Source–sink status of small and large wetland fragments and growth rate of a population network

Abstract

Source-sink status of small and large wetland fragments and growth rate of a population network Pasinelli, G; Runge, J P; Schiegg, K Pasinelli, G; Runge, J P; Schiegg, K (2011). Source-sink status of small and large wetland fragments and growth rate of a population network. In: Liu, J; Hull, V; Morzillo, A T; Wiens, J A. Sources, Sinks and Sustainability. England, 216-238. ISBN 978-0-521-19947-6. Postprint available at: http://www.zora.uzh.chPosted at the Zurich Open Repository and Archive, University of Zurich. http://www.zora.uzh.chOriginally published at: Pasinelli, G; Runge, J P; Schiegg, K (2011). Source-sink status of small and large wetland fragments and growth rate of a population network. In: Liu, J; Hull, V; Morzillo, A T; Wiens, J A. Sources, Sinks and Sustainability. England, 216-238. ISBN 978-0-521-19947-6. Source-sink status of small and large wetland fragments and growth rate of a population network AbstractMany organisms persist in populations that are spatially structured by human-induced loss and fragmentation of their native habitats. Despite this, the demographic contributions of local populations to a population network and to the growth rate of such a network are still largely unexplored. Using data on individually marked young and adult female reed buntings ( Emberiza schoeniclus ) from 21 local populations studied over six years in northeastern Switzerland , we examined the source-sink status of small and large local populations with recently developed metrics. We hypothesized that including emigration to the population network (the C r metric) would classify more local populations as sources than when only focusing on the ability of local populations to maintain themselves (the Rr metric). We further tested the hypothesis that the relative contribution of small and large local populations to the population network does not differ. The inclusion of emigration to the population network resulted in significantly higher values than when only considering the contribution of local populations to themselves, the difference between the metrics averaging 30%. Despite this, most local populations in our study turned out to be sinks (C r value <1), suggesting that substantial immigration is required for maintaining local populations as well as the entire population network (growth rate of network always <1). Both large and small populations contributed equally to the population network. We conclude that (a) the source-sink status of local populations is more comprehensively described by metrics including emigration (such as C r ) than by metrics focusing on processes within local populations (such as Rr ); (b) the network of local populations studied here is not viable without immigration; and (c) small local populations can be as valuable as large local populations in their contribution to a population network. 216gilberto pasinelli , jonathan p. runge and karin schiegg 10Source-sink status of small and large wetland fragments and growth rate of a population network SummaryMany organisms pers...

Patchy population structure in a short‐distance migrant: evidence from genetic and demographic data

“…beyond the scale of our study) could therefore explain high immigration into and the apparent lack of genetic structure in our study population. In fact, demographic data indicate that the entire patchy population in our study area is a sink (Pasinelli et al . 2008b, submitted).…”

“…The true immigration rate will lie between the minimum and maximum estimates, and we further approximated it by treating unbanded individuals of the previous year as immigrants, but correcting for the number of assumed unbanded philopatric individuals. This was carried out in the following way: (iii) assuming that the probability of being philopatric is the same for both unbanded and banded breeding individuals [philopatry rates of banded adult females across years: 0.436 (95% CI 0.428–0.445), Pasinelli et al . 2008b submitted], we determined the number of unbanded but presumably philopatric individuals for 2002.…”

Equal nonbreeding period survival in adults and juveniles of a long‐distant migrant bird

“…Adult survival is often underestimated, because breeding dispersal is common in many species (Schaub and Von Hirschheydt ; Pasinelli et al. ; Bötsch et al. ).…”

New support for an old hypothesis: density affects extra‐pair paternity

“…In our study area, reed bunting males established territories in old reed habitat, in which most nests were built by the females (see Pasinelli et al. , for details). Nests were located using behavioral cues, including nest building and parental visitation patterns, during incubation and nestling care.…”