Methodology: to sample the occurrence and density of winter ANHU in Washington, I gathered their numbers as reported on Christmas Bird Counts (CBC) for the 2009-10 season, just completed. Rather than work from the list of counts mentioned on the W.O.S site or totals reported to National Audubon Society (N.A.S.), both of which were incomplete, I constructed a list of as many counts in WA State as I could find, 49 in all, including counts which straddled the state borders with BC, ID and OR. Ultimately I was unable to locate totals for two of those counts, but it is likely that both were zero. Rather than take data from NAS, much as yet unreported, I contacted count compilers directly, asking only for pure tallies of ANHU with any measures of observer effort excluded. Also requested were the localities of birds recorded in trans-border counts. This also provided a nice opportunity to become familiar with the nature of count circles and previous history of ANHU in certain parts of the state, to me unfamiliar. While slightly inexact, this method has likely produced the best record available of numbers and localities of ANHU in WA. for the period.

In taking the raw numbers as an expression of ANHU occurrence, my assumption was that while there might be some duplication of sightings in urban areas, as birds flew around on their feeder circuits, this would be balanced by observers missing "floaters" at feeders. While nothing in the following totals is necessarily surprising, I believe it is a good representation of the nature of the recent growth in numbers of Annas Hummingbirds locally.

Results: In 21 counts East of the Cascade Crest, only 3 birds were reported, 2 on the Yakima Valley count (which also saw 2 other birds during that week). The Walla Walla count reported one bird, which was not a first count record as I mistakenly stated in an earlier post.In 27 counts West of the Cascade Crest a total of 775 ANHU was reported.

Discussion:The Seattle tally of 337 birds was more than triple the total from last year (107), whereas the Tacoma number of 56 was less than last year's high of 66. Expanding population centers of Kent/Auburn (52), Edmonds (31), Kitsap(39) and Vashon (a healthy 75), produced large tallies of hummingbirds. This all attests to the fact that in mild, lowland areas, perhaps including the maritime influence, high ANHU numbers occured roughly in parallel with the density of the human population and its yards decked out with blooming shrubs and feeders. To illustrate this point, the Satsop count, which match most of those criteria, perhaps does not have a large human population, as the count compiler reported no ANHU. Upland counts west of the crest, potentially much colder and less populated, such as North Cascades and Camas Prairie/ Trout Lake also had no birds. The inclusion of higher elevation habitat in the count circle may also explain why the Eastside count reported only 24 ANHU, compared to the much larger count totals of neighboring lowland Seattle.

A personal observation is that birders in recent years seem to have become more adept at identifying male Annas from their insect-like calls and prominent dive noise. This might support the overall accuracy of these CBC totals, while not explaining the steady increase in total birds observed in the last ten years. While there is no exact evidence in the above data to explain the growth of ANHU numbers, they remind me of the enormous growth of NW/American Crows in recent years. Where we go so do opportunitsic avian species. I would be pleased to have any comments by email, which would enhance or correct this discussion. And thanks to the many compilers, who answered my pleas for information and described the intricacies of their count circles.DH



















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David Hutchinson, Owner
Flora & Fauna: Nature Books
Discovery Gardens: Native Plants
3212 W.Government Way
Seattle,WA.98199
http://www.ffbooks.net/
206-623-4727



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