Sunday, January 15, 2017

The Total 2016 CBC Analysis

The 45th Tucson Valley Christmas Bird Count was held on Wednesday, December 14, 2016. One hundred seventeen field observers in twenty-seven areas and eight feeder watchers tallied an impressive 156 species and 62,488 individuals. While we fell short of our amazing total of 166 species from two years ago, this number is our third highest total ever.
The resident Tucson Vermilion Flycatcher population has been exploding. Read on to find out how many were seen this year.
These past five years have been a very rewarding time for me as the compiler, and I am especially in awe at all the time and effort that so many area leaders and participants have put into making this CBC a success. When I took it over I redesigned the area boundaries significantly with the goal of increasing participation. By creating manageably-sized areas with well-drawn maps and notes to help area leaders effectively cover their areas, I hoped to make the CBC more interesting and more fun. It worked – participation has nearly doubled over the previous 10-year average. My efforts weren’t without detractors. One observer complained that bird numbers were too high and must be overcounted (the evidence is that we actually still undercount them), and another was so disgruntled that his old CBC area had been broken up that he tried sabotaging the CBC – he abandoned the team he had promised to lead with no warning, birded on his own all day, told birders in several areas that they were in his area, and he turned in a completely useless data sheet at the end of the day. There have been other minor headaches, but overall I’ve been extremely heartened by the response of the participants.

And then there’s an amazing side effect of the redrawn areas – more birds, more species, and more interesting species being discovered. This year’s total was the third highest ever, and in fact, the past five years have tied or surpassed the species totals of all previous 40 years since the circle center was relocated to its current location near River and Oracle roads. While it used to be considered a good year to surpass 140 species, the new normal is in the 150’s, and it still remains to be seen if 170 species can be done. But the time has come for me to pass on the baton. I expect the new area boundaries and area notes (in a few cases greatly improved by the area leaders) will continue to reap their rewards as Luke Safford takes charge of deciding future dates of the count and recruits area leaders. I wish him as much fun in coordinating people and crunching the numbers as I have had.

Now for that number crunching:

Four species were seen during the three days before or after count day, noted as count-week (CW) birds: Blue-winged Teal, Zone-tailed Hawk, Barn Swallow, and Lazuli Bunting. There were also three species that we get most years and almost certainly were within the circle on count day, just missed due to bad luck: Wilson's Snipe, Crissal Thrasher, and Vesper Sparrow. Two species were reported from count day that I did not accept due to lack of documentation and written details to support the reports: Violet-green Swallow and Lawrence’s Goldfinch. That makes a total of nine species that under different circumstances might have brought us to 165, one short of tying the record. And who knows what unknown rarities are still lurking along the Santa Cruz River, in alleys, well-wooded apartment complexes, or up in the difficult-to reach pine-oak woodlands of Mount Kimball?
Woodhouse's Scrub-Jays were found in good numbers in the foothill canyons.
Birds missed were far outnumbered by unexpected finds and exciting rarities. This year’s biggest surprises included two additions to the all-master list. The Birky team was near the Starr Pass golf course and looked up at 1:30 p.m. to see three Black Vultures flying south. It was a great find, but not totally unexpected – from the Area Notes that I composed five years ago: “Anywhere near the western edge of the circle keep an eye out for Black Vultures, a very few of which inhabit the Tucson Mountains and may drift over your edge of the circle from time to time.” The other new species was Rufous Hummingbird, with two present at feeders on opposite side of the Pusch Ridge foothills. We have had Rufous/Allen’s three times over the past 45 counts, but this is the first time that any have been convincingly identified to species, thanks to Larry Norris, expert hummingbird bander.

The list of other rarities was impressive. A Western Grebe on Silverbell Lake had been there for a few days. A Northern Beardless-Tyrannulet near the bottom of the Finger Rock trail was a last-minute lucky find. A single Hammond’s Flycatcher along the Santa Cruz river was where it could be expected even if rare, while a well-documented Dusky Flycatcher was more of a surprise in Pima Canyon. Three Cassin’s Kingbirds were found, and this is the seventh year in a row for this species, now come to be almost expected. Mind-blowing were two Bell’s Vireos; surprising was that these were both discovered on the day of the count, while a third in Pima Canyon (probably there for its third winter) couldn’t be relocated that day. A Juniper Titmouse pair was very close to where a single bird had been found just four days earlier on the slopes of Mount Kimball. Eastern Bluebirds are making news, with one at McCormick Park, while the ones at the Tucson Country Club first found three years ago intriguingly appear to have been present all year. Three Mountain Bluebirds in Oro Valley were a surprise. The Santa Cruz River always produces a few semi-hardy vagrants from the east, which this year included single Northern Parula, Townsend's Warbler, and Black-and-white Warbler, while two Clay-colored Sparrows were found along the river as well. Summer Tanagers were found at Reid Park and Evergreen Cemetery, while Sweetwater Wetlands managed to reproduce staked out Yellow Warbler and the Baltimore Oriole back for its fourth winter (and this time coaxed to stick around for the CBC for only the second time with several orange feeders that I built and hung around the area).
This Northern Beardless-Tyrannulet was recorded for only the 8th time in 45 counts.
Looking at numbers of individuals counted, I’m not going to try any meaningful trend analysis, as to be honest that would require some statistical massaging of the numbers using effort data. Of course with so many more observers doing a more thorough job we’re bound to be observing more birds in any event, but I have to mention two species that clearly are increasing in numbers. Our 64 Broad-billed Hummingbirds and 392 Vermilion Flycatchers are not only new highs for our count, but will also be new all-time national highs. It was only six years ago that we first just barely broke the century mark with this ruby beauty, and the Kingsville, Texas record of 116 in 2003 still seemed only a long shot. The most amazing thing about this unprecedented population explosion from what used to be a very tiny number of resident birds is that it remains completely unstudied and the cause utterly unknown. With this relatively common, easy to observe, and easy to identify species, our Christmas Bird Count data actually has some tangible value. 
Our 64 Broad-billed Hummingbirds is a new all-time national high.
Another twelve species and subspecies had new high numbers for our count, and I’ll mention only the three that are relatively common permanent residents, indicating a likely real increase in their local population that could warrant further investigation: 87 Ladder-backed Woodpeckers, 209 Black-tailed Gnatcatchers, and 42 Rufous-winged Sparrows. It will be interesting to see if other regional CBCs shows similar increases.

