Tropical Ecology and Conservation [Monteverde Institute]

Creator

Justin Pochman

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Publication Date

September 2001

Abstract

Two congeneric warbler species in Monteverde occupy similar niches and may be competing for resources. The Three-striped Warbler (Basileuterus tristriatus) and the Golden-crowned Warbler (B. culicivorus) are both forest interior species that glean and sally for insects within several meters of the ground. This study looks at foraging preferences in these two species in areas of overlap and non-overlap, which is particularly important in light of recent geographic shifts upslope by the Golden-crowned Warbler (Donnelly 1998; Pounds 1999). The results show that the Three-striped and the Goldencrowned Warbler significantly overlap in both altitude (between 1420 m and 1485 m) and in habitat. They each used different microhabitats with greater frequency - the Threestriped Warbler preferred to forage in leaves and among epiphytes while the Goldencrowned preferred to forage on branch interiors and on stems of bushes. When the species did not overlap, the Three-striped Warbler foraged at a mean height of 2.4 m and the Golden-crowned Warblers at a mean height of 2.8 m. They shifted these heights up and down respectively when they were found overlapping (Three-striped = 2.1 m, Goldencrowned = 3.3 m). When individuals were actually observed foraging in the same species flock, they continued to display these trends in mean foraging height (Three-striped = 2.8 m, Golden-crowned = 4.0 m). Therefore this study shows that based on microhabitat preferences and vertical stratification, these two species of warbler partition their niches. Dos especies del género Basilueterus ocupan nichos parecidos y pueden competir por recursos. La Reinita cabecilistada (B. tristriatus) y La Reinita Coronidorada (B. culicivorous) son especies del interior del bosque que rebuscan activamente entre el follaje, metiendo el pico entre hojas y haciendo vuelos veloces tras insectos usualmente dentro del sotobosque. Este estudio investiga preferencias de forrajeo de estas especies, tanto en áreas donde se encuentran ambas especies como en áreas donde hay una sola especie, lo cual es relevante, especialmente en el contexto de reciente colonización por la Reinita Coronidorada de elevaciones altas (Donnelly 1998; Pounds 1999). Los resultados indican que las dos reinitas son encontrados en una franja altitudinal (1420 -1485 m), en el mismo tipo de hábitat. Usan diferente micro hábitats: La Reinita Cabecilistada forrajea entre hojas y epifitas mientras La Reinita Coronidorada forrajea en los interiores de ramas y tallos. En áreas donde solo La Reinita Cabecilistada se encuentra, hace forrajeos a 2.4 m de alto y donde solo existe La Reinita Coronidorada, ella forrajea a 2.8 m. Ellos cambian de alturas preferidas a alturas de forrajeo cuando están juntos en el hábitat, con La Reinita Cabecilistada prefiriendo alturas de 2.1 m y La Reinita Coronidorada de 3.3 m. En las ocasiones cuando las dos especies forrajean en el mismo grupo de especies mixtas, La Reinita Cabecilistada se encuentra a los 2.8 m mientras La Reinita Coronidorada esta a los 4.0 m. Por eso, el estudio muestra que las dos especies reparten los nichos a través de diferencias en sus micro hábitats preferidos y alturas de forrajeo preferidas.

Description

Student affiliation: Department of Environmental, Population and Organismic Biology, University of Colorado at Boulder Digitized by MVI

Genre

Reports

Holding Location

Monteverde Institute MVI

Identifier

M39-00081

Niche partitioning of Monteverde warbler species based on differences in microhabitat and vertical stratification

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