Influence of snowmelt timing on the diet quality of Pyrenean rock ptarmigan (Lagopus muta pyrenaica): Implications for reproductive success
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Date
2016
Authors
García González, Ricardo
Aldezabal, Arantza
Amaia Laskurain, Nere
Margalida, Antoni
Novoa, Claude
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Abstract
The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) is the southernmost subspecies of
the species in Europe and is considered threatened as a consequence of changes in landscape,
human pressure, climate change, and low genetic diversity. Previous studies have
shown a relationship between the date of snowmelt and reproductive success in the Pyrenean
ptarmigan. It is well established that birds laying early in the breeding season have
higher reproductive success, but the specific mechanism for this relationship is debated.
We present an explicative model of the relationship between snowmelt date and breeding
success mediated by food quality for grouse in alpine environments. From microhistological
analyses of 121 faecal samples collected during three years in the Canigou Massif (Eastern
Pyrenees), and the assessment of the chemical composition of the main dietary components,
we estimated the potential quality of individual diets. Potential dietary quality was correlated
with free-urate faecal N, a proxy of the digestible protein content ingested by
ptarmigan, and both were correlated with phenological stage of consumed plants, which in
turn depends on snowmelt date. Our findings suggest that the average snowmelt date is
subject to a strong interannual variability influencing laying date. In years of early snowmelt,
hens benefit from a longer period of high quality food resources potentially leading to a
higher breeding success. On the contrary, in years of late snowmelt, hens begin their breeding
period in poorer nutrient condition because the peaks of protein content of their main
food items are delayed with respect to laying date, hence reducing breeding performance.
We discuss the possible mismatch between breeding and snowmelt timing.
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Plos One, 2016, vol. 11, núm. 2, e0148632