjust migratory habits to environmental change

This research was funded by a grant from the Netherlands Organization for Scientific Research awarded to TO (ref 019.172EN.011).Long-distance migratory animals must contend with global climate change, but they differ greatly in whether and how they adjust. Species that socially learn their migration routes may have an advantage in this process compared to other species, as learned changes that are passed on to the next generation can speed up adjustment. However, evidence from the wild that social learning helps migrants adjust to environmental change is absent. Here, we study the behavioral processes by which barnacle geese (Branta leucopsis) adjust spring-staging site choice along the Norwegian coast, which appears to be a response to climate change and population growth. We compared individual-based models to an empirical description of geese colonizing a new staging site in the 1990s. The data included 43 years of estimated annual food conditions and goose numbers at both staging sites (1975–2017), as well as annual age-dependent switching events between the two staging sites from one year to the next (2000–2017). Using Approximate Bayesian Computation, we assessed the relative likelihood of models with different “decision rules”, which define how individuals choose a staging site. In the best performing model, individuals traveled in groups and staging site choice was made by the oldest group member. Groups normally returned to the same staging site each year, but exhibited a higher probability of switching staging site in years with larger numbers of geese at the staging site. The decision did not depend on food availability in the current year. Switching rates between staging sites decreased with age, which was best explained by a higher probability of switching between groups by younger geese, and not by young geese being more responsive to current conditions. We found no evidence that the experienced foraging conditions in previous years affected staging site choice. Our findings demonstrate that copying behavior and density-dependent group decisions explain how geese adjust their migratory habits rapidly in response to changes in food availability and competition. We conclude that considering social processes can be essential to understand how migratory animals respond to changing environments.Publisher PDFPeer reviewe

The connectivity of spring stopover sites for geese heading to arctic breeding grounds

During the spring migration arctic-breeding geese pause in temperate and sub-arctic staging areas in order to deposit body reserves for breeding. Focusing on a single arctic stopover site in West-Spitsbergen, Svalbard, Norway (Varsol-bukta, 77 degrees 45'N, 14 degrees 24'E), behavioural strategies of Barnacle Geese Branta leucopsis were investigated and body condition and presence of individually marked birds recorded. Individuals using different staging areas earlier along the migration route (Helgeland and Vesteralen on the Norwegian mainland) and heading to different breeding colonies (the close-by Nordenskioldkysten, and the distant Kongsfjorden) were compared during springs 2003-05. Birds in Vesteralen left the staging area earlier than those in Helgeland, and arrived earlier in Varsolbukta as well. In Varsolbukta, females gained body condition at a similar rate regardless of their colony affiliation, whereas males from Nordenskioldkysten exhibited a smaller overall increase in condition compared to males from Kongsfjorden. The Kongsfjorden birds stayed for a shorter period (average 2.8 days) than those from Nordenskioldkysten (average 4.0 days). Nordenskioldkysten birds frequently left Varsolbukta for short periods presumably visiting the breeding area in order to optimise nest initiation with respect to prevailing snow conditions. The date of final departure was also correlated with nest initiation date at Nordenskioldkysten. No such relationship for the Kongsfjorden birds was found. We suggest that the geese adopt a 'hopping' strategy, using a network of stopover sites in Svalbard during spring with a last stopover at a buffer area in the proximity to the breeding area. For this vulnerable population it is important to identify the sites forming the links in this chain, and to establish their function and utilisation by geese during the vital prebreeding period

Fugler i Norge 2003 – Rapport fras Norsk faunakomité for fugl (NFKF)

