Oral Session: Dispersal and Population Structure 15:30 - 17:00 Tuesday, 27Th August, 2019 Nightjar Parallel Oral Sessions I Chair
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Oral Session: Dispersal and Population structure 15:30 - 17:00 Tuesday, 27th August, 2019 Nightjar Parallel oral sessions I Chair OS-1 Why we should care about habitat differences in movements: using spatially explicit integrated population models to assess habitat source-sink status Matthieu Paquet, Debora Arlt, Jonas Knape, Matthew Low, Pär Forslund, Tomas Pärt SLU, Uppsala, Sweden Abstract Assessing the source-sink status and dynamics of populations is of major importance for understanding population dynamics and to inform decisions concerning the management of natural populations and species. However, in-depth assessment of the source or sink status of habitats or populations has been proven difficult because it would require the clear distinction between survival and permanent emigration. This is of particular importance since habitat characteristics can affect both survival and movement decisions or distances. Therefore, ignoring habitat-specific movements may be either conceal or amplify habitat differences in contributions to the growth rate of a population (hereafter productivity). We aimed to better assess the source- sink status and temporal variation of two contrasting habitats using 24 years of habitat-specific local movements and demographic data of a farmland passerine, the northern wheatear (Oenanthe oenanthe). To do so, we combined multi-event Integrated Population models with spatial capture recapture models. This let us better estimate apparent survival of fledglings and adult breeders in the two contrasting habitats by taking into account estimated habitat-specific emigration both within and to outside the study population. Our results highlight that taking into account habitat-specific local movements have important consequences on habitat source-sink status and habitat differences in productivity. Synopsis Matthieu Paquet: Taking into account movements to better assess habitat source-sink status OS-2 Individual characteristics and environmental factors associated with natal dispersal in fragmented habitats Hugo Robles1,2, Carlos Ciudad3, Zeno Porro4, Julien Fattebert1, Gilberto Pasinelli1, Matthias Tschumi1, Marta Vila5, Martin Grüebler1 1Swiss Ornithological Institute, Sempach, Switzerland. 2University of Antwerp, Antwerp, Belgium. 3University of León, León, Spain. 4University of Pavia, Pavia, Italy. 5University of A Coruña, A Coruña, Spain Abstract Natal dispersal critically influences (meta)population dynamics. However, the underlying mechanisms of dispersal are poorly understood due to the difficulty of tracking the movements of individuals at different behavioural stages. By assessing the influence of several individual characteristics and environmental factors on the movements of radio-tracked juvenile middle spotted woodpeckers during departure and transfer stages in fragmented habitats, we revealed multiple associations that may drive dispersal. Birds from smaller habitat patches delayed departure, moved faster at transfer and ended up farther away from their natal nests than birds from larger patches, suggesting that, while habitat loss/fragmentation may inhibit departure, fast/long- distance dispersal can be a behavioural mechanism to overcome fragmentation. In addition, individuals from high quality territories delayed departure, suggesting that dispersal may help escaping degraded habitats. Larger individuals initiated dispersal earlier than smaller birds, which supports the size-dependent emigration hypothesis under fragmented scenarios. Moreover, we found positive density-dependent age at departure (i.e., delayed departure at higher densities) for birds in patches surrounded by hard edges but not in patches with softer edges, which may indicate a strong effect of competition mediated by landscape structure on dispersal timing. However, birds from areas with high population density moved slower and ended up at shorter distances during transfer, which may support the conspecific attraction hypothesis when searching for a new home. Finally, females from better connected patches, but not from more isolated patches, moved faster and farther than males, showing that fragmentation may mask the sex-biased dispersal frequently observed in vertebrates. Synopsis NA OS-3 The role of dispersal in adaptation to climate change: an experimental approach Koosje Lamers1, Marion Nicolaus1, Raymond Klaassen1, Jan-Åke Nilsson2, Christiaan Both1 1Conservation Ecology, GELIFES, University of Groningen, Groningen, Netherlands. 2Evolutionary Ecology, Lund University, Lund, Sweden Abstract Climate change advances spring onset, and shifts the optimal timing of breeding. In a changing world, dispersal could accelerate adaptation if migrating individuals that arrive late at a breeding site continue migration northward to areas with later spring phenology. Whether prolonged migration can aid adaptation to climate change depends on (1) whether these dispersers contribute their genes to these northern populations and (2) whether the timing of migration and breeding has a genetic component rather than being determined by rearing environment. Through translocation of female pied flycatchers (Ficedula hypoleuca) from the Netherlands to Sweden, we “experimentally dispersed” birds to determine whether southern immigrants have advanced timing and if long-distance dispersal affects reproductive success. Moreover, through egg translocations to Sweden, we created a common garden set-up of wild birds with various origins (natural Swedish, “hybrid”, and Dutch) that we monitor to determine whether genetic or ontogenetic effects determine the timing of the annual cycle. We show that translocated Dutch females breed earlier than Swedish control females. Moreover, our common garden experiment suggests that between-population variation in timing of the annual cycle is based on genetic differences. Dutch recruits in Sweden adhered to Dutch timing and bred earlier than their Swedish counterparts. Our preliminary work reveals potential for long-distance dispersal to accelerate adaptation to climate change through spreading genes for early timing from early to late populations. Synopsis @KoosjeLamers: Can dispersal help migrant birds track climate change? What pied flycatcher translocations from the Netherands to Sweden tell us. OS-4 Delayed dispersal and sociality in an Afrotropical facultative cooperative breeder Laurence Cousseau1, Dries Van de Loock1,2,3, Carl Vangestel4, Luc Lens1 1Ghent University, Ghent, Belgium. 2University of Antwerp, Antwerp, Belgium. 3National Museums of Kenya, Nairobi, Kenya. 4Royal Belgian Institute of Natural Sciences, Brussels, Belgium Abstract Cooperative breeding species are often characterized by a non-random spatial distribution of individuals, where close relatives are spatially clustered. Such local kin structure may facilitate kin selection, promoting indirect fitness benefits arising from cooperation. However, kin selection alone does not explain the evolution of sociality. While already existing theories on group formation mainly focus on delayed dispersal, the recently proposed “dual benefits” uses the conflict theory to generate predictions on group sizes, delayed dispersal and genetic composition of social group. We investigated what factors affect sociality and dispersal patterns in the facultative cooperative breeding placid greenbul (Phyllastrephus placidus), in the severely fragmented cloud forests of the Taita Hills (Kenya). Preliminary results show that 64% of pairs breed in groups with one up to five subordinates. Among groups, on average 75% of subordinates were related to the breeding female. More specifically, 73% of all groups had only related subordinates, 22% only unrelated, and 5% had a combination of both. The proportion of related subordinates increased with the age of the breeding females. Since the number of related subordinates, but not group sizes, also increases with female age, this suggests that younger females compensate the lack of retained offspring by recruiting unrelated subordinates. In addition, up to 90% of the offspring delayed dispersal until the first subsequent breeding season whereas almost all were dispersed in their fourth year after fledging. However, birds disperse on average sooner in smaller forest patches, likely because less breeding opportunities are available. Synopsis NA OS-5 Natal dispersal displacement patterns in resident bird species: an interspecific comparison Martin U. Grüebler1, Hugo Robles2,1, Bettina Almasi1 1Swiss Ornithological Institute, Sempach, Switzerland. 2University of Antwerp, Antwerp, Belgium Abstract Natal dispersal is a fundamental process that links demography to space. Dispersal is a three-stage process: two stationary stages (departure and settlement) separated by an exploratory transience phase. Even though transience is the key stage of dispersal displacement, processes shaping the movements in the long-lasting time period between leaving the natal range and occupying a first breeding range are highly neglected. Even worse, comparable interspecific research on the patterns of natal dispersal based on movement trajectories during transience remains limited. Here, we present natal dispersal displacements of three short-lived resident bird species, the little owl (Athene noctua), the barn owl (Tyto alba) and the middle-spotted woodpecker (Dendrocoptes medius) recorded by tracking studies including large parts of the transience phase. The three species showed striking similarities in the natal dispersal patterns: departure