Biological Correlates of Extinction Risk in Resident Philippine Avifauna

Kyle D Kittelberger,Çağan Hakkı Şekercioğlu,Montague H C Neate-Clegg,Mary Rose C Posa,John Mclaughlin,J David Blount

doi:10.3389/fevo.2021.664764

Abstract

The majority of the world’s biodiversity occurs in the tropics, but human actions in these regions have precipitated an extinction crisis due to habitat degradation, overexploitation, and climate change. Understanding which ecological, biogeographical, and life-history traits predict extinction risk is critical for conserving species. The Philippines is a hotspot of biodiversity and endemism, but it is a region that also suffers from an extremely high level of deforestation, habitat degradation, and wildlife exploitation. We investigated the biological correlates of extinction risk based on the IUCN Red List threat status among resident Philippine birds using a broad range of ecological, biogeographical, and life history traits previously identified as correlates of extinction risk in birds. We found strong support across competing models for endemism, narrower elevational ranges, high forest dependency, and larger body size as correlates significantly associated with extinction risk. Additionally, we compared observed threat status with threat status fitted by our model, finding fourteen species that are not currently recognized by the IUCN Red List as threatened that may be more threatened than currently believed and therefore warrant heightened conservation focus, and predicted threat statuses for the four Philippine Data Deficient bird species. We also assessed species described in recent taxonomic splits that are recognized by BirdLife International, finding 12 species that have a fitted threat status more severe than their IUCN-designated ones. Our findings provide a framework for avian conservation efforts to identify birds with specific biological correlates that increase a species’ vulnerability to extinction both in the Philippine Archipelago and elsewhere on other tropical islands.

Highlights

The majority of the world’s biodiversity is found in the tropics (Myers et al, 2000; Brown, 2014; Barlow et al, 2018), but human actions in these regions are expected to precipitate an extinction crisis as habitats are diminished and degraded (Pimm and Raven, 2000; Barlow et al, 2018)
Endemism was significantly associated with threat status in our top-ranked model (Figure 3B; 1.560 ± 0.276 se, z = 5.656, p < 0.001), with endemic species being more threatened with extinction than non-endemic residents
Elevational range was significantly associated with threat status in our top-ranked model (Figure 3A; −0.541 ± 0.097 se, z = −5.603, p < 0.001), with species that have narrower elevational ranges being more threatened than those that occur at broader elevational ranges

Summary

Introduction

The majority of the world’s biodiversity is found in the tropics (Myers et al, 2000; Brown, 2014; Barlow et al, 2018), but human actions in these regions are expected to precipitate an extinction crisis as habitats are diminished and degraded (Pimm and Raven, 2000; Barlow et al, 2018). Extinction risk among taxa is phylogenetically non-random (e.g., Russell et al, 1998; Hughes, 1999; Von Euler, 2001; Yessoufou et al, 2012; Wang et al, 2018) and influenced by species’ biology, ecological, biogeographical, and life history traits (hereafter “biological correlates”). Such ecological variables that impact extinction risk include poor dispersal ability. Forest fragmentation and deforestation can compound species’ poor dispersal abilities (Barlow et al, 2006; Sekercioglu, 2007; Moore et al, 2008; Lees and Peres, 2009; Visco et al, 2015; Sheard et al, 2020) and push forest interior species upslope to more suitable habitat (Ocampo-Peñuela and Pimm, 2015), resulting in the extinction of small, isolated populations that are constrained by elevation (Kattan et al, 1994)

Methods

Results

Discussion

Conclusion