Bird Communities in Transition: The Lago Guri Islands

Abstract

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Understory Bird Communities in Amazonian Rainforest Fragments: Species Turnover through 25 Years Post-Isolation in Recovering Landscapes

“…Even in the first interval after isolation, species colonized fragments (Figure 2). This could represent a carryover from the crowding effects immediately following isolation [17], [19], although colonizations have also been reported for forest islands isolated by comparable distance in Lago Guri, Venezuela [46]. In general, extinction rates exceeded colonization rates in the first or second intervals after isolation, through about 10 years, but the rates were more evenly matched in later intervals.…”

“…This is not due only to area effects reducing potential population size in fragments (e.g. [46]), but also to species rarity- a manifestion of the Allee effect (e.g., [66]). That is, rare species may be unlikely to have two individuals that could potentially form a pair colonize a fragment in the same time window, an effect that could be common across taxa and landscapes (e.g., [67]).…”

Functional and phylogenetic structure of island bird communities

“…As a result, eight transect trails were sampled on the largest study island (area >1000 ha), four on the two islands between 100 and 1000 ha, two on the four islands between 10 and 100 ha, and one on each of the remaining small islands (c. 1 ha for most islands) (Wang, Chen & Ding ) (Table S1). Transects were generally placed along ridge‐lines, and we cleared narrow census trails (about 20 cm wide) to facilitate surveys (Terborgh, Lopez & Tello ). We used a Global Positioning System to record the total length of transects on each island, and used stratified random placement to capture all habitat types on study islands, and then collected bird occupancy data along these transects.…”

A conceptual framework for studying species composition in fragments, islands and other patchy ecosystems

“…Best represented of these six classes are the old low‐contrast fragments with at least thirty‐two studies of diversity patterns in Pleistocene‐age montane fragments (reviewed by Watson, 1999) and old high‐contrast fragments with many studies of land‐bridge islands (reviewed by Lawlor, 1986; Quinn & Harrison, 1988). Young high‐contrast fragments are poorly understood, known primarily from studies of biota inhabiting hill‐top remnants in artificial dams (Coleman et al ., 1982; Karr, 1982; Sieving & Karr, 1997; Terborgh et al. , 1997, 1998; Lynam & Billick, 1999).…”