Passerine phenology in the largest tropical dry forest of South America: effects of climate and resource availability

Abstract

In tropical dry areas, rainfall is predicted to be the most important climatic variable influencing bird phenology because it triggers food and foliage production. In addition, because resources are scarce, the moulting and breeding seasons are not expected to overlap. We conducted a 2year study on the phenology of passerine birds at one site in Caatinga, South America's largest dry forest region to: (a) evaluate the contributions of climate, foliage cover, and food abundance to the onset of the breeding and moulting seasons, (b) assess the duration of the breeding and moulting seasons, and (c) measure the frequency of the bird moult-breeding overlap. Birds can use rainfall or humidity as environmental cues to start their breeding seasons. The effects of water availability are mediated by both foliage cover and food abundance, but foliage cover is more important to the onset of the bird breeding season than food abundance. In contrast, both foliage cover and food abundance equally influence the timing of the primary moult. Because we found several cases of moult-breeding overlap, we suggest that some passerine species adapt that strategy to adjust the timing of their life history stages to the relatively short period of abundant resource availability.

Seasonal Changes in Bird Assemblages of a Forest-Steppe Ecotone in North Patagonia

“…energetically expensive activity within a bird's annual cycle (Lindström et al 1993, Murphy 1996. Therefore, it is more common that breeding and molting overlap in the tropics (Foster 1974, Johnson et al 2012, de Araujo et al 2017, whereas in temperate zones there is a low overlap between these two demanding activities (Jenni & Winkler 1994, Murphy 1996, Jahn et al 2017. At our study site, we found this last pattern, as birds began to molt after breeding and during a period of favorable climatic conditions.…”

Unmasking complex migration syndromes and seasonal plumage colouration in the White‐naped Xenopsaris (Xenopsaris albinucha)

“…2016, Araujo et al . 2017). The observed decrease in the number of records of Xenopsaris in the Caatinga between April and November is congruent with both rainfall seasonality (Fig.…”

Monitoring Avian Productivity and Survivorship at the Sandia Wetlands at Los Alamos National Laboratory (2014-2019)

“…To assess a bird's breeding status, we considered birds with a brood-patch score of 2, 3, or 4 as breeding because vascularization of the brood patch is characteristic of incubating birds (Cox et al 2013, De Araujo et al 2017. Scores of 0, 1, and 5 were assumed to be non-breeding on site.…”