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.
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| 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?
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| 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).
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| 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.
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| 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).
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| 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.
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| 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.
