Colorado Birds the Colorado Field Ornithologists’ Quarterly

Vol. 51 No. 3 Summer 2017 Colorado Birds The Colorado Field Ornithologists’ Quarterly

The Hungry Bird: Sapsucking Woodpeckers Barn Owl Nest Box Swap In the Scope: Subspecies in Colorado Colorado Field Ornithologists PO Box 929, Indian Hills, Colorado 80454 cfobirds.org

Colorado Birds (USPS 0446-190) (ISSN 1094-0030) is published quarterly by the Col- orado Field Ornithologists, P.O. Box 929, Indian Hills, CO 80454. Subscriptions are obtained through annual membership dues. Nonprofit postage paid at Louisville, CO. POSTMASTER: Send address changes to Colorado Birds, P.O. Box 929, Indian Hills, CO 80454.

Officers and Directors of Colorado Field Ornithologists: Dates indicate end of current term. An asterisk indicates eligibility for re-election. Terms expire at the annual convention.

Officers: President: David Gillilan, Littleton, 2019*, [email protected]; Vice Pres- ident: Christy Carello, Golden, 2019*, [email protected]; Secretary: Chris Ow- ens, Longmont, 2019, [email protected]; Treasurer: Michael Kiessig, Indian Hills, 2019*, [email protected]

Directors: Amber Carver, Littleton, 2018*; Gloria Nikolai, Colorado Springs, 2018*; Christian Nunes, Longmont, 2019; Christy Payne, Wheat Ridge, 2020*; Jason St. Pierre, Durango, 2019*

Colorado Bird Records Committee: Dates indicate end of current term. An asterisk indicates eligibility to serve another term. Terms expire 12/31.

Chair: Mark Peterson, Colorado Springs, 2018*, [email protected]

Committee Members: Lisa Edwards, Secretary; Peter Gent, Boulder, 2017*; Tony Leu- kering, Largo, Florida, 2018; Dan Maynard, Denver, 2017*; Kathy Mihm Dunning, Den- ver, 2018*; Christian Nunes, Longmont, 2019*; Steven Mlodinow, Longmont, 2019*

Immediate Past President: Doug Faulkner

Colorado Birds Quarterly:

Editor: Scott W. Gillihan, [email protected]

Staff: Christy Carello, science editor, [email protected]; Debbie Marshall, design and layout, [email protected]

Annual Membership Dues (renewable quarterly): General $25; Youth (under 18) $12; Institution $30. Membership dues entitle members to a subscription to Colorado Birds, which is published quarterly. Back issues/extra copies may be ordered for $7.50. Send requests for extra copies/back issues, change of address and membership renewals to [email protected]. Contributions are tax deductible to the extent allowed by law.

126 Colorado Birds Summer 2017 Vol. 51 No. 3 The Colorado Field Ornithologists’ Quarterly Vol. 51 No. 3 Summer 2017

PRESIDENT’S MESSAGE...... 128 David Gillilan

CFO BOARD MEETING MINUTES...... 130 Chris Owens

CORRECTION: BIRDS AT LAIR O' THE BEAR PARK OVER THE LAST DECADE...... 133 Scott W. Gillihan

SUMMER OBSERVATIONS OF PACIFIC WRENS LIKELY BREEDING IN COLORADO...... 134 Mike Britten, Jeff Connor, and Kurt Fristrup

NEWS FROM THE FIELD: WINTER 2016–2017..... 142 David Dowell

IN THE SCOPE: SELECTED BIRD SUBSPECIES OF INTEREST IN COLORADO: PART 1...... 154 Tony Leukering and Steven G. Mlodinow

THE HUNGRY BIRD...... 170 Dave Leatherman

EXCHANGING AN ACTIVE BARN OWL Purple NEST BOX...... 174 Sandpiper, Scott Rashid 1st Colorado record, Iron Spring Creek near where it enters Dillon Reservoir, Summit Coun- ty, 19 Dec 16. Photo by Bill Maynard PRESIDENT’S MESSAGE

Like many incoming Colorado Field Ornithologist presidents before me, my first President’s Message for our flagship journalColorado Birds is being written shortly after the conclusion of another suc- cessful annual convention and membership meeting, this one having taken place in Steamboat Springs. I was first inspired to join CFO by the prospect of attending an upcoming convention (Trinidad, 2012), which may very well be how many of you first became members of CFO as well. CFO and conventions have been closely entwined from the start; CFO was created in 1965 as a statewide entity to sponsor annual conventions (Colorado Birds, Vol. 46:3, July 2012). At the conclusion of my first convention in Trinidad, I pondered which I had enjoyed more; all the birds I saw, or getting to know so many other birders. Though I leaned toward the latter, I was glad I didn’t have to choose between them. At our Steamboat convention, events like the welcome picnic held at The Nature Conservancy’s Carpenter Ranch, and the banquet and annual David Gillilan meeting held at the Colorado Moun- tain College with expansive views out over the valley, were just as popular as the dozens of field trips ranging near and far across northwestern Colorado, the keynote address by Sheri Williamson, and the presentations of scientific papers, all of which were superb. Though we continue to experiment with our convention formats, we expect our next convention, based in eastern Boulder County in May 2018 (precise venues and dates not yet available), to continue the trend of mixing people who like birds with birds, and other birders, and people who study birds! Boulder County provides us with a variety of good venues to host events, and an opportunity to send field trips in virtually every direction through a huge range of habitats, from high peaks to the plains and everything in between. It also gives us a chance to host a convention in an area that has not hosted the convention since 1987. Though convention work understandably dominates the thoughts and time of the CFO board during the first half of the year, I would be remiss in failing to remind our membership that a great deal of work is done year-round on a great number of matters, large and small, by an all-volunteer board, which also serves as its own unpaid staff.

128 Colorado Birds Summer 2017 Vol. 51 No. 3 I would also like to recognize the significant contributions of three board members who just left the board after many years of hard and exceptional work: Doug Faulkner, who has served several stints with CFO as editor of Colorado Birds, CBRC chair, and president; Lisa Edwards, our membership chair who also did anything and everything else, and could (did?) keep the entire organization functional; and Ted Floyd, who in the last several years was most likely the one who communicated to you most of the information you needed to know about CFO events. We wish them all well, and don’t be at all surprised if we continue to see more of their handiwork in the future. On the flip side, the membership voted to bring in three new board members, Sue Riffe, Jason St. Pierre, and Christy Payne, who we welcome. Work they’ve already done as volunteers for the Steam- boat convention has proved them to be a very competent and ener- getic group. There has been a distinct shift in the demographics of the board recently, some of it intentional; when I joined the board just three years ago I could legitimately count myself as being part of the younger set, notwithstanding that I am older than CFO, and two- thirds of us, including all four officers, were male. That has changed, on all counts; today’s officers and board members now look a lot more like the overall CFO membership in both age and gender. And though we now have fewer experienced board members (ten current members came on board within the last three years), I’m confident that the board still has the people it needs to accomplish CFO’s goals.

Colorado Birds Summer 2017 Vol. 51 No. 3 129 CFO BOARD MEETING MINUTES

4 February 2017 Chatfield State Park Littleton, CO

Chris Owens

President Doug Faulkner called the meeting to order at 11:11 a.m. Other officers present included Vice President David Gillilan, Trea- surer Michael Kiessig, Secretary Chris Owens; directors present were Mark Peterson, Amber Carver, Gloria Nikolai, Lisa Edwards, Christy Carello, and Christian Nunes. Guests Larry Modesitt and Buzz Scha- umberg were also present. Scott Gillihan and Ted Floyd sent their regrets.

Secretary’s Report: Chris Ow- further discussed after the upcoming ens’ minutes from the 3 December convention and annual meeting in 2016, meeting were approved with no Steamboat Springs. changes or additions. Western Field Ornithologists Treasurer’s report: Treasurer Mi- Partnership: Larry Modesitt, for- chael Kiessig previously submitted mer CFO BOD member, and current his report electronically to the board. Western Field Ornithologists, WFO, Prior to the board meeting, President board member, made a presentation Doug Faulkner convened a subcom- to the CFO BOD members on the mittee to go through the Treasurer’s similarities and differences between budget projections, including conven- WFO and CFO. WE have an official tion expenses, so as to be in a better partnership with WFO and intend to position to discuss options and make keep a working relationship. Primar- recommendations to the full board at ily the differences are in membership the meeting. The budget projections numbers, convention focus, internal indicate that CFO continues to be in organizational operations, and money good financial shape and will maintain making ventures including special its intended reserve amount, but that events, and membership categories. recurring expenses for important parts WFO will be hosting their conven- of CFO’s mission, such as publication tion this fall, 16–20 August 2017, in of Colorado Birds, maintenance of Pueblo, Colorado. Larry encouraged three websites, and funding of grants all BOD members to attend. He also and scholarships, have been going up suggested we work together as partners and need to be addressed. The focus to encourage members from both or- at the board meeting was in develop- ganizations to attend both conferenc- ing different ideas and options that es. WFO hopes to cooperate further will continue to keep the organization in the coming years since our partner- in good financial shape, that will be ship is mutually beneficial. CFO will

130 Colorado Birds Summer 2017 Vol. 51 No. 3 update and publish the WFO conven- funds used by CFO throughout the tion on our website. year to sponsor grants, scholarships, Least Tern and Piping Plover and other matters. Registration is on Update from SE Colorado: Doug re- on track for opening in early spring, ported that there has been a change in and will be online only, as in recent leadership in the management of the years. Convention information will be Army Corps of Engineers responsible posted on the Next Convention page for operations at John Martin Reser- of the CFO website as it is finalized. voir. This is the area of the state with 2017 Budget: The CFO budget the biggest population of least terns passed unanimously while meeting and piping plovers. We are very grate- our cash reserves goal of $25,000. ful to have had so many years with the support of the Corps for habitat pro- Committee Reports tection. CFO acknowledged this by Colorado Birds, the CFO publica- awarding a Landowner’s Award to the tion: The Winter issue came out on Corps at the 2016 annual convention time in January. Lisa will work with in Lamar last May. the printer to see what ways CFO Succession for Board of Directors could help streamline the printing Positions: The members leaving have process. We will continue to encour- been very active in performing various age members to elect to receive the functions of the board, which means journal in electronic form which will we will have large shoes to fill, but this help CFO keep costs down. This will will also provide new opportunities for allow for further funding of operations continuing and new directors to jump CFO is committed to supporting. The in with new ideas and become more BOD discussed other costs for pub- involved in other areas of the board’s lishing the journal and will look to work. realigning costs in hopes of further Convention Planning: Conven- reductions. tion planning has been well under- Membership: Lisa reported that way for months, but final details and membership is fine with twelve stu- plans are still being ironed out, mak- dents receiving publications. She is ing this the start of a very busy part still scanning in past journals having of the year for board members. Steam- finished the 1960s. She and Doug are boat is a more expensive venue than splitting the storage of the archived many that we have used, which has copies. required some adjustments. The board Publicity: Ted Floyd sent his re- is pleased to have arranged for lower- grets. He did not report any concerns cost lodging at the convention venue, and has electronically submitted a to help hold down expenses for our rough draft of the brochure for the members, but the board also recog- 2017 convention. nized the need to adjust some con- Quarterly Field Trips: Doug vention pricing for the dual purposes Faulkner expects that the usual field of covering expenses and generating trips will be conducted this year. He

Colorado Birds Summer 2017 Vol. 51 No. 3 131 will inform the BOD if that needs to nominations for awards. The BOD change. He led a discussion about ex- discussed and decided upon the sub- panding opportunities to farther cor- mitted nominations for awards. ners of the state while recalling the Colorado Birds Record Commit- well received trips conducted in the tee (CBRC): Mark Peterson reported Grand Junction area in the past cou- that all members are doing well with ple of years. The BOD discussed some submitted records. He raised a ques- possible leaders. tion about the CBRC bylaws and if Project Grants: Christy Carello there were any changes needed to in- presented summaries of the grants re- corporate Ebird submissions into the quested through her committee. Us- CBRC website and voting structure. ing the stated mission of CFO as our After discussion the BOD decided benchmark for funding projects, the that no changes were necessary and BOD thoroughly discussed the merits the CBRC could continue pursuing of each proposal. Funding awards were more information about Ebird submis- moved and seconded, then passed sions into CBRC. unanimously. Next Meeting: The next BOD Social Media: Christian Nunes re- meeting will take place in Steamboat ported that there are 1767 members Springs on 29 April 2017. on Facebook and it is actively used by Adjournment: President Doug the members. All is going smoothly. Faulkner adjourned the meeting at Awards: Amber Carver presented 4:10 p.m.

