Global climate change and reindeer: effects of winter weather on the autumn weight and growth of calves

Abstract

Reindeer/caribou (Rangifer tarandus), which constitute a biological resource of vital importance for the physical and cultural survival of Arctic residents, and inhabit extremely seasonal environments, have received little attention in the global change debate. We investigated how body weight and growth rate of reindeer calves were affected by large-scale climatic variability [measured by the North Atlantic Oscillation (NAO) winter index] and density in one population in central Norway. Body weights of calves in summer and early winter, as well as their growth rate (summer to early winter), were significantly influenced by density and the NAO index when cohorts were in utero. Males were heavier and had higher absolute growth than females, but there was no evidence that preweaning condition of male and female calves were influenced differently by the NAO winter index. Increasing NAO index had a negative effect on calves' body weight and growth rate. Increasing density significantly reduced body weight and growth rate of calves, and accentuated the effect of the NAO winter index. Winters with a higher NAO index are thus severe for reindeer calves in this area and their effects are associated with nutritional stress experienced by the dams during pregnancy or immediately after calving. Moreover, increased density may enhance intra-specific competition and limits food available at the individual level within cohorts. We conclude that if the current pattern of global warming continues, with greater change occurring in northern latitudes and during winter as is predicted, reduced body weight of reindeer calves may be a consequence in areas where winters with a high NAO index are severe. This will likely have an effect on the livelihood of many northern indigenous peoples, both economically and culturally.

Allen's Rule Revisited: Temperature Influences Bone Elongation During a Critical Period of Postnatal Development

“…Many biologists have suggested that phenotypic plasticity (accommodation) could be a main driver of evolutionary innovation (West-Eberhard, 2005b;Crispo, 2007;Beldade et al, 2011;Minelli and Fusco, 2012;Wund, 2012), especially when "cryptic genetic variation" is revealed under certain environmental stimuli (Led on- Rettig et al, 2010;Palmer, 2012) such as in the temperature experiments here. Knowledge of the timing and degree to which phenotypic growth plasticity permits mammals to immediately adjust to novel temperature conditions is especially important in analyses of skeletal variation in fluctuating environments, particularly in relation to global climate change (Weladji and Holand, 2003).…”

Multiple pathways mediate the effects of climate change on maternal reproductive traits in a red deer population

“…Further, weather may be related to the trait in a variety of ways. For example, warmer temperatures have been associated with both increased and decreased body size in northern ungulate populations, depending on the time of year considered Stenseth 1999, Weladji andHoland 2003). Therefore identifying the critical time windows during which different environmental cues affect trait expression is crucial for understanding phenological changes (van de Pol and Cockburn 2011).…”

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

“…Indices based on large-scale alterations of atmospheric pressure, such as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO), are connected to climate change (Hurrell 1995, Forchammer & Post 2000, Aanes et al 2002, Weladji & Holand 2006 with high precipitation and the resultant heavy accumulation of snow associated with high values of winter NAO (Weladji & Holand 2003, Helle & Kojola 2008. Spring NAO can also be influential.…”