Recent increase in body size of the American marten Martes americana in Alaska

Abstract

Using museum specimens, we studied recent changes in skull size of the American marten Martes americana, in continental Alaska. In Alaska, global warming has resulted in milder winters that may contribute to an improved food supply in the wild. In the present study, we tested the hypothesis that body size of the marten had increased during the second half of the 20th century, in response to global warming. We found that skull size, and by implication body size, increased significantly during the second half of the 20th century, possibly due to an improved food supply and/or lower metabolic demands in winter. Improved food availability in winter may result from the improved nutritional conditions for prey, and/or from increased access to prey resulting from a longer snow-free season. Longitude had a significant positive effect on skull size and a significant negative effect on teeth size. In Alaska, the climate is milder along the western coast and becomes harsher inland. Hence, the milder climate was associated with larger body size providing further support for our prediction that body size of the American marten was influenced by food availability and reduced energy expenditure. The negative relationship between longitude and teeth size may indicate a trend towards a larger prey in inland marten populations, but we have no data to support or refute this hypothesis.

Body size of the weasel Mustela nivalis and the stoat M. erminea in Sweden

“…Recent increases in body size of several species of mammals in temperate climates have been attributed to direct (energy savings) and indirect (through food availability) effects of increased ambient temperature (Yom-Tov 2003;Yom-Tov and Geffen 2006;Yom-Tov et al 2007;Yom-Tov et al 2008), and the results of this study further support this hypothesis. However, as mentioned in the Introduction, this hypothesis is by no means the exclusive explanation for body size in these two species, and the observed trends may be a result of other factors mentioned above.…”

Management strategies for a large-scale mountain pine beetle outbreak: Modelling impacts on American martens

“…Not all climate change effects, however, will necessarily be detrimental. For marten in interior Alaska, Yom-Tov et al (2008) found increasing body size in the last half of the 20th century and proposed enhanced prey abundance and reduced energy expenditure due to climate change as the causes. However, we thought a positive effect on marten in our sub-boreal forest was not likely.…”

Wintering French Mallard and Teal Are Heavier and in Better Body Condition than 30 Years Ago: Effects of a Changing Environment?

“…Long-term changes in phenology, distribution and/ or morphometrics of animal populations are increasingly reported, and often attributed to global climate change (reviews in Hughes 2000;McCarthy 2001;Walther et al 2002; Thorup et al 2007; see also Prop et al 1998; Thomas and Lennon 1999;Hatzofe and Yom-Tov 2002). Increase in mean body size at the population level has been demonstrated in some species Yom-Tov 2004, 2005;Yom-Tov et al 2008; review in Millien et al 2006), though the opposite has also been reported (e.g. Smith et al 1998;Yom-Tov 2001;Yom-Tov et al 2006a).…”