期刊
ECOLOGY
卷 94, 期 8, 页码 1815-1827出版社
WILEY
DOI: 10.1890/12-1424.1
关键词
capital breeders; income breeders; isotopes; maternal allocation; migratory caribou; nitrogen; northern Quebec and Labrador; Canada; Rangifer tarandus
类别
资金
- ArcticNet
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Hydro-Quebec
- Xstrata Nickel-Mine Raglan
- Federation des Pourvoiries du Quebec
- CircumArctic Rangifer Monitoring and Assessment network (CARMA)
- Ministere des Resources Naturelles et de la Faune du Quebec
- Labrador and Newfoundland Wildlife Division
- First Air
- Makivik Corporation
- Federation Quebecoise des Chasseurs et Pecheurs
- Fondation de la Faune du Quebec
- Institute for Environmental Monitoring and Research
- Canada Foundation for Innovation
- NSERC
- Fonds Quebecois de Recherche sur la Nature et les Technologies
Nitrogen (N) is a limiting nutrient for many herbivores, especially when plant availability and N content are low during the period of maternal investment, which is common for arctic ungulates. We used natural abundance of N isotopes to quantify allocation of maternal nitrogen to neonatal calves and milk in wild migratory caribou (Rangifer tarandus). We contrasted female-calf pairs from two herds in northern Quebec/Labrador, Canada: Riviere-George herd (RG; low population size with heavy calves) and the Riviere-aux-Feuilles herd (RAF; high population size and small calves). We assessed whether females of both herds relied on body protein or dietary N to produce the neonatal calf and milk at calving and weaning. Female caribou of both herds relied mostly on body N for fetal development. RAF females allocated less body N to calves than did RG females (92% vs. 95% of calf N), which was consistent with the production of calves that were 8% smaller in RAF than in RG. Allocation of body N to milk was also high for both herds, similar at calving for RAF and RG females (88% vs. 91% of milk N, respectively), but lower in RAF than RG females (95% vs. 99% of milk N) at weaning, which was consistent with a small but significantly greater reliance on dietary N supplies to support milk production at weaning. Female caribou used body protein stores to ensure a constant supply of N for fetal growth and milk production that minimized the effects of trophic mismatches on reproduction. The combination of migration and capital investment may therefore allow females to produce calves and attenuate the effects of both temporal and spatial mismatches between vegetation green-up and calf growth, which ultimately would reduce trophic feedbacks on population growth. Our data suggest that small changes in maternal allocation of proteins over the long period of gestation produce significant changes in calf mass as females respond to changes in resources that accompany changes in the size and distribution of the population.
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