The Conservation Ecology of Neotropical Tree Cavity Communities in Forest and Agro-Ecosystems in the Alexander Skutch Biological Corridor, Costa Rica
Saker, Christopher Paul Duncan
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Shade coffee agro-ecosystems with a diversified canopy have been documented to provide quality habitat for a variety of vertebrates. For tree cavity dependent species however, shade coffee may be lacking critical habitat. I chose to investigate whether cavity abundance and the number cavity forming dead trees i.e., snags differed between shade coffee and other disturbed/undisturbed habitats within the Alexander Skutch Biological Corridor (ASBC) in Costa Rica. I also chose to investigate whether artificial tree cavities could be used in ecological restoration projects for cavity-nesting species in agro-ecosystems like shade coffee. To accomplish these tasks, I first conducted a comprehensive survey of tree cavities and snags in 1) primary cloud forest (elevation 1100-1400m), 2) primary middle elevation old-growth rainforest (650-750m), 3) selectively logged secondary middle elevation rainforest (650-700m), and (4) shade coffee (900-1000m) and installed motion-sensor cameras across from selected cavities within each habitat to monitor/compare potential occupancy/use. I then installed artificial tree cavities constructed of bamboo in 3 of the 4 habitats with iButton temperature loggers to test the prediction that shade coffee artificial cavities would have a greater number of occupancy detections due to the low number of cavities in this habitat compared with other habitat types. My findings showed an almost complete absence of snags and tree cavities in shade coffee supporting the hypothesis that shade coffee does not provide habitat for cavity-dependent species. Consistent with my prediction, artificial bamboo tree cavities in shade coffee were occupied/used most relative to the other habitats, further supporting the hypothesis that habitat for cavity-nesting species is limited is this agro-ecosystem. This thesis provides evidence that tree cavity restoration through the use of artificial cavities and a change in the management practices of shade coffee farms should be a priority for those concerned with biodiversity in shade coffee agro-ecosystems. A similar study conducted over a broader geographic range would show whether the lack of available habitat for cavity nesting species in shade coffee is reflected in other areas.