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Nest predation processes and farmland birds

habitat selection and population dynamics of predators and prey

Roos, Staffan (2004). Nest predation processes and farmland birds. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., ; 301
ISBN 91-576-6535-4
[Doctoral thesis]

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Abstract

It is generally expected that predators affect the breeding biology of prey species, but most studies have had a prey-biased view of the predator-prey relationship. Without studying the predator, one may draw erroneous conclusions of how predators and prey interact and conservation strategies for prey species could therefore be misleading. In this thesis, I investigated whether omnivorous avian generalists known to depredate nests of passerine birds, mainly the magpie (Pica pica) and the hooded crow (Corvus corone cornix), affected breeding habitat selection and population dynamics of one of their prey species, the red-backed shrike (Lanius collurio) in a Swedish farmland landscape (c. 94 km 2). The studies were performed between 1997 and 2003. My results showed that red-backed shrikes avoided to breed close to magpies and hooded crows, and that the spatial dynamics of red-backed shrikes between years were linked to corresponding spatial dynamics of the two corvid species. By avoiding corvids, red-backed shrikes increased their breeding success. The distribution and population dynamics of magpies were closely linked to human settlements. Thus, in areas with many houses and farms, magpies occurred in higher population densities and had higher repro d ucti ve success than in areas with few houses and farms. The studied magpie population increased in numbers by c. 86% between 1997 and 2003. At the same time did the red-backed shrike population decrease by c. 40% and this decline in numbers was closel y linked to the increase of magpies both at a landscape and at a local scale (km 2 -squares). My results also suggest that corvid nest predators form a search-image for shrub nests and therefore display density-dependent nest predation. However, the density-dependent nest predation risk was nest-site and time specific. Thus, corvids formed a search-image for nests in junipers early in the season, while it was changed towards thorny deciduous shrubs late in the season, probably as a result of corresponding seasonal changes in shrub specific nest densities. My results suggest that the effects of nest predation potentially could affect nest site choice, habitat patch choice and population dynamics of many song birds.

Authors/Creators:Roos, Staffan
Title:Nest predation processes and farmland birds
Subtitle:habitat selection and population dynamics of predators and prey
Year of publishing :April 2004
Volume:301
Number of Pages:38
Papers/manuscripts:
NumberReferences
ALLI. Roos, S. and Pärt, T. 2004. Nest predators affect spatial dynamics of breeding red-backed shrikes (Lanius collurio). Journal of Animal Ecology 73: 117-127. II. Roos, S., Siggstedt, J., and Pärt, T. Habitat selection and breeding success of magpies (Pica pica) in farmland: The relative importance of grasslands and human settlements. Manuscript. III. Roos, S. An increasing magpie (Pica pica) population limit the distribution of red-backed shrikes (Lanius collurio). Manuscript. IV. Roos, S. 2002. Functional response, seasonal decline and landscape differences in nest predation risk. Oecologia 133: 608-615. V. Roos, S. and Pärt, T. When to expect density-dependent predation? An example with nest predators and shrub-nesting birds. Submitted manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-6535-4
ISSN:1404-6230
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L20 Animal ecology
Subjects:Not in use, please see Agris categories
Agrovoc terms:passeriformes, habitats, selection, predator prey relations, nesting, reproductive performance, farmland, sweden
Keywords:Corvids, red-backed shrike, Lanius collurio, magpie, Pica pica, spatial avoidance, prey refuge, functional response, search image, density-dependent predation
URN:NBN:urn:nbn:se:slu:epsilon-183
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-183
ID Code:513
Department:(NL, NJ) > Institutionen för naturvårdsbiologi (fr.o.m. 970101)
Deposited By: Staffan Roos
Deposited On:14 Apr 2004 00:00
Metadata Last Modified:02 Dec 2014 10:05

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