Functional connectivity and avian population ecology in intensively-managed forest landscapes

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Functional connectivity, the relative ease with which organisms move among resource patches, is a critical parameter influencing gene flow and population persistence, especially when habitat is fragmented. This parameter reflects the behavioural response of individuals to landscape structure and it is generally considered to be species-specific. Rapid developments in tracking technology have made it possible to monitor the movements of a wide range of organisms, but small animals remain difficult to track owing to technological limitations. For example, passerine birds, representing ca. 2/3 of all bird species currently known, cannot be tracked daily using currently available GPS tags, except for larger species. Until tracking technology allows documenting the daily movements of smaller organisms, we will need to design field experiments to gain insight into dispersal or habitat selection. In this research program, my students and I will use translocation experiments to create territorial vacancies and monitor the replacement of removed individuals. We will perform 25-km translocations in mixed forest plots surrounded by spruce plantations or similar forest (controls), to determine whether landscape context influences the replacement of temporarily absent males. We hypothesize that intensive forest management will influence the movements of translocated individuals as well as immigration of individuals potentially available to recolonize vacancies. Our previous research has shown that spruce plantations are much less permeable than deciduous forest to the movements of a migratory bird species (the Ovenbird). However, the specific mechanisms underlying this pattern and its consequences for habitat occupancy remain to be discovered. Therefore, we will perform translocations on this and two other migrant bird species to determine whether sensitivity to matrix type reflects the species' foraging niche (foliage gleaning vs ground foraging). Translocations will be performed on territorial males, whose response to matrix type and habitat fragmentation may differ from that of natal dispersers. The latter are thought to play a key role in functional connectivity. Hence, we will also capture individuals prospecting for territories during the post-breeding season and determine whether they return the following spring. This will make it possible to determine whether breeding site selection by first-year individuals takes place in fall or spring. We will also perform short-distance translocation experiments and track birds using radio-telemetry to test the hypothesis that landscape permeability is most strongly influenced by edge crossings rather than by the permeability of matrix types present. We will then use our empirical data to model bird movements using circuit theory and other methods. These models will be used to contrast forest management scenarios on focal species.