Investigating patterns and processes of demographic variation: environmental correlates of pre-breeding survival in red-billed choughs Pyrrhocorax pyrrhocorax

Reid, J.M., Bignal, E. M., Bignal, S., Mccracken, D. I., Bogdanova, M. I. and Monaghan, P. (2008) Investigating patterns and processes of demographic variation: environmental correlates of pre-breeding survival in red-billed choughs Pyrrhocorax pyrrhocorax. Journal of Animal Ecology, 77(4), pp. 777-788. (doi: 10.1111/j.1365-2656.2008.01400.x) (PMID:18479340)

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Publisher's URL: http://dx.doi.org/10.1111/j.1365-2656.2008.01400.x

Abstract

1. Quantifying the pattern of temporal and spatial variation in demography, and identifying the factors that cause this variation, are essential steps towards understanding the structure and dynamics of any population. 2. One critical but understudied demographic rate is pre-breeding survival. We used long-term colour-ringing data to quantify temporal (among-year) and spatial (among-nest site) variation in pre-breeding survival in red-billed choughs (Pyrrhocorax pyrrhocorax) inhabiting Islay, Scotland, and identified environmental correlates of this variation. 3. Random-effects capture-mark-recapture models demonstrated substantial temporal and spatial process variance in first-year survival; survival from fledging to age 1 year varied markedly among choughs fledged in different years and fledged from different nest sites. Spatial variance exceeded temporal variance across choughs fledged from well-studied nest sites. 4. The best-supported models of temporal variation suggested that first-year survival was higher in years following high tipulid larvae abundance and when weather conditions favoured increased invertebrate productivity and/or availability to foraging choughs. These variables explained up to 80% of estimated temporal process variance. 5. The best-supported models of spatial variation suggested that first-year survival was higher in choughs fledged from nest sites that were further from exposed coasts and closer to flocking areas, and surrounded by better habitat and higher chough density. These variables explained up to 40% of estimated spatial process variance. 6. Importantly, spatio-temporal models indicated interactive effects of weather, tipulid abundance, local habitat and local chough density on first-year survival, suggesting that detrimental effects of poor weather and low tipulid abundance may be reduced in choughs fledged from nest sites surrounded by better foraging habitat and lower chough density. 7. These analyses demonstrate substantial temporal and small-scale spatial variation in pre-breeding survival, a key demographic rate, and indicate that this variation may reflect interactive effects of weather, prey abundance, habitat and geography. These patterns illustrate the value of holistic models of demographic variation, and indicate environmental factors that may limit the growth rate of Islay's protected chough population

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Monaghan, Professor Pat
Authors: Reid, J.M., Bignal, E. M., Bignal, S., Mccracken, D. I., Bogdanova, M. I., and Monaghan, P.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Journal of Animal Ecology
ISSN:0021-8790

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
409841Turning population ecology into conservation strategy - development of a natural care scheme for red-billed choughs in ScotlandPatricia MonaghanNatural Environment Research Council (NERC)NE/D001161/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED