J.D. Nichols
M. S. Lindberg
J.E. Hines
Aivars Mednis
Peter Blums
2003
<p><span>1. We used up to 35 years of capture-recapture data from nearly 3300 individual female </span>ducks<span> nesting on </span>Engure<span> </span>Marsh<span>, </span>Latvia<span>, and multistate modelling to test predictions about the influence of environmental, habitat and management </span>factors<span> on </span>breeding<span> </span>dispersal<span> probability within the </span>marsh<span>. 2. Analyses based on observed </span>dispersal<span> distances of common pochards and tufted </span>ducks<span> provided no evidence that </span>breeding<span> success in year t influenced </span>dispersal<span> distance between t and t + 1. 3. </span>Breeding<span> </span>dispersal<span> distances (year t to t + 1) of pochards and tufted </span>ducks<span> were associated with a delay in relative nest initiation dates in year t + 1. The delay was greater for pochards (c. 4 days) than for tufted </span>ducks<span> (c. 2 days) when females dispersed > 0.8 km. 4. Northern shovelers and tufted </span>ducks<span> moved from a large island to small islands at low water levels and from small islands to the large island at high water levels before the construction of elevated small islands (1960-82). Following this habitat management (1983-94), </span>breeding<span> fidelity was extremely high and not influenced by water level in the </span>marsh<span> for either species. 5. Because pochard nesting habitats in black-headed gull colonies were saturated during the entire study period, nesting females moved into and out of colonies with similar probabilities. Local survival probabilities and incubation body masses were higher for both yearlings (SY) and adults (ASY) nesting within gull colonies, suggesting that these females were of better quality than females nesting outside of the colonies. 6. Tufted </span>ducks<span> showed higher probabilities of moving from islands to emergent marshes when water levels were higher both before and after habitat management. However, rates of movement for a given water level were higher during the period before management than after. 7. Both pochards and tufted </span>ducks<span> exhibited asymmetric movement with respect to proximity to water, with higher movement probabilities to near-water nesting locations than away from these locations. 8. Multistate capture-recapture models provided analyses that were useful in investigating sources of variation in </span>breeding<span> </span>dispersal<span> probabilities.</span></p>
application/pdf
10.1046/j.1365-2656.2003.00698.x
en
British Ecological Society
Factors affecting breeding dispersal of European ducks on Engure Marsh, Latvia
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