THE NORWEGIAN BIRD REPORT 2003 - a report on locally uncommon and scarce birds in Norway in 2003, by the Norwegian Bird Records Committee (NFKF) The basis of this report is the annual reports produced by the county rarities committees. All counties contributed to the report for 2003, although the Svalbard archipelago and Jan Mayen as well as Finnmark, Troms, Sogn & Fjordane and Vest-Agder counties did not publish own county reports. We believe this report reflects fairly well observations from Norway in 2003. Readers should take care to note the geographical or time delimitation of the records stated for the different species, as stated in codes immediately after the scientific name of the species. The Norwegian Bird Records Committee (NFKF) has published annual reports since 1991. The occurrence of Bewick’s Swan Cygnus columbianus was the best in NFKFs history, while the occurence of Lesser White-fronted Geese Anser erythropus at the traditional feeding and roosting site Valdakmyra, Porsanger (FI) continued to be low. One breeding pair of Pink-footed Goose Anser brachyrhynchus at Grindøya, Troms county was the first breeding attempt on the Norwegian mainland (excepting an attempt by a hybrid pair). Bar-headed Goose Anser indicus was seen in exceptionally good numbers. Gadwalls Anas strepera have occurred in steadily increasing numbers in Norway in recent years, and 2003 was the best year to date for this species. One breeding record of Smew Mergellus albellus from Vikna, Nord-Trøndelag county was the first breeding record in Norway outside Finnmark. The occurrence of Common Quail Coturnix coturnix and Corncrake Crex crex was the second best, while the occurrence of Spotted Crake Porzana porzana was the third best in NFKFs history. The Eurasian Hobby Falco subbuteo is a raptor that has occurred in high numbers in recent years, and 2003 was the best year ever. The occurrence of Avocets Recurvirostra avosetta and Black-tailed Godwits Limosa limosa was the best ever in NFKFs history, while the occurrence of migrating Broad-billed Sandpiper Limicola falcinellus was poor with only one individual during the autumn migration period. Migrating Pomarine Skuas Stercorarius pomarinus and Long-tailed Skuas Stercorarius longicaudus were seen in good numbers and the occurrence of Glaucous Gulls Larus hyperboreus was the best in NFKFs history. Also the occurrence of Little Gulls Larus minutus was very good, givingc the second best year ever. Turtle Doves Streptopelia turtur had a very good year during both spring and autumn, giving the best year in NFKFs history. The number of Hoopoes Upupa epops was the third best since 1991. The occurrences of Wood Larks Lullula arborea and Richard’s Pipits Anthus richardi was the third best, while the occurrence of Red-throated Pipits Anthus cervinus was very low. The number of Pied Wagtails Motacilla alba yarrellii, singing Grasshopper Warblers Locustella naevia, Yellow-browed Warblers Phylloscopus inornatus and Red-breasted Flycatchers Ficedula parva was the highest ever recorded, while Marsh Warbler Acrocephalus palustris, Barred Warblers Sylvia nisoria and Great Grey Shrikes Lanius excubitor experienced second best numbers since 1991. The number of Golden Oriole Oriolus oriolus was the lowest ever recorded in NFKFs history. Two-barred Crossbills Loxia leucoptera continued to occur in good numbers after the autumn 2002 influx, but very few individuals remained after the summer. The Hawfinch Coccothraustes coccothraustes still show a marked increase in the north of its distribution range, especially in the Trøndelag counties. The Ortolan Bunting Emberiza hortulana continued to occur in low numbers while the occurrence of Little Buntings Emberiza pusilla was the second best in NFKFs history

Whooper Swan Cygnus cygnus January population censuses for Northwest Mainland Europe, 1995-2015

Internationally coordinated censuses of Whooper Swans Cygnus cygnus across continental northwest Europe were undertaken in mid-winter 1995, 2000, 2005, 2010 and 2015. The estimate of 138,500 birds in 2015, the highest to date, represented a more than doubling of the population size (at an annual increase of 4.1%) since the first census total of 59,000 swans in 1995. The largest increase was in Denmark, where numbers almost trebled from 21,740 in 1995 to 62,620 in 2015. More than 97% of all swans were counted in just six countries. The percentage of total numbers increased significantly between 1995 and 2015 in Denmark (from 36.5% to 45.2%) and Germany (26.0% to 34.7%), but declined significantly in Sweden (14.2% to 8.4%), Norway (13.1% to 3.6%), Poland (6.2% to 4.0%) and the Netherlands (2.4% to 1.7%). The counts show an increasing discrepancy between national trends in abundance for Whooper Swans in Sweden and especially in Denmark in comparison with results obtained only from mid-winter International Waterbird Count (IWC) site coverage. This demonstrates the increasing tendency for Whooper Swans to winter in areas away from traditionally counted IWC sites and confirms the continued need for a regular cycle of coordinated dedicated swan counts to anchor population trends generated from other data sources.Peer reviewe

