VARIATION IN TERRITORY FIDELITY AND TERRITORY SHIFTS AMONG RED-SQUIRREL, SCIURUS-VULGARIS, FEMALES

In resource-limited systems where territories are defended year-round or during the breeding season, individuals sometimes shift to new terr itories. Here, data on territory establishment and site fidelity in a population of Eurasian red squirrels, in a coniferous woodland, are us ed to test three hypotheses explaining territory shifts: (1) a female actively bequeaths her territory to some of her offspring; (2) an old female leaves her territory to her offspring when her future reproduct ive potential is lower than that of her offspring; (3) a female that i nitially settled on a poor quality territory shifts to a vacant, highe r quality territory. Of 44 adult females, only seven moved from the te rritories on which they first settled to adjacent, vacant territories. Females that shifted did not actively bequeath their territories to t heir offspring. However, females on territories with poor food resourc es were most likely to shift and they shifted only when the new territ ories contained more food than the old ones. After shifting, females i mproved their reproductive rate. These results suggest that territory shifts are adaptive and occur as a response to poor breeding condition s.