From winter time to summer time – what ends the "hunger gap" for Svalbard reindeer?

The term "hunger gap" (no: “vårknipa”) traditionally used in agricultural communities, refers to the period at the end of winter when winter provisions are depleting, yet the growing season has not yet started. In contemporary usage, the term also describes the food situation for wild animals, which may encounter challenging conditions at the end of winter. This situation is particularly pronounced in the Arctic, where the Svalbard reindeer is awaiting new plant growth after an eight-month-long winter. The limited winter food supply has prompted various morphological, physiological, and behavioral adaptations to conserve energy, crucial for overcoming the "hunger gap". The aim of my thesis is to investigate annual and individual variation in what ends the “hunger gap” for reindeer. I will utilize a dataset of activity and heart rate monitoring of ca 50 GPS-marked female Svalbard reindeer. In these data there is a very rapid increase in activity and heart rate from a “winter mode” to “summer mode”, a signal I define as the end of the “hunger gap”. I hypothesize a relatively large annual variation in the date of this switch, cause by annual variation in snow melt, spring temperatures and plant growth. On the individual level I will investigate the effect of body condition, age and reproductive status on the date of the “end of hunger gap” signal. I will be provided with activity and heart rate data from my supervisor, and will myself collect the required data on ground spring temperatures and calf at heel status together with a field assistant in august 2024.