The 116th CBC in Wyoming

This is my first year as Regional Editor for Wyoming, and I thank Keith Evans for being editor for Wyoming and Utah the last 17 years!  Nineteen CBCs were conducted in Wyoming for the 116th Christmas Bird Count, and 103,423 birds of 111 species were recorded. The number of species typically ranges from 110 to 133, so CBC-116 was on the lower end of the spectrum.  Weather was fairly typical for the 116th count. Although most standing water was frozen, open water was present on most rivers and streams. Unlike the past two years, Wyoming did not experience any “polar vortexes” of 20 below temperatures in the weeks prior to the count.

Cody had the highest number of species (66), followed by Kane and Jackson, each with 60 species.  The greatest number of individual birds was recorded at Kane (22,592), although over 16,000 of these were European Starlings.  Casper (11,506) and Riverton (10,377) were the only other counts with over 10,000 birds.  Species with the highest combined counts included European Starling (31,249), House Sparrow (9603), Canada Goose (8820), Mallard (7018), and Eurasian Collared-Dove (5887).  Eurasian Collared-Doves were first documented in Wyoming in 1998 but now outnumber Rock Pigeons (4147 individuals on the 116th count) in the winter.

Likely the most unusual bird recorded was a Swamp Sparrow in Dubois.  Another Swamp Sparrow was recorded during count week in Laramie; otherwise no extraordinary species were observed in the state. Several species that typically migrate south lingered through the early winter.  The most noteworthy of these were Western and Pied-billed grebes, Virginia Rail, Sandhill Crane, Marsh Wren, Gray Catbird, Hermit Thrush, and Common Grackle. Mountain Bluebirds also remained through the early winter, occurring on five counts.  Seventeen species occurred only on one count, while seven species were recorded in all 19 CBC circles, including Mallard, Rough-legged Hawk, Eurasian Collared-Dove, European Starling, American Tree Sparrow, House Finch, and House Sparrow.

There has been some discussion on the apparent declining numbers of Golden Eagles on the Wyobirds list serve recently, which apparently has some merit based on CBC data. The number of Golden Eagles recorded during CBCs has shown a steady downward trend over the last 20 years, from an average of nearly 0.3 per party-hour in1997 to about 0.17/party-hour in 2015.

Upland gamebirds made notable appearances this year, with seven species recorded, including first records of Gray Partridge on the Crowheart CBC and a pair of Sharp-tailed Grouse photographed on a house’s front lawn in north Cheyenne. The status of Greater Sage-Grouse is of conservation concern.  This species was counted only on the Bates Hole CBC, with 138 birds. Over the last 20 years Greater Sage-Grouse have been observed on two to seven Wyoming CBCs. The number of Greater Sage-Grouse counted per party-hour increased from around 0.25 in 1997 to a high of around 0.75 in 2010, but decreased to around 0.15 in 2015.  

One statistic I found to be rather sobering was the number of exotic birds counted. Of the 103,423 individual birds tallied on CBCs in Wyoming this year, over half (50.5% to be exact) were introduced exotics! Upland gamebirds including Ring-necked Pheasant, Chukar, and Gray Partridge accounted for a small fraction of these (1.3%). Four species (Rock Pigeon, Eurasian Collared-Dove, European Starling, and House Sparrow) composed 49.2% of all of the birds tallied, although the 16,284 European Starlings counted on the Kane circle composed almost 1/3 of this total.  This was very surprising to me, as outside of Alaska, Wyoming is certainly the most rural state in the U.S., yet over half of the birds counted during the CBC are not native! There are certainly some biases with the CBC, as the vast majority of them are centered on towns, where exotics are much more common, but I was still surprised that exotic birds are such a major component of the avifauna, especially in a sparsely populated state like Wyoming.

I would like to give a big shout out to the Jackson and Cody CBCs, who had 52 and 49 field observers, respectively! I would also like to thank the compilers and observers for submitting photos and rare bird documentation forms for the unusual birds observed on Wyoming CBCs this year.