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Barnacles on Birds

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On the morning of August 7, 1938, about 15 miles south of the Farallon Islands, off San Francisco Bay, California, the writer collected two female Pacific Fulnars (Fulmarus glacialis rodgersii). The birds were shot on the wing while circling the Allan Hancock Foundation cruiser, Velcro III, as she lay hove-to, dredging for marine life. After a bit of unique maneuvering of the Velcro by Captain Hancock, the birds were picked up and immediately inspected for ectoparasites by the staff parasitologist, Gus Augustson. A peculiar condition of the belly became apparent. Small clusters of young peduncled barnacles of the genus Lepas were attached to the outer barbs of the belly feathers. There were several dozen clusters, each composed of three or four individuals of different sizes, with a few solitary individuals between. This illustrates the gregarious instinct of the free-swimming larva at the time of attachment.

Upon returning to the laboratory with several of the barnacles preserved in alcohol, the specific identity of the cirriped was established as Lepas hillii Leack, a species that is distinguished with difficulty from the cosmopolitan goose-necked barnacle (Leper anatifera Linnaeus) . The smallest specimens were barely distinguishable as to species, but the larger ones had well-calcified capitular valves and distinct peduncles. One specimen had a capitulum 3.0 mm. long with a peduncular length of 1.1 mm.

We can look upon this condition as accidental and occurring only during a period of the year when the fulmars are consistently roosting on the water. Certain species of littoral se&e barnacles are able to withstand considerable desiccation between the tides, but members of the genus Lepas regularly attach themselves to floating materials or permanently submerged objects, as described in Hoek’s report on the cirripedia of the Challenger Expedition (Challenger Reports, Zoology, vol. 8, 1883). Thus we must assume that in order for these barnacles to have developed to the aforementioned size, the fulmars must have been on the water most of the time.

Accounts of barnacles on birds seem to be rather scarce in the literature; at least, the writer has found it so in the reports on cirripedians. However, I might quote from Hoek’s review of the literature the following (op. cit., p. 7) : “A new genus (Ornitholepas) was proposed (1874) by TargioniTozzetti for a species of Cirripedia inhabiting the tail feathers of Priofinus cineveus, a bird of the Southern Atlantic and the Indian Ocean. Gerstaker supposes that the Ornitkolepas australis, TargioniTozzetti, is only a larva of a Cirriped in its Cypris-stage.”

Since this observation the writer has had opportunity to collect a considerable number of oceanic birds, some of which were confined to the surface by molting primaries, but no other occurrence of barnacles on the feathers has been noted.

Allan Hancock Foundation, University of Southern California,, April 8, 1940

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