Daily accumulation of body reserves under increased predation risk in captive Greenfinches Carduelis chloris

The effect of increased perceived risk of predation on the trajectory descr ibing the daily gain in body mass of captive Greenfinches Carduelis chloris was tested. Theoretically, increased risk of predation is expected to shif t the gain in body mass towards the latter part of the day and reduce body mass. The perceived risk of predation was increased with a stuffed flying h awk three times per day. Following each presentation of the predator, forag ing stopped and the birds lost mass. When feeding resumed, the birds compen sated for the mass loss by increasing the rate of body mass gain, in line w ith theoretical predictions. In the presence of the predator, the daily acc umulation of body reserves was lower compared with risk-free situations. Ho wever, on the days following presentation of the hawk, when the birds were presumably aware of an increased risk of predation, Greenfinches did not ex hibit the predicted change in reserve accumulation, but rather maintained t heir usual pattern of body mass gain.