The future distribution of wetland birds breeding in Europe validated against observed changes in distribution

Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas and climate and land-use data to predict distributional changes over a century (the 1970s-2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas. Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km yr(-1) towards the north (5% northeast, 45% north, and 40% northwest), compared to a slower observed average shift of ca. 3.9 km yr(-1). Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to 'climate debt'. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds' resilience to the expected environmental changes in the future

The future distribution of wetland birds breeding in Europe validated against observed changes in distribution

Publisher Copyright: © 2022 The Author(s). Published by IOP Publishing Ltd.Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas and climate and land-use data to predict distributional changes over a century (the 1970s-2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas. Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km yr-1 towards the north (5% northeast, 45% north, and 40% northwest), compared to a slower observed average shift of ca. 3.9 km yr-1. Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to 'climate debt'. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds' resilience to the expected environmental changes in the future.Peer reviewe

Ecological barriers mediate spatiotemporal shifts of bird communities at a continental scale

This study was supported by the Swiss National Science Foundation (grant P2BEP3_195232) and by the Academy of Finland (project 323527 and project 329251).Species' range shifts and local extinctions caused by climate change lead to community composition changes. At large spatial scales, ecological barriers, such as biome boundaries, coastlines, and elevation, can influence a community's ability to shift in response to climate change. Yet, ecological barriers are rarely considered in climate change studies, potentially hindering predictions of biodiversity shifts. We used data from two consecutive European breeding bird atlases to calculate the geographic distance and direction between communities in the 1980s and their compositional best match in the 2010s and modeled their response to barriers. The ecological barriers affected both the distance and direction of bird community composition shifts, with coastlines and elevation having the strongest influence. Our results underscore the relevance of combining ecological barriers and community shift projections for identifying the forces hindering community adjustments under global change. Notably, due to (macro)ecological barriers, communities are not able to track their climatic niches, which may lead to drastic changes, and potential losses, in community compositions in the future.Publisher PDFPeer reviewe

Northward range expansion in spring-staging barnacle geese is a response to climate change and population growth, mediated by individual experience

The study was funded by the Norwegian Environment Agency, the Research Council of Norway (the projects ‘LANDRING 134716/720’, ‘AGRIGOOSE 165836’, ‘MIGRAPOP 204342’), the European Union (the project FRAGILE EVK2‐2001‐00235), the County Governor of Nordland, the Wildfowl and Wetlands Trust, the Fram Centre in Tromsø and a grant from the Netherlands Organization for Scientific Research awarded to TO (ref 019.172EN.011).All long-distance migrants must cope with changing environments, but species differ greatly in how they do so. In some species, individuals might be able to adjust by learning from individual experiences and by copying others. This could greatly speed up the process of adjustment, but evidence from the wild is scarce. Here, we investigated the processes by which a rapidly growing population of barnacle geese (Branta leucopsis) responded to strong environmental changes on spring-staging areas in Norway. One area, Helgeland, has been the traditional site. Since the mid-1990s, an increasing number of geese stage in another area 250 km further north, Vesterålen. We collected data on goose numbers and weather conditions from 1975 to 2017 to explore the extent to which the increase in population size and a warmer climate contributed to this change in staging area use. During the study period, the estimated onset of grass growth advanced on average by 0.54 days/year in each of the two areas. The total production of digestible biomass for barnacle geese during the staging period increased in Vesterålen but remained stable in Helgeland. The goose population has doubled in size during the past 25 years, with most of the growth being accommodated in Vesterålen. The observations suggest that this dramatic increase would not have happened without higher temperatures in Vesterålen. Records of individually marked geese indicate that from the initial years of colonization onwards, especially young geese tended to switch to Vesterålen, thereby predominating in the flocks at Vesterålen. Older birds had a lower probability of switching to Vesterålen, but over the years, the probability increased for all ages. Our findings suggest that barnacle geese integrate socially learned behaviour with adjustments to individual experiences, allowing the population to respond rapidly and accurately to global change.Publisher PDFPeer reviewe