On February 6, I received multiple phone calls alerting me to the presence of a frigatebird at Seaside Cove. I hopped into my car and drove to Seaside where I found Jay Withgott (who originally found the bird) and Steve Warner. The bird had just disappeared behind Tillamook Head, but shortly reappeared fairly high up. I got to see it glide north, make a couple banks, allowing decent views through the spotting scope, before it turned, heading south and behind the Head again. It did not reappear again.
The white head tells us this is a sub-adult bird, variously described as a 2nd stage juvenile or 2nd basic in references. There are two Pacific Ocean frigatebirds that look more or less the same at this stage in their life-cycle. I’ve spent the weekend sifting through the arcanery of juvenile frigatebird identification and have settled on MAGNIFICENT FRIGATEBIRD and have produced the following descriptive account (others may disagree with some or all of my conclusions):
Magnificent Frigatebird (Fregata magnificens)
Number of individuals, sex, age, plumage: presumably “basic II” (juvenile 2nd stage in Harrison), based on extent of white in head and breast. Sex probably not assignable.
Locality: Seaside Cove, Seaside, Clatsop Co., OR
Time of Day: 14:15
Reporting observer address: Mike Patterson
Other observers: Originally reported by Jay Withgott, who was still present when I arrived. Also present were Steve Warner, Neal Maine, Dave Hiebert and his wife.
Light conditions: partly cloudy with filtered sun.
Optical equipment: Bushnell Spotting Scope set at 20X
Distance from bird: I only saw the bird from a distance of about 1km, though others who had more time with the bird saw it more closely.
Duration of observation: Less than 5 minutes, though others had considerably longer observational time.
Habitat: Near ocean
Behavior: By the time I arrived, the bird was flying high and taking advantage of vertical lift along the edge of Tillamook Head. I saw the bird soar north briefly then bank around to the south fairly high up. It continued south until it disappeared behind the Head. We did not see it again in spite of continued effort for another 45 minutes.
Description: Overall, large bird with long tapered wings, a long forked tail and a very white head and pale bill. The bird soared and banked without much flapping.
Wings, tail, upper back and lower belly/undertail coverts were all a fairly uniform dark, blackish-brown. From the distance I was observing, no finer detail was visible in these areas.
Head was dull white with no trace of darker feathering visible at the distance I was observing from. The bill was long and pale.
Throat, breast and upper belly were white. The white was restricted to the center and appeared to be cleanly bordered by dark blackish-brown. I was surprised to see so little white in this area or farther down into the lower belly (which was my expectation given the all white head).
Similar Species: The frigatebird group is more or less unmistakable, but within that group, sorting sub-adults can be problematic. For species likely to occur in the North America the extent of white on the head and underwings can be used to eliminate LESSER FRIGATEBIRD.
Eliminating GREAT FRIGATEBIRD is more difficult. Harrison (1985) states in his discussion of Magnificent Frigatebird: “Second-stage juveniles [2nd-cycle] probably indistinguishable from white-headed populations of Great Frigatebird until white tips of axillaries appear.” I did not get views sufficient enough to resolve axillary characters. Howell (1994) does not seem to depend on this single field mark and focuses more on the extent and shape of the white markings on the breast and belly which favors Magnificent Frigatebird. The clean white head without cinnamon tones also favors Magnificent Frigatebird (Peter Pyle pers. comm.) though not all references agree on whether the lack of a cinnamon wash on 2nd-cycle birds eliminates Great Frigatebird.
Previous experience: I have seen Magnificent Frigatebird in Costa Rica and Florida. I have no experience with other frigatebird species.
This account is based on sketches produced immediately after the bird disappeared behind Tillamook Head.
Harrison P. 1985. Seabird: an identification guide. Houghton-Mifflin Co. Boston.
Howell, S.N.G. 1994. A New Look at an Old Problem. Birding. 26(6): 400-415.
Howell, S.N.G., I. Lewington and W. Russell. 2014. Rare Birds of North America. Princeton University Press.
And an extensive search of images on-line.