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Breakdown of the ideal free distribution under conditions of severe and low competition

Sirovnik, Janja and Voelkl, Bernhard and Keeling, Linda and Wuerbel, Hanno and Toscano, Michael Jeffrey (2021). Breakdown of the ideal free distribution under conditions of severe and low competition. Behavioral Ecology and Sociobiology. 75 , 31
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Abstract

Under the ideal free distribution (IFD), the number of organisms competing for a resource at different sites is proportional to the resource distribution among sites. The ideal free distribution of competitors in a heterogeneous environment often predicts habitat matching, where the relative number of individuals using any two patches matches the relative availability of resources in those same two patches. If a resource is scarce, access might be restricted to individuals with high resource holding potential, resulting in deviation from the IFD. The distribution of animals may also deviate from the IFD in the case of resource abundance, when social attraction or preference for specific locations rather than competition may determine distribution. While it was originally developed to explain habitat choice, we apply the habitat matching rule to microscale foraging decisions. We show that chickens feeding from two nondepleting feeders distribute proportionally to feeder space under intermediate levels of competition. However, chicken distribution between the feeders deviates from the IFD when feeder space is limited and competition high. Further, despite decreasing aggression with increasing feeder space, deviation from IFD is also observed under an excess supply of feeder space, indicating different mechanisms responsible for deviations from the IFD. Besides demonstrating IFD sensitivity to competition, these findings highlight IFD's potential as a biological basis for determining minimal resource requirements in animal housing.Significance statementThe ideal free distribution (IFD) predicts how animals ought to distribute themselves within a habitat in order to maximize their payoff. Recent studies, however, have questioned the validity of the IFD concept following anomalous results. We studied the IFD in chickens by systematically varying the amount and distribution of space at two feed troughs. We show that when tested over a sufficiently large range, the distribution of birds depends on the overall resource availability. Furthermore, behavioral data suggest that distinctly different mechanisms account for deviations from the IFD at shortage and excess supply of feeder space, respectively.

Authors/Creators:Sirovnik, Janja and Voelkl, Bernhard and Keeling, Linda and Wuerbel, Hanno and Toscano, Michael Jeffrey
Title:Breakdown of the ideal free distribution under conditions of severe and low competition
Series Name/Journal:Behavioral Ecology and Sociobiology
Year of publishing :2021
Volume:75
Article number:31
Number of Pages:11
Publisher:SPRINGER
ISSN:0340-5443
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Keywords:Laying hens, Feeder space, Matching rule, Social attraction, Aggression
URN:NBN:urn:nbn:se:slu:epsilon-p-110672
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-110672
Additional ID:
Type of IDID
DOI10.1007/s00265-020-02949-3
Web of Science (WoS)000612029500005
ID Code:22436
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Environment and Health
Deposited By: SLUpub Connector
Deposited On:19 Feb 2021 13:43
Metadata Last Modified:19 Feb 2021 13:51

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