Effects of Hurricanes Irma and Maria on Abundance and Occupancy of Margarops fuscatus (Pearly-eyed Thrasher) in the Luquillo Experimental Forest, Puerto Rico
| Authors: | Alberto C. Cruz-Mendoza, Frank F. Rivera-Milan, Wayne J. Arendt, Laura L. Fidalgo-De Souza, Jessica Ilse, Joseph M. Wunderle Jr. |
| Year: | 2023 |
| Type: | Scientific Journal |
| Station: | International Institute of Tropical Forestry |
| Source: | The Caribbean Naturalist |
Abstract
Margarops fuscatus (Pearly-eyed Thrasher) is recognized for its vagility, dispersal ability, aggressive behavior, opportunistic diet, high reproductive potential, and ability to inhabit marginal habitats. Given these traits, we predicted that thrasher post-hurricane site occupancy and abundance in the first post-hurricane year (2018) after hurricanes Irma and María (2017) would change with elevation, forest type, and vegetation damage. To document the hurricanes’ effects on thrasher site occupancy and abundance along an elevation gradient (150–1074 m a.s.l.) in the Luquillo Experimental Forest (LEF), we compared point-count results obtained before the hurricanes (1998, 2005) and after the hurricanes (2018). We estimated thrasher occupancy with a single-season model and abundance with an N-mixture single-season model, with year as a covariate in all models. Elevation (with a quadratic effect) was the most important covariate for site occupancy and abundance estimation. Occupancy across 110 count sites decreased from 0.77 (0.03 SE) in 1998 to 0.50 (0.03) in 2005 to 0.37 (0.03) in 2018 after the hurricanes. Abundance estimates decreased from an average of 11 (0.75 SE) individuals/site in 1998 to 4.39 (0.37) in 2005 and 2.33 (0.19) in 2018. Occupancy and abundance were highest at mid-elevation (400–800 m) sites in all years, and there was no evidence of a shift in elevational range after the 2 hurricanes in 2018. Despite post-hurricane occupancy and abundance declines, the Pearly-eyed Thrasher remains a potential threat as a predator and competitor of endangered wildlife in mid-elevation forests in the LEF.