Abundance and Breeding Productivity of Resident Avian Species in Guanica State Forest.

KORNEGAY, MARY EDYTHE. Abundance and Breeding Productivity of Resident Avian Species in Guánica State Forest. (Under the direction of Dr. Jaime A. Collazo.) Effective conservation is possible only when sound demographic data are available with which to engage in conservation planning and assess the response of a system to management actions. I investigated the utility of a productivity index and analyzed factors affecting abundance estimates for avian species in Guánica State Forest, Puerto Rico in 20092010. The index of breeding productivity used by the Monitoring Avian Productivity and Survivorship (MAPS) program, derived from the ratio of juvenile to adult captures in mistnets, assumes similar age-specific capture probabilities. I tested this assumption using a robust design framework and found equivocal support for equal age-specific capture probabilities for Puerto Rican Bullfinches (Loxigilla portoricensis), but no support for Bananaquits (Coereba flaveola) and Adelaide’s Warblers (Dendroica adelaidae). Temporary emigration rates indicated that the majority of birds were unavailable or became unavailable for capture, whereas occupancy data from a concurrent telemetry study indicated that the majority of individuals were present in the study area. Net avoidance was prevalent, which was consistent with low recapture rates. Results suggested that annual estimates of productivity based on the ratio of captured juveniles to adults can be biased and speciesspecific. I suggest increasing net density and shifting net locations as possible ways to increase capture probabilities. Alternatively, adjusted estimates of population size could be used to index productivity if knowledge of the breeding chronology and dispersal patterns of focal species is available. I conducted time-of-detection point counts to obtain estimates of avian abundance and determine factors affecting detection probabilities. LiDAR measurements of vegetation structure were significantly different between the two tracts of Guánica State Forest, which differ in their time since disturbance by at least 40 years. Avian species density was generally higher in the tract of the forest disturbed more recently. The prevalence of support for models with unequal probabilities of first and subsequent detections (Mb) in candidate sets could indicate a tendency of observers to anticipate calls made by birds that were already detected earlier in the survey period. The prevalence of support for models with heterogeneity in detection probabilities among individuals (Mh) could indicate variation in singing rates or distances from observer. Although LiDAR is a useful tool for landscape level studies for modeling species-habitat relationships, covariates derived from LiDAR did not account for as much variation in the data as did field measurements of vegetation structure and distance from observer. Abundance and Breeding Productivity of Resident Avian Species in Guánica State Forest by Mary Edythe Kornegay A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science