Tropical Ecology and Conservation [Monteverde Institute]

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Publication Date

September 1999

Abstract

The study of competition is important because the presence of one of the competing species reduces the fitness of the other; therefore, one of the species eventually will go extinct. This leads to the idea that all species must occupy different niches in order to coexist. Theories on niche partitioning in tropical forests have become important in order to explain their immense species richness and biodiversity. Two very similar species in the Monteverde area are the Gray-breasted Wood-Wren (Henicorhina leucophrys) and the Ochraceous Wren (Troglodytes ochraceus). These sympatric species are both foliage gleaners and are often found together in insectivorous mixed species foraging flocks, making them potential competitors. The purpose of this study was to determine if Gray-breasted Wood-Wrens and Ochraceous Wrens were partitioning their habitat in order to preclude competition. Preliminary data suggested that Ochraceous Wrens would be found higher vertically than Gray-breasted Wood-Wrens. Observations of these wrens were made visually and by call in the Monteverde Cloud Forest Reserve. Vertical height was divided into three zones: understory, middle, and canopy. Zone and altitude were recorded for each wren sighting. A significant difference was discovered in vertical height between the two species of wren but no altitudinal preference was found. Gray-breasted Wood-Wrens preferred to live in the understory while Ochraceous Wrens preferred the canopy. Therefore, these two species are able to coexist in the same environment by vertical habitat partitioning. El mejor competidor entre dos especies causa que el otro desaparezca. Las teorías sobre la división de los nichos en bosques tropicales son importantes para explicar la riqueza de especies y biodiversidad. Dos especies que son muy similares en el área de Monteverde son el Soterrey de Selva Pechigris y el Soterrey Ocroso. Estas especies son simpáticas y las dos son insectívoros, y están juntos en bandadas mixtas de insectívoros entonces ellos son potenciales competidores. El propósito de este estudio fue determinar si Soterreces de Selva Pechigris y Sotereces Ocroso tenían división en sus hábitats para evitar la competencia. Información preliminar sugiere que los Soterreces Ocroso permanezcan más alto verticalmente que los Soterreces de Selva Pechigris. Las observaciones se hicieron por avistamientos y cantos en la Reserva Bosque Nuboso Monteverde. Se estratifico verticalmente en tres zonas: sotobosque, mitad, y dosel. Se anotó la zona y la elevación para cada avistamiento. Una diferencia significativa se encontró en la distribución vertical pero no por elevación. El Soterrey de Selva Pechigris prefiere el sotobosque y el Soterrey Ocroso prefiere el dosel, por lo que lo utilizan los nichos diferentes.

Description

Student affilliation: Department of Biology, Occidental College Born Digital

Genre

Reports

Holding Location

Monteverde Institute MVI

Identifier

M39-00014

Vertical niche partitioning between Gray-breasted wood-wrens (Henicorhina-leucophrys) and Ochraceous wrens (Troglodytes ochraceus)

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