Is mother condition related to offspring condition in migratory caribou (Rangifer tarandus) at calving and weaning?

Abstract

Maternal characteristics can affect offspring traits, yet they are seldom included when considering density dependence of juvenile traits and population dynamics. We quantified the influence of population size and maternal traits on body condition of migratory caribou (Rangifer tarandus (L., 1758)) calves at birth and weaning. We contrasted female-calf pairs of the Rivière-George (RG) herd, which has recently declined to low population size, with pairs of the much larger Rivière-aux-Feuilles (RAF) herd. Calves of the RAF herd were lighter, smaller, and leaner than calves of the RG herd at both birth and weaning. Differences between herds, however, were much greater at weaning than at calving, suggesting a combined effect of herd size and summer range conditions on calf growth. Maternal mass was positively related to calf body condition during both periods. The positive influence of maternal mass on calf body condition was greater for RAF than RG calves at birth, but it was similar for the two herds at weaning. Our results show that the negative effect of population size on calf body condition can be modulated by maternal mass at calving, and that the positive effect of maternal mass is greater at weaning.Résumé : Les caractéristiques maternelles peuvent influencer les traits de leur progéniture, mais sont rarement considérées lors de l'étude des effets de la densité sur les traits des juvéniles et la dynamique des populations. Nous avons évalué l'influence de la taille de population et des caractéristiques maternelles sur la condition physique des faons du caribou migrateur (Rangifer tarandus (L., 1758)) à la mise bas et au sevrage. Nous avons comparé des paires de femelle-faon du troupeau Rivière-George (RG) dont la taille de population a récemment décliné, à des paires du troupeau Rivière-aux-Feuilles (RAF) qui est présentement à taille de population élevée. Les faons du RAF présentaient une masse corporelle, une taille corporelle et un indice de gras des reins inférieurs aux faons du RG tant à la mise bas qu'au sevrage. Ces différences entre les troupeaux étaient plus importantes au sevrage qu'à la mise bas, suggérant un effet négatif combiné de la taille de population et des conditions d'alimentation estivale sur la croissance des faons. La masse maternelle était positivement corrélée à la masse des faons et ce, aux deux périodes. L'influence positive de la masse maternelle sur la masse du faon était plus forte pour le RAF que pour le RG à la naissance, mais semblable pour les deux troupeaux au sevrage. Nos résultats indiquent que l'effet négatif d'une taille de population élevée sur la condition corporelle des faons peut être modulé par la masse maternelle à la mise bas, et que cet effet positif de la masse maternelle est plus important au sevrage qu'à la mise bas.

An enigmatic group of arctic island caribou and the potential implications for conservation of biodiversity

“…If so, these caribou re ect cryptic biodiversity among the Canadian Arctic Archipelago. A second possibility is that the large-bodied ultra pearyi represent a hybrid form (intergrades between pearyi x groenlandicus), aligning with previously described morphological clines (Manning, 1960;Ban eld, 1961;omas & Everson, 1982) and as assumed for all caribou occupying islands south of 74°N. A third possibility is that the ultra pearyi may belong to the typical pearyi group, along with caribou occurring on islands north of 74°N (i.e., QEI).…”

“…omas & Everson (1982) found a similar north-south morphological cline among those caribou, from western QEI in the north, across Prince of Wales and Somerset islands, and along the mainland Boothia Peninsula. To accommodate their described north-south morphological cline, they attributed three classi cations for the caribou: typical pearyi, intergrades between pearyi and groenlandicus (referred to as pearyi x groenlandicus), and typical groenlandicus ( omas & Everson, 1982).…”

“…To accommodate their described north-south morphological cline, they attributed three classi cations for the caribou: typical pearyi, intergrades between pearyi and groenlandicus (referred to as pearyi x groenlandicus), and typical groenlandicus ( omas & Everson, 1982).…”

“…In turn, recent studies have shown that demographic factors can directly impact body condition. For example, among migratory caribou, major in uences on body size include reproductive rates (Taillon et al, 2012), as well as population density, intraspeci c competition, and migration duration (Courturier et al, 2010).…”

Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore

“…The condition of ungulates in winter is an important determinant of future fitness because of its impact on individual body condition at the start of the breeding season (Forchhammer et al 2001;Steinheim et al 2002;Solberg et al 2007;Rodriguez-Hidalgo et al 2010;Taillon et al 2012;Hurley et al 2014). In this paper, we mechanistically link changes in annual weather patterns and variation in the spatial and temporal patterns of plant phenology across landscapes with the winter body condition of adult female mule deer to facilitate understanding of how changing weather patterns may affect this important species.…”