A citizen-based platform reveals the distribution of functional groups inside a large city from the Southern Hemisphere: e-Bird and the urban birds of Santiago (Central Chile)

Pablo Gutiérrez-Tapia,Sergio A Castro,M Ignacio Azócar

doi:10.1186/s40693-018-0073-x

Abstract

BackgroundCurrent knowledge of urban bird ecology and biodiversity relies on evidence from cities of the Northern Hemisphere, while the Southern Hemisphere is underrepresented. Santiago is a large city from South America, located in central Chile, which is both a biodiversity hotspot and an Endemic Bird Area. This work is a synthesis, which aims to provide a diversity account for Santiago, and to describe the broad geographic distribution and bird functional patterns.MethodsWe synthesized a seven-year (2009–2016) bird register from the eBird database (21,865 georeferenced registers at Santiago) into a single avifaunal account, along with the observed number of individuals. We complemented these registers by using available literature about Santiago’s avifauna (28 references). We investigated the proportion of native/exotic, migrants/residents, conservation categories, and urban nesting status. We classified Santiago’s birds into seven trophic guilds. We plotted species richness and number of individuals for each functional group, by interpolating trough the Inverse Distance Weighted Method.ResultsWe found that Santiago’s avifauna (46 species) is composed mainly by native (41), resident (38), non-threatened species (46) that breed inside the city (31). Some functional groups inhabit a large portion of Santiago’s urban surface, reaching high values of richness and abundance. Among these groups are the native, urban-nesters and resident species; even though exotics possess low species richness (5), they are abundant and inhabit the complete urban surface of the city.The dominant trophic guilds are omnivorous (11) and granivorous (10). Insectivorous are the third most abundant trophic guild, and show the highest species richness (13).ConclusionThe functional groups with lower species richness are less abundant and display reduced and patchy distributions in Santiago. This is probably because of the low availability of suitable habitats and/or restricted food supply (migrants, carnivorous, nectarivorous, frugivorous, herbivorous and piscivorous). The high insectivorous richness reported in Santiago, along with similar patterns reported in several cities in the Neotropics, provides evidence to postulate a pattern of high species richness of this guild in cities across this biogeographic realm.

Highlights

Current knowledge of urban bird ecology and biodiversity relies on evidence from cities of the Northern Hemisphere, while the Southern Hemisphere is underrepresented
Santiago lies inside the biogeographic sub-region of central Chile [41], which roughly overlaps with the central Chile hotspot of biodiversity [30] and the central Chile Endemic Bird Area Endemic bird area (EBA) [42]
After applying our criteria to classify birds as urban dwellers, we concluded that Santiago hosts an assemblage of 46 urban bird species, representing 11 orders, 24 families and 43 genera (Table 1)

Summary

Introduction

Current knowledge of urban bird ecology and biodiversity relies on evidence from cities of the Northern Hemisphere, while the Southern Hemisphere is underrepresented. Current knowledge of urban bird diversity relies in evidence from cities from the Northern Hemisphere, located mainly in North America and Europe [3, 6, 7]. There are few studies in other continents such as Africa, Australia, and South America [8, 9] This unbalance in geographic coverage is emphasized when bearing in mind that several biogeographic regions, other than the Nearctic and the Palearctic, and more than a half of the geographical units which harbor the entire breeding range of two or more restricted-range bird species (Endemic Bird Areas of the world, EBAs) are located in the Southern Hemisphere [10, 11]. Studies of urban avifauna at these understudied continents are necessary, because they could enlighten the general biodiversity patterns of urban avifauna of the world, with an emphasis on the species composition of the avifauna in underrepresented continents

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