North American Birds

VOLUME 69 NO2 2016

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

Issue link: http://nab.aba.org/i/705084

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V O L U M E 6 9 ( 2 0 1 6 ) • N U M B E R 2 267 C O LO R A D O & W YO M I N G juv. Thayer's Gull was far se. in Kiowa 8 Feb (DAL, JT). Colorado's first Iceland Gull was discovered in 1999, with the state garnering a total of 15 records by the end of 2010, but an additional 19 have been accepted by the C.B.R.C. since then. Continuing the trend, this season saw an additional five records: a first-cycle at Boulder Reservoir, Boulder 1 Dec (DD), 1-2 ads. at Larimer 1-22 Dec (SGM), a second-cycle bird at Lagerman Reservoir, Boulder 17-21 Dec (ph. DD, m.ob.), and an ad. at Barr Lake, Adams 4 Feb (DD). Where were these birds in Jan? Nowhere in non- coastal North America w. of the Mississippi River is Lesser Black-backed Gull as common as in Colorado. We continue to enumerate the occurrence of the species in the Region. This season, the species was noted in 14 of 64 (all e.) counties, with single-day high counts reaching 6 each in Adams and Boulder, 9 in Arapahoe, 13 in Pueblo, and 18 in Larimer (4 & 22 Dec; SGM et al.), the last providing a new Colorado maximum. Larimer hosted 4 Herring Gull x Glaucous-winged Gull hybrids through the season and provided another Colorado maximum. Wyoming's twenty-sec - ond Glaucous Gull (sixth in winter) loitered at the JTL Ponds, Natrona 3-21 Dec (ZH, CM, RW, ph. DJ), while the only Regional Great Black-backed Gull was the returning ad. at Pueblo Reservoir (m.ob.). After years of practicing their craft, Grand Junction's C.B.C. Western Screech-Owl team nearly cracked the century mark 14 Dec, tallying a C.B.C.-record-breaking 99 indi - viduals. Both the number and distribution of Colorado-wintering White-winged Doves continue to increase, with reports from eight counties this season, including high-elevation Park's first-ever documented occurrence, at Lake George 4 Jan (ph. A. Jack). Colorado has just over 10 winter records of Red-headed Woodpecker, with only five noted in eBird, four of those outside typical range in the state. One observer has accounted for three of those four, with 2 in Florence, Fremont , where sin - gle imms. were noted in winter 2012-2013 and then 4 Dec this winter (RMi). The Acorn Woodpecker colony continues near Durango (present since before Jun 1995), as does the female in sw. Colorado Springs present since at least Dec 2012. Bucking recent years' ex - pectations, Fremont played host to only two species of sapsucker this winter, missing out on Red-naped. Also not expected were female Williamson's in Denver 20 Dec (ph. GW, J. Oberbeck) and Boulder 28 Feb (B. Spencer); single Red-napeds in Mesa 4 Jan (L. Stigen), La Plata 7 Jan–9 Feb (RMo), and Montezuma 22 Jun (B. Wolff); and a Yellow-bellied x Red- naped hybrid in Fremont 11 Jan (ph. MP). Despite being considered rare in the Region in winter, reports of the genus came from 14 Colorado counties. FLYCATCHERS THROUGH WARBLERS Very rare in Colorado until the early 2000s and nearly unknown there in winter until recently, single Black Phoebes were noted at two sites each in Fremont and Mesa, where the species is now nearly expected at this season. Usually found as singles at a few Colorado lo - cales in winter, Say's Phoebe put on a show this season (though paling next to the 2015- 2016 showing), being tallied in 11 counties from Boulder southward on the e. side and in Mesa. A Western Scrub-Jay at Rocky Ford, Otero 10 Dec–24 Jan (SO) and 2 ne. of Las Animas, Bent 15 Dec (D. Russell, J. Stulp, JT) were well out on the plains, while one pres - ent through 15 Feb at Rawlins, Carbon (PJ) was somewhat extralimital for Wyoming and another in Albany 14 Feb (ph. J. Carlisle) was just the third for Laramie. The 250 Black- billed Magpies at the Evanston Landfill, Uinta 14 Dec (HW) provided a record eBird count for Wyoming. Two weather events in Wyoming resulted in some amazing Horned Lark concentrations: blizzard conditions 15 Dec in Laramie led to two counts with a sum of 3600 birds (DJ), and after a chinook wind SA Winter warblers provided much food for thought this season. With fewer than 10 antecedent Colorado and Regional winter records, the 2 Orange-crowned Warblers at Grand Junction 14 Dec (MH et al.) provided a new winter maximum; the two previous seasonal records were in 2006 and 2010. A male Pine Warbler was a nice surprise near Fort Lyon, Bent 15 Dec (ph. BKP), whereas one at the Denver West Office Park, Jefferson 5 Jan–14 Feb (m.ob., ph. GW) was at the epicenter of Interior West winter range of the species; the site has hosted the species in five winters since 2004-2005. The Colorado winter show of Yellow-rumped Warbler was both expected and surprising this season. The distribution of Myrtle Warbler was about on par with expectations: 2 on the West Slope (singles in Delta and Mesa), 40 on the e. side, scattered down the urban corridor from Larimer and Weld s. to Fremont and Pueblo, with a whopping 27 at the CF&I ponds in s. Pueblo 23 Dec (MP). However, either our understanding of the occurrence of Audubon's Warbler is off or this winter saw an atypical showing of the subspecies. The 18 tallied on the West Slope is not too surprising, but 42 on the e. side—12 of these at the CF&I ponds 23 Dec (MP)—seems almost incredible, as current thinking has Myrtle the expected wintering taxon there. Intergrades are not at all rare in the Region, with winter records in eBird from five e. Colorado counties (Adams, Boulder , Logan , Pueblo , and Yuma), and observers should be cautious with identification of Audubon's in areas where very historically very uncom - mon. As expected, the sole Wyoming report of Yellow-rumped Warbler this season, adding to just a dozen previous, was of a Myrtle, in Laramie 1-4 Dec (CB). Yellow-breasted Chat is Regionally exceedingly rare after Sep, though Andrews and Righter (1992) indicate very rare occurrence from late Sep through about 25 Oct and with an isolated record from the end of Nov. Two were found in Dec, providing the first Regional winter reports, and both were on the West Slope! The first graced the Ranch at Roaring Fork near Carbondale, Garfield 11-15 Dec (ph. D. Filby, ph. JR). The individual at Gunnison 8-20 Dec (J. Coop, ph. AA) was quite unexpected, as the species is not at all common in the county, even in summer! The most interesting aspect of these records, however, was that both individuals were referable not to the w. subspecies auricollis but to nominate virens, a subspecies noted fewer than 10 times previously in Colorado, primarily in the ne. corner but w. to Lincoln. One wonders how many other misplaced Yellow-breasted Chats were tucked away in the massive swaths of West Slope Colorado that are rarely, if ever, birded. Surely, we did not find all of them. This Yellow-breasted Chat 11-14 (here 11) December 2014 near Carbondale, Garfield County provided only the second winter record for Colorado. Inter- estingly, the first was noted just three days earlier and was present 8-20 December 2014 at Gunnison, Gunnison County. Both were found on the West Slope, where the species is otherwise unknown after September. Both individals appear to represent to the nominate subspecies (virens) rather than the local breeding subspecies, auricollis. Photograph by Dick Filby.

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