Monday, January 20, 2014

The 42nd Tucson Valley CBC Summary

Harris's Hawk – A declining species in Tucson?

This was a Christmas Bird Count to remember. A record number of 164 species – tying what seems to be the all-time state high – was well beyond expectations while at the same time setting higher bar that’s clearly attainable in future years.

As it was my second year as compiler, doing my best to recruit observers as much as possible, the showing of 103 participants (98 in the field and five feeder watchers) was a bit below last year’s 117, even if well above the long-term average and miles ahead of any other Arizona CBC. It looked like many CBCs had fewer participants than normal this year, but you wouldn’t know from our species total that we had fewer than last year. So just imagine what the potential is, given maybe 10-15 more skilled birders, 20 more pairs of eyes of any skill level, and another 20-30 feeder watchers, where surely some oddities are going unreported. I do expect that we’ll have more and more in future years, and all participants are welcome to help in future recruiting efforts.

Species seen within three days either side of the CBC day were: a fly-by Neotropic Cormorant photographed a couple days before the count (their numbers begin to increase only in early January), Violet-crowned Hummingbird (at the Birky feeder up until 3 days before the CBC), Yellow-bellied Sapsucker, Cassin’s Vireo, Western Tanager (a new species for the master list, along the Santa Cruz River), Swamp Sparrow, and American Goldfinch. Seen just one day before count-week began was a Gray Flycatcher, and a few rarities found well before and after the count may have also been in the circle on count day, including Eastern Phoebe, Northern Parula, Black-and-white Warbler, Harris’s Sparrow, and Dickcissel. And let's not forget what must the most difficult bird to detect that is most certainly in the circle every year: Common Poorwill. That species is known to hibernate, apparently doesn't become active until late January, and there are only 3 CBC records out of the past 42 years. Most years we don't even try, but this year I was up at Finger Rock Canyon shortly after midnight at the start of the day, and after the countdown Larry Liese drove up Tumamoc Hill for another attempt. We'll keep trying for that one in future years. Combine more observers with a good year for northern things that we missed but show up from time-to-time (Common Goldeneye, Lark Bunting, Snow and Canada Goose, Pine Siskin, Red Crossbill, Cassin’s Finch), and it’s clear that 170 or more is a distinctive possibility for this rich CBC circle.

We had several staked-out rarities, some of which were local “megas” – first count-records of Red-shouldered Hawk, Louisiana Waterthrush, and Black Scoter top the list, the latter being the most unexpected from a historical perspective (but present since November 22 and seen by dozens of birders, so not a surprise on count day). The others were three Greater White-fronted Geese at Arthur Pack Golf Course, a Broad-tailed Hummingbird returning for a 3rd year to a West University private yard (and a second in the Catalina Foothills), Lewis’s Woodpecker at Reid Park, Greater Pewee at Evergreen Cemetery, Cassin’s Kingbird at Reid Park (plus a surprise bird in the NE section of the circle), Yellow Warbler (one on the lower Santa Cruz and one at Fort Lowell Park), Townsend’s Warbler (one staked out at Winterhaven a couple days before the CBC), Wilson’s Warbler (the Roger Road WRF stakeout supplemented by a good find in the El Encanto neighborhood), Summer Tanager (only one at Reid Park a poor showing after last year’s record number), and a Bullock’s Oriole (one adult male returning to a feeder in Oro Valley, with details provided by supplemental birders).

Surprises help make the CBC such a fun event. The award for most unexpected rarity goes to the Palm Warbler that appeared just upstream from the Roger Road WRF, and what makes it even more surprising is that it was seen flying off (after good views and even a photo by several very good observers), never to be seen again. Slightly less astounding but still exciting rarities were: two Ring-billed Gulls (one seen by the same team as the Palm Warbler, and another flying along the dry Rillito River several miles upstream – and described to be of a different plumage, so clearly a second individual); a bright male Pine Warbler at the Tucson Country Club golf course (the dull stake-out female was missed at Reid Park, despite being seen the day before and after the CBC – missed not only by the team covering that area but also by many other birders who were coincidentally looking for it that same day); a Magnificent Hummingbird at a feeder near Ventana Canyon; an Empidonax flycatcher on the Pusch Peak Trail; a Barn Swallow at the Silverbell recharge basins; and single Mountain Bluebirds at Reid Park and Evergreen Cemetery. Three other notable species are rare birds for our circle because they occur occasionally only at the very highest elevations where there are bits of habitat which have not been covered well since the 1970’s: Steller’s Jay, Juniper Titmouse, and Townsend’s Solitaire. So many thanks go to Scott and John who made the hike all the way up to Mount Kimball, an elevation change equivalent to hiking to the bottom of the Grand Canyon and back.

We had new or tied record high counts for ten species. Some of these might represent just an odd year, where concentrations just happened to cross paths with CBC counters or reflect what was just a good breeding season farther north, such as American Wigeon, Hooded Merganser, Great Egret, Sharp-shinned Hawk, and Marsh Wren. Who knows why we tallied so many Common Ravens, but the ones here are not known to migrate, nor has anyone commented on a growing population. Not so with Eurasian Collared-Dove, which has been increasing greatly since the first arrived here just a few years ago; Broad-billed Hummingbird which continues to increase year after year; and Vermilion Flycatcher, whose rocketing population is a mystery and a delight. The tied number of four Virginia Rails will surely be outdone in the future, as we discovered the potential of Sweetwater Wetlands by visiting it at night after the countdown; when we had tallied none during the day, a late-night bike ride by the compiler to add just one more species to the count showed that they were much more responsive to playback after dark, as were the Soras. We had historically high counts of another 36 species (ranking among the top five in the past 42 years), but many, if not all of these merely reflect the large number of observers we had this year.

Low counts were notable among many species, representing more noticeable long- and short-term trends than most of the high count species. Those species with possibly meaningless low numbers (perhaps a poor breeding season farther north just this year, or a movable winter population that occurred somewhere outside our CBC circle) were Redhead (the odd one out, as almost all other waterfowl species had higher than usual counts), Least Sandpiper, Brewer’s Sparrow, Brewer’s Blackbird, and Brown-headed Cowbird. But the non-migratory species we should be keeping an eye on for their low numbers are Harris’s Hawk, Inca Dove (whose population has crashed inexplicably in the past 15 years), Gilded Flicker, Loggerhead Shrike, Cactus Wren, Crissal Thrasher (a difficult species to detect in any event, a real decline for this one is hard to confirm), Canyon Towhee, and Black-throated Sparrow.

Thank you everyone for helping to make this such a great and meaningful CBC.

The 2014 Tucson Valley Christmas Bird Count will be held on Sunday, December 14.

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