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Territory quality affects the relative importance of habitat heterogeneity and interference competition in a long-lived territorial songbird

Grünkorn, T.; Potiek, A.; Looft, V.; Jonker, R. M.; Chakarov, Nayden LU and Krüger, O. (2014) In Journal of Avian Biology 45(1). p.15-21
Abstract
Density-dependent reproduction is commonly explained by either the habitat heterogeneity (HHH) or individual adjustment (IAH) hypothesis. Under the HHH, high quality territories are assumed to be occupied first. At higher density, occupation of low-quality territories increases due to lower availability of high-quality territories, which reduces mean reproductive success. Alternatively, the IAH assumes that increased competition at higher densities reduces reproductive success in all territories. For birds of prey, HHH plays an important role in territorial species, and IAH in socially breeding species. To test the generality of this hypothesis, we studied the mechanism behind density dependence in raven Corvus corax, a long-lived... (More)
Density-dependent reproduction is commonly explained by either the habitat heterogeneity (HHH) or individual adjustment (IAH) hypothesis. Under the HHH, high quality territories are assumed to be occupied first. At higher density, occupation of low-quality territories increases due to lower availability of high-quality territories, which reduces mean reproductive success. Alternatively, the IAH assumes that increased competition at higher densities reduces reproductive success in all territories. For birds of prey, HHH plays an important role in territorial species, and IAH in socially breeding species. To test the generality of this hypothesis, we studied the mechanism behind density dependence in raven Corvus corax, a long-lived passerine bird, using long-term population data from a large number of territories. Population density decreased reproduction, which was explained by increased usage of low quality territories at higher density, supporting the HHH. Density reduced reproduction in low quality territories, but not in high and intermediate quality territories. We additionally compared the explanatory power of different models describing brood size, representing IAH, HHH, or a combination of both. The best model represented a combination of both hypotheses, in which the effect of density depended on territory quality. Our conclusion that both IAH and HHH are supported can be explained by the biology of ravens, where territorial adults not only experience interference competition with other territorial adults, but also with social groups of juveniles and floaters. We conclude that the relative importance of IAH and HHH may depend on variation in territory quality and social structure. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
dependent population regulation, density-dependence, individual, adjustment, numerical response, accipiter-gentilis, clutch size, reproduction, fecundity, performance, hypotheses
in
Journal of Avian Biology
volume
45
issue
1
pages
15 - 21
publisher
Federation of European Neuroscience Societies and Blackwell Publishing Ltd
external identifiers
  • scopus:84892531951
ISSN
0908-8857
DOI
10.1111/j.1600-048X.2013.00182.x
language
English
LU publication?
no
id
22ec447d-0e81-4b58-96a4-c950cb0affb2 (old id 4936969)
date added to LUP
2015-01-21 15:24:34
date last changed
2017-03-19 04:16:31
@article{22ec447d-0e81-4b58-96a4-c950cb0affb2,
  abstract     = {Density-dependent reproduction is commonly explained by either the habitat heterogeneity (HHH) or individual adjustment (IAH) hypothesis. Under the HHH, high quality territories are assumed to be occupied first. At higher density, occupation of low-quality territories increases due to lower availability of high-quality territories, which reduces mean reproductive success. Alternatively, the IAH assumes that increased competition at higher densities reduces reproductive success in all territories. For birds of prey, HHH plays an important role in territorial species, and IAH in socially breeding species. To test the generality of this hypothesis, we studied the mechanism behind density dependence in raven Corvus corax, a long-lived passerine bird, using long-term population data from a large number of territories. Population density decreased reproduction, which was explained by increased usage of low quality territories at higher density, supporting the HHH. Density reduced reproduction in low quality territories, but not in high and intermediate quality territories. We additionally compared the explanatory power of different models describing brood size, representing IAH, HHH, or a combination of both. The best model represented a combination of both hypotheses, in which the effect of density depended on territory quality. Our conclusion that both IAH and HHH are supported can be explained by the biology of ravens, where territorial adults not only experience interference competition with other territorial adults, but also with social groups of juveniles and floaters. We conclude that the relative importance of IAH and HHH may depend on variation in territory quality and social structure.},
  author       = {Grünkorn, T. and Potiek, A. and Looft, V. and Jonker, R. M. and Chakarov, Nayden and Krüger, O.},
  issn         = {0908-8857},
  keyword      = {dependent population regulation,density-dependence,individual,adjustment,numerical response,accipiter-gentilis,clutch size,reproduction,fecundity,performance,hypotheses},
  language     = {eng},
  number       = {1},
  pages        = {15--21},
  publisher    = {Federation of European Neuroscience Societies and Blackwell Publishing Ltd},
  series       = {Journal of Avian Biology},
  title        = {Territory quality affects the relative importance of habitat heterogeneity and interference competition in a long-lived territorial songbird},
  url          = {http://dx.doi.org/10.1111/j.1600-048X.2013.00182.x},
  volume       = {45},
  year         = {2014},
}