Patterns of predator behaviour and Wood Warbler Phylloscopus sibilatrix nest survival in a primaeval forest

Abstract

Understanding the foraging behaviour of predators is key to interpreting the role of anti‐predator adaptations of birds in reducing nest losses. Conducting research in primaeval habitats, with a low level of direct human interference, is particularly valuable in the understanding of predator–prey interactions. Using nest cameras, we investigated the identity and behaviour of potential and actual predators appearing at Wood Warbler Phylloscopus sibilatrix nests, and the importance of different predator groups for nest survival, in the primaeval part of Białowieża Forest (Poland). Mammals formed the main predator group (30 of 32 nest depredations), particularly medium‐sized carnivores (24 of 32), which attacked nests more frequently than merely passing by. This contrasted with other species, especially small rodents, which were commonly recorded near nests but rarely attacked them. Most nest attacks (22 of 32) took place at night and nest survival did not depend on nest visibility, indicating a reduced utility of nest concealment in defence against predators using mainly sound or olfaction when hunting. Daily nest survival declined strongly with nest progression (from egg‐laying to fledging of chicks), probably due to increased predator detection of nests containing older and louder chicks, rather than to increasing parental activity at nests during the day. The set of actual nest predators differed from some previous studies in human‐transformed habitats, showing that Wood Warblers may face different threats in modified vs. near‐pristine environments.

Numerical response of mammalian carnivores to rodents affects bird reproduction in temperate forests: A case of apparent competition?

“…Rodents have been documented to predate and/or destroy nests of several bird species in general (Kirkpatrick & Conway, ; Walankiewicz, ) and have been suspected to be an important nest predator of wood warbler nests via circumstantial indirect evidence (Mildenberger, ; Wesołowski, ; Wesołowski et al, ). However, direct evidence from using nest cameras in Northern Switzerland (this study, Grendelmeier et al, ), Marburg, Germany (Stelbrink, ), Wales, UK (Mallord et al, ), England, UK (Bellamy et al, ; Maziarz et al, ) and Białowieża National Park, Poland (Maziarz et al, ) now suggest that rodents are not important predators of wood warbler nests. Low predation by rodents is astonishing, considering that rodents were filmed moving around and even inspecting nests without predation occurring on many occasions (Maziarz et al, ).…”

“…(b) Rodent‐hunting predators (RHP hereafter) comprised the pine marten ( Martes martes ), the red fox ( Vulpes vulpes ), the stone marten ( Martes foina ), and the tawny owl ( Strix aluco ). We did not count house cats ( Felis catus ) as RHP, because we assume that their distribution and hunting behavior are strongly influenced by humans, and because they are not important nest predators in Switzerland (this study; Grendelmeier et al, ), in Germany (Stelbrink, ), in Wales and England (Bellamy et al, ; Mallord et al, ; Maziarz, Piggott, & Burgess, ) or in Poland (Maziarz et al, ). During 4 years, only four Eurasian lynx ( Lynx lynx ) and two European wildcats ( Felis silvestris silvestris ) could be photographed, but neither species depredated nests.…”

Does acoustically simulated predation risk affect settlement and reproduction of a migratory passerine?

“…Aside from being responsible for nest losses, most of the predator species identified in this and other studies (Bellamy et al, 2018;Grendelmeier et al, 2015;Mallord et al, 2012;Maziarz, Grendelmeier, et al, 2018;Maziarz, Piggott, et al, 2018) are capable of taking adults at nests. This indicates that both nest survival and an…”

“…We used the number of nestlings from the last visit before fledging, which was determined by camera traps placed at all nests in our experimental plots and at as many nests as possible outside of the plots (for details on nest camera use, see Grendelmeier et al, 2015 andMaziarz, Grendelmeier, et al, 2018;Maziarz, Piggott, et al, 2018). For the analysis of clutch size, we used only clutches that were complete as judged from repeated nest checks.…”

“…Based on these findings, it can be hypothesized that wood warblers actively avoid breeding sites with high rodent densities. ), red fox (Vulpes vulpes) and tawny owl (Strix aluco) throughout the species' range, and non-rodent-hunting Eurasian jay (Garrulus glandarius, hereafter jay) in Western Europe are the most important predators of wood warbler nests (Bellamy et al, 2018;Grendelmeier et al, 2015;Mallord et al, 2012;Maziarz, Grendelmeier, et al, 2018;Maziarz, Piggott, et al, 2018), and nest survival is lower in years with high rodent abundance compared to other years . One such factor may be the presence of rodent-hunting predators, for which numerical increases in response to high rodent numbers have been shown (e.g., Jȩdrzejewski, Jȩdrzejewska, & Szymura, 1995;Schmidt & Ostfeld, 2003).…”