Monday, March 2, 2015

The 2014 Tucson Valley CBC in Review

Our 12 Cassin's Vireos broke an eleven-year-old record national high count.
If you missed the Tucson Valley CBC this past December 14, or if you did participate and missed the countdown and potluck, you missed an exciting time. At the end of the initial reading down the main species list, we still had no idea how many species had been tallied, as there seemed to be plenty of misses – silences when I called out expected species. But then we went group by group and heard of some amazing finds, and it seemed we might have a pretty good species total after all. By the end of the countdown, the total came to an amazing 165 species. The previous high for Arizona was 164, which was set only two years ago by Green Valley, and which we tied just last year. Then when entering the data into a spreadsheet I discovered a Canada Goose that hadn't been noticed during the countdown. 166 species was our official tally.

To see what's possible in the future I'll go over our misses.

Crissal Thrasher, present in very small numbers only in a few spots, and sometimes hopelessly secretive, was missed for only the 3rd time. Redhead was missed for only the 4th time and was especially painful as two were at Reid Park the night before the count (and not reported there again until 11 days later). Common Merganser is a rare bird here, but it was a bit frustrating when one was found at Sweetwater Wetlands three days after the count. Also a frustrating miss was Swamp Sparrow, as our single staked-out bird was findable the day before and again two days after the count, but it wouldn't cooperate on count day. A similar miss was the Bullock's Oriole at a feeder in the NW which was back for its fourth year but disappeared just a couple days before the count. A Magnificent Hummingbird at the Ventana Canyon trailhead had been present just a few days before the count as well. Other species we missed that have been seen on more than half of the counts since 1971 are Eastern Meadowlark, Long-billed Dowitcher, Acorn Woodpecker, and Barn Owl. Black-necked Stilt was a big miss, only the second time in the past 16 years.

In any event it's clear that 170 species is certainly a possibility – maybe even 175 or more. But to do that we'd have to get all those expected species, no misses of anything seen on more than half the counts, as well as find a bunch of unusual birds. But to get even 166, we had a lot of unusual species.

Most unusual were three species new for the all-time list: Baltimore Oriole (found in November and still around today, but wandering widely); Virginia's Warbler (on the lower Santa Cruz River), and Bell's Vireo (in Pima Canyon). Nearly rare and found for only the second time were Red-breasted Sapsucker (the continuing bird at McCormick Park), Hammond's Flycatcher (in Pima Canyon, and though common south of here we just don't have much habitat for it), and Louisiana Waterthrush (probably a returning bird for its second year on the Santa Cruz River). Species with only two previous CBC records were American Avocet, Hairy Woodpecker, Pine Warbler, and Tree Swallow; those with three previous records were Common Poorwill, Lucy's Warbler, Yellow-bellied Sapsucker; and those with four previous records were Clay-colored Sparrow and Lazuli Bunting. What is most amazing about these latter two is that, as expected with birds this rare, we had only ever recorded just one individual in those previous years; this time we had seven of the former and ten of the latter.

A final note regarding rarities, here is a simple list of the 18 species seen on fewer than a third of historic CBCs and therefore not a slam-dunk in the future and commendable finds: Double-crested Cormorant, Snowy Egret, Lewis's Woodpecker, Northern Beardless-Tyrannulet, Ash-throated Flycatcher, Cassin's Kingbird, Steller's Jay, Barn Swallow, Red-breasted Nuthatch, Brown Creeper, Eastern Bluebird, Northern Parula, Yellow Warbler, Townsend's Warbler, Black-and-white Warbler, Wilson's Warbler, Summer Tanager, White-throated Sparrow, and Red Crossbill. Virginia Rail also statistically ranks in this category, except that almost all the years it was missed date to pre-Sweetwater Wetlands time; we've missed it only four times since 1998. Eurasian Collared-Dove has been seen on only seven previous counts, but that's another story that we're all quite familiar with. Neither of these two species can be counted as rarities, and we can expect them in the future.