132 Colorado Birds Summer 2017 Vol. 51 No. 3 Correction: Birds at Lair o’ the Bear Park Over the Last Decade

Scott W. Gillihan Due to an unfortunate error on my part during the editorial process, Tables 1 and 2 of Mike Foster’s article in the Spring issue (Foster 2017) omitted some critical information. A corrected version of the full article has been posted to the CFO website; the missing information appears below. My apologies to our readers and to Mike Foster for the error.

Literature Cited Foster, M. F. 2017. Birds at Lair o’ the Bear Park over the last decade. Colo- rado Birds 51:65–78.

These rows were omitted from the bottom of Table 1 (p. 72):

Species Observed Possible Probable Confirmed Dark-eyed Junco X Western Tanager FF Black-headed Grosbeak FL Lazuli Bunting FL Common Grackle # Brown-headed Cowbird FL Bullock’s Oriole FF

Breeding Codes O = migrants, nonbreeders at site T = territorial behavior ON = occupied nest # = in suitable nesting habitat C = courtship, copulation, feeding CF = carrying food X = < 7 singing males NB - nest building FF = feeding fledgling M = > 7 or more singing males FL = fledged recently NY = nest with young P = obvious pair

In Table 2 (pp. 72–74), these 35 species names should have appeared in italics, indicating species for which breeding status is based on best available information.

Blue-winged Teal Least Flycatcher Sage Thrasher Wilson’s Warbler Green-winged Teal Hammond’s Flycatcher European Starling Brewer’s Sparrow Eurasian Collared-Dove Eastern Kingbird House Sparrow Lincoln’s Sparrow Yellow-billed Cuckoo Red-eyed Vireo Evening Grosbeak White-throated Sparrow Calliope Hummingbird Bank Swallow Northern Waterthrush Blue Grosbeak Williamson’s Sapsucker Canyon Wren Common Yellowthroat Western Meadowlark Red-naped Sapsucker Winter Wren American Redstart Brewer’s Blackbird American Three-toed Woodpecker Golden-crowned Kinglet Northern Parula Great-tailed Grackle Willow Flycatcher Brown Thrasher Prairie Warbler

Colorado Birds Summer 2017 Vol. 51 No. 3 133 Summer Observations of Pacific Wrens Likely Breeding in Colorado

Mike Britten, Jeff Connor, and Kurt Fristrup On 20 June 2015, while participating in the Rocky Mountain Na- tional Park (RMNP) “summer solstice bird count,” we (Mike and Jeff) heard a “stub-tailed wren” singing continually near Calypso Cas- cades in Wild Basin, Boulder County. The song had a ventriloquial quality amid the roar of the Calypso Cascades. We were not able to see the bird well even though we searched for it from 6:30 to 7:00 a.m. MDT. We caught brief glimpses of the bird moving mouse-like among the moss-covered boulders and downed trees in old-growth, mixed-conifer habitat. We saw it fly once (to a new singing perch); it was immediately followed by a second small dark bird that likely was a second stub-tailed wren. While neither of us had experience identifying Pacific Wrens (Troglodytes pacificus), we both thought it was likely a Pacific Wren because the song was very high pitched, buzzy, and long (5–8 sec- onds) and sounded similar to Pacific Wren recordings we had heard. We recorded the song using our smartphone video application and reported this in the count tally as a probable Pacific Wren. Mike revisited the site on 23 June 2015 (5:22–7:30 a.m. MDT) and heard a wren singing constantly from arrival until 7:00 a.m. It sang once more at 7:15 a.m. During this visit, Mike saw the bird several times and had a good look as it moved along a large moss-covered log. It was obvi- ously a small and dark stub-tailed wren. Mike made several recordings of the song using the video capabil- ity of his camera (Canon Power- Shot SX40HS). Mike revisited Fig. 1. Photograph of a Pacific Wren (Troglodytes pacificus) the site again on in Wild Basin in Rocky Mountain National Park, Boulder 28 June 2015; a County, Colorado.

134 Colorado Birds Summer 2017 Vol. 51 No. 3 wren was singing when he arrived at 5:45 a.m. and sang steadily through 7:15 a.m., when he left. Mike finally got very good looks, took several photos, and made additional audio/video recordings. Overall, the bird was dark rufous brown with darker (almost Fig. 2. Sonogram of a Pacific Wren (Trog- black) barring, especially under- lodytes pacificus) song in June 2015 in Wild neath and toward the tail (Fig. 1). Basin, Rocky Mountain National Park, The wings were barred dark brown Colorado. (almost black) and rufous buff color with the buffy barring light- est on the outer primaries. The tail was short and barred dark brown (almost black) and buffy. It had a single row of small white flecks just above the wings. The throat was not distinctly paler than the Fig. 3. Sonogram of a Pacific Wren (Trog- rest of the underparts. The bird lodytes pacificus) song in June 2015 in Wild had a distinct buffy supercilium. Basin, Rocky Mountain National Park, The bill was relatively straight, Colorado. short, and brownish (darker above than below). The eye was dark. The legs appeared long for the size of the bird and were flesh colored. Kurt converted the audio files into sonograms (Figs. 2 and 3). We shared the video files, photographs, and sonograms with Dr. David Toews, lead author of the Fig. 4. Comparison of the median frequen- Birds of North America (BNA) cies and frequency ranges of Winter Wrens species account for Pacific Wren (Troglodytes hiemalis), Pacific Wrens (T. (Toews and Irwin 2012) and pacificus), and the June 2015 Rocky Moun- with Dr. Sallie Hejl and Jennifer tain National Park “stub-tailed wren.” Holmes, two of three coauthors of the BNA species account for the Winter Wren (Hejl et al. 2002). All agreed this documentation is consistent with identification of the Colorado bird as a Pacific Wren. Kurt performed a cursory quantitative analysis of some Winter and Pacific Wren songs downloaded from xeno-canto.org to confirm the expert identifications of the Calypso Cascades wren songs. Measure- ments of the median and lower and upper quartile frequency values

Colorado Birds Summer 2017 Vol. 51 No. 3 135 were extracted from 34 Winter Wren songs, 12 Pacific Wren songs, and four songs from Calypso Cascades using Raven software (Charif et al. 2004). Fig. 4 illustrates the unusually high median frequency of the Calypso Cascades wrens, which is coupled with a relatively low interquartile bandwidth. Because this bird was present and singing vigorously on three separate mornings in the latter half of June, and because we saw two wrens the first time, we speculated that this was a breeding occurrence of Pacific Wrens in Colorado.

Taxonomic History and Occurrence of Winter Wren Subspecies Until recently, Winter Wrens across the Holarctic were considered one species, T. hiemalis, with six distinct clades (Drovetski et al. 2004). Genetic analyses of wrens in an area of British Columbia (Toews and Irwin 2008), where breeding T. h. hiemalis and T. h. pacificus coexist, concluded that the two North American clades repre- sent distinct taxa that have been separated for ~4 million years. The authors saw no genetic evidence of interbreeding in the study area and proposed that the two taxa, which are very similar in appearance, maintain genetic separation by singing distinctly different songs and called them “cryptic species.” Based on this work, the American Or- nithologists’ Union split Troglodytes wrens into the Pacific Wren T.( pacificus) of western North America, Winter Wren (T. hiemalis) of eastern North America, and Northern Wren (T. troglodytes) of Eur- asia (AOU 2010). Leukering and Pieplow (2010) use the term “stub-tailed wren” to refer to unidentifiedT. hiemalis or T. pacificuswrens in Colorado and provide information on correctly identifying these taxa based on plumage and vocalizations. They comment that “A very small number (<5) have been noted singing in the mountains in summer, and we might look for some form to breed in the abundant suitable habitat there,” noting that T. pacificus had been recently reported breeding in Arizona. Bailey and Niedrach (1965) reported ~37 total records of Winter Wren for Colorado, including three specimens (two September and one October specimen, no sub-specific identity given). They noted that both T. pacificus and T. hiemalis have been described and con- clude that “the two subspecies probably migrate through or winter in eastern counties.” They considered the only four summer records (all in July) as “open to doubt” and likely to be misidentifications of House Wrens, possibly short-tailed birds of the year. Andrews and Righter (1992) reported the Winter Wren as a “rare fall migrant and winter resident on eastern plains; most records are

136 Colorado Birds Summer 2017 Vol. 51 No. 3 near the edge of the foothills.” They noted there are 10 summer records from the mountains but that they are undocumented and provided no further information. We accessed Colorado Bird Records Committee records for T. pacificus and T. hiemalis (http://coloradobirdrecords.org/ July 2016). There were 23 reports; 14 were accepted by the Committee. Three reports were summer reports; one from Brainard Lake west of Ward (21 June 2000) and two from RMNP (one from Wild Basin [17–25

Table 1. eBird records of Troglodytes pacificus, T. hiemalis, and T. pacificus/hiemalis in June, July, and August in Colorado.

County Identified as Location Date # Notes Boulder T. pacificus Lower Wild Basin 7/9/2015 1 "Singing male." Boulder T. pacificus Rocky Mountain NP--Ouzel Falls 7/7/2015 1 "...foraging and singing…" Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/3/2015 1 "Singing at Calypso Cascade" Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/10/2015 1 Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/12/2015 1 Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/3/2016 1 Singing Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/9/2016 1 Singing Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/10/2016 1 Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/12/2016 1 Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/17/2016 1 Singing Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/20/2016 1 Singing Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/22/2016 1 Singing Boulder T. pacificus Rocky Mountain NP--Wild Basin area 7/24/2016 4 Singing bird and "...a female tending two fledglings." Boulder T. pacificus/ Rocky Mountain NP--Ouzel Falls 7/2/2014 4 Singing bird with "...three baby wrens hiemalis right next to it, hopping and creeping around on a large downed log." Pitkin T. pacificus/ Snowmass 8/25/1987 1 Note: record from before T. pacificus hiemalis recognized as a species. Summit T. pacificus/ Lily Pad Lake trail 8/28/2012 1 hiemalis Boulder T. hiemalis Calypso Fall/Wild Basin 7/24/2001 1 "Single Wren singing it's heart out." Note: record from before T. pacificus recognized as a species. Boulder T. hiemalis Rocky Mountain NP--Ouzel Falls 7/29/2001 1 Note: record from before T. pacificus recognized as a species. Larimer T. hiemalis Rocky Mountain NP--Glacier Gorge/ 7/2/2012 1 "Singing." Loch Vale Boulder T. hiemalis Rocky Mountain NP--Ouzel Falls 7/4/2014 1 "Heard singing at very close range."

Colorado Birds Summer 2017 Vol. 51 No. 3 137 July 2011] and one from along the trail to Black Lake [2 July 2012]). These three reports were accepted by the Committee as T. hiemalis. We downloaded eBird observation records of T. pacificus, T. pacificus/hiemalis, and T. hiemalis for North America on 14 July 2016 (http://ebird.org/ebird/explore). On 24 March 2017 we downloaded subsequent 2016 T. pacificus observations for Colorado. Table 1 summarizes June, July, and August records for these taxa for Colorado. Seventeen of the 20 total observations are from the Wild Basin/Ca- lypso Cascades area in RMNP. Two records include observations of an adult(s) with fledglings: the 2 July 2014 observation submitted by Bill Rowe, and the 24 July 2016 record submitted by Christian Nunes. Another noteworthy record is of a singing T. hiemalis in Gla- cier Gorge (also in RMNP) about 10 km north-northwest of Calypso Cascades reported by Kathy Mihm Dunning. Table 2 summarizes June, July, and August eBird Pacific Wren observations in Colorado, Arizona, New Mexico, South Dakota, Utah, and Wyoming through July 2016. These records document breeding in Arizona (Oak Creek Canyon on the Mogollon Rim), South Dako- ta (Ward Draw in the Black Hills), and Utah (Wasatch Mountains).

Habitat and Locations for the Pacific Wren The Wild Basin wren occurred along Cony Creek at Calypso Cas- cades at approximately 2,774 m elevation. The Creek flows down a

Table 2. eBird records of Pacific Wren (Troglodytes pacificus) in June, July, and August in Colorado, Arizona, New Mexico, South Dakota, Utah, and Wyoming. Records retrieved 14 July 2016.

