Relationship between Species Richness of Excavator Birds and Cavity–adopters in Seven Tropical Forests in Costa Rica

Abstract

The abundance of wood cavities is thought to be a limiting factor for bird species that depend on these cavities for nesting. Thus, it is expected that number of cavity adopters correlates with number of cavity excavators across communities. We used available published data to compare composition and richness of cavity adopters and cavity excavators across seven forest localities in Costa Rica. Species richness and composition of cavity excavator and cavity adopter bird assemblages varied among the seven forests. Species composition of excavators and adopters was more similar between nearby localities and between localities with similar forest types. Richness of wood-cavity adopters (using mostly cavities created by excavators) tended to increase with richness of excavators. The lack of association between cavity adopters and cavity excavators in some localities may be compensated by high abundance of a few species of excavators. The abundance of adopters and their dependence on forested habitats and on cavities excavated by woodpeckers varied largely across localities.

Linking fungi, trees, and hole-using birds in a Neotropical tree-cavity network: Pathways of cavity production and implications for conservation

“…Preliminary data suggest that non-excavators in South American forests rely primarily on nonexcavated cavities produced directly by decay, rather than excavated cavities produced by woodpeckers, not because they avoid woodpecker cavities but because non-excavated cavities are more abundant (Cockle et al, 2011a,b;Cornelius et al, 2008). A greater reliance on non-excavated cavities may explain why two recent studies failed to demonstrate correlations in the abundance or richness of woodpeckers and non-excavators in the tropical Americas (Sandoval and Barrantes, 2009;Siqueira Pereira et al, 2009). Non-excavated cavities take longer to form, and conserving them in logged forests may be more challenging than conserving woodpeckers and their cavities.…”

Peer Review #2 of "Effect of fragmentation on the Costa Rican dry forest avifauna (v0.2)"

“…Thus, the dry-forest bird-community was composed of resident, breeding species with terrestrial habits. Each bird species was classified into one of three forest dependency categories following Stiles (1985) with modifications by Sandoval and Barrantes (2009): 1 = species that live and reproduce in extensive mature forest; 2 = species that require habitats with 40-50% of forest cover; 3 = species that inhabit open areas. Species in categories 1 and 2 are likely more affected by habitat fragmentation than those species included in category 3.…”

Effect of fragmentation on the Costa Rican dry forest avifauna

“…Therefore, the dry-forest birdcommunity was composed by resident, breeding species with terrestrial habits. Each bird species was classified into one of three forest dependency categories according to Stiles (1985) with modifications made by Sandoval and Barrantes (2009): 1 = species that live and reproduce in extensive mature forest; 2 = species that require habitats with 40-50% of forest cover; 3 = species that inhabit open areas.…”