Printed in 1989 Oregon Birds 15(3):198-200.
Although the inhibiting effects of a solar eclipse on bird singing has been fairly well demonstrated (Kellogg and Hutchinson 1964, Fox 1966, Elliott and Elliott 1974, Morgan 1982), the change in waterbird behavior during a solar eclipse has received only limited attention (Kellogg and Hutchinson 1964:190, DuMont 1970).
On 26 February 1979, local newspapers predicted that a total solar eclipse would occur at 0812 Pacific Standard Time (PST) and last about 49 seconds at Newport and Yaquina Estuary (Schleyer 1979). I arrived at the area west of the Highway 101 bridge near the mouth of Yaquina Estuary at 0745 PST and planned to make detailed observations of waterbirds during the eclipse. I had a good view of the area designated as the Estuary Mouth in Bayer (1983:Fig. 1), including the largest rock groin (about 400 m west of the bridge) that ran from the shore to near the middle of the Yaquina channel. A low tide +0.6 m above Mean Lower Low Water occurred at 0554 PST; during the eclipse, the sky was mostly cloudy with a wind of 15-25 mph.
I planned to leave a portable cassette tape recorder running before, during, and after the eclipse to determine differences in bird vocalizations (see Kellogg and Hutchinson 1964). Unfortunately, this did not work because it was too windy and there was occasional rain, which masked the sound of vocalizing birds on the tape recorder. Thus, I could only use the tape recorder to record my observations during the eclipse.
There was a low diversity of birds in this area before and during the eclipse. There were only Black Turnstones, "large" gulls (predominately Western and Western x Glaucous-winged Gull hybrids, but there may also have been some Glaucous-winged, Herring, and Thayer's Gulls), White-winged and Surf Scoters, Brandt's Cormorants, and unidentified cormorants that were Brandt's, Pelagic, or Double-crested Cormorants. No predators of birds were noted before, during, or after the eclipse to influence the behavior of the birds.
I found that as the sky grew darker at 0809 that Black Turnstones flew away from the rocks on the large rock groin where they had been feeding. By 0812 PST at the time of the total eclipse, gulls and scoters also flew away from the shore, and many gulls also flew away from the rock groin on which they had been resting. Most cormorants that had also been resting on the rock groin flew away and landed in the middle of the channel, but 2 Brandt's Cormorants remained on the rock groin. Then hundreds of gulls began flying over the middle of the channel. Many of the gulls were giving alarm calls, which they had not been doing previously.
By 0813 PST, it was noticeably brighter, and the gulls were now vocalizing infrequently. At 0815, there were still two large nonfeeding flocks (i.e., roosting rafts) of cormorants, gulls, and scoters floating in the middle of the channel. At 0815:30, Black Turnstones flew back to the rock groin where they had been previously foraging and began feeding again. At 0815:45, 5 "large" gulls flew back to the rock groin and landed. At 0815:50, several hundred gulls were again flying for no apparent reason (i.e., no predator was present and there was no source of human disturbance); evidently the gulls were "nervous." Some scoters now swam toward the shore and began diving as they normally did while foraging. At 0818, several cormorants landed on the rock groin, but there were still many cormorants, gulls, and scoters in two roosting rafts in the middle of the channel. At 0820, most gulls and the scoters were flying or swimming closer to shore. At 0823, the roosting rafts had completely broken up, and bird activity had appeared to return to normal.
In conclusion, waterbird behavior changed during the short eclipse at the Yaquina. Birds that had been feeding, stopped. Many flew to the middle of the channel where they formed roosting rafts, and many gulls flew over the mid-channel giving alarm calls and appeared disoriented. Since these birds would behave similarly if they were suddenly disturbed by humans or predators, I would typify these waterbirds as being "disturbed" and "confused." Elsewhere, Dumont (1970) similarly reported that gulls, ducks, and shorebirds during a 120 second total eclipse at Chesapeake Bay also acted frightened and disoriented, but the gulls he observed did not vocalize.
I am grateful to Judy Sprauer and Marilyn Guin of the Hatfield Marine Science Center Library at Newport for kindly obtaining copies of some of the references.
Bayer, R. D. 1983. Seasonal occurrences of ten waterbird species at Yaquina Estuary, Oregon. Murrelet 64:78-86. DuMont, P. G. 1970. Notes during sun eclipse at mouth of Chesapeake Bay. Atlantic Naturalist 25:88-89. Elliott, J. A. and G. H. Elliott. 1974. Observations on bird singing during a solar eclipse. Canadian Field-Naturalist 88:213-217. Fox, G. A. 1966. Observations of the effect of a solar eclipse on bird activities. Blue Jay 24:87-88. Kellogg, P. P. and C. M. Hutchinson. 1964. The solar eclipse and bird song. Living Bird 3:185-193. Morgan, J. P. 1982. Response of birds to an eclipse of the sun. Blue Jay 40:82-89. Schleyer, R. J. 1979. On Monday, dusk will come as you're starting day. Corvallis Gazette-Times, Feb. 24, p. 16, col. 1.