Erosion of tropical bird diversity over a century is influenced by abundance, diet and subtle climatic tolerances

Jenna R Curtis,Bruce Mccune,Randall P Moore,Ghislain Rompré,W Douglas Robinson

doi:10.1038/s41598-021-89496-7

Jenna R Curtis, Bruce Mccune + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-89496-7

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Abstract

Human alteration of landscapes leads to attrition of biodiversity. Recommendations for maximizing retention of species richness typically focus on protection and preservation of large habitat patches. Despite a century of protection from human disturbance, 27% of the 228 bird species initially detected on Barro Colorado Island (BCI), Panama, a large hilltop forest fragment isolated by waters of Gatun Lake, are now absent. Lost species were more likely to be initially uncommon and terrestrial insectivores. Analyses of the regional avifauna, exhaustively inventoried and mapped across 24 subregions, identified strong geographical discontinuities in species distributions associated with a steep transisthmian rainfall gradient. Having lost mostly species preferring humid forests, the BCI species assemblage continues to shift from one originally typical of wetter forests toward one now resembling bird communities in drier forests. Even when habitat remnants are large and protected for 100 years, altered habitat characteristics resulting from isolation produce non-random loss of species linked with their commonness, dietary preferences and subtle climatic sensitivities.

Highlights

Human alteration of landscapes leads to attrition of biodiversity
At 1562 ha, Barro Colorado Island (BCI) is the largest island in Gatun Lake and the most protected from human disturbance
For species detected on BCI during any inventory period, we considered six categorical and two continuous attributes previously associated with extinction risk in tropical b irds[7,50] (Supplementary Information, Species Traits)

Summary

Introduction

Human alteration of landscapes leads to attrition of biodiversity. Recommendations for maximizing retention of species richness typically focus on protection and preservation of large habitat patches. Despite a century of protection from human disturbance, 27% of the 228 bird species initially detected on Barro Colorado Island (BCI), Panama, a large hilltop forest fragment isolated by waters of Gatun Lake, are absent. Even when habitat remnants are large and protected for 100 years, altered habitat characteristics resulting from isolation produce non-random loss of species linked with their commonness, dietary preferences and subtle climatic sensitivities. A century-long history of ornithological surveys in humid forests of southern Central America provides an opportunity to identify predictors of species extirpation following habitat isolation. Barro Colorado Island (BCI) has been isolated since 1914 from nearby lowland forests of central Panama following construction of the Panama Canal and filling of Gatun Lake. Described losses of early successional species are explained[39,41], but the loss of forest-dwelling species when tall forest on the island has effectively doubled in extent during the last century is puzzling

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