The Effect of Winter Food on Reproduction in the Arctic Fox, Alopex-Lagopus - a Field Experiment

• (1) The population of arctic foxes in Fennoscandia is very small and has been so for around 60 years in spite of total protection for over half a century. The reasons why the arctic fox population has not increased to its former size are unknown. The population numbers fluctuate highly in relation to vole numbers. There is also very high interannual variation in reproduction among arctic foxes. (2) To determine the effect of winter food availability on reproductive success, we carried out a feeding experiment. The study area is situated above the treeline from an altitude of 700 m to mountains of 1600 m in Swedish Lapland. We added food (reindeer and moose carcasses) to dens during the winter months, January-April 1985-89. To determine the effect of this extra food on reproduction, we made inventories at both food-manipulated dens and control dens. These inventories of dens took place during July so we could check not only if dens were occupied, but also whether a litter was born and assess the number of cubs appearing outside the den. (3) The proportion of occupied dens in the experimental group was significantly higher than in the control group. The number of cubs at weaning in the food-manipulated dens was also higher than in control dens in each year. However, no effect on litter size was found. (4) From these results we conclude that the larger number of cubs produced in dens with extra winter food shows that reproduction under present dietary poor conditions was limited by available food. Many canid species show this close relation between reproduction and food availability, with pregnancy rates and litter sizes declining with the abundance of the main food.

Subject headings

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

Keyword

POPULATION

Animal physiology

Zoofysiologi

zoofysiologi

Zoological physiology

Publication and Content Type

ref (subject category)

art (subject category)