Consistent nest-site selection across habitats increases fitness in Asian Houbara

Guilherme, Joao L., Burnside, Robert J., Collar, Nigel J. and Dolman, Paul M. (2018) Consistent nest-site selection across habitats increases fitness in Asian Houbara. Auk, 135 (2). pp. 192-205. ISSN 0004-8038

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      Abstract

      Nest-site choice profoundly influences reproductive success and the survival of incubating adults. Asian Houbara (Chlamydotis macqueenii) nest in subtly contrasting habitats where the main cause of nest failure is predation. We examined nest-site selection across three semi-arid shrub habitats that differed in vegetation structure and hypothesized that increased concealment would reduce nest predation. We quantified vegetation structure at 210 nests and 194 random control sites at two scales, the ‘nest area’ (50 m radius, considering mean ‘shrub height’ and mean ‘shrub frequency’) and ‘nest scrape’ (2 m radius, considering a ‘concealment index’). Variance ratio tests showed variance in both shrub height and concealment index were lower at nests than at random sites, indicating non-random selection. Analysis of the probability of nest occurrence for nest area indicated consistent selection of intermediate shrub heights (shrub height + shrub height2) in the Astragalus, Salsola arbuscula and S. rigida shrub assemblages (29.5–31.5 cm), although this was not supported statistically in S. rigida as the vegetation available was already similar to the optimal nest structure. Nest survival analysis, controlling for date, showed that shrub height (but not its quadratic term) in the nest area reduced nest predation rate. Females likely traded off nesting in even taller shrubs that may confer greater nest success against the ability to see approaching danger and thus to reduce the risk of being depredated themselves (head height during vigilance when incubating is ~30cm), as we have no records of females being depredated on the nest. At the nest scrape, females strongly selected better concealed locations, although the concealment index did not affect nest success. We suggest that concealing the scrape among shrubs may have other roles, such as thermoregulation.

      Item Type: Article
      Uncontrolled Keywords: nest placement,nest predation,nest success,nest survival,vegetation structure,visual security,predation risk,chlamydotis macqueenii
      Faculty \ School: Faculty of Science > School of Environmental Sciences
      University of East Anglia > Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
      University of East Anglia > Faculty of Science > Research Groups > Environmental Biology
      University of East Anglia > Faculty of Science > Research Groups > Resources, Sustainability and Governance
      Depositing User: Pure Connector
      Date Deposited: 17 Nov 2017 06:05
      Last Modified: 03 Aug 2018 00:50
      URI: https://ueaeprints.uea.ac.uk/id/eprint/65481
      DOI: 10.1642/AUK-17-156.1

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