Ground nesting birds in roadside borders of the Argentine Pampas: habitat use and predation risk of artificial nests

Daniela María Depalma,Myriam Emilia Mermoz

doi:10.1007/bf03546072

Abstract

Habitat loss and fragmentation have led to grassland bird declines, with ground nesters particularly vulnerable. Roadsides could provide habitat, although their suitability depends on several roadside and field characteristics. Vegetation structure determines foraging and nesting site availability. In addition, road delimits sharp edges where the activity of nest predators is usually higher, whereas herbaceous vegetation determines ground nest concealment. Trees could provide lookouts to predators, and modified habitat and woodlands in surrounding fields could offer additional resources to predators. Our objective was to assess habitat suitability for ground nester birds in roadsides belonging to one modified grassland of the Argentine Pampas. We surveyed birds (90 plots) and monitored artificial nests (60 plots) in different road types: unpaved, paved of one-lane per side, and paved of two-lanes per side. Within each road type, we evaluated the relationship that ground nesters abundance had with vegetation structure of roadsides and surrounding fields. In addition, we related predation of artificial nests with the proximity to the road, roadside vegetation, and modified land and woodlands of surrounding fields. We made 2832 records of 84 species using roadsides, including 1083 records of 13 ground nesting species. Abundance of ground nesters increased with tall grass cover of roadsides and decreased with the number of native trees within roadsides. Roughly half (31/60) of the artificial nests were predated and 82.6% of the identified egg-marks were of mammal teeth. Nest predation decreased with nest proximity to the road. Our results emphasize the importance of tall grass cover of roadsides for the conservation of ground nesting species, and the necessity of monitoring natural nests in order to clarify the effect of trees, proximity to the road, and other environmental variables on nest success.

Highlights

Habitat loss and fragmentation have led to the decline of grassland bird populations worldwide (Askins et al 2007, Zuckerberg et al 2009, Azpiroz et al 2012, Reif 2013)
It has been proposed that roadside networks can provide habitat (Meunier et al 1999, Bergin et al 2000), their suitability for grassland birds depends on several factors affecting bird abundance and nest predation
In order to assess the suitability of roadsides for ground nesting birds in one modified grassland of the Argentine Pampas, we evaluated the influence of roadside factors and surrounding field factors on bird abundance, and on the predation of artificial nests

Summary

Introduction

Habitat loss and fragmentation have led to the decline of grassland bird populations worldwide (Askins et al 2007, Zuckerberg et al 2009, Azpiroz et al 2012, Reif 2013). Conservation researchers have become interested in habitat remnants that could benefit the conservation of these species (Weidman & Litvaitis 2011, Duchardt et al 2016, Port & Schottler 2017). In this context, it has been proposed that roadside networks can provide habitat (Meunier et al 1999, Bergin et al 2000), their suitability for grassland birds depends on several factors affecting bird abundance and nest predation. Some grassland birds might avoid these areas since woodlands can increase the abundance of specialist predators (Vickery et al 2009, Ellison et al 2013) and brood parasites (Patten et al 2006, Pietz et al 2009), and modified land may offer resources to generalist predators (Evans 2004, BenítezLópez et al 2010)

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