State # unique observations Location(s) Year(s) Notes CO 13 1 location – Wild Basin, Rocky Mountain NP 2015 These observations are all from July in the same area. AZ 4 2 locations – Oak Creek Canyon and Woods 2015 Breeding documented at Canyon Lake Oak Creek Canyon. NM 1 1 location – Santa Fe NF 2010 Two birds. SD 9 4 locations – Ward Draw, Hell Canyon, Long 2007– Breeding documented at Draw Rd., Pacific Wren Trail 2015 Ward Draw. UT 21 11 locations – Big Cottonwood Canyon, 1997– Breeding documented at Millcreek Canyon, City Creek Canyon, Lamb's 2015 several sites. Canyon, Bowman Fork Trail, Smith and Morehouse Res., Dry Canyon, SE of Wallsburg, Noblett's Creek Trail, Teasdale, Zion NP WY 2 2 locations – Cascade Canyon and Two Ocean 2008, Lake, Grand Teton NP 2015

138 Colorado Birds Summer 2017 Vol. 51 No. 3 steep north-facing slope, creating a loud roar (note the low frequency noise in the sonograms) even past peak runoff in July. As described earlier, the area is a jumble of moss-covered boulders and downed trees and the forest is old-growth, mixed-conifer. The area where we first heard the bird singing includes a small wetland with standing water. In July 2015 Mike also hiked to Black Lake in RMNP, listening and looking without success for wrens in the area that Dunning reported a singing T. hiemalis on 2 July 2012. The habitat was also old- growth conifer forest on a north-facing slope with abundant boulders and downed trees, and with a small stream nearby. Elevation at this site is ~3,050 m. In 2011, the year before Dunning’s report, a wind storm caused a massive blowdown, which left few standing trees. Toews and Irwin (2012) describe T. pacificus use of old-growth forest structures, including snags, root masses, downed trees, and the bases of large standing trees for nesting, foraging, and roosting. They note that this association with old-growth forest is unique among North American wrens. They also say that breeding territories are primarily found along rivers and streams (at least in the Pacific coast range of T. pacificus). They give an elevation range of sea level to 3,788 m (in the Sierra Nevada Mountains, citing Small 1994). The Wild Basin habitat for Pacific Wrens matches the habitat described by Toews and Irwin well. The Utah eBird reports are primarily from the Wasatch Range east of Salt Lake City (~six canyon locations). There is also a 1 June 1997 report from Teasdale, Utah, and a July report from Zion Na- tional Park. The South Dakota summer reports are from two or three locations in the Black Hills (Hell Canyon, Ward Draw, and a general location just east of Hell Canyon). Three of the Arizona observations, including a breeding observation, are from Oak Creek Canyon south of Flagstaff; the only other summer observation from Arizona is from Wood’s Canyon Lake about 80 km southeast of Oak Creek Canyon. The two Wyoming summer observations are from Grand Teton National Park.

Conclusion It seems likely, based on documentation of stub-tailed wrens over multiple years that includes observations of singing adults and fledglings, that T. pacificus breeds at Wild Basin in RMNP. It also seems possible, based on older records of Winter Wrens in summer in Colo- rado, that there is a small T. pacificus population in the Colorado Front Range and other ranges breeding in old-growth, mixed-conifer forest along mountain streams. It is possible that T. pacificus once oc-

Colorado Birds Summer 2017 Vol. 51 No. 3 139 cupied a broader range in the interior western United States during colder times and that the small scattered populations in the Front Range, Black Hills, Tetons, Wasatch Range, and Mogollon Rim are relict populations. The National Audubon Society considers both Winter and Pacific Wrens as “climate threatened” species (National Audubon Society 2015). Interestingly, the climate suitability models in the Audubon Society report show slightly increasing climate suitability for Pacific Wren in summer and winter in the mountains of Colorado, Utah, and Wyoming from 2000 through 2080. Regardless of model predic- tions, breeding Pacific Wrens in Colorado may be threatened by rap- id climate change and related factors (e.g., increased risk of wildfire in old-growth, mixed-conifer forests).

Acknowledgments Thanks to Bill Rowe and Tony Leukering for sharing their observations and knowledge of wrens in Wild Basin and Colorado. Thanks to David Toews, Sallie Hejl, and Jennifer Holmes for reviewing photographs, movies, and sonograms to confirm identification. Thanks also to Jacob Job and Sonya Daw for helpful comments on the manuscript.

Literature Cited [AOU] American Ornithologists’ Union. 2010. Fifty-first supplement to the American Ornithologists’ Union Check-list of North American Birds. The Auk 127:726–744. Andrews, R., and R. Righter.1992. Colorado Birds: A Reference to their Dis- tribution and Habitat. Denver Museum of Natural History, Denver, CO. Bailey, A. M., and R. J. Niedrach. 1965. Birds of Colorado. Denver Museum of Natural History, Denver, CO. Charif, R. A., C. W. Clark, and K. M. Fristrup. 2004. Raven 1.2 User’s Man- ual. Cornell Laboratory of Ornithology, Ithaca, NY. Drovetski, S. V., R. M. Zink, S. Rohwer, I. V. Fadeev, E. V. Nesterov, I. Kara- godin, E. A. Koblik, and Y. A. Red’kin. 2004. Complex biogeographic history of a Holarctic passerine. Proceedings of the Royal Society B 271(1538). doi:10.1098/rspb.2003.2638. Hejl, S. J., J. A. Holmes, and D. E. Kroodsma. 2002. Winter Wren (Trog- lodytes hiemalis), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, NY. http://bna.birds.cornell.edu/bna/ species/623. doi:10.2173/bna.623. Leukering, T., and N. Pieplow. 2010. Pacific and Winter Wrens. Colorado Birds 44:281–286. National Audubon Society. 2015. Audubon’s Birds and Climate Change Re- port: A Primer for Practitioners. Version 1.3. National Audubon Society, New York. http://climate.audubon.org/. Small, A. 1994. California Birds: Their Status and Distribution. Ibis Publish- ing, Vista, CA.

140 Colorado Birds Summer 2017 Vol. 51 No. 3 Toews, D. P. L., and D. E. Irwin. 2008. Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology 17:2691–2705. Toews, D. P. L., and D. E. Irwin. 2012. Pacific Wren Troglodytes( pacificus), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Or- nithology, Ithaca, NY. http://bna.birds.cornell.edu/bna/species/720.

Mike Britten, Ecologist, National Park Service Rocky Mountain Inventory and Monitoring Network, Fort Collins, CO Jeff Connor, Biologist (retired), Rocky Mountain National Park, Estes Park, CO Kurt Fristrup, Bioacoustical Scientist, National Park Service Natural Sounds and Night Skies Division, Fort Collins, CO

Colorado Birds Summer 2017 Vol. 51 No. 3 141 NEWS FROM THE FIELD

Winter 2016–2017 (December–February)

David Dowell “News from the Field” contains reports of rare birds found in Colorado. These reports are compiled from eBird (ebird.org), the COBirds listserv ([email protected]), and the West Slope Birding Network ([email protected]). The reports contained herein are largely unchecked, and the editors do not necessarily vouch for their authenticity. Species in capitals are those for which the Colorado Bird Records Committee (CBRC) requests documentation. Please submit your sightings of these “review” species through the CFO website at coloradobirdrecords.org. Season Overview Winter 2016–2017 was warmer than average, resulting in more ice-free patches on the lakes than usual. Opportunities to view water birds produced good numbers of birds and numerous rarities. The relatively mild weather for winter also might help explain the large number of warm-season passerines found in Colorado this winter: Western Kingbird, Blue-gray Gnatcatcher, Eastern Phoebe, Oven- bird, Grasshopper Sparrow, Chipping Sparrow, Lark Sparrow, Savan- nah Sparrow, and Bullock’s Oriole. The star of the show during winter 2016–2017 was a Purple Sand- piper, found by Jack and Ryan Bushong at Dillon Reservoir in Sum- mit County. This unusual-looking shorebird breeds in high-latitude tundra and winters along rocky Atlantic coasts of the US, Canada, and Europe. This surprise visitor to Colorado made daily appearances 16–31 Dec at its favorite spot in the Blue River inlet of Dillon Reser- voir, feeding on what appeared to be aquatic worms. This sighting of Purple Sandpiper represents a new state record, and was species #502 on the Colorado list. In the list of reports below, county names are italicized, and the fol- lowing abbreviations are used: CFO – Colorado Field Ornithologists; CG – campground; DFO – Denver Field Ornithologists; m.ob. – many observers; NA – Natural Area; NHS – National Historic Site; NP – National Park; NWR – National Wildlife Refuge; Res. – Reservoir; SP – State Park; STL – State Trust Lands; SWA – State Wildlife Area.

Greater White-fronted Goose: 1 BRANT (Black): 1 at Hidden / at Parachute, Garfield, 17 Feb (Vic Mayham Lake (Adams), Aurora Res. Zerbi); rare for this region. (Arapahoe) and then East Lake Shores

142 Colorado Birds Summer 2017 Vol. 51 No. 3 One Tundra Swan and two Trumpeter Swans, Rice’s Pond at Fountain Creek Regional Park, El Paso County, during Hooded Merganser, Cherry Creek SP, the Fountain CBC on 14 Dec 16. Photo Arapahoe County, 3 December 2016. by Bill Maynard Photo by Todd Deininger

Park (Adams), 13–31 Dec (Chris Ru- 24 Jan (Rick Harner). 2 at Colorado rik, Meg Reck, Kim Mauritz, m.ob.). 1 River SP, Mesa, 4–18 Feb (Eileen at Aurora Res., Arapahoe, 15–23 Jan Cunningham, Carol Ortenzio, m.ob.). (David Blue, Sean Walters, Steven 2 at Jumbo Res., Logan, 12 Feb (Da- Mlodinow, m.ob.). 1 at Indian Tree vid Dowell, Tim Smart, Joey Kellner, Golf Course, Jefferson, 26 Jan–3 Mar Kathy Mihm Dunning). (Doug Faulkner, m.ob.). Tundra Swan: Reports from Arap- Trumpeter Swan: 2 at Fountain ahoe, Bent, Boulder, Chaffee, Delta, Creek Regional Park, El Paso, 14–15 Denver, Douglas, El Paso, Jefferson, La Dec (Ted Floyd, m.ob.). 1 near De- Plata, Larimer, Mesa, Montrose, Mor- Beque, Mesa, 12–26 Dec (Tom & Kay gan, and Pueblo, 1 Dec–14 Feb. McConnell, Carol Ortenzio, JoAnn EURASIAN WIGEON: 1 in Ca- Riggle). 1 at Crown Hill Regional ñon City, Fremont, 7–18 Dec (Mark Park, Jefferson, 25 Dec (Paul Welsch- Peterson, m.ob.). 1 at Verhoeff Res., inger, m.ob.). 1 at Rocky Mountain Bent, 12 Feb (Janeal W. Thompson, Arsenal NWR, Adams, 26 Dec (Susan Jane Stulp). Rosine). 1 at Chatfield SP,Douglas , 27 AMERICAN BLACK DUCK: 1 Dec–27 Feb (Jeff Beavers, m.ob.). 2 at Poudre Ponds, Weld, 4 Dec (Steven near Ovid, Sedgwick, 2 Jan (Sean Wal- Mlodinow, Nick Moore). 1 at Woods ters, Steven Mlodinow). 1 at Highline Lake, Weld, 25–27 Feb (Steven Mlodi- Lake SP, Mesa, 31 Dec–2 Jan (Mike now, m.ob.). Henwood, Denise & Mark Vollmar). Blue-winged Teal: 1 at Verhoeff 1 near Grand Junction, Mesa, 2 Jan Res., Bent, 12 Feb (Jane Stulp, Janeal (Denise & Mark Vollmar). 2 near W. Thompson). 1 at Belmar Park, Grand Junction, Mesa, 10 Jan (Diane Jefferson, 28 Feb (Art Hudak, Mark Trappett). 13 at Browns Park NWR, Chavez). Moffat, 17–29 Jan (Tresa Moulton, Surf Scoter: 1 at Rocky Mountain Tom Litteral). 6 near Delta, Delta, Arsenal NWR, Adams, 2 Dec (Mi-

