Data from: Appalachian-breeding Vermivora chrysoptera (Golden-winged Warbler) occur at very low densities in mid-elevation forests and agroforestry systems throughout the Andes and isolated massifs of northern Colombia

Vermivora chrysoptera (Golden-winged Warbler) is one of the most striking
but also one of the most vulnerable migratory warblers on Earth. To
understand its non-breeding ecology in northern South America, where the
steeply declining Appalachian breeding population is known to spend the
non-breeding season, we conducted 2,534 surveys between 2018 and 2023 in
isolated massifs and the Andes of Colombia. Our goal was to evaluate the
distribution, detection rates, elevational range, habitat preferences and
microhabitat associations of the species. We obtained 54 detections, with
a very low detection rate (2.13%) compared to rates reported from Central
America (~10%). Detections covered a wide range of elevations (634 – 2,551
m a.s.l.), with support for a mid-elevation peak at around 1,750 m a.s.l.
Importantly, detection elevation was negatively correlated with latitude
such that peak abundances occurred at higher elevations closer to the
equator. Most detections were in mature or secondary forests (72%), but
birds also occurred along forest edges (17%) and in agroforestry systems
(11%), such as shade-grown coffee. We found weak evidence for a female
preference for lower elevations, as well as more frequent use of
agroforestry systems relative to males. Logistic regressions provided some
support for a preference for forest over agriculture in both sexes, as
well as a higher detection probability at points with intermediate canopy
height and canopy cover. Our results highlight the low density at which
the species occurs across the northern Andes of Colombia and other
isolated massifs. The association with forested habitats and the
relatively narrow elevation range occupied by most birds, implies that
focusing conservation efforts on protecting or restoring forests at
elevations where detection rates peaked would likely be an effective
strategy for ensuring that non-breeding habitat remains for
Appalachian-breeding Vermivora chrysoptera.