Glacier influence on bird assemblages in habitat islands of the high Bolivian Andes

Tatiana Cardenas,Kazuya Naoki,Sophie Cauvy‐Fraunié,Quentin Struelens,Maria Isabel Gómez,Carlos Miguel Landivar,Fabien Anthelme,Rosa Isela Meneses,Olivier Dangles

doi:10.1111/ddi.13458

Abstract

AbstractAimClimate projections for the upcoming decades predict a significant loss of ice mass particularly critical for glaciers in tropical mountains. In the dry landscapes of the southern Andes (from Southern Peru to Chile), this global trend has strong ecological impacts on high‐altitude wetlands that support a unique avifauna for feeding, roosting and nesting. As glacier runoffs are expected to affect the area and the quality of wetland habitats, these changes may potentially affect bird communities. To address this issue, we studied the structural and functional diversity of bird assemblages in glacier‐fed high‐altitude wetlands (>4500 m).LocationFive valleys of the Cordillera Real, Bolivia.MethodsWe surveyed bird communities during dry, wet and intermediate seasons in 40 wetlands (total of 27,720 observations of birds and habitats from 540 transects) showing different degrees of dependence on glacial meltwater. We examined the potential effect of glacier retreat on bird communities through changes in wetland area and environmental quality and heterogeneity.ResultsWe found strong relationship between wetland area and taxonomic and functional diversity, but not on phylogenetic diversity. Generalized additive models revealed that avian diversity was influenced by wetland's productivity and elevation and maximized at intermediate levels of glacier influence. Multivariate analysis further showed that habitat productivity and humidity, both potentially influenced by future glacial retreat trends, are the main drivers of bird community composition, with the wettest habitats being crucial for aquatic birds and uncommon species.Main conclusionsGlacier retreat may significantly affect bird community diversity and composition through changes in both area and quality of high‐altitude wetlands, with a particular concern for aquatic birds.

Highlights

Glaciers are sensitive climate indicators and rapidly react to climatic variations with alteration of their mass (Oerlemans, 2001)
Among the species–area relationship (SAR) models fitted to our data, the linear function better described the relationship between species richness and wetland area
Following the objectives of our study, we found (a) strong relationship between wetlands area and species richness, evenness and functional diversity, (b) glacier cover, productivity and elevation had a non-linear influence on bird richness; and (c) at a wetland scale, we found bird assemblages shaped by environmental gradients of humidity and productivity from wetter to drier habitats

Summary

Introduction

Glaciers are sensitive climate indicators and rapidly react to climatic variations with alteration of their mass (Oerlemans, 2001). Glaciers have lost ice mass at an average rate of 220 ± 30 Gt/year during the 2006–2015 period (Intergovernmental Panel on Climate Change -IPCC, 2019) and projections for the 21st century indicate a continuing downward trend in glacier cover in almost all regions (Huss & Hock, 2018; IPCC, 2019; Dussaillant et al, 2019). According to the various IPCC scenarios, by 2100, the glacier mass is expected to decrease by 35% to 55% at the global scale and by up to 90% in both Europe and the tropical regions (Huss et al, 2017). A more rapid decline is expected for small glaciers with relatively small accumulation zones (Bosson et al, 2019; IPCC, 2019). Ice loss has vital consequences on the hydrological cycle (flooding/drought), wild and agricultural biodiversity, and human livelihoods (Hock et al, 2019; Huss et al, 2017)

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