One statistic I like to keep track of for the fun of it is how many species for which Tucson Valley holds the national high. One year we were second in the nation with 17 species. We won’t know for sure until all compilers have uploaded their data to the National Audubon CBC website (and even then many don’t make the February 28 deadline). It’s worth mentioning that Cooper’s Hawk may have leveled out after almost annual increases over the past several years, but our 110 is almost certainly the national high, in addition to the uncontestable record highs we had of Vermilion Flycatcher and Broad-billed Hummingbird. Other species for which Tucson should keep the title for include Gila Woodpecker – 623, Verdin – 824, and Yellow-headed Blackbird – 27856. We’re also contenders for House Finch, Phainopepla, Black-tailed Gnatcatcher, Plumbeous Vireo, and Rock Pigeon, and our two Bell’s Vireo will not likely be matched by any other CBC. Sometimes Tucson gets the high for the following, but other CBC’s have already reported higher numbers of them: Mourning Dove (Phoenix-Tres Rios), Curve-billed Thrasher (Green Valley-Madera Canyon), Lesser Goldfinch (Auburn, California), Cassin’s Vireo (Hassayampa), and Black-throated Gray Warbler (Long Beach-El Dorado, CA).
Thirteen Black-throated Gray Warblers were found in seven areas.
While such high numbers are fun, it’s even more important to keep an eye on species that appear to be declining, and most revealing numbers are those of our relatively common resident species. Inca Doves continue to limp along, and our five this year ties our record low. Cactus Wren numbers are either steady or declining, and while Canyon Towhee numbers appear to have rebounded from last year’s low at first glance, that number was probably affected by the weather, and their numbers are still low compared to the long-term averages. House Sparrow numbers also seem to be low compared to the long term. Other species showing their lowest total in the past five years include Gambel's Quail, Harris's Hawk, Rock Pigeon (Feral Pigeon), and Gilded Flicker, all species to keep an eye on. Abert's Towhee presents a bit of a mystery, with this year’s total being the fifth highest count in the circle’s history. In fact, the species does seem to have increased its urban population in recent years. But despite the ideal birding conditions and near record-number of participants this was actually the lowest total in the five years since the circle was redesigned. Is that a real decline or just a hiccup in the numbers? Time may tell, but it would be nice to have someone doing serious research on all of these species during the whole year.
It would be interesting to know whether a real trend in Cactus Wren can be seen.
Numbers of migrants that winter here are much harder to interpret and many more questions are raised instead of answered. For example, we set a record high number of Lincoln’s Sparrows, but is that because of an actual population increase or were other areas they prefer to winter in not as good this year, bringing more to our circle? We certainly get Rock Wrens wintering here in addition to our resident birds, but does this year’s low number reflect a real population change in the migrants or our residents – or both? We seem to have Phainopeplas year-round, but their migration is poorly understood. So is our record number of 523 (far surpassing the previous high of 471 set back in 1982) reflective of a local population explosion or did birds come to winter here from elsewhere for an unknown reason? Already with bated breath I look forward to participating in next year’s Tucson Valley Christmas Bird Count to see what the numbers will show.


  1. Sorry I missed it this year. I did meet Luke at SW, and we simultaneously spotted the Oriole by the parking lot oranges. Your help, enthusiasm and knowledge will be big shoes to fill. Thank you for all the memories on the counts. Hope to join your team again some time, even if you're not leading the counters! Bravo, bravo, bravo.

  2. Thank you so much for all you have done. I do have a couple of comments about numbers. The number of blackbirds (3 species) I counted in count day was far surpassed just a few days later when I had more time to count. The other day, I had 540, but on count day, 300 less than that. Partly it was because I couldn't stay long enough on count day. For that reason alone, I agree that most birds are under-counted. I am puzzled by your apparently contradictory statements regarding Rock Pigeons. You said we might have had the record high, but they are declining (if I remember correctly). All I can tell you is that I am seeing many in the city, so they are still quite abundant. The most likely place to find them is on the electric wires along streets. Perhaps we should make an effort to bird these, since they also collect a lot of doves. As for Phainopeplas, I have observed up to two near my home, but this year we have three.

    1. Hi Pat,

      We get a lot of Rock Pigeons compared to most other CBC's across the country. So while ours might be a high count for the the year compared to other CBC's, it could still be low compared to our own history of huge numbers.