Evaluation of the “safe nesting zone” hypothesis across an urban gradient: a multi‐scale study

Abstract

. Evaluation of the ''safe nesting zone'' hypothesis across an urban gradient: a multi-scale study. Á/ Ecography 28: 59 Á/70.Urban areas have been considered ''safe zones'' for nesting birds because of low abundance of predators, and consequently low predation pressure. We studied risk of artificial ground nest predation across an urban gradient at regional (100)/100 km) and local scales (5)/5 km, within town) in Finland, Italy, and Spain. Risk of nest predation differed between countries, being greatest in Spain (66%), intermediate in Finland (51%), and lowest in Italy (29%). At the regional scale, risk of nest predation in Finland was lower in small villages and in forest area than in more urbanized sites. In Spain, the risk of nest predation was lower in villages than in the other habitat types. No differences in nest predation risk among habitat types were observed in Italy. At the local level, the risk of nest predation in Finland was higher within the town than in the surrounding forest. In Spain, the risk of nest predation in the surrounding forest area was as high as in the most urbanized areas. No difference in nest predation risk was observed between study plots in Italy at the local level analysis. Our results indicate that nest predation in town centers and their residential areas is similar to or higher than in villages and forest areas refuting the safe nesting zone hypothesis. Risk of nest predation also differed between residential area types within towns. Moreover, the abundance of potential nest predators differed between countries. Magpies and crows were more abundant in Finland than in Italy and Spain, whereas cats, dogs and pedestrians were less abundant in Finland than in the other countries. In Finland, risk of nest predation increased with the abundance of magpies. In Italy and Spain, risk of nest predation increased with the number of pedestrians and in Italy also with the number of cats. In all countries, the risk of nest predation increased with the visibility of the nest. According to our results, urban areas cannot be seen as ''safe nesting zones''. Actually, changes in nest predation pressure may cause changes in habitat selection patterns and affect bird community structure in urban environments.

Rural–urban gradient and land use in a millenary metropolis: how urbanization affects avian functional groups and the role of old villas in bird assemblage patterning

“…Blair, 1996;Bolger et al, 1997;Clergeau et al, 1998Clergeau et al, , 2006aJokimäki et al, 2005), whereas others have highlighted that local features (such as the reciprocal distribution of green areas or the vegetation diversity hosted by a given green area) may also influence bird communities and are of particular importance in estimating the likelihood of finding bird species (Clergeau et al, 2001;Melles et al, 2003). Our results showed that features at both landscape and local scales can explain bird community structures.…”

“…Urbanization acts against high canopy and foliage exploiters and strongly favours ground feeding-granivorous and omnivorous species vs. aerial insectivores (decreasing due to the urban pollution). Likewise it favours cavity nesting species (especially those using anthropogenic cavities) vs. "ground nesters" (Lancaster and Rees, 1979;Beissinger and Osborne, 1982;Mills et al, 1989;Allen and O'Conner, 2000;Jokimäki et al, 2005;Chace and Walsh, 2006;Clergeau et al, 2006a). According to our analysis of nesting functional groups, the increased urbanization level clearly represents a detriment for the species nesting on the ground, this being likely due to nest predation and decreasing habitat quality and availability (Jokimäki et al, 2005).…”

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).…”