Petit Manan Island is well known for its seabird inhabitants, most notably our Atlantic Puffins and Arctic Terns. However, a total of eight species of marine birds return yearly to nest on Petit Manan Island. Most of these birds have conspicuous nests, such as the terns and Laughing Gulls which lay their eggs on the ground’s surface. The Alcids, such as Puffins, Black Guillemots, and Razorbills, lay their eggs in burrows or rock crevices, but the adults are still easily observed on the rocks and surrounding waters. But Leach’s Storm-Petrels, the smallest seabird denizen of Petit Manan, are a little bit trickier to detect.
Leach’s Storm-Petrels differ from the other seabirds on PMI in a variety of ways. Taxonomically, they are the only species representing a group of seabirds called the Tubenoses to be found on PMI. Also, they are nocturnal and nest in often long, twisting sod burrows. The burrow entrances are smaller than the size of a fist, and tucked underneath rotting logs, debris and rocks. These life history traits make observing storm-petrels quite the challenge, and prevent accurate estimations of breeding pairs on nesting islands.
This summer we have been testing a new methodology to s
urvey for active storm-petrel burrows. Instead of just reaching as far into each burrow to feel for birds and eggs, we have been playing a recording of storm-petrel vocalizations outside of each potential burrow entrance. The results have been extremely exciting! The birds have been responding with their strange, goblin-giggling call from deep within their burrows. But more importantly, this method has allowed us to find more birds than just by feeling in the burrows. In fact, 63% of the storm-petrels we located only because we heard them – their burrows did not allow us to reach them. Overall, 93% of the adults we located using both methods responded to playback. Hopefully this monitoring technique will provide new insights into Leach’s Storm Petrels nesting on Maine coastal islands!