TY - JOUR

T1 - Spatial segregation of the endemic versus non-endemic hummingbird on Robinson Crusoe Island, Chile

T2 - the effect of competitor abundance but not resources or habitat

AU - Vizentin-Bugoni, Jeferson

AU - Sonne, Jesper

AU - Hodum, Peter

AU - Hagen, Erin

AU - Cordeiro, Juliana

PY - 2017/7

Y1 - 2017/7

N2 - Competitive pressure from invasive species tends to have a particularly strong impact on remote islands, and knowledge of such phenomena can be crucial to the conservation of endemic biodiversity. Of the two hummingbird species inhabiting Robinson Crusoe Island, Juan Fernández Archipelago, Chile, one (Green-backed Firecrown, Sephanoides sephaniodes) has a wide mainland distribution while the other (Juan Fernández Firecrown, Sephanoides fernandensis) is endemic and critically endangered. Even though habitat degradation and predation by exotic mammal species are known to pose major threats, little attention has been given to the influence of interspecific competition for floral nectar resources. In this study, we investigated the existence of interspecific competition by testing for spatial segregation of the two species using point counts dispersed within their suitable habitats. We additionally considered the influence of habitat type and flower abundance, which could also cause spatial segregation between the species. We found a negative association between the point count abundance of the two hummingbirds species, which remained consistent when accounting for the role of habitat type and flower abundance. Together, this could be an indication of interspecific competition in which individuals of S. fernandensis may benefit from aggregation by sharing the individual costs of chasing the vastly more abundant S. sephaniodes.

AB - Competitive pressure from invasive species tends to have a particularly strong impact on remote islands, and knowledge of such phenomena can be crucial to the conservation of endemic biodiversity. Of the two hummingbird species inhabiting Robinson Crusoe Island, Juan Fernández Archipelago, Chile, one (Green-backed Firecrown, Sephanoides sephaniodes) has a wide mainland distribution while the other (Juan Fernández Firecrown, Sephanoides fernandensis) is endemic and critically endangered. Even though habitat degradation and predation by exotic mammal species are known to pose major threats, little attention has been given to the influence of interspecific competition for floral nectar resources. In this study, we investigated the existence of interspecific competition by testing for spatial segregation of the two species using point counts dispersed within their suitable habitats. We additionally considered the influence of habitat type and flower abundance, which could also cause spatial segregation between the species. We found a negative association between the point count abundance of the two hummingbirds species, which remained consistent when accounting for the role of habitat type and flower abundance. Together, this could be an indication of interspecific competition in which individuals of S. fernandensis may benefit from aggregation by sharing the individual costs of chasing the vastly more abundant S. sephaniodes.

KW - Competition

KW - Juan Fernández Archipelago

KW - Oceanic archipelago

KW - Sephanoides fernandensis

KW - Sephanoides sephaniodes

KW - Trochilidae

UR - http://www.scopus.com/inward/record.url?scp=85021185293&partnerID=8YFLogxK

U2 - 10.1007/s10336-017-1431-1

DO - 10.1007/s10336-017-1431-1

M3 - Journal article

AN - SCOPUS:85021185293

VL - 158

SP - 793

EP - 798

JO - Journal fur Ornithologie

JF - Journal fur Ornithologie

SN - 0021-8375

IS - 3

ER -