Now for some interesting numbers. We broke our own previous high counts for 27 species, tying quite a few more, mostly rarities. Of special note are five species for which we usually hold the national high count each year, but by topping our own previous high we also set a new all-time national high. There are only about 30-40 species which have their all-time highs broken each year, scattered among hundreds of circles, so for our one circle to claim five of those is quite amazing. They were (with the previous national high with count name and year in parentheses):

Cooper's Hawk 136 (104, Tucson Valley 2012)
Broad-billed Hummingbird 59 (40, Santa Catalina Mountains 2011)
Vermilion Flycatcher 384 (267, Tucson Valley 2013)
Cassin's Vireo 12 (10, San Diego 2003)
Verdin 877 (797, Tucson Valley 2012)

It's worth mentioning that we tied 19 Plumbeous Vireos, the all-time high for which we set in 2012.

Speaking of national highs, each year Tucson Valley regularly ranks among the top ten counts in the country for the number of species with the annual high, often for about ten species. In addition to the six all-time records above, barring any dark horses, we had the national high count for another nine species: Rock Pigeon, Mourning Dove, Gila Woodpecker, Black-throated Gray Warbler, Louisiana Waterthrush (our single bird tied with at least three other counts), Summer Tanager, Yellow-headed Blackbird, Lesser Goldfinch, and House Finch. Fifteen national highs would rank us in the top three or four, with the the usual top contenders being Matagorda County-Mad Island Marsh, Texas and our own Atascosa Highlands.

We topped several of our own high counts. Seven of our own record highs were of rare birds for which we just saw a few more, except for the already-mentioned surprises of Lazuli Bunting and Clay-colored Sparrow. The others were (our previous high in parentheses):

Yellow-bellied Sapsucker 2 (1)
Gray Flycatcher 3 (2)
Tree Swallow 4 (1)
Townsend's Warbler 4 (1)
Pine Warbler 2 (1)
Wilson's Warbler 3 (2)

Other species were counted in record numbers for all sorts of reasons. They were:

Anna's Hummingbird 408 (357)
Costa's Hummingbird 56 (52)
Ladder-backed Woodpecker 84 (81)
Red-breasted Nuthatch 27 (8)
Black-throated Gray Warbler 29 (12)
Abert's Towhee 461 (397)
Yellow-headed Blackbird 19055 (13600)
Lesser Goldfinch 2486 (1739)

In the case of Ladder-backed Woodpecker, barely topping our old record, having a lot observers in the field seems to be an obvious factor. But it was clear already in early November that there were a lot of Black-throated Gray Warblers around. Abert's Towhees have been increasing into urban Tucson in past years, so that wasn't a surprise. It was an invasion year for Red-breasted Nuthatches with strays being seen already in September, but having a team hike up to Mount Kimball helped boost those numbers.

Finally, it's worth mentioning a few species for which we recorded fewer than normal numbers. Each one could be the topic of an extensive discussion, with many theories that would need to be examined in detail. In each case there may be multiple causes, with the effect being local or regional, temporary or long-term, random or meaningful. But the ones that repeat from last year are in boldface below. I thought I should mention that this is our lowest count ever for Inca Dove, and there seems the distinct possibility that we'll miss it entirely in the future. The high count from 1980 reported 3932 Inca Doves.

Killdeer 61
Least Sandpiper 26
Inca Dove 5
Greater Roadrunner 11
Gilded Flicker 17
Loggerhead Shrike 6
Cactus Wren 182
European Starling 1064
Canyon Towhee 22
Rufous-crowned Sparrow 9
Lark Bunting 5
Western Meadowlark 6
Brown-headed Cowbird 12

I want to thank all of the Area Leaders for all their help in organizing their teams, getting their data to me on time, and keeping track of all the effort data. I also wanted to especially thank Jennie MacFarland for setting up the potluck countdown and Tucson Audubon Society for paying for the rental space. And thanks to everyone who helped chip in to cover my costs.

No comments:

Post a Comment