PATTERNS OF ACTIVITY AND BURROW ATTENDANCE IN CORYS SHEARWATER CALONECTRIS-DIOMEDEA AS REVEALED BY A NOVEL LOGGING TECHNIQUE

We monitored the attendance and activity of Gory's Shearwater Calonect ris diomedea on Berlenga Island, Portugal, during the breeding season. To achieve this, we developed a novel logging technique to record the date and time of entrances and departures from the burrows, as well a s the identity of each member of a pair, The technique enabled nonintr usive assessment of the activity of burrow-nesting animals over prolon ged periods and provided very reliable information. Our study showed t hat males attended the nests more frequently than females during the p re-laying and chick-rearing periods, We did not find such differences during the incubation period, and both members spent similar amounts o f time incubating the eggs, An index of activity (defined as number of entrances plus exits from the nest) achieved higher scores during the pre-laying and incubation periods, but the activity decreased signifi cantly during the chick-rearing period. We did not find any effect of moonlight on the levels of activity, hour of arrival at the colony or time spent inside the burrows in breeding birds.