Date of Award

5-2008

Level of Access Assigned by Author

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Malcolm L. Hunter, Jr.

Second Committee Member

Catherine E. Burns

Third Committee Member

William B. Krohn

Abstract

Forests that are not managed sustainably eventually lose their economic and ecological value and are more likely to be converted to other land-uses. Avian cavity nesters are particularly sensitive to logging operations and therefore, I used this guild to determine the effect of selective logging on subtropical montane forests of the Andes and to inform management recommendations. Montane forests have an elevation gradient that defines different forest types and I studied two of these: the piedmont (400-750 m above sea level) and the cloud forest (1500-2200 m). In both forest types, I found significantly fewer avian cavity nesters and fewer usable cavities in harvested treatments than in control forests. Usable cavities represented less than 1.00 % of the total stem density in control treatments of both forest types, and were less abundant in harvested treatments (0.15 % of the total stems in piedmont and 0.54 % in cloud forest). Most of the usable cavities in the piedmont were found in 30-50 cm DBH trees (mean ± SE: 44.51±22.64) and in the cloud forest in trees > 60 cm DBH (70.69±25.84). Usable cavities in the piedmont were more likely to occur in Calycophyllum multiflorum trees, while in the cloud forest they were likely to occur in Blepharocalyx gigantea trees. After two breeding seasons, 44% of the usable cavities in the piedmont and 57% in the cloud forest were no longer usable. Snags in the cloud forest have a greater probability of retaining usable cavities than snags in the piedmont. Cavities used by birds for nesting were not a random subset of all available cavities. In both the piedmont and cloud forests, as mean plot DBH increased there was a greater probability of encountering a nest and cavities excavated by woodpeckers were used more often than expected according to their availability. To assure the conservation of cavity-nesting birds, logging operations should retain trees with usable cavities. However, solely retaining certain tree species of a particular DBH will not be sufficient and it is necessary to retain trees likely to harbor usable cavities in the future and those selected by birds for breeding.

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