Colorado Birds Summer 2017 Vol. 51 No. 3 143 Black Rosy-Finch, Fawn Brook Inn, Al- Leucistic House Finch, Chautauqua lenspark, Boulder County, 27 December Park, Boulder County, 29 December 2016. Photo by David Waltman 2016. Photo by Jane Baryames

Lapland Longspur, Chico Basin Ranch, Canyon Towhee, John Martin Reservoir, El Paso County, 12 December 2016. Bent County, 12 December 2016. Pho- Photo by Bill Maynard to by Janeal Thompson

Lincoln’s Sparrow, Van’s Grove–Hasty, Swamp Sparrow, Fountain Creek Re- Bent County, 12 December 2016. Pho- gional Park, El Paso County, 2 Decem- to by Janeal Thompson ber 2016. Photo by Bill Maynard

144 Colorado Birds Summer 2017 Vol. 51 No. 3 Scaled Quail, Lamar, Prowers County, Dunlin, McClellan Reservoir, Arapahoe 10 December 2016. Photo by Dave County, 3 February 2017. Photo by Leatherman Joey Kellner chael Lanzone, Andrew McGann). Miller, m.ob.). 2 at Cherry Creek SP, As many as 3 at Aurora Res., Arapa- Arapahoe, 4 Dec (Art Hudak, Mark hoe, 2–10 Dec, ongoing from Oct Chavez). 1 at Chatfield SP,Jefferson , and Nov. 1 at Windsor Lake, Weld, 6 Dec, ongoing from Nov. 2 at South 4–5 Dec (Steven Mlodinow, Nick Platte Res., Arapahoe, 8 Dec–6 Jan Moore). 1 in La Veta, Huerfano, 31 (Diane Roberts, m.ob.). 1 at Sands Dec (Paul & Polly Neldner, m.ob.). Lake SWA, Chaffee, 11 Dec–19 Jan White-winged Scoter: As many as (Jack Harlan, Sherrie York, m.ob.). 1 3 at Aurora Res., Arapahoe, 2 Dec–12 at Lowell Ponds SWA, Adams, 3–21 Feb, ongoing from Oct and Nov. Dec (Bob Canter, Gabriel Wiltse). Black Scoter: 1 at Aurora Res., 1 at Hamilton Res., Larimer, 23 Dec Arapahoe, 2 Dec, ongoing from Nov. (group led by Nick Komar, m.ob.). 2 3 at Adobe Creek Res., Bent, 3 Dec at Rocky Mountain Arsenal NWR, (David Dowell). 1 at South Platte Adams, 24 Dec (Peter and William Res., Arapahoe, 11–26 Dec (Steve VanDyke). 1 at Horsetooth Res., Lar- Stachowiak, m.ob.). imer, 1–15 Jan (David Dowell, m.ob.). Long-tailed Duck: 1 at Lake Hasty, 1 at Dry Creek Res., Larimer, 1 Jan Bent, 23 Nov–2 Dec (Duane Nelson, (David Dowell). 1 at Pueblo Res., Janeal Thompson). 1 at Stagecoach Pueblo, 1 Jan–10 Feb (group led by Res., Routt, 2–4 Dec (JoAnn Riggle, Joey Kellner, m.ob.). 1 at Rueter-Hess Jason Szyba, m.ob.). 2 at Fossil Creek Res., Douglas, 8–20 Jan (Tim Ryan). Res., Larimer, 3 Dec (Cynthia Mad- Bufflehead × Common Goldeneye sen, David Hill, Mary Keithler, Chris (hybrid): 1 in Craig, Moffat, 10 Feb Goulart, Sue Summers). 1 at Aurora (Jan Leonard). Res., Arapahoe, 3–31 Dec (Brooke Red-throated Loon: 1 at Valmont

Colorado Birds Summer 2017 Vol. 51 No. 3 145 Lesser Black-backed Gull, 2nd cycle, Greater Yellowlegs, private property– Prospect Lake in Memorial Park, Colo- Hasty, Bent County, 8 January 2017. rado Springs, El Paso County, 26 Feb- Photo by Janeal Thompson ruary 17. Photo by Bill Maynard

Res., Boulder, 6 Dec (David Dowell, cival, Mark Peterson, Tony Leukering, Christian Nunes). 1 at Chatfield SP, Glenn Walbek, Kathy Mihm Dun- Douglas, 6 Dec (David Suddjian, Lisa ning, m.ob.). 1 at Valmont Res., Boul- Edwards, Loch Kilpatrick). 1 at Pueb- der, 4 Dec–13 Jan (Jeff Parks, m.ob.). lo Res., Pueblo, 10 Dec (Robb Hinds). 1 at Walden Ponds, Boulder, 9 Jan 1 at Highline Lake SP, Mesa, 13–17 (Kim Mauritz). Dec (Kathleen McGinley, Mike Hen- Clark’s Grebe: 1 at Navajo Res., wood, Eileen Cunningham, m.ob.). Archuleta, 22 Feb (Jim Beatty); no pri- 1 at Adobe Creek Res., Kiowa, 5 Feb or winter records in western Colorado. (Steven Mlodinow, David Dowell). Great Egret: 1 near Delta, Delta, Pacific Loon: 1 at Marston Res., 3–16 Dec (Bill Harris, Rick Harner, Denver, 25 Nov–4 Dec (Ira Sanders, Maureen Briggs). 1 at Connected m.ob.). 1 at Pueblo Res., Pueblo, 4 Lakes SP, Mesa, 6 Dec (Maureen Dec, ongoing from Nov. 1 at Valmont Briggs). Res., Boulder, 4–9 Dec (Jeff Parks, Turkey Vulture: 1 in Berthoud, David Dowell). 1 at Aurora Res., Larimer, 4 Feb (Brittany Woiderski). Arapahoe, 10 Dec (Steven Mlodinow, Dunlin: 1 at Cherry Creek SP, Nick Moore). 1 at John Martin Res., Arapahoe, 7 Dec (Art Hudak, Mark Bent, 14–15 Dec (Jane Stulp, Janeal Chavez, m.ob.). 1 at McLellen Res- W. Thompson, Dave Leatherman, ervoir, Arapahoe, 17 Dec (Ed Holub, m.ob.). Thomas Holub, Nelson Ford) and 24 Red-necked Grebe: 1 at Boulder Jan–14 Feb (Gregg Goodrich, m.ob.). Res., Boulder, 28 Oct–6 Dec (Da- 1 at Pueblo Res., Pueblo, 21 Jan–5 Feb vid Dowell, m.ob.). 1 (30 Oct–Feb (Jesse and Renee Casias, m.ob.). 28) and for a while 2 (9–22 Jan) at PURPLE SANDPIPER: 1 at Dil- Pueblo Res., Pueblo (Brandon K. Per- lon Res., Summit, 16–31 Dec (Ryan

146 Colorado Birds Summer 2017 Vol. 51 No. 3 Red-tailed Hawk (Krider’s), Lamar, Bald Eagle, Washington Park, Denver Prowers County, 22 February 2017. County, 29 January 2017. Photo by Photo by Dave Leatherman Todd Deininger and Jack Bushong, m.ob.); first state ICELAND GULL (Iceland / record. Kumlien’s): 1 adult at Cherry Creek Baird’s Sandpiper: 1 at John Mar- SP, Arapahoe, 3–5 Dec (Glenn Wal- tin Res., Bent, 26 Feb (Duane Nelson). bek, Tim Ryan). As many as 2 adults Least Sandpiper: 2 at Rocky Ford (8 Dec–28 Jan) and 1 first cycle (8–21 SWA, Otero, 30 Jan (Stanley Oswald). Jan) at Aurora Res., Arapahoe (Da- Long-billed Dowitcher: 2 at Boyd vid Dowell, Kathy Mihm Dunning, Lake, Larimer, 20 Feb (Mike McCloy, Glenn Walbek, Steven Mlodinow, Andy Bankert). 2 at Pueblo Chemical Nick Moore, m.ob.). 1 first cycle at Depot, Pueblo, 22 Feb (Clark Jones). Horsetooth Res., Larimer, 30 Dec AMERICAN WOODCOCK: (David Dowell). 1 (1 Jan) and then 3 2 (8–11 Jan) and then 1 (13 Jan–28 (3 Jan) first cycle at Larimer County Feb) at Bobcat Ridge NA, Larimer, 8 Landfill, Larimer (Nick Komar, Sean Jan (David Wade, Cole Wild, m.ob.); Walters, Tom Thomson, David Dow- third winter in a row for American ell, Steven Mlodinow). 1 first cycle Woodcock at this location. at Big Johnson Res., El Paso, 11 Jan Spotted Sandpiper: Reports from (Mark Peterson). 1 adult at Prewitt 10 different locations in Adams, Arap- Res., Washington, 12 Feb (Joey Kell- ahoe, Archuleta, Douglas, Garfield, La ner, Tim Smart, Kathy Mihm Dun- Plata, Mesa, and Pueblo, 2 Dec–18 Feb. ning, David Dowell). 1 first cycle at Franklin’s Gull: 1 at Horsetooth Horseshoe Res., Larimer, 26–28 Feb Res., Larimer, 14 Jan (Nick Komar, (David Dowell, David Wade). 1 adult David Wade). at Woods Lake, Weld, 25 Feb (Steven California Gull: 1 at Ridgway Res., Mlodinow). Ouray, 11 Jan (Kathy Mihm Dun- GLAUCOUS-WINGED GULL: ning); rare for this date and location. 1 first cycle at Larimer County Land-

Colorado Birds Summer 2017 Vol. 51 No. 3 147 Red-bellied Woodpecker female, Chico Ferruginous Hawk, Prowers County, 10 Basin Ranch, El Paso County, 1 Dec February 2017. Photo by Jane Stulp 16. Photo by Bill Maynard fill, Larimer, 30 Dec (David Dowell). 3 near Cañon City, Fremont, 30 Dec–1 2 first cycle at Aurora Res.,Arapahoe , Jan (Dan Belter, David Tønnessen, 15–28 Jan (Sean Walters, Steven Kara Carragher, Richard Bunn, Mark Mlodinow, m.ob.). Peterson, Jan Allbright, Lisa Ed- Great Black-backed Gull: 1 adult, wards). joined by a second adult 7–12 Jan, at Red-naped Sapsucker: 2 in Du- Pueblo Res., Pueblo, 18 Nov–26 Feb rango, La Plata, 14 Dec–19 Feb (Kristi (Wendy Wibbens, Brandon Percival, Dranginis, Ryan Votta, Aaron Keller, Glenn Walbek, Loch Kilpatrick, Amy Dobbins). 1 in Lyons, Boulder, m.ob.). 1 adult at John Martin Res., 27 Dec–31 Jan (Peter Burke, m.ob.). Bent, 15 Dec–1 Jan (Mark Peterson, Eastern Phoebe: 1 near Boulder, Brad Steger, Duane Nelson, Janeal Boulder, 18 Dec (Christian Nunes, W. Thompson). 1 first cycle at Au- Peter Gent). 1 at South Platte Park, rora Res., Arapahoe, 22 Dec–5 Feb Arapahoe, 18 Dec and 19 Feb (Ben (David Dowell, m.ob.). 1 adult at Au- Sampson, Doug Ward). rora Res., Arapahoe, 13–28 Jan (Glenn Western Kingbird: 1 at Cherry Walbek, m.ob.). 1 first cycle at Boul- Creek SP, Arapahoe, 25 Feb (Susan der Res., Boulder, 6 Feb (Ted Floyd). 1 Rosine, Wendy Wibbens). first cycle at Horseshoe Res.,Larimer , PACIFIC WREN: 1 in Durango, 27 Feb–1 Apr (David Wade, m.ob.). La Plata, 19 Jan–8 Feb (Ryan Votta, Band-tailed Pigeon: 1 at Green m.ob.). Mountain Falls, Teller, 15–17 Jan Carolina Wren: 1 in Colorado (Richard Bunn, Jan Allbright). Springs, El Paso, 6 Dec (Jo Romero). Barn Owl: 1 near Ridgway, Ouray, 1 in Lamar, Prowers, 17 Jan–19 Feb 21 Dec (Kent Nelson); rare for this (Dave Leatherman, m.ob.). date, location and elevation. Blue-gray Gnatcatcher: 1 at John White-throated Swift: As many as Martin Res., Bent, 15 Dec (Mark Pe-

