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.


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