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Galapagos Shearwaters Killed by Man-o'-war Birds

Ronald W. Smith

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While collecting in the Galapagos Archipelago for the Academy of Natural Sciences of Philadelphia, in February of 1937, the following observations of man-o’-war birds and shearwaters were made at Tower Island. On the morning of February 18, 1937, while at anchor close to the beach in Darwin Bay, violent squalls and torrential rains raged intermittently. The nearness of our schooner to the beach and the stormy weather seemed to cause the greater part of the large colony of Ridgway Man-o’-war Birds (Fregata minor ridgwayi) and Red-footed Boobies (Sula sula), which were nesting in the low bushes at the head of the bay, to mill about in the lee of our boat.

Numerous Galapagos Shearwaters (Puffinus lhermineri subalaris) were skimming about and plunging into the roughened water at this time. When a shearwater dove near the soaring man-o’-war birds, several of the latter dropped near the surface of the water and seized it when it reappeared at the surface. The struggling shearwater was carried some twenty feet in the air and then tossed from one man-o’-war to another. After a few minutes it was dropped to the water from where it was immediately retrieved, fluttering feebly, and again tossed about in the air until it appeared nearly dead. At the end of about ten minutes of “playing” with the shearwater, it was again dropped into the water. Thereupon a number of other man-o’-wars which had not taken any part in the preceding fray swooped down at the apparently lifeless form floating on the surface, but they made no attempt to seize it.

At least four shearwarters were thus beaten to death within an hour, after which the gales diminished and we left for other parts of the island.

In the course of other observations on man-o’-war birds, in various places in the Galapagos Islands and eastern Polynesia, the bullying of boobies and terns frequently was seen, but in no instance were there attacks so severe as those noted on the shearwaters at Tower Island.

Museum of Vertebrate Zoology, University of CaIifomia, Berkeley, California, July 10, 1939

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