Too risky to settle: avian community structure changes in response to perceived predation risk on adults and offspring

Abstract

Predation risk is widely hypothesized as an important force structuring communities, but this potential force is rarely tested experimentally, particularly in terrestrial vertebrate communities. How animals respond to predation risk is generally considered predictable from species life-history and natural-history traits, but rigorous tests of these predictions remain scarce. We report on a large-scale playback experiment with a forest bird community that addresses two questions: (i) does perceived predation risk shape the richness and composition of a breeding bird community? And (ii) can species life-history and natural-history traits predict prey community responses to different types of predation risk? On 9 ha plots, we manipulated cues of three avian predators that preferentially prey on either adult birds or offspring, or both, throughout the breeding season. We found that increased perception of predation risk led to generally negative responses in the abundance, occurrence and/or detection probability of most prey species, which in turn reduced the species richness and shifted the composition of the breeding bird community. Species-level responses were largely predicted from the key natural-history trait of body size, but we did not find support for the life-history theory prediction of the relationship between species' slow/fast life-history strategy and their response to predation risk.

Variation in coexisting birds to exploit spatial heterogeneity in small mammal activity

“…However, preliminary spatial analyses failed (p > 0.60) to support a relationship between mouse activity clusters and veery or ovenbird nest success (Emmering ). In addition, based on rodent removal studies, Brunner et al () found no experimental evidence for competition among rodents (mice, chipmunks and squirrels) at our site, concluding: ‘with only weak or nonexistent competition among these three common rodent species, we expect their patterns of habitat occupancy and population dynamics to be largely independent of one another’. For these reasons, we focus our present analyses on chipmunks only.…”

When the birds go unheard: highway noise disrupts information transfer between bird species

“…Additionally, non-lethal effects on prey behaviour could lower bird densities in noisy areas. That is, if prey perception of risk was elevated by noise [18] because of the lack of social (this study) or personally collected information concerning lethal risks, then prey might selectively avoid such areas [19]. In sum, either a loss of antipredator information or disruption of appropriate responses to alarm calls could lead to decreased density of prey birds via increased predation success or prey avoidance.…”

Reducing cuckoo parasitism risk via informed habitat choices

“…By using a silent control, we avoided the potential problems mentioned above, but on the other hand we cannot rule out the possibility that the playback (increased vocal activity in a site) or merely the presence of a playback machine affected the behavior of individuals in the playback sites. However, taking into account the scale of our experiment (average patch size ¼ 8 ha), any such effects are most likely negligible-and probably far weaker than the potential effects of, for example, heterospecific attraction or avoidance had the playback control been used instead of the silent control (for similar arguments, see Farrell et al 2012, Hua et al 2013. Similar experimental designs using silent controls have been applied extensively in studies of avian habitat selection (e.g., Hahn and Silverman 2006, Farrell et al 2012, Hua et al 2013, Ware et al 2015.…”

“…However, taking into account the scale of our experiment (average patch size ¼ 8 ha), any such effects are most likely negligible-and probably far weaker than the potential effects of, for example, heterospecific attraction or avoidance had the playback control been used instead of the silent control (for similar arguments, see Farrell et al 2012, Hua et al 2013. Similar experimental designs using silent controls have been applied extensively in studies of avian habitat selection (e.g., Hahn and Silverman 2006, Farrell et al 2012, Hua et al 2013, Ware et al 2015. Nonetheless, if the increased vocal activity due to the playback-or the mere presence of a playback machinerepels birds, one could expect a consistent negative effect on bird abundance across sites and species, irrespective of the latter's status as cuckoo hosts.…”