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001-es BibID:	BIBFORM021579
Első szerző:	Barta Zoltán (biológus, zoológus)
Cím:	Annual routines of non-migratory birds : optimal moult strategies / Zoltán Barta, Alasdair I. Houston, John M. McNamara, Robert K. Welham, Anders Hedenström, Thomas P. Weber, Orsolya Feró
Dátum:	2006
ISSN:	0030-1299
Megjegyzések:	In a periodically changing environment it is important for animals to properly time the major events of their life in order to maximise their lifetime fitness. For a non-migratory bird the timing of breeding and moult are thought to be the most crucial. We develop a state-dependent optimal annual routine model that incorporates explicit density dependence in the food supply. In the model the birds' decisions depend on the time of year, their energy reserves, breeding status, experience, and the quality of two types of feathers (outer and inner primaries). Our model predicts that, under a seasonal environment, feathers with large effects on flight ability, higher abrasion rate and lower energetic cost of moult should be moulted closer to the winter (i.e. later) than those with the opposite attributes. Therefore, we argue that the sequence of moult may be an adaptive response to the problem of optimal timing of moult of differing feathers within the same feather tract. The model also predicts that environmental seasonality greatly affects optimal annual routines. Under high seasonality birds breed first then immediately moult, whereas under low seasonality an alternation occurs between breeding and moulting some of the feathers in one year and having a complete moult but no breeding in the other year. Increasing food abundance has a similar effect.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Oikos. - 112 (2006), p. 580-593. -
További szerzők:	Houston, Alasdair I. McNamara, John M. Welham, Robert K. Hedenström, Anders Weber, Thomas P. Feró Orsolya
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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001-es BibID:	BIBFORM018796
Első szerző:	Barta Zoltán (biológus, zoológus)
Cím:	Optimal moult strategies in migratory birds / Zoltán Barta, John M. McNamara, Alasdair I. Houston, Thomas P. Weber, Anders Hedenström, Orsolya Feró
Dátum:	2008
Megjegyzések:	Avian migration, which involves billions of birds flying vast distances, is known to influence all aspects of avian life. Here we investigate how birds fit moult into an annual cycle determined by the need to migrate. Large variation exists in moulting patterns in relation to migration: for instance, moult can occur after breeding in the summer or after arrival in the wintering quarters. Here we use an optimal annual routine model to investigate why this variation exists. The modelled bird's decisions depend on the time of year, its energy reserves, breeding status, experience, flight feather quality and location. Our results suggest that the temporal and spatial variations in food are an important influence on a migratory bird's annual cycle. Summer moult occurs when food has a high peak on the breeding site in the summer, but it is less seasonal elsewhere. Winter moult occurs if there is a short period of high food availability in summer and a strong winter peak at different locations (i.e. the food is very seasonal but in opposite phase on these areas). This finding might explain why only long-distance migrants have a winter moult.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban optimal annual routines moult migration birds state-dependent dynamic models dynamic programming
Megjelenés:	Philosophical Transactions Of The Royal Society of London, Series B. - 363 : 1490 (2008), p. 211-230. -
További szerzők:	McNamara, John M. Houston, Alasdair I. Weber, Thomas P. Hedenström, Anders Feró Orsolya
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM018802
Első szerző:	Hedenström, Anders
Cím:	Migration speed and scheduling of annual events by migrating birds in relation to climate change / A. Hedenström, Z. Barta, B. Helm, A. I. Houston, J. M. McNamara, N. Jonzén
Dátum:	2007
Megjegyzések:	Empirical evidence for changed timing of migration in birds is emerging from both American and Euro-African migration systems. These changes are usually interpreted as a consequence of changes in climate. Responses in timing of migration and breeding may differ among species, and the adaptive significance is not well understood. There is a lack of theoretical understanding about time-shifts in life-history events due to climatic changes. In the present paper, we use 2 separate modelling approaches to investigate the effects of climate change on migration. We first use a simple model of flight speed and foraging to explore which factors may influence migration speed and stopover itinerary. Our second approach derives predictions based on an annual routine model, where behavioural strategies regarding timing of migration, breeding, moult and number of breeding attempts are modelled in an environment comprising 4 locations (breeding and wintering sites and 2 stopover sites). This approach takes account of interrelationships between behaviours and seasons as a step towards realistic modelling of migratory connectivity. Departure from the wintering site is advanced in relation to the advancement of spring if the moult is in summer, but not so for species with a winter moult, while arrival at the breeding site is advanced for both moult scenarios. Timing of breeding and number of successful broods were also affected by spring advancement, while start of moult is relatively unaffected by climate change. These optimal solutions under the modelled set of parameters are discussed with respect to current knowledge of the mechanisms underlying seasonal timing in birds.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Annual routines Climate change Phenology Timing of breeding Bird migration
Megjelenés:	Climate Research. - 35 : 1-2 (2007), p. 79-91. -
További szerzők:	Helm, B. Houston, A. I. McNamara, John M. Jonzén, N. Barta Zoltán (1967-) (biológus, zoológus)
Pályázati támogatás:	OTKA NF 61143 OTKA T046661
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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