Seasonal connectivity in settlement decision of migratory birds
Lead Research Organisation:
University of Cambridge
Department Name: Zoology
Abstract
In migratory bird species, the ability of individuals to settle on good quality winter and breeding habitat can determine their survival and reproductive success. Recent evidence shows that in migratory systems, some individuals can occupy the best sites at both ends of the range. This connectivity has considerable consequences for demography, life histories and conservation. In many migratory birds, parents migrate independently of their offspring, so juveniles must choose winter and breeding locations without any guidance. As adults tend to return to the sites they have used previously, these juvenile decisions are critical. This study will identify the mechanisms that determine juvenile settlement decisions, and their implications for population regulation, in black-tailed godwits, a migratory shorebird. Studies of migratory species are complicated by the vast distances over which individuals move. The godwit system is ideal for such studies because large numbers of marked individuals are routinely tracked throughout the range, and because chemical signatures in feathers can determine the wintering habitat of breeding birds. Understanding these settlement decisions will allow us to predict the consequences of the loss of different sites throughout the range for this species, and to identify the key parameters of importance in similar migratory species.
Publications
Alves J
(2010)
Population overlap and habitat segregation in wintering Black-tailed Godwits Limosa limosa
in Bird Study
Alves J
(2011)
Overtaking on migration: does longer distance migration always incur a penalty?
in Oikos
Alves J
(2013)
Costs, benefits, and fitness consequences of different migratory strategies
in Ecology
Alves JA
(2013)
Sex-biases in distribution and resource use at different spatial scales in a migratory shorebird.
in Ecology and evolution
Goss-Custard JD
(2006)
Intake rates and the functional response in shorebirds (Charadriiformes) eating macro-invertebrates.
in Biological reviews of the Cambridge Philosophical Society
Gunnarsson T
(2006)
Large-scale habitat associations of birds in lowland Iceland: Implications for conservation
in Biological Conservation
Gunnarsson T
(2010)
Sexing of Black-tailed Godwits Limosa limosa islandica : a comparison of behavioural, molecular, biometric and field-based techniques
in Bird Study
Gunnarsson TG
(2012)
Rapid changes in phenotype distribution during range expansion in a migratory bird.
in Proceedings. Biological sciences
Gunnarsson TG
(2006)
Population-scale drivers of individual arrival times in migratory birds.
in The Journal of animal ecology
Knudsen E
(2011)
Challenging claims in the study of migratory birds and climate change.
in Biological reviews of the Cambridge Philosophical Society
| Description | Recent widespread declines in many migratory bird species are likely to result from interactions between habitat loss and climatic changes. Addressing the causes of these declines is complicated by the need to understand the links between processes in breeding and wintering locations often thousands of kilometres apart. Our long-term study of Icelandic black-tailed godwits has provided some of the strongest evidence for these links. As this population is one of the few that is currently increasing, it provides a rare opportunity to explore drivers of demographic variation that are frequently obscured during population declines. Our population-wide tracking of individual black-tailed godwits as they migrate throughout their range has shown that individual godwits tend to occupy either good breeding and winter locations or poor quality breeding and winter locations - a pattern known as seasonal matching. As adults of most migratory bird species are highly site-faithful in summer and winter, juvenile settlement decisions must be critical in initiating this seasonal matching, and thus in determining the consequences for individual fitness and potential population-scale processes. Through extensive marking and tracking of godwit chicks in Iceland, we have shown that a key settlement decision that initiates seasonal matching is natal site-fidelity, and DNA-sexing has allowed us to show that males recruit into the breeding sites from which they were hatched but females do not, which is why seasonal matching is stronger in males than females. Winter settlement patterns of juvenile godwits do not show any clear sex bias but geographic variation in juvenile settlement suggests that birds from poorer quality breeding habitats are more likely to be found in the north of the winter range, suggesting that they may have fewer opportunities to locate better quality sites elsewhere in the range. A continued expansion into poorer quality breeding habitat may therefore result in an increasing proportion of the population occupying poorer quality winter habitats, even though better quality sites are available, simply because later migration limits opportunities for exploration and philopatry constrains adults to the sites selected as juveniles. In summary, juvenile settlement decisions underlie the initiation of seasonal matching which can determine subsquent individual fitness. Settlement in summer is influenced by natal site-fidelity (in males but not females) and in winter by the constraints of timing of migration and winter site-fidelity. The interactions between these behavioural constraints and spatial variation in habitat quality are thus likely to determine current and future responses to climatic and habitat changes in migratory species. |
| Exploitation Route | This work is fundamental to understanding responses to habitat change and climate change. |
| Sectors | Environment |
| Description | There have been a number of other studies that have subsequently looked at seasonal conectedness. This subject is important as changs in one season can have disproportionate impacts in the other season. |
| First Year Of Impact | 2008 |
| Sector | Environment,Government, Democracy and Justice |
| Impact Types | Societal |
| Description | Development of International Species Action Plans |
| Description | Collaboration between universities and citizen scientists |
| Organisation | University of Iceland |
| Country | Iceland |
| Sector | Academic/University |
| PI Contribution | This research involves collaboration between the Universities of East Anglia, Cambridge and Iceland, with substantial collaboration and contributions from volunteer 'citizen scientists' from across Europe who collect data for the research. |
| Description | Public communication |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Primary Audience | Public/other audiences |
| Results and Impact | Regular communication with volunteers who contribute data to the study, and frequent presentations of research findings to the public We regularly give public presentations (2-3 per year) on our research in order to foster public understanding of science and to encourage direct involvement in the study by volunteer citizen scientists |
| Year(s) Of Engagement Activity | Pre-2006 |
| Description | Public communication |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Public/other audiences |
| Results and Impact | Regular communication with volunteers who contribute data to the study, and frequent presentations of research findings to the public We regularly give public presentations (2-3 per year) on our research in order to foster public understanding of science and to encourage direct involvement in the study by volunteer citizen scientists |
| Year(s) Of Engagement Activity | Pre-2006,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018 |