Does Urbanization Affect Predation of Bird Nests? A Meta-Analysis

Abstract

Urbanization can affect interspecific interactions such as predator-prey relationships. Several hypotheses have been postulated to predict how predation on bird nests changes along urbanization gradients; some predict increased and others decreased predation pressures in urban compared to rural habitats. Using a formal meta-analytical approach, we carried out a systematic literature review to test whether predation on natural and artificial bird nests increased or decreased with urbanization. We found that the effect was highly heterogeneous among studies, due to contrasting results between studies that used artificial nests and those that used natural nests. For artificial nests, survival rate tended to decrease with increasing urbanization, with higher predation in more urbanized study sites. For natural nests, survival tended to increase with the level of urbanization. The latter finding supports predictions of the "urban habitats as predation-safe zones" and "urban nest predator paradox" hypotheses, but the effect may be confounded by many studies not distinguishing between predation and other sources of mortality. None of the other considered methodological and ecological variables explained the variation in a robust way. The discrepancy between the results of artificial and natural nest studies may be due to differences in experimental design (e.g., cavity nests have been more commonly studied in natural nest studies), intrinsic differences between the two nest types (e.g., lack of parental nest defense in artificial nests), or sampling bias. We conclude that the direction of the relationship between urbanization and nest predation is likely to depend on the methodology of the study. Therefore, results from studies using different methodologies, particularly natural or artificial nests, should be generalized with caution to avoid over-interpretations.

Trophic structure in a rapidly urbanizing planet

“…Earlier studies provided conflicting evidence on the response to predators to urbanization; some showed declines in predation pressure (predation relaxation), while others showed increases in predator abundance (predator proliferation) (Fischer et al., ; Shochat, ). A similar pattern has been observed in urban bird communities (Vincze et al., ).…”

Land‐sharing vs. land‐sparing urban development modulate predator–prey interactions in Europe

“…) is not homogeneous in city landscapes, potentially explaining the variability in the results found in previous local‐scale studies (e.g., Vincze et al. ). Moreover, our results indicate that urban planning (i.e., the urban development type) plays a crucial role in affecting nest survival among urban birds, with land‐sparing areas favoring a higher survival probability of ground nests.…”

“…A recent meta‐analysis on urban nest predation found very heterogeneous results attributed to different study methods, differences in local nest predator communities and differences in the urbanization level of the focal study areas (Vincze et al. ). The large‐scale cross‐city perspective of our approach is particularly important because many of the previous studies analyzed urban nest predation at a very small scale (i.e., park/woodlot level), making generalizations for management purposes difficult (Lepczyk et al.…”

A review of urban impacts on avian life‐history evolution: Does city living lead to slower pace of life?

“…Nest survival was higher in urban habitats in six studies in eight species, did not differ in four studies on five species, and was lower in five studies on five species. A recent review on nest predation indicated that for artificial nests, survival rate tends to decrease with increasing urbanization, with higher predation in more urbanized study sites, but the opposite is true for natural nests, where survival tends to increase with the level of urbanization (Vincze et al., ).…”