Employees of the Laboratory of Population Ecology of the IEE RAS for the first time studied the patterns and causes of mortality in young yellow ground squirrels, a large species of ground squirrels with summer-winter hibernation lasting up to 9 months. For this, the analysis of “survival curves” was used, a quantitative method based on tracing the individual fates of young animals. It turned out that in the first days after the end of milk feeding, young ground squirrels die en masse: more than half of the cubs die even before the start of resettlement from the natal (native) site, and only about 17% survive until hibernation begins. In this case, first of all, cubs with a low body weight and those who left the nest to the surface later than others die, practically regardless of gender. Compared to other types of terrestrial squirrels, mothers of yellow ground squirrels feed their cubs with milk for a very short time and stop caring for their offspring early, which, perhaps, determines the mass death of ground squirrels. Apparently, female yellow ground squirrels do not have the ability to regulate the amount of parental investment in order to compensate for adverse environmental conditions - they do not have enough time for this. Under the conditions of an extremely short season of activity (3–4 months), the female is forced to cut off parental care to prepare for her own hibernation, while the cubs direct all their efforts towards rapid growth and weight gain, spending little time and energy on social contacts, and settle down. Thus, we can talk about the formation of the “fast and lonely life” syndrome in this desert herbivorous hibernator species, which depends on the availability of fresh food in a short period before the onset of a hot summer.
This work was supported by the Russian Science Foundation grant 22-24-00610.
Vasilieva NA, Savinetskaya LE, Tchabovsky AV (2022) Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation: effects of individual characteristics, environment, and maternal investment. Current Zoology zoac097. https://doi.org/10.1093/cz/zoac097
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