148 Colorado Birds Summer 2017 Vol. 51 No. 3 White-breasted Nuthatch, Lamar, Prow- ers County, 14 January 2017. Photo by Janeal Thompson

Common Raven, Lagerman Reservoir, 11 Nov–11 Dec (Janeal W. Thomp- Boulder County, 21 January 2017. son, m.ob.). Photo by Todd Deininger Grasshopper Sparrow: 1 at Chat- field SP,Douglas / Jefferson, 17 Dec terson, Brad Steger). 1 in Hotchkiss, (Joey Kellner). Delta, 1 Jan (Dennis Garrison). 2 at Chipping Sparrow: 1 near Frank- Brewster’s Ridge, Mesa, 21 Feb (De- town, Douglas, 6 Dec (Hugh Kingery). nise & Mark Vollmar). Lark Sparrow: 1 at Parker Re- Varied Thrush: 1 near Sterling, gional Park, Douglas, 3 Dec (Chris Logan, 20 Dec–2 Jan (William Kaemp- Gilbert). fer, m.ob.). 1 at Ken Caryl Valley, Jef- Fox Sparrow (Red): 1 in Colorado ferson, 29 Dec (David Suddjian). Springs, El Paso, 27 Feb (Richard Tay- Bohemian Waxwing: 200–400 in lor, David Tønnessen, m.ob.). the Steamboat Springs area including Golden-crowned Sparrow: 1 near 120 at one location, Routt, 14–17 Dec Grand Junction, Mesa, 6 Dec–8 Jan (Tresa Moulton, Yampa Valley Bird (Carol Ortenzio, m.ob.). 1 at Rocky Club). 1 in Boulder, Boulder, 19 Dec Ford SWA, Otero, 16 Dec (Kathy (Mark Chavez). 22 in Allenspark, Mihm Dunning). Boulder, 28 Dec (Chris Wood, Jessie Harris’s Sparrow: 1 in Craig, Mof- Barry). 1 at Rocky Mountain NP, Lar- fat, 4–25 Jan (Jan Leonard, Judith imer, 1 Jan (Sean Walters). Orton, Forrest Luke). 1 in Jeffer- Ovenbird: 1 at Fort Lyon Wildlife son, Park, 5–28 Jan (John W. Cobb, Easement, Bent, 15 Dec (Kathy Mihm m.ob.). Other reports from the Front Dunning, Lisa Edwards). Range and eastern plains. Palm Warbler: 1 at First Creek Savannah Sparrow: 1 near Boul- Open Space, Denver, 4 Dec (Todd der, Boulder, 18 Dec and 24 Feb Deininger). (Christian Nunes, Peter Gent). Pine Warbler: 1 in Lamar, Prowers, EASTERN MEADOWLARK

Colorado Birds Summer 2017 Vol. 51 No. 3 149 Harris’s Sparrow, Colon Orchard, Fre- Golden-crowned Sparrow, Rocky Ford mont County, 18 December 2016 during SWA, Otero County. 16 December Penrose CBC. Photo by Bill Maynard 2016. Photo by Kathy Mihm Dunning

Rusty Blackbird, Cherry Creek, Arapa- Ovenbird, Ft. Lyon Wildlife Easement, hoe County, 3 December 2016. Photo Bent County, 15 December 2016. Pho- by Todd Deininger to by Kathy Mihm Dunning

Pine Warbler, Willow Valley, Lamar, Yellow-rumped Warbler, Willow Val- Prowers County, 8 December 2016. ley, Lamar, Prowers County, 5 January Photo by Janeal Thompson 2017. Photo by Janeal Thompson

150 Colorado Birds Summer 2017 Vol. 51 No. 3 Marsh Wren, Lamar Community Col- Carolina Wren, Lamar Community Col- lege, Prowers County, 18 January 2017. lege, Prowers County, 18 January 2017. Photo by Janeal Thompson Photo by Janeal Thompson

(Lilian’s): 1 at John Martin Res., Ward). 2 in La Veta, Huerfano, 31 Bent, 5 Feb (Steven Mlodinow, David Dec–1 Jan (Dave Silverman, m.ob.). Dowell). 3 at Wheat Ridge Greenbelt, Jefferson, Rusty Blackbird: As many as 5 2–7 Jan (Aaron Shipe). As many as 4 at Cherry Creek SP, Arapahoe, 26 near Hudson, Weld, 2–21 Jan (Doug Nov–11 Dec (Mary Keithler, m.ob.). Shoffner, m.ob.). 1 at Lake Pueblo SP, As many as 6 at Rocky Mountain Ar- Pueblo, 10 Jan (Brandon K. Percival). senal NWR, Adams, 1–4 Dec (Brian 3 at Barr Lake SP, Adams, 21 Jan–12 Berry, m.ob.). 1 at Marjorie Perry Na- Feb (Kim Mauritz, George Ho). 2 at ture Preserve, Arapahoe, 4 Dec (Sunny Cherry Creek Valley Ecological Park, Bradford). 2 at Valco Ponds SWA, Arapahoe, 10 Feb (Sunny Bradford). Pueblo, 4–17 Dec (Steve Larson, Loch Bullock’s Oriole: 1 in Boulder, Boul- Kilpatrick, Glenn Walbek, m.ob.). 1 der, 13–18 Dec (Laura Osborn, m.ob.). at Adams and Bunker Res., Weld, 27 White-winged Crossbill: 1 at Left Dec (Taylor Long, Steven Mlodinow, Hand Res., Boulder, 15 Jan (Christian Chris Wood, Jessie Barry). 1 at South Nunes). 12 at Winter Park Ski Area, Platte River, Adams, 28 Dec (Doug Grand, 12 Feb (Andy Boyce).

ACKNOWLEDGMENTS The sightings reported by contributing observers to eBird, COBirds, and the West Slope Birding Network are greatly appreciated. Volunteer compilers contributed significantly to this report: Joyce Takamine (COBirds), Jim Beatty (southwest Colorado), Coen Dex- ter (west), Dave Leatherman, Forrest Luke (northwest), Rich Miller, Brandon Percival, John Rawinski (San Luis Valley), and David Silverman. Much of the information in this report was obtained from the eBird Basic Dataset from the Cornell Lab of Ornithology, Ithaca, New York.

David Dowell, [email protected]

Colorado Birds Summer 2017 Vol. 51 No. 3 151 Wilson’s Snipe, Bobcat Ridge Natu- ral Area, Larimer County, 26 January 2017. Photo by Dave Leatherman Greater Roadrunner, Lake Hasty, Bent County, 8 February 2017. Photo by Ja- neal Thompson

Red-tailed Hawk, Boulder County, Barn Owl, Wertz Pond (feedlot), La- 13 January 2017. Photo by Todd mar, Prowers County, 12 February Deininger 2017. Photo by Janeal Thompson

152 Colorado Birds Summer 2017 Vol. 51 No. 3 Eastern Screech-Owl, Ft. Collins, Lar- imer County, 27 January 2017. Photo by Dave Leatherman Yellow-bellied Sapsucker, Willow Val- ley, Lamar, Prowers County, 4 January 2017. Photo by Janeal Thompson

Mountain Chickadee, Chautauqua Ruby-crowned Kinglet, John Martin Park, Boulder County, 17 February Reservoir, Bent County, 15 December 2017. Photo by Jane Baryames 2016. Photo by Janeal Thompson

Eastern Bluebird, Lamar Community Cedar Waxwing, Boulder, Boulder College, Prowers County, 11 February County, 24 February 2017. Photo by 2017. Photo by Janeal Thompson Jane Baryames

Colorado Birds Summer 2017 Vol. 51 No. 3 153 IN THE SCOPE

Selected Bird Subspecies of Interest in Colorado: Part 1

Tony Leukering and Steven G. Mlodinow Birders have long ignored identification to the subspecies level, but that has changed, with a recent surge of interest. This is likely driven, in part, by the splitting fever in vogue in avian taxonomy (leading to the addition of five species to the Colorado list in the past 15 years!) but undoubtedly also due to enhanced coverage in popular field guides. An additional cause may be eBird’s (www. ebird.org) facility for reporting of birds to the subspecies/subspecies group level for some species. Colorado, where three major life zones converge, is a fantastic place to study subspecies: how they interact where they meet (including interbreeding), differences in their habitat choices and migration timing, and other life history disparities. Previous “In The Scope” essays have treated this topic in a more species-focused fashion, primarily from the potential-future-splits point of view. This essay treats field-identifiable subspecies in a more- distant fashion with the aim of introducing Colorado’s birders to some of the amazing variety within species that occur in our state. While some of these subspecies have potential to be elevated to spe-

Fig. 1 (back cover). This pale beauty is a juvenile Krider’s Red-tailed Hawk, as discerned by the overall paleness, with relatively little in the way of markings on the head and the white ground color to the tail. Despite previous decades of little definitive evidence of occurrence in Colorado, recent years have seen a plethora of reports backed by confirmatory photographs, most of adults. Smith Point, Chambers Co., TX; 13 November 2012. Photo by Tony Leu- kering

Fig. 2 (back cover). The depicted flying sprite is an Eastern Blue-gray Gnatcatcher. The most- easily used plumage feature to differentiate this form from the western subspecies is the extensive white on the outer rectrices, which extends all the way to the white undertail coverts. On West- ern Blue-gray, the white does not quite extend to the undertail coverts, resulting in a band of black separating the coverts from the white of the rectrices. Smith Point, Chambers Co., TX; 7 October 2012. Photo by Tony Leukering

Fig. 3 (back cover). Unlike the form that breeds in Colorado, individuals of the Eastern/ Northern subspecies group of Hermit Thrushes are smaller than Swainson’s Thrushes and have browner upperparts and more-orange tails. This bird, with its gray flanks, is probably referable to the western subspecies of the group, euborius, the form of most likely occurrence in the state. Cape May Point, Cape May Co., NJ; 17 January 2015. Photo by Tony Leukering

154 Colorado Birds Summer 2017 Vol. 51 No. 3 cies rank, many do not. The pictures on the back cover of this issue provide just a few illustrative examples of the variety inherent in Colorado’s avifauna. This essay is not intended as a thorough treatment of the subject, but as a primer, and a primer that will occur in this venue in multiple parts, with the species presented in this first part being chosen for the relative ease in which birders can provide distributional data and, generally, for the widespread distribution in the state of the species. In fact, birders can greatly expand upon our knowledge of subspecies distributions, as we have so many more eyes in the field than do taxonomists. Before digging into subspecies, though, we should take a mo- ment to define what constitutes a subspecies. Many taxonomists in the late nineteenth century and first half of the twentieth century named subspecies on the basis of average differences between populations under study, resulting in a plethora of subspecies, many poorly defined or undefinable. Amadon (1949) followed by Mayr et al. (1953) and Patten and Unitt (2002) attacked this problem with the somewhat misleadingly named “75% rule.” Depending on what parameters are chosen, the 75% rule definition means that 90–97% of the individuals of one population must be distinguishable from the equivalent percentage of the other population to be considered a subspecies (Remsen 2010). Many of the earlier classified subspecies are now placed together in “subspecies groups”—one or more subspecies of generally similar appearance and differing from other such groups

Fig. 4 (back cover). Red Fox Sparrows are of annual occurrence in Colorado in very small numbers, being found primarily in late fall and winter. They differ in many respects from the breeding form, which is generally absent from the state in late fall and winter. The most-readily discerned plumage differences are the upperparts streaking, the thin wing bars, and the sizable patches of rufous coloration on the head. However, beware of hybrid Red × Slate-colored Fox Sparrows, which can show a bewildering mix of characteristics. Cape May Point, Cape May Co., NJ; 3 January 2014. Photo by Sam Galick

Fig. 5 (back cover). Pink-sided Junco provides one of the treats of junco ogling in Colorado from mid-fall through mid-spring. This adult (probably a male) shows off its soft gray head and upperparts contrasting with the extensive pink sides and the black loral area. This subspecies of Dark-eyed Junco is larger, and sports more white in the tail, than all Colorado juncos other than White-winged. Lyons, Boulder Co., CO; 31 January 2017. Photo by Steven G. Mlodinow

Fig. 6 (back cover). This immature White-crowned Sparrow, given this excellent view, is readily determined to belong to the Gambel’s subspecies by the pale loral area and orange bill. That form is a fall through spring visitor to the state from its far-northern breeding range. Virtually all White-crowned Sparrows in the state in winter are referable to this form. Union Reservoir, Weld Co., CO; January 2017. Photo by Steven G. Mlodinow

Colorado Birds Summer 2017 Vol. 51 No. 3 155 in a fairly consistent fashion; these groupings better conform to the 75% rule.

A sampling of polytypic species of Colorado “Polytypic” is a great little word that means “of multiple types” and is a descriptor of those species composed of two or more subspecies; the antithesis of it is “monotypic.” For polytypic species, one subspecies is the “nominate” one, that is, the one for which the species was named and is indicated in the subspecies trinomial by having the species name (which always has a lower-case first letter) repeated (e.g., Chordeiles minor minor, the widespread subspecies of Common Nighthawk). Other subspecies for that species have names differing from the species name (e.g., Chordeiles minor henryi, the southwestern U.S. breeding form of Common Nighthawk; see Leukering 2016a). In this essay, occurrence of individual subspecies in Colorado has been garnered primarily from Bailey and Niedrach (1965) and Pyle (1997, 2008). As a beginning to this discussion, those polytypic species that have already seen treatment in Colorado Birds are listed in Table 1, along with a reference to the paper treating it (the full citation of which can be found in the Literature Cited section). Below, we discuss the occurrence in Colorado of ten polytypic species, presented in current taxonomic order promulgated by the Amer- ican Ornithological Society (AOU 1998 and supplements, including the 58th [Chesser et al. 2017]). For each species, we note the various subspecies that have been officially recorded in Coloradoin boldface the first time that each appears, with “officially” defined by Bailey and Niedrach (1965) and Pyle (1997, 2008). We also include notation of other subspecies for which there is some evidence of occurrence in the state (usually photographic) or for which potential occurrence is inferred from the subspecies’ proximity to the state border. For each subspecies or subspecies group, we provide a telegraphic indication of known range (whether resident or migratory) and some gross es- timation of the frequency of occurrence or potential occurrence. For a few species of particular interest, we provide greater detail on the occurrence in Colorado of the various subspecies. We provide a brief synopsis of how the various subspecies of individual species might be identified in the field, though refer readers to field-guide treatments and other publications where such are covered thoroughly. Where there are widely used English names for individual subspecies or subspecies groups, those are noted. Red-tailed Hawk (Buteo jamaicensis) – This species is found in a plethora of color morphs and subspecies in Colorado and winter

156 Colorado Birds Summer 2017 Vol. 51 No. 3 ogling of buteos can be very fun, interesting, and challenging. See Wheeler (2003) for subspecific identification criteria in general. • harlani (Harlan’s Hawk), occurring in both dark and light morphs, is an uncommon migrant and winterer from its eastern Alas- ka and west-central Canada breeding grounds. Harlan’s is decidedly more common in eastern Colorado than on the West Slope, where it is apparently regular only in the Grand Valley (in and near Grand Junction). This subspecies occurs widely in eastern Colorado from early October through mid-April and, as with Red-tailed Hawk in general, is not often found a great distance from trees. Thus, it is sought most successfully in the I-25 corridor and along the major plains riparian zones. See Schmoker and Liguori (2010) for details of an Alaskan “recovery” of a Colorado-wintering Harlan’s Hawk. See Ligouri and Sullivan (2010a) for an in-depth discussion of this subspecies’s identification • calurus (Western Red-tailed Hawk) occurs throughout the state as breeder, resident, and migrant, but meets and hybridizes with borealis widely on the eastern plains. This form occurs in three morphs—light, intermediate (rufous), and dark—with, probably, all present in varying numbers in winter, particularly on the West Slope. Virtually all eastern-Colorado breeders are of the light morph, which generally exhibit a dark throat, a heavy belly band, and usually extensive brown or rufous barring on the upper leg feathers (= ”flags”), and often have multiple dark tail bands. • borealis (Eastern Red-tailed Hawk) breeds and winters in eastern Colorado, but see above. Many individual Red-tailed Hawks in eastern Colorado are intermediate in appearance between Western and Eastern Red-tailed Hawks, particularly in summer; the migration and winter seasons there see an influx of Easterns. Adult Eastern Red-taileds have white throats, sometimes with a dark frame; fairly minimal belly bands; unmarked whitish flags; and any banding in the tail being restricted to a single dark subterminal band. • krideri (Krider’s Hawk; subsumed into borealis by Pyle 2008; Fig. 1 on back cover) may actually be a pale morph of Eastern Red-tailed Hawk (Wheeler 2003, Pyle 2008), rather than a good subspecies of its own. That is because its entire known breeding range is embedded within the range of Eastern Red-tailed Hawk, a phenomenon precluded by subspecies theory. Regardless, there has been a recent plethora of well-photographed individuals referable to this form in northeastern Colorado, after decades of numerous unsubstantiated reports; recent advances in field-guide treatment of Krider’s (particularly its differentiation from light-morph Har- lan’s Hawk) are probably the primary cause of this change. For a de-

Colorado Birds Summer 2017 Vol. 51 No. 3 157 tailed discussion of Krider’s identification, see Ligouri and Sullivan (2010b). • abieticola (Northern Red-tailed Hawk; subsumed into borealis by Pyle 2008) breeds in the extensive Canadian boreal forest, but vacates virtually all of the breeding range for winter. Little is known of this taxon, though Liguori and Sullivan (2014) thoroughly treated our current knowledge of its identification. However, that paper presented little about its distribution. Wheeler (unpubl. ms.) considers this taxon to be simply part of the incredibly extensive variation in appearance in his expanded borealis. There are 15 reports in eBird of this form from Colorado, with all but one from the northern plains (primarily Weld County); the other is from Bent County. Sandhill Crane (Antigone canadensis) – Two subspecies occur in Colorado with, generally, Greater Sandhill Crane (tabida) being found in western Colorado and Lesser Sandhill Crane (canadensis) traveling through eastern Colorado. Greater is the form that concen- trates in the San Luis Valley in spring, breeds in northwestern Colo- rado in summer, and has fairly recently been found wintering in the Colorado River drainage on the West Slope. Lesser is a long-distance migrant that passes through eastern Colorado on its way to winter grounds to our south and east; it is considerably less abundant as a spring migrant, as virtually the entire subspecies’ population passes through eastern Nebraska at that season. The recent occurrence of Sandhill Crane breeders and summering individuals in Larimer and Weld counties are presumably of Greaters, as Lesser is unknown to breed anywhere near Colorado. Greater averages some 10–15% larger than Lesser. However, there is overlap between the two subspecies in the five mensural characters reported by Pyle (2008), though only minimal for most, particularly leg length. Greaters have flatter crowns, giving a more aggressive look, while Lessers tend to have more rounded forecrowns, producing a gentler look. Additionally, Greaters have more extensive red crowns than Lessers (Gerber et al. 2014). By age, Greaters have browner flight feathers, Lessers blacker flight feathers (Pyle 2008), probably producing a more-contrasting upper wing in Lesser. Northern Flicker (Colaptes auratus) – Virtually all Colorado birders are aware of two types of flickers in Colorado, the more westerly occurring Red-shafted (cafer) and the more easterly Yellow-shafted (auratus). However, what seems much less widely known is that intergrades between the two are frequent, even common, in eastern Colorado, particularly in migration and winter, when intergrades can outnumber the parental subspecies at some locations. Indeed, subspecific identification is far more complicated than presented in field

158 Colorado Birds Summer 2017 Vol. 51 No. 3 guides. Readers should understand that the task is quite challenging and that identifying flickers to subspeciessolely on wing/tail color or head pattern is utterly unreliable. A future “In The Scope” column will treat this tricky situation. Warbling Vireo (Vireo gilvus) – Western (swainsoni) and East- ern (gilvus) Warbling Vireos have received particular focus in recent years in eastern Colorado, as both subspecies breed there. Un- fortunately, male song is currently the only reliable differentiating character, though Westerns average drabber in appearance and are smaller-billed. Also unfortunately, the species account in the recently published second Colorado Breeding Bird Atlas (Leukering 2016b) did not provide specifics on the breeding-season distribution of the two taxa. In general, Eastern Warbling breeds in cottonwood/willow riparian habitat on the plains while Western Warbling is found in montane and western deciduous-forest types. The specifics, though, are a bit more convoluted. Both subspecies breed in a narrow band of longitude just to the east of the Front Range edge and can be found singing nearly side by side at some locations. A paper concerning the breeding distribution of Warbling Vireo taxa in eastern Colo- rado is planned for Colorado Birds. The excellent Earbirding.com blog (Spencer 2012) provides a great introduction into differentiating these two taxa, which may well be split soon. Blue-gray Gnatcatcher (Polioptila caerulea) – Western Blue-gray Gnatcatcher (obscura) is the standard Colorado gnatcatcher, breeding commonly in suitable habitats from the Front Range and Mesa de Maya (the ridge of foothills extending east from the Rockies to the westernmost portion of Oklahoma’s panhandle), westward, and occurring statewide during migration (excepting at upper elevations). However, most range maps show a gap in the Blue-gray Gnatcatcher breeding range extending from central Kansas and Nebraska to central Colorado. Yet, there are gnatcatchers breeding, at least locally, between the Front Range and central Kansas/Nebraska. Recently, some of these have been identified as Eastern Blue-gray Gnatcatch- ers (caerulea; Fig. 2 on back cover), with breeding first confirmed at South Republican State Wildlife Area (SWA; formerly Bonny Lake State Park), Yuma County (Leukering 2016c). Breeding is also sus- pected at Simmons SWA, Yuma County, and Tamarack Ranch SWA, Logan County. During migration, Western is fairly common east to Colorado’s eastern border, while scattered records of Eastern have been noted as far west as Lincoln and western Weld counties (Fig. 7). As far as we are aware, the subspecific identity of the few wintering individuals (most regularly near Grand Junction; Righter et al. 2004) has not been ascertained.

Colorado Birds Summer 2017 Vol. 51 No. 3 159 Blue-gray Gnatcatcher subspecific identification is most reliably accomplished by differences in song and call (Pieplow 2012). The undertail pattern can also be quite useful (see Sibley 2014), and the upperpart coloration tends to be more richly blue in Eastern versus grayish-blue in Western, though this is difficult to reliably use in the field. Hermit Thrush (Catharus guttatus) – Differentiation within Her- mit Thrush is complex, and is best presented in subspecies groups. While Hermit Thrush occurrence in Colorado is not as complex as that for Dark-eyed Junco (see below), the difficulty of field differentiation of Hermit Thrush subspecies makes for a less-tractable problem than that presented by juncos. All plumage descriptions here are taken from Pyle (1997). • auduboni group (Western Mountain group) – The three subspecies of this group are montane, with a breeding distribution centered on the Great Basin, occupying suitable habitat from eastern Cali- fornia north to southeast Washington and southern Montana south to west Texas and into Mexico. Their upperparts are usually grayish, with their tails being relatively dull, but still contrasting with the even-duller upperparts. The nominate subspecies of the group (auduboni) is the form breeding in the Rocky Mountains and is the largest form of Catharus thrush of any species. The back is “medium- pale grayish brown,” the flanks are washed with the same color, and the undertail coverts are pale buff. This subspecies apparently vacates the U.S. for winter (Pyle 1997), thus is the longest-distance migrant of this group. The other two subspecies, sequoiensis and po- lionotus, have not been recorded in the state, but the latter (which has white undertail coverts) seems of likely occurrence on the West Slope (breeds eastern California to northwestern Utah and Ari- zona, winters south from southern Fig. 7. Distribution of records of Eastern Arizona). Blue-gray Gnatcatcher (subsp. caerulea) in • guttatus group (Western Colorado (eBird 2017). Lowland group) – As a group, the

160 Colorado Birds Summer 2017 Vol. 51 No. 3 eight subspecies are nearly entirely confined as breeders to west of the Continental Divide. As indicated by the group’s other moniker, Dwarf Hermit Thrush, these are small thrushes—in fact, the smallest Catharus thrushes in the U.S. and Canada. The northwesternmost- breeding subspecies, guttatus, breeds from coastal southern Alaska to western British Columbia and winters from northern California south to Arizona and east to western Texas and into Mexico. As with other terrestrial migratory Pacific Northwest taxa (e.g., Cas- sin’s Vireo and Townsend’s Warbler), this subspecies probably occurs regularly and in some numbers in the state, as evidenced by the 11 Colorado specimens housed at the Denver Museum of Nature and Science (DMNS; Bailey and Niedrach 1965). The Northern Rockies subspecies, oromelus, breeds from southern interior British Columbia to northwestern Montana southwest to northeastern California and winters from southern New Mexico to southern Texas and south into Mexico. Despite the group name of “Western Lowland,” this is the subspecies that breeds in stunted, treeline and near-treeline forest in and near Glacier National Park, Montana (where it extends onto the east side of the Continental Divide). Of course, treeline there is about 2140 m (6500 feet), so, relatively low compared to Colorado elevations. Not surprisingly with those summer and winter ranges, this subspecies also occurs, probably regularly and in numbers, in Colo- rado, with 13 state-obtained specimens housed at DMNS (Bailey and Niedrach 1965). The Colorado specimens of Dwarf Hermit Thrush are predominantly from eastern low elevations: 10 and 11 specimens, respectively (the odd specimens out were one each of both subspecies from Grand County and one of oromelus from Montezuma County). From our experience in eastern Colorado, these forms may account for the lion’s share of early-season Hermit Thrush occurrences in the state. Certainly, mid-April in Colorado’s mountains is not conducive to breeding Hermit Thrushes and these two forms are among the longest-distance migrants in the species (thus need more time to make their spring migrations). Since guttatus is heading to coastal-plain habitats, it seems intuitively likely that this form would be amongst the earliest migrants to pass through Colorado, perhaps dispropor- tionately so relative to the local breeding form (auduboni, above). The upperparts of this subspecies group are generally browner than in the other two subspecies groups. The back of guttatus is “moderately dark grayish brown” contrasting somewhat with a rump that is washed pale rufous; its flanks are washed brownish gray. This back of oromelus is “moderately pale brownish gray, without rufous” and the flanks are washed pale grayish. • faxoni group (Northern group [a mistake in Pyle (1997) has

Colorado Birds Summer 2017 Vol. 51 No. 3 161 this group as the nanus group, despite that the subspecies nanus is included in the Western Lowland group]). – This group is composed of medium-sized Hermit Thrushes (thus, smaller than Swainson’s Thrush) and has two subspecies, euborius and faxoni. The group has the largest breeding range of the Hermit Thrush subspecies groups, ranging from central Alaska to the Canadian Maritimes and south in the eastern U.S. to the northern Georgia highlands. The two forms of Northern Hermit Thrush meet somewhere in western Canada and both winter east of the Rocky Mountains, so both would be expected to occur in Colorado; in fact, there are specimens of both housed in DMNS. Of the six specimens at DMNS, five are ofeuborius (Fig. 3 on back cover) and one is of faxoni, all taken in eastern Colorado (Bailey and Niedrach 1965). The fiveeuborius are scattered in spring (22 Apr–20 May) and fall (29 Sep–5 Oct). The single faxoni was collected 8 February 1939 and was reported as referable to crymophilus of Newfoundland (Bailey and Niedrach 1965), but that taxon was considered by Pyle (1997) to be incorrectly based on old specimens whose color had changed—a well-known phenomenon among some bird groups. Interestingly, two of the five eBird records from Colorado of this subspecies group are also from winter, though both were in Boulder in the same winter (2016–2017) and separated by some 4.75 km (though both were in close proximity to Boulder Creek, so the two reports may refer to the same individual). The others were from spring (one on 15 Apr 2011, two on 16 Apr 2016) and fall (19 Oct 2010). The back of euborius is “moderately dark brown with a medium-dull rufous wash” and with the flanks “washed grayish brown, sometimes tinged tawny,” while faxoni has the back “brown with a medium-bright rufous wash” and the flanks “washed tawny brown.” Spotted Towhee (Pipilo maculatus) – The predominant subspecies of Spotted Towhee in Colorado, during all seasons, is montanus, hereafter “Montane,” and as for all subspecies noted here, part of Pyle’s (1997) Interior group. This subspecies breeds in montane shrubland and low-elevation riparian forest. However, the breeding and migratory ranges of arcticus, hereafter “Prairie,” apparently include the northeastern corner of Colorado. Bailey and Niedrach (1965) note 34 specimens of arcticus at DMNS, “the majority … from the prairie counties of eastern Colorado taken in April and May,” but with an anomalous record of a June specimen from Jefferson County. eBird (2017) shows a scattering of summer (May–Jul) records of Prairie Spotted Towhee from northeastern Colorado (Fig. 8), with a small number from elsewhere on the plains. Winter and migration records of Prairie come primarily from northeastern Colorado, but with scattered records west to the I-25 corridor from Pueblo north (Fig. 9) and

162 Colorado Birds Summer 2017 Vol. 51 No. 3 with a February specimen from Adams County (Bailey and Niedrach 1965). Note, however, that most such records are from heavily birded locales (most are indicated as eBird hotspots), thus the map may be tracking birding effort more precisely than actual occurrence. Ad- ditionally, the Great Basin subspecies, curtatus, probably occurs in migration and winter (perhaps most likely on the West Slope), as A. R. Phillips notated labels of three Colorado specimens in the DMNS collection as referring to that subspecies, with one of those from Den- ver (Leukering pers. obs.). Differentiation of Montane and Prairie relies primarily on the extent of white on the outer rectrices (most easily noted on the under side of the tail) and, particularly, the amount of white spangling above. These white features are more extensive in Prairie as compared to Montane, though data from Pyle (1997) suggest that the difference in amount of white in the tail is only marginally greater (27– 42 mm on the outermost rectrix in Prairie, 25–40 in Montane). Pyle (1997) notes color differences of the head, back, and rump in males of the two subspecies, montanus being “uniformly black,” arcticus being “grayish black.” It also seems likely that there are at least average differences in female color; Pyle (1997) describes female montanus as blackish slate, arcticus as slaty brown. Since Montane and Prairie are subspecies, and since the subspecies apparently meet in northeastern Colorado, intergrades are to be expected, and apparent intergrades are not unusual. Finally, Great Basin Spotted Towhee is described by Pyle (1997) as having head, back, and rump uniformly blackish in males, dark slaty brown in females. Fox Sparrow (Passerella iliaca) – Colorado hosts two subspecies groups, with the breeding form being schistacea, the nominate member of the Slate-colored group. Slate-colored breeds primarily in the Rocky Mountains from Colorado north to northern British Columbia. It is quite rare on Colorado’s plains at any time and is very rare anywhere in the state between September and March, though a feeder at No Name, Garfield County, has an inexplicable history of hosting the form (eight winters between 1998–1999 and 2015–2016, inclusive; T. McConnell pers. comm., eBird 2017). Despite mention in Bailey and Niedrach (1965), we seriously doubt the identification of eight at Morrison 28 January 1956; it is difficult enough to find eight together in the breeding season when they are expected, much less in winter when there are so few proven reports. Other old non-specimen reports of this subspecies group in Colorado in winter and on the plains are likewise of questionable authenticity. The Red Fox Sparrow (P.i. iliaca group; Fig. 4 on back cover) breeding range stretches from western Alaska to the Canadian Maritimes,

Colorado Birds Summer 2017 Vol. 51 No. 3 163 while the regular winter range extends from southeastern Minne- sota and southeastern Canada south to Texas and northern Florida. This subspecies group is represented in the state by zaboria (Bailey and Niedrach 1965), whose breeding range spans interior Alaska to Manitoba. Differentiation of Red and Slate-colored is well covered in most relevant field guides. Red Fox Sparrow occurs annually in Colorado during winter and migration, with most records coming from the I-25 corridor (likely due in part to birder and feeder density) plus a scattering eastward across Colorado’s plains. There are three Red Fox Sparrow records from Colorado’s West Slope, including the slope’s first in Ouray County (Levad and Leukering 2001, Leukering 2002:105). The other West Slope records hail from Delta and Mont- ezuma counties (CBRC 2017). The Sooty Fox Sparrow (P. i. unalaschcencis group) is a long-distance migrant, breeding as far north as southern Alaska and wintering south to northern Baja California. It has occurred as far astray as New Hampshire and certainly has the potential of appearing in Colorado. Potentially confounding the identification of both Red and Sooty Fox Sparrows is the enigmatic P. i. altivagans, which breeds

Fig. 8. Distribution of summer (May– Fig. 9. Distribution of winter and migra- Jun) records of Prairie Spotted Towhee tion records of Montane Spotted Towhee (subsp. arcticus) in Colorado (eBird (subsp. arcticus) in Colorado (eBird 2017). 2017).

164 Colorado Birds Summer 2017 Vol. 51 No. 3 primarily in northeastern British Columbia and looks like a combina- tion of unalaschcencis, schistacea, and iliaca and is also a long-distance migrant, wintering in southern California. Finally, Red and Sooty Fox Sparrows interbreed where their ranges meet in south-coastal Alaska. Identifying a Sooty Fox Sparrow in Colorado would be complicated by the possibility of this hybrid (see Mlodinow et al. 2012 for more details). Dark-eyed Junco (Junco hyemalis) – A book could be written on the subspecies of this widespread and incredibly variable beast. In fact, one has been (Miller 1941). Many disagree with the current taxonomic treatment of juncos; at least a few forms or groups of forms might deserve elevation to species status, reversing the great lumping of juncos beginning in 1973 (Eisenmann et al. 1973). As in the Her- mit Thrush account, we treat this species by subspecies group. The various field guides, particularly the National Geographic Society (Dunn and Alderfer 2011) and Sibley (2014) guides, treat the identification of various subspecies groups fairly well. Note that appearance varies not only by subspecies, but by age and sex, with immatures and females being generally duller and browner than are adults and males within each subspecies and that field determination of some immature females to subspecies group (to say nothing of individual subspecies!) is problematic, at best. • oreganus group (Oregon Junco) – The Cascades-breeding simil- limus is a medium-bright form that is probably of sporadic occurrence as a migrant and winterer. From its Sierran and western Great Basin breeding range, thurberi is a stunningly bright form of regular occurrence in small numbers in western Colorado. Bailey and Niedrach (1965) report a single Colorado specimen of another bright subspecies, nominate oreganus, collected in Denver 16 October 1885. The subspecies shufeldti (including montanus) is the dull, widespread, and common wintering form in Colorado; the breeding range includes interior western Canada and the northern Rockies. • hyemalis group (Slate-colored Junco) – Nominate hyemalis is a migrant and wintering form throughout Colorado, but more common in the eastern half than in the western half. Cassiar Junco (cismontanus), the males of which are colored like Slate-colored but has the head contrast of Oregon, is considered by Pyle (1997) and eBird as a “good” subspecies of Slate-colored. However, many (including Miller 1941 and Nunes pers. comm.) consider it to comprise a hybrid swarm of individuals originating where hyemalis Slate-colored and oreganus Oregon meet in western Canada and southeast Alaska. Such birds are of regular occurrence in small numbers along the Front Range edge in eastern Colorado, with

Colorado Birds Summer 2017 Vol. 51 No. 3 165 scattered records on the plains south to the New Mexico border and west of the Front Range. • mearnsii group (Pink-sided Junco) – The pale mearnsii (Fig. 5 on back cover) is the sole member of this “group” and is about the most numerous wintering junco in the eastern portion of the state. Pink-sided is a large junco, with pale head plumage contrasting with blackish lores, extensive white in the tail, and with bright pink side coloration (not orange at all) that extends closer to the belly’s lon- gitudinal midline than in any other form of junco, at least in adults. Were it not for the pink sides, Pink-sided Junco would be much more likely to be confused with White-winged Junco than with other forms. • aikeni group (White-winged Junco) – The largest form of the genus, aikeni is another monotypic “group” of Dark-eyed Junco subspecies and is restricted as a breeder to the Black Hills of South Da- kota and nearby ranges in northeastern Wyoming. It is an uncommon winter resident along the Front Range and Wet Mountains, particularly in the ponderosa pine zone, and is a rare winter resident and migrant on Colorado’s eastern plains. This subspecies has been recently treated in Colorado Birds (Leukering 2016e). • caniceps group (Gray-headed Junco) – The southern Rockies breeding form, caniceps, is widespread in montane parts of the state in all seasons and fairly rare to very rare on the eastern plains in migration and winter. Though dorsalis (Red-backed Junco) has yet to be confirmed as occurring in the state, the breeding range approaches Colorado fairly closely in northern Arizona and should be looked for, particularly in Montezuma County. It can be differentiated from Gray-headed most easily by its two-toned bill (like that of Yellow- eyed Junco). An apparent intergrade Gray-headed × Red-backed was photographed in Jefferson County (Leukering and Mlodinow 2012). Such intergrades are not rare in northern Arizona. White-crowned Sparrow (Zonotrichia leucophrys) – Of the five subspecies of White-crowned Sparrow, two, possibly three, occur in Colorado. The summering, Mountain White-crowned Sparrow (ori- antha), and wintering Gambel’s White-crowned Sparrow (gambelii; Fig. 6 on back cover), replace each other seasonally in the state, with surprisingly little temporal overlap in occurrence. The very first Mountains typically arrive in mid-April, but the hordes not until May. The departure of Colorado’s breeders probably begins in late August, though most depart in September, with only a very few stragglers found here in the first half of October. The first Gambel’s typically arrive in the state in mid-September (there are a few earlier records) with peak fall passage occurring in the first three weeks of October;

166 Colorado Birds Summer 2017 Vol. 51 No. 3 the majority of Gambel’s continue farther south for the winter. The first half of April sees the beginning of northward Gambel’s migration, with the peak occurring near the end of April, coinciding with the beginning of the influx of Mountains. By mid-May, Gambel’s has become somewhat rare and the subspecies is all but gone by the last week of May. The Eastern White-crowned Sparrow (nominate leucophrys) probably occurs nearly annually in northeastern Colorado, given the occurrence of dark-lored White-crowned Sparrows (see below) in an area where Mountain White-crowneds are fairly rare and with seasonal occurrence outside the norm for Mountains. While few birders seem to endeavor to differentiate the two subspecies, there are at least three characters (other than seasonal occurrence timing) that provide certain (or nearly so) identification. Some vocalizations—song and contact call—differ by subspecies, though those aspects are not covered here (though see Sibley 2014). The two best appearance clues are bill color—pink in Mountain, orange in Gambel’s—and color of the loral area—dark in Mountain (hence the term “dark-lored”), pale in Gambel’s. These features are most distinctive in adult plumage, less so in immature plumage. De- termining whether the loral area is dark or light can be particularly tricky in immatures. As with many sparrow species (juncos provide a particularly good example), determining whether the loral area is actually contrastingly dark is best done with a view in profile. The loral feathers lie in such a way as to nearly always look dark when viewed from head on; appearance can be deceiving even on individuals with the head turned only partly toward the observer. Under nor- mal field conditions, Eastern White-crowned Sparrow looks identical to Mountain White-crowned Sparrow, though Pyle (1997) describes the difference in upperparts coloration as “medium-pale brownish and reddish” in Mountain and “medium-dark grayish brown and reddish” in Eastern. Because field differentiation of these two “dark-lored” subspecies is so difficult, eBird has a category—“White-crowned Sparrow (dark-lored)”—that can be used if subspecies identification is uncertain. We strongly encourage its use for dark-lored birds found in Colorado between mid-October and mid-April, inclusive, particularly for individuals found in the northeastern corner.

Acknowledgments Thanks to Sam Galick for filling a photo-need hole on very short notice.

Literature Cited Amadon, D. 1949. The seventy-five per cent rule for subspecies. The Condor 51:250–258. [AOU] American Ornithologists’ Union. 1998. Check-list of North American Birds, 7th ed. Allen Press, Lawrence, KS.

Colorado Birds Summer 2017 Vol. 51 No. 3 167 Bailey, A. M., and R. J. Niedrach. 1965. Birds of Colorado, vol. 2. Denver Museum of Natural History, Denver, CO. Chesser, R. T., K. J. Burns, C. Cicero, J. L. Dunn, A. W. Kratter, I. J. Lovette, P. C. Ras- mussen, J. V. Remsen, Jr., J. D. Rising, D. F. Stotz, and K. Winker. 2017. Fifth-eighth supplement to the American Ornithological Society’s Check-list of North American Birds. The Auk: Ornithological Advances 134:751–773. [CBRC] Colorado Bird Records Committee. 2017. Fox Sparrow (Red) – Passerella iliaca iliaca/zaboria. http://coloradobirdrecords.org/Reports/SpeciesDetail.aspx?id=6002. (Accessed 19 June 2017.) Dunn, J. L., and J. Alderfer. 2011. National Geographic Field Guide to the Birds of North America, 6th ed. National Geographic Society, Washington, DC. eBird. 2017. eBird: An online database of bird distribution and abundance. Cornell Lab of Ornithology, Ithaca, NY. http://www.ebird.org. (Accessed: 19 June 2017.) Eisenmann, E., D. Amadon, R. C. Banks, E. R. Blake, T. R. Howell, N. K. Johnson, G. H. Lowery Jr., K. C. Parkes, and R. W. Storer. 1973. Thirty-second supplement to the American Ornithologists’ Union Check-List of North American Birds. The Auk 90:411–419. Gerber, B. D., J. F. Dwyer, S. A. Nesbitt, R. C. Drewjen, C. D. Littlefield, T. C. Ta- cha, and P. A. Vohs. 2014. Sandhill Crane (Antigone canadensis). The Birds of North America (P. G. Rodewald, Ed.). Cornell Lab of Ornithology, Ithaca, NY. https://bird- sna.org/Species-Account/bna/species/sancra. (Accessed 20 July 2017.) Leukering, T. 2002. Report of the Colorado Bird Records Committee: 2000 records. Journal of the Colorado Field Ornithologists 36:82–113. Leukering, T. 2010a. Identifying Solitary Sandpiper species: Why and how. Colorado Birds 44:203–206. Leukering, T. 2011. Downy and Hairy woodpeckers in Colorado. Colorado Birds 45:317–325. Leukering, T. 2016a. Lesser Nighthawk: Identification pitfalls. Colorado Birds 50:105– 113. Leukering, T. 2016b. Warbling Vireo (Vireo gilvus). Pp. 356–357 in The Second Colo- rado Breeding Bird Atlas (L. Wickersham, Ed.). Colorado Bird Atlas Partnership and Colorado Parks and Wildlife, Denver. Leukering, T. 2016c. Blue-gray Gnatcatcher (Polioptila caerulea). Pp. 422–423 in The Second Colorado Breeding Bird Atlas (L. Wickersham, Ed.). Colorado Bird Atlas Partnership and Colorado Parks and Wildlife, Denver. Leukering, T. 2016d. Yellow-rumped Warblers: An under-appreciated field identification problem. Colorado Birds 50:158–165. Leukering, T. 2016e. White-winged Junco in Colorado. Colorado Birds 50:240–248. Leukering, T., and S. G. Mlodinow. 2012. Colorado and Wyoming. North American Birds 66:309–314. Leukering, T., and N. Pieplow. 2009. Lilian’s Meadowlark: A cryptic species (?) and a rare Colorado breeder. Colorado Birds 43:222–228. Leukering, T., and N. Pieplow. 2010. Eastern and western Marsh Wrens. Colorado Birds 44:61–66. Leukering, T., and N. Pieplow. 2014. Identifying Curve-billed Thrasher subspecies: Why and how. Colorado Birds 48:296–304. Levad, R. and T. Leukering. 2001. Found! The West Slope’s first great migrant trap! Journal of the Colorado Field Ornithologists 35:17–19.

168 Colorado Birds Summer 2017 Vol. 51 No. 3 Ligouri, J., and B. L. Sullivan. 2010a. Comparison of Harlan’s with Eastern and Western Red-tailed Hawks. Birding 42:30–37. Ligouri, J., and B. L. Sullivan. 2010b. A study of Krider’s Red-tailed Hawk. Birding 42:38–45. Liguori, J., and B. L. Sullivan. 2014. Northern Red-tailed Hawk (Buteo jamaicensis abieticola) revisited. North American Birds 67:374–383. Mayr, E., E. G. Linsley, and R. L. Usinger. 1953. Methods and Principles of Systematic Zoology. McGraw Hill, New York. Miller, A. H. 1941.Speciation in the genus Junco. University of California Publications in Zoology 44:173–434. Mlodinow, S. G. 2014. The White-breasted Nuthatches of Colorado. Colorado Birds 48:180–186. Mlodinow, S. G., B. Tweit, and D. Irons. 2012. The Sooty Fox Sparrows of Washington’s Puget Trough. Birding 44:56–62. Mlodinow, S. G., T. Leukering, and N. Pieplow. 2013. Russet-backed Thrush in Colo- rado. Colorado Birds 47:135–142. Moore, N. 2016. A closer look at Colorado’s Brown Creepers. Colorado Birds 50:210– 216. Patten, M. A., and P. Unitt. 2002. Diagnosability versus mean differences of Sage Spar- row subspecies. The Auk 119:26–35. Pieplow, N. 2007. Colorado’s crossbill types: 2, 4, and 5. Colorado Birds 41:202–206. Pieplow, N. 2012. Eastern and western Blue-gray Gnatcatchers. http://earbirding.com/ blog/archives/3518. (Accessed 19 June 2017.) Pyle, P. 1997. Identification Guide to North American Birds, Part I. Slate Creek Press, Bolinas, CA. Pyle, P. 2008. Identification Guide to North American Birds, Part II. Slate Creek Press, Bolinas, CA. Remsen, J. V., Jr. 2010. Subspecies as a meaningful taxonomic rank in avian classifica- tion. Ornithological Monographs 67:62–78. Righter, R., R. Levad, C. Dexter, and K. Potter. 2004. Birds of Western Colorado Plateau and Mesa Country. Grand Valley Audubon Society, Grand Junction, CO. Schmoker, B., and J. Liguori. 2010. Photo-recovery of a Harlan’s Red-tailed Hawk in Colorado and Alaska. Colorado Birds 44:16–19. Semo, L. S., and R. Righter. 2006. Separation of Canada and Cackling geese in Colo- rado. Colorado Birds 40:204–227. Sibley, D. A. 2014. The Sibley Guide to Birds. Alfred A. Knopf, Inc., New York. Spencer, A. 2012. Identifying eastern and western Warbling Vireos. Earbirding. http:// earbirding.com/blog/archives/3667. (Accessed 3 July 2017.) Wheeler, B. K. 2003. Raptors of Western North America. Princeton University Press, Princeton, NJ.

Tony Leukering, 1 Pindo Palm St. W, Largo, FL 33770 ([email protected]) Steven G. Mlodinow, 2218 Watersong Circle, Longmont Colorado 80504 ([email protected])

Colorado Birds Summer 2017 Vol. 51 No. 3 169 THE HUNGRY BIRD

Sapsucking Woodpeckers Not Named “Sapsucker”

Dave Leatherman Members of the bird family Picidae have common names that end with both “woodpecker” and “sapsucker.” From these monikers we might imply the former limit their activity to extraction of prey from wood, while the latter limit their intake to sap. Not true. For years since the task of diagnosing animal damage to trees landed in my inbox at the Colorado State Forest Service, I have noticed odd patterns of sap wells on living trees that do not have the tidy “tic-tac-toe” appearance typical of our true sapsuckers (Red-naped, Williamson’s, and Yellow-bellied). At first I thought certain “sloppy” patterns of peck holes in the bark of live trees not infested with insects were attributable to other woodpeckers modifying the work of true sapsuckers while poaching a drink. Mooching from, and modification of, wounds originally made by sapsuckers certainly occurs. This is well documented in the literature, including the prominent ecologist Paul Erlich and his students at Gothic near Crested Butte, Colorado, and in the Pacific Northwest (Nickell 1965, Erlich and Daily 1988, Daily et al. 1993). Using-old school observation and motion detector cameras, researchers captured a wide assortment of animals playing out a real life version of the children’s story “Little Red Hen.” Hummingbirds, flies and wasps, butterflies, nuthatches, chipmunks, even bobcats were caught in the act of sap theft. The sapsuckers provided access to the food, and the rest answered the chicken chef’s ques- tion of “who will help me eat the bread?” Signifi- cantly, the studies in the Rockies and elsewhere proposed drinking from sapsucker wells to be so important to migrat- Fig. 1. Female Downy Woodpecker drinking from sap wells