Recognition of burrows olfactory signature in blue petrels, Halobaena caerulea: an efficient discrimination mechanism in the dark

Previous work has shown that blue petrels need olfaction to home. We investigated whether they also recognize an olfactory signature of their own nest. We performed T-maze experiments in which maze arms were connected with the subject birdʹs burrow and with the burrow of a conspecific neighbour. Of 23 birds, 16 were able to recognize the arm leading to their own burrow. In a second experiment, we positioned the maze in front of the subjectʹs burrow but the maze arms were closed and did not enter the burrow. Consequently, no burrow odours could be sensed by the bird. In this case, 85% of birds (17 of 20) failed to choose, suggesting that petrels were not motivated to choose by positional cues in the absence of odour cues. We explored this idea further by performing a homing experiment whereby homing birds had to relocate an artificially displaced burrow entrance. Blue petrels homed, ignoring the natural burrow entrance and using the new artificial one. The ability to smell their own burrow allows blue petrels to return to the colony at night and to find the correct nest.