From primary forest to farmland: ecology and conservation of cavity-nesting birds

COCKLE, KRISTINA L

Manaus

Congreso; Congreso de Ornitologia Neotropical; 2015

Globally, about 1000 species of birds depend on the limited, multi-annual resource of nesting cavities in trees. These birds interact through facilitation and competition for cavities, and are particularly vulnerable to logging and deforestation. My work has shown that whereas in North America cavity-nesters rely primarily on woodpeckers to produce cavities, in the Neotropics they mainly rely on natural decay processes (fungi and insects). In the subtropical Atlantic forest of Argentina, logging and agriculture severely reduced cavity supply and abundance of cavity-nesting birds, but did not affect the persistence of remnant cavities or daily survival of nests. Instead, high cavity persistence was associated with non-excavated cavities in living sections of healthy trees, irrespective of habitat. Whereas cavities in dead trees had a median persistence of just 2 years, 80% of cavities in live healthy trees remained available after 9 years, over which time they were used by 4.6 ± 0.5 (mean ± SE) nesting pairs. Nest survival was also higher in living trees, and improved with increasing cavity height and decreasing entrance diameter. My results highlight the conservation value of live cavity-bearing trees in anthropogenic habitats. They also suggest that logging and farming may shift the Atlantic forest toward a faster ?cavity life-history?, with increased use of woodpecker cavities that are quickly produced and quickly destroyed. A pressing policy issue for Neotropical forests is to move beyond minimum diameter cutting limits and instead focus on retention and recruitment of large living trees in anthropogenic habitats.