Bridled Quail-dove Geotrygon mystacea population assessment after hurricanes Irma and Maria, St. Eustatius, Caribbean Netherlands
Structural vegetation damage and food limitation are important effects of major hurricanes, particularly
for fruit/seed-eating, forest-dependent Caribbean birdswith restricted distributions and small
populations, such as the Bridled Quail-dove Geotrygon mystacea. Motivated by the lack of abundance
estimates, corrected for detection probability, we conducted distance-sampling surveys inside
and outside theQuill National Park eachMay in 2016-2019.Detection mode was the most important
covariate, with others receiving no support fromthe data. Detectability of available single individuals
and clusters of individuals within 60mof transect centrelines averaged 0.957 0.114 standard error
for audio detections, 0.434 0.052 for visual detections, and 0.693 0.064 for detection modes
combined. Availability averaged 0.475 0.138 and the product of detectability and availability
averaged 0.329 0.098. Density averaged 1.459 0.277 individuals ha-1 and population size
averaged 642 122 individuals in 440 ha. Density did not differ along and away from forest trails,
but was higher inside than outside the park and at elevations within 201-400 m than 100-200mand
401-600 m.Density declined by 76%after hurricanes IrmaandMaria in 2017.We suggest thatmajor
hurricanes together with free-ranging livestock overgrazing degraded foraging habitats, limited food
supply, and caused a population bottleneck. Our methodology can be implemented across the
distribution range to assess population status and trends and evaluate the result of management
actions at key conservation sites. Bridled Quail-dove populations probably were declining on most
islands before the 2017 hurricanes and population status warrants revision.
Keywords: Bridled Quail-Dove, distance sampling, hurricanes, population assessment, St.
Eustatius