Predation rate on artificial nests increases with human housing density in suburban habitats

Abstract

Predation causes most nest failure in birds. Predator communities are likely to vary across a gradient of increasing urbanization, so nest predation also is likely to vary across this gradient. Although predation is thought to decline with increasing urbanization, relatively little is known about variation in predation pressure within strata along an urban gradient and how factors known to affect nest success, such as nest location, interact with urban variables, such as human housing density. Native habitats are frequently fragmented and isolated by suburban residential development, thus we quantified predation rates on artificial nests located in natural oak scrub patches within a suburban matrix in south‐central Florida. We examined patterns of predation based on nest location relative to habitat edges, artificial nest weathering treatment, nest shrub height, and human housing density. Over two 18‐d trials, we placed a total of 240 nests, each containing a single quail egg and a clay sham, along three roadside transects. Nest predation was not influenced by proximity to edge, nest weathering, or trial date, but was highest at high housing density and lowest at low housing density. The proportion of quail eggs removed from nests increased with human housing density. Birds were the most frequent predators of artificial nests, but the relative frequency of predation by birds or mammals did not differ relative to any of our treatments. Higher rates of nest predation with increasing human housing density within suburban habitats may reflect changes in habitat structure and composition that increase the vulnerability of nests to predation or changes in the composition of the predator community. Our results modify the conclusions of previous studies by suggesting that at scales smaller than the entire urban gradient, nest predation may increase with human housing density, one common measure of urbanization.

The reproductive biology of the Syrian Woodpecker Dendrocopos syriacus in a newly colonized area of south-eastern Poland

“…Those observations indicate that the level of nest predation experienced by this species may depend on geographical location and may also be modified by the type of environment in which the birds nest (e.g., Thorington and Bowman 2003;Jokimäki et al 2005). This is because this species colonizes a variety of very different habitats (Mendelssohn and Yom-Tov 1999;Aghanajafizadeh et al 2011;Fröhlich and Ciach 2013).…”

Conserving Biodiversity in Urbanizing Areas: Nontraditional Views from a Bird's Perspective

“…Such changes in predator communities are frequently cited as causes of the commonly reported negative association between some sensitive Neotropical migratory species and urbanization, yet the link between urbanization and increased nest predation has surprisingly mixed empirical support from studies of natural nests (Phillips et al 2005; Bakermans and Rodewald 2006; Burhans and Thompson 2006;Rodewald and Shustack 2008b). Most studies reporting higher rates of predation in urban environments have used artificial nests (Gering and Blair 1999;Jokimaki and Huhta 2000;Thorington and Bowman 2003;Jokimaki et al 2005), which can result in biased estimates of nest predation due to species-specific responses of nest predators (Thompson and Burhans 2004). Our long-term studies of nest predation in central Ohio and western Washington suggest that nest predation in urbanizing landscapes show high temporal and spatial variability, and urbanization seems to be inconsistently related to daily mortality rates (Marzluff et al 2007; A.D. Rodewald, unpublished data).…”

Environment and Biodiversity

“…Plant data are derived from 1000 quadrats (1 m 2 ) placed across the city of available habitat types. A range of processes may contribute to such changes in abundance, including natural food availability, the availability of artificiallyprovided supplementary food, nest site availability and quality, predation pressure and interspecific competition (Clergeau et al, 1998;Thorington and Bowman, 2003;Shochat, 2004;Faeth et al, 2005). The ratios of different types of habitat available are likely to change systematically with increasing urban development.…”