Browsing by Autor "David Ocampo"

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Nest location and architecture as primary drivers of variation in UV reflectance in avian eggs
(Royal Society, 2025) Maria Elisa Mendiwelso; Carlos Daniel Cadena; David Ocampo
Two main hypotheses have been proposed to explain the function of ultraviolet (UV) reflection in avian eggs. The UV resistance hypothesis suggests that high UV reflectance protects embryos against solar exposure in open nests, whereas the egg detectability hypothesis posits that higher UV reflectance helps eggs stand out against the dark background of the nest, making them easier for parents to locate in enclosed nests. Therefore, eggshell reflection in the UV spectrum may serve multiple (possibly even opposing) forces, including UV protection and visual signalling. We tested these two hypotheses using large-scale comparative analyses of eggshell UV reflection for over 500 avian species while considering the influence of various ecological, life history and environmental traits associated with light exposure. We did not find strong support for either of the two hypotheses across all birds. However, in two clades exhibiting notably high levels of UV reflectance (Passeriformes and Charadriiformes), species with higher UV reflectance values predominantly nest in open nests, suggesting a stronger effect of the UV resistance hypothesis. This research contributes to a deeper understanding of the mechanisms driving UV coloration in avian eggs and unravels the interplay between life history traits potentially associated with UV reflectance in specific clades under variable nesting conditions.
The Andean Cock-of-the-rock ( <i>Rupicola peruvianus</i> ) is a frugivorous bird predator
(Wilson Ornithological Society, 2018) Laura Mahecha; Nickole Villabona; Laura Sierra; David Ocampo; Oscar Laverde-R.
Cotingas are considered essentially frugivorous, but a few records suggest they might include small vertebrates in their diet, mainly during the breeding season. In March 2015, we recorded a young male of an Andean Cock-of-the-rock (Rupicola peruvianus) chasing and eating an adult Canada Warbler (Cardellina canadensis) in Santa Maria, Boyacá (Colombia). The next day, we observed another adult male chasing a Swainson's Thrush (Catharus ustulatus), but we were unable to observe the end of the chase. Observations of hunting small vertebrates suggest this species may be omnivorous, not only during the breeding season but throughout its annual cycle. These may be rare cases, but notably both events involved migratory species that may not recognize these colorful birds as possible predators because they are not exposed to cotingas in the temperate zone. Predation on adult birds is difficult to observe in the wild, but this information is essential to better understand the life histories of birds and the different selection pressures acting on them.
When do tropical birds breed? The case of Colombian species assemblages
(2025) Miguel Moreno-Palacios; David Ocampo; María Ángela Echeverry-Gálvis; Camila Gómez; Gustavo A. Londoño; Carlos Daniel Cadena
ABSTRACT Understanding when tropical birds breed is key to life-history theory and to predicting how species will respond to environmental change. While early views emphasized the potential for year-round breeding in the tropics, accumulating evidence suggests that reproductive activity in most tropical birds follows some degree of seasonality, often linked to rainfall and associated food pulses. However, large-scale evaluations across ecological gradients remain scarce. Here, we investigated the breeding seasonality of Colombian resident birds using over 80,000 records compiled from bird banding programs and the Global Biodiversity Information Facility (GBIF). These data included birds in breeding conditions, active nests, nestlings, and adults displaying reproductive behavior. We asked four main questions: (1) Do Colombian birds exhibit seasonal breeding activity? (2) Does the degree of seasonality vary with latitude and elevation? (3) Are there geographic differences in breeding patterns across Colombia’s biogeographic regions? (4) How does breeding activity vary among feeding guilds? We used time-series, circular statistics, and generalized additive models (GAMs) to evaluate breeding patterns at national and regional levels, incorporating geographic variables and trophic guild. We found a clear seasonal pattern in breeding activity, with a main peak in April and low but consistent activity throughout the year, especially in the Andes. Breeding was more synchronized at higher latitudes and more extended near the Equator. Elevation also shaped seasonality: lowland bird assemblages showed broader breeding seasons, while mid- and high-elevation assemblages had narrower seasonal windows, driven by a shift in the breeding peak toward mid-year in highland birds. Regional and trophic guild variation was also marked. Caribbean birds bred sharply in April, Andean birds had prolonged reproductive activity peaking in March and June, and Chocoan birds peaked in March, followed by a decline. Breeding generally coincided with the start of rains and avoided extreme dry or wet months, in line with hygric niche theory. Feeding guilds differed as well: frugivores-nectarivores, omnivores, and invertivores bred mainly early in the year, while granivores peaked mid-year. Together, our findings offer new insights into tropical bird reproduction by showing that breeding activity in Colombia follows clear seasonal patterns shaped by rainfall regimes, elevation, and trophic ecology, contributing to the growing evidence of the complexity of breeding seasonality at tropical and near-equatorial latitudes.