The 119th CBC in Wyoming

All 20 of Wyoming’s CBCs were conducted for the 119th Christmas Bird Count, and 88,633 birds of 115 species were recorded. The number of species typically ranges from 110 to 133, so CBC-119 was somewhat in the lower end of the spectrum.  

Casper had the highest number of species (65), followed by Story-Big Horn (54), Sheridan (53), and two count circles each with 52 species (Buffalo and Cody).  The lowest number of species (21) was recorded at the Gillette CBC, followed by Guernsey-Fort Laramie (30), and Pinedale and Sundance (each with 33 species).  The greatest number of individual birds was recorded at Casper (16,721), Kane (14,016), Sheridan (5724), and Riverton (5474), while the fewest were recorded at Pinedale (1040), Sundance (1352), Buffalo (1731), and Dubois (1850).  Species with the highest combined counts were European Starling (22,138), Canada Goose (14,108), House Sparrow (8812), Mallard (6089), Rock Pigeon (5100), and Eurasian Collared-Dove (4102).

Unusual species for the state or circle requiring documentation included Short-eared Owl, Vesper Sparrow, and White-throated Sparrow at Cody, Red-breasted Nuthatch, Sandhill Crane, and Woodhouse’s Jay at Evanston, Fox Sparrow at Lander, Lapland Longspur at Riverton, and Cackling Goose at Sheridan. Although not uncommon to get a few individuals in winter, the large numbers of Cackling Geese overwintering, at least during the early winter, was unusual, especially the 600 reported at Cheyenne.

Twenty-two species occurred only on one count, while four species were recorded on all 20 CBC circles, including Bald Eagle, Eurasian Collared-Dove, Black-capped Chickadee, and House Finch.  The early part of the 2018/2019 winter in Wyoming was not very severe, and several species that typically migrate south lingered through the early winter, including Common Loon, Western Grebe, Sandhill Crane, Ring-billed Gull, Marsh Wren, Green-tailed Towhee, and Common Grackle.  Weather was rather mild for those counts conducted early in the count period (mid-December), with high temperatures in the 50s in some locations, while much colder temperatures with lows below 0 degrees greeted CBC participants conducting counts in late December and early January.

Relatively large numbers of Greater Sage-Grouse were observed on the two counts that normally have this species, including 178 at Bates Hole and 176 at Evanston.  An additional 12 were counted at Green River.  Stacey Scott, compiler for the Bates Hole count, had some interesting observations regarding Greater Sage-Grouse. He noted that at both Bates Hole and Evanston, Greater Sage-Grouse occur primarily on rangeland managed by time controlled grazing where cattle are rotated on a regular basis and plants are allowed to recover before being grazed again. At Bates Hole, the last time a sage-grouse was seen during the CBC on rangeland not under a time controlled grazing program was in 2001.  Greater Sage-Grouse at Bates Hole used to be found on several ranches within the count circle, but since 2001 they have been concentrated on the part of the circle controlled by the only two large ranches that follow the time controlled grazing system, with no sage-grouse found on ranches that practice season long grazing. There appeared to be a large contingent of both Bald Eagle and Golden Eagle wintering in the state. Bald Eagles were counted on all 20 circles, with 357 individuals, while Golden Eagles were seen on 19 of the 20 circles, with 167 counted.  These two species have shown opposite trends in Wyoming based on CBC data over the last 20 years, with Bald Eagles increasing and Golden Eagles decreasing, as shown in the graphs below.

By Wyoming standards, the number of participants for the 119th CBC was very high, with 399 participants in the field and 89 feeder watchers statewide.  Jackson Hole had the highest number of participants in the field, with 58, followed by Casper (38) and Sheridan (33). However, kudos also is due to the three participants who managed to cover the Guernsey-Fort Laramie CBC circle.  I would like to thank everyone who participated in the 119th CBC in Wyoming, as well as the compilers and observers for submitting rare bird documentation forms for the unusual birds observed during Wyoming CBCs this year.