Macgillivray warbler photographed in the headquarters area. From a Kodachrome by Ranger-Naturalist Ralph Welles and Florence Welles.

The summer of 1952, by contrast with 1951, was unusual because of the prolonged persistence of the snow and a consequently much delayed season. Although causal relations must be assumed with the greatest of caution and with much more investigation than has been possible, it is nevertheless interesting to note certain differences between the two seasons.

Several species whose upward altitudinal limits fluctuate substantially were greatly reduced or entirely absent from elevations above 6000 feet in contrast to last summer when the snow melted early. Included in this group are the Lazuli Bunting, Passerina amoena (Say); Fox Sparrow, Passerella iliaca (Merrem); and Western Wood Pewee, Contopus richardsonii (Swainson). Also conspicuously absent at higher elevations were Turkey Vultures, Cathartes aura (Linnaeus).

Perhaps the most spectacular change in the avifauna from last summer was the conspicuous decline in numbers of Red Crossbills, Loxia curvirostra Linnaeus. During the summer of 1952 I saw about 0.9 crossbills per hour in the field compared to 5.5 per hour in 1951. During 1952 they were only in restless flocks whereas in 1951 singing males were observed commonly. Also in 1951 groups feeding in cones or "mineral pecking" could be observed from small distances. Pine Siskins, Spinus pinus (Wilson), however, continue to be common this summer. Huge flocks of several hundred individuals were observed frequently in the Headquarters Area during late July and early August.

It is of interest, to note further, that there was a conspicuous reduction in the numbers of Rosy Finches, Leucosticte tephrocotis (Swainson). This has been particularly noticeable on Dutton Ridge where they were very abundant during the summer of 1951.

There was also a reduction in the density of breeding Lincoln Sparrows, Melospiza lincolnii (Audubon), in the higher montane meadows. The study area in the upper Munson Meadow which I have had under observation for several summers had only two, possibly three, breeding pairs compared to the usual five or six. Although I do not have quantitative data, a similar reduction appears to have occurred in other high-elevation meadows. It seems quite likely that the persistence of the snow in these areas may have been responsible. It should be noted also that there has been a noticeable reduction in the numbers of Dippers, Cinclus mexicanus Swainson, appearing in the upper portions of the streams in mid-summer. Whether this represents a reduction in population or a restrictive effect of the snow on the normal mid-summer migration to higher elevations is not clear.

Despite the fact that there was a severe reduction in the cone crop on the whitebark pine, ponderosa pine, and firs, compared with 1951, there was, during the summer of 1952, a marked increase in Clark's Nutcrackers, Nucifraga columbiana (Wilson). This is noticeable throughout the high country as well as at the Rim Village, although more pronounced at the latter. It is of interest to note that we saw a considerable number of color-banded individuals which were banded during the summer of 1950 but which failed to reappear during the summer of 1951. The movements of this species continue to be enigmatic! There was also a remarkable increase in the number of Ravens, Corvus corax Linnaeus, observed. At least three small flocks, probably family groups, were observed repeatedly. These were commonly seen in the vicinity of Park Headquarters, Rim Village, and the Watchman, respectively.

Also of interest were the substantially greater recorded numbers of Booming Nighthawks, Chordeiles minor (Forster). Mr. and Mrs. Jack D. Lee reported observing them nightly at Lost Creek in Pinnacle Valley. I confirmed this on three occasions. They were apparently similarly common in the Panhandle. I also observed nighthawks at Arant Point on July 8 and above Castle Creek Canyon (5800 ft.) on August 5.

Several important observations were obtained on swallows. On July 28, I saw three Cliff Swallows, Petrochelidon pyrrhonota (Vieillot), within the Crater wall near Garfield Peak. This is the second record for the Park. On August 2, Ranger-naturalist C. F. Yocom and I saw two Rough-winged Swallows along the Garfield Peak Trail. These are the first records for the Park since 1937 and the first for the Lake area. On July 19 I found a nest of Violet Green Swallows, Tachycineta thalassina (Swainson), in a cavity in one of the Wheeler Creek Pinnacles. This is the first breeding record for the Park.

Despite the heavy snow, the population reproductive activity, and upward migration of Blue Grouse, Dendragapus obscurus (Say), was quite normal.

References

Farner, Donald S. 1951. Ornithological notes of interest. Crater Lake Nature Notes, 17:16-18.

Farner, Donald S. 1951. The Red Crossbill irruption of 1951. Crater Lake Nature Notes, 17:19.

Farner, Donald S. 1952. The Birds of Crater Lake National Park. University of Kansas Press, ix-200 pp.