Avian Conservation and Ecology (Dec 2021)
Functional connectivity of managed forest landscapes for the Ovenbird: an experimental assessment of within-patch movement behavior
Abstract
Conservation efforts addressing the impacts of habitat loss and fragmentation on movements must rely on operational definitions of land-cover types that are relevant to the behavioral decisions made by the species of interest. Travel costs, and ultimately landscape resistance (or permeability to movement) can be assessed through experiments standardizing the motivation of individuals to move across specific landscape elements, including habitat patches, the matrix, and their edges. So far, most studies modeling landscape permeability based on cost values have focused on habitat-specialist species and characterized landscape composition based on contrasting, human-defined cover types such as forest and open land. We experimentally evaluated the permeability to movement of different forest-cover types for the Ovenbird (Seiurus aurocapilla), a neotropical migratory species breeding in mature deciduous or mixed forest. We compared homing time and movement patterns of 60 radio-tracked males translocated over 500 m and released in untreated or partially harvested mature deciduous stands, as well as in conifer plantations, in northwestern New Brunswick, Canada. Although there was no strong effect of forest-cover type on homing time, path tortuosity, or travel speed, individuals released in conifer plantations tended to move faster and straighter than those released within untreated forest. Considering that translocated Ovenbirds have been shown to be less likely to return to capture sites in landscapes dominated by conifer plantations, our results suggest that they minimize time spent in inhospitable cover types. Responses to conifer plantation edges and similar interfaces may thus represent decisive components of time-based functional connectivity estimates. Hence, it appears that not all forest-cover types offer an equal resistance to Ovenbird movements and, consequently, a dichotomic habitat/non-habitat view may be too simplistic when assessing or modeling landscape permeability for passerine birds.
