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June 2021

Vol. 49, No. 3

Field Notes: Bathing by Double-crested Cormorants

William E. Davis, Jr.


Figure 1
. (left). A bathing cormorant beat its wings furiously in the water. Figure 2. (right). This bathing cormorant flapped its wings until the head and upper body were clear of the water.

For all of March and most of April 2020, I was situated in an oceanfront house on Big Pine Key in Florida, where I had ample opportunity to watch and photograph Double-crested Cormorants (Phalacrocorax auritus) on the tidal flats, in shallow and deep water, and on our long dock. I recorded their behavior in my journal. The comments on Double-crested Cormorants bathing that follow are taken from my journal notes.

Double-crested Cormorants Bathe

On March 26 at 6:02 pm, I noticed a commotion out in the deeper water beyond the dock and found that a Double-crested Cormorant was bathing. With its body half-submerged, it ducked its head under water and rapidly flapped its wings, creating a substantial disturbance to the surrounding water. The bathing bout lasted 2–3 seconds and was repeated multiple times. The initial phase of bathing, submerging the head, looked very similar to the shallow-water foraging behavior that I had been watching closely (Davis 2021). A second cormorant surfaced about 20 feet from the bathing bird and began to bathe as well. Two days later at 6:34 pm, a cormorant was bathing out beyond the dock, putting its head completely under water and then flapping furiously with both wings. It repeated this bathing bout every few-to-10 seconds. A second cormorant swam in close to the first bird and did the head submerging routine. The first cormorant flew off and the second cormorant proceeded to flap its wings and do the normal bathing routine. The first cormorant returned and then both flew off and alit on rocks exposed by low tide at the water’s edge. The two birds faced into the wind and repeatedly flapped their wings and fluffed their feathers while remaining perched. At 7:08 pm, I saw another cormorant bathing in the same area. The following day at 6:10 pm, I saw a cormorant bathing out beyond the dock, with 2–3 second bouts of splashing followed by up to 10-second intervals between bouts.

On April 5 at 5:12 pm, I saw another bathing cormorant by the end of the dock and was able to photograph it as it bathed, beating its wings furiously in the water (Figure 1). On April 8 at 4:38 pm, a cormorant looked like it was shallow-water foraging, dipping its head under water, but it quickly burst into a frenzy of wing beating and shaking, bathing. After several bouts of bathing, it leapt ashore, opened its wings, and began preening. At 4:59 pm, another cormorant bathed, dipping its head under water followed by wildly flapping wings that caused the head and front part of the body to rise out of the water (Figure 2). At 5:04 pm, it flew to shore, joining other cormorants, flapped its wings, shook its tail from side to side, and shook its head before beginning to preen. At 5:28 pm, a cormorant bathed, bringing its head and the front of its body out of the water as the result of the wing-flapping. It sometimes flapped its wings with its head under water. It had been quite a cormorant show with lots of data recorded. On April 10 at 12:12 pm, I watched a cormorant bathing near the end of the dock. It was the earliest time of day that I had seen a cormorant bathe. Of the 12 cormorants that I observed bathing, 11 were seen after 3:00 pm, suggesting that bathing in cormorants is generally a late afternoon behavior. On two occasions, two cormorants bathed together or one immediately after the other, suggesting a tendency towards group bathing behavior.

The Double-crested Cormorant account in Birds of the World (Dorr et al. 2020) describes the bathing procedures, quoting Van Tets 1959, but does not describe any tendency towards group bathing.

Conclusions

I conclude: bathing is common in Double-crested Cormorants; the tendency towards group bathing exists and watching other birds bathe is an incentive to bathe; cormorant bathing is primarily an afternoon or end-of-day phenomenon; and, as with bathing shorebirds, gulls, and terns, preening normally follows bathing and can be considered a stage in the bathing process.

Literature Cited

  • Davis, W. E., Jr. 2021. Shallow-water Foraging Behavior by Double-crested Cormorants. Bird Observer 49:60–61.
  • Dorr, B. S., J. J. Hatch, and D. V. Weseloh. 2020. Double-crested Cormorant (Phalacrocorax auritus), Version 1.0. In Birds of the World (A. F. Poole, ed.). Cornell Lab of Ornithology, Ithaca, New York. https://doi.org/10.2173/bow.doccor.01
  • Van Tets, G. F. 1959. A comparative study of the reproductive behavior and natural history of three sympatric cormorants (Phalacrocorax auritus, P. penicillatus, & P. pelagicus) at Mandarte Island. B.C. Master’s Thesis, University of British Columbia, Vancouver. Online: https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0106056 Accessed April 6, 2021.

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