Global warming has increased the summer survival rate of yellow-bellied marmots, and lowered winter, and particularly this effect manifests itself among cubs and yearling individuals. This is the conclusion reached by researchers after analyzing data about a population of this North American species. In an article for the journal PNAS , the authors notedthat the complex response of marmots on climate change warns against simple hypotheses linking global warming and the well-being of certain types.
Plants and animals living in a temperate climate, adapted to the regular change of seasons. However, due to global warming the usual natural cycles are broken. For example, snow is now melting faster, vegetation starts earlier and the risk of droughts increases. To adapt to such rapid changes may not all kinds.
A team of researchers headed Line Cordes (Cordes, Line S.) from Bangor University decided to find out how the consequences of climate change manage yellow-bellied marmots (Marmota flaviventris) — large rodents that live in the mountains of Western North America. In the spring and summer, they actively feed and accumulate fat reserves, and in the autumn fall to eight-month hibernation. It is assumed that the growth duration of the warm season is beneficial to the marmots, allowing them to store more fat, however, strict evidence of this is no idea.
Scientists focused on the population that inhabits the Rocky mountains in Colorado. After analyzing the data collected from 1979 to 2018, they found that during this time survival of marmots in summer rose, and winter — fell. Most clearly this effect was observed in young of the year (young of the year) and yearling individuals. The survival rate during the year almost has not changed.
The authors suggested that the observed effect is related to climate change. For forty years, the maximum summer and minimum winter temperatures in the survey area increased by about two degrees Celsius, the summer has become drier and the vegetation period increased by 50 days. Snowfall has decreased by three and a half meters, and the date of its spring thaw moved on sixteen days ago.
Comparing weather data with survival Surkov, the researchers came to the conclusion that individuals from different age classes react differently to some climatic factors. For example, year survival rate of juveniles increased through the reduction of winter precipitation, and winter — has decreased due to droughts and increase the growing season. The latter seems surprising, because herbivores should benefit from a longer summer. Perhaps the reason of mistiming in phenology between the peak of plant growth and the birth of cubs, or increased activity of predators.
As for the other age classes, the summer survival rate of yearling animals increased in response to rising summer temperatures and lengthening the growing season. The authors, however, believe that this is a temporary phenomenon, because in General, yellow-bellied marmots are not adapted to living in a warm dry climate. Finally, more severe droughts and earlier melting of snow had a negative impact on winter survival of adult individuals, but these correlations were not statistically significant.
The results obtained caution against simple conclusions about the impact of climate change on living organisms. In the case of yellow-bellied marmots real picture was much more complicated than the assumptions about the benefits of lengthening the growing season. According to the authors, in the future winter survival of this species will continue to decline, and the summer — to grow. How exactly will this affect the overall population is unclear. However, the vulnerability of marmots during hibernation causes anxiety.
Weather conditions is not the only factor that affects the survival of yellow-bellied marmots. According to a recent study, this species is more gregarious species live less “stand-offish”. This distinguishes them from other social mammals, whose close social ties are associated with greater life expectancy.
Sergey Knee High