Vegetation structure governs nest predation in three types of conifer forest habitats
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ORIGINAL PAPER
Vegetation structure governs nest predation in three types of conifer forest habitats Uzi Dagan1 · Ido Izhaki1 Received: 28 August 2019 / Revised: 15 March 2020 / Accepted: 29 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The primary hazard for open-cup nesting birds is nest predation. Vegetation structure and coverage may affect nest predation through various mechanisms such as the ability of a predator to locate the nests, which may vary between breeding habitats. We examined the association between vegetation structure and nest predation in three different types of pine plantations using artificial nests of the Sardinian warbler, Sylvia melanocephala, which were located 30 cm above ground in low bushes. We also assessed the relationship between bird abundance and nest predation in each type of forest. Finally, we identified predators through their bite marks on 3D-printed plaster eggs that were placed in the nests. The percentage of nests predated in pine forests with high understory coverage was significantly higher than in pine forests with only sparse understory. We also found that the nest predation rate positively correlated with total bird abundance and the abundance of S. melanocephala. The species of nest predators varied between different forest types, although rodents and birds were the most and second-most abundant predators, respectively, in each forest type. These results show that patches with only sparse understory vegetation within the forests generate nesting sites for birds with less risk of predation. But because bird abundance in this habitat type was relatively low, the net effect of preserving such habitat on the number of hatched birds should be further studied. Keywords Pine forest · Plantation · Understory · Vegetation · Bird nesting · Bird community · Habitat structure
Introduction One of the key factors determining the ecological value of a habitat is its ability to support reproduction. Birds are exposed to various kinds of hazards during breeding (Thompson 2007). The risk is higher during the nesting stage, mainly due to predators, which are responsible for an average of 80% of losses of eggs for open-cup nesters (Martin 1993a). The activities of incubating parents and the scent of the eggs provide cues to predators during the egg stage of nesting. Fledglings give the strongest cues to predators, followed by nestlings and then eggs (Thompson 2007). Nevertheless, Jackson et al. (1989) suggested that in fact, Communicated by Claus Bässler. * Ido Izhaki [email protected] Uzi Dagan [email protected] 1
Department of Evolutionary and Environmental Biology, University of Haifa, 3498838 Haifa, Israel
the egg stage is the most vulnerable, and Powell and Frasch (2000) produced a model that predicted that the egg stage is the most vulnerable to predation in a hardwood forest. The nest predation rate in forests varies among different habitat types and vegetation structures (Bellamy et al. 2018). In hardwood forest habitats, t
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