Abstract: Editions Quae

Abstract: Keynote talk in the Symposium 'HOST-PARASITE INTERACTIONS IN SEABIRDS: EVOLUTIONARY ECOLOGY AND ECO-EPIDEMIOLOGICAL ISSUES' (organized by Thierry BOULINIER & Sarah BURTHE) of the 2nd World Seabird Conference, Cape Town, South Africa, October 2015.
Abstract: Nest ectoparasites are common components of the seabird breeding environment whose presence can have major consequences for seabird reproductive success and population dynamics. Ticks are among the most frequent parasite inhabitants of seabird colonies and are known to have direct major impacts on the birds when infestations are high, as well as indirect effects via the transmission of infectious agents. As seabirds show strong seasonality in colony attendance and these parasites are temporary, associated with the host only during the bloodmeal, ticks have evolved well-adapted life history strategies to successfully exploit both their biotic (seabird) and abiotic (colony) environments. However, different seabird species frequently breed within the same colony, setting up an interesting dilemma for a parasite: specialize to exploit a single host type, or remain a generalist and exploit less well each host type ? In this talk, I address this question by focusing on work that we have carried out on a model system involving a ubiquitous seabird ectoparasite, the tick Ixodes uriae, which has a bipolar distribution. I present patterns of contemporary population genetic structure of this tick at the within-colony scale from distinct regions of its worldwide distribution and link this structure to phenotypic patterns of host-associated specialisation. As this tick transmits an array of vector-borne disease agents, including human Lyme disease bacteria, I follow up with a discussion on how adaptation to the seabird host may cascade down to alter the epidemiology and evolutionary pathway of tick-borne microparasites. Finally, I will outline how comparative studies that we are currently developing with another widespread seabird tick, the soft tick Carios capensis, should shed further light on cascading effects of vector ecology and evolution on the circulation of tick-borne agents at broad geographic scales.

Abstract: Before making dispersal decisions, many species are known to gather social information by prospecting potential future breeding sites, especially when they have failed breeding. So far, the role of current breeding performance on the occurrence of prospecting movements has mainly been studied at limited spatial scales, because of difficulties in tracking free-ranging, fast-moving individuals between distant breeding patches. Little information is thus available on individual behaviour and the spatial extent of prospecting movements in response to breeding failure. To address this issue, black-legged kittiwakes which breeding success was manipulated were tracked with GPS at the end of incubation in two Norwegian colonies. Crucially, and as predicted, prospecting visits to other breeding colonies were recorded in 33% of artificially-failed breeders, but never in successful ones. They occurred at large (40km) as well as local spatial scales (1km). Time-budgets of successful and failed breeders differed significantly in terms of trip duration, but also foraging, resting and nesting propensities. These results provide important elements to assess trade-offs between prospecting and other activities. They show that a substantial proportion of failed breeders prospect as early as within a week after failure at the egg stage and suggest that these individuals assess their options of future reproduction by prospecting alternative areas, although dispersal decisions may also involve more complex behavioural processes. Because they link breeding colonies situated tens of kilometres apart, prospecting movements may have critical implications for the dynamics of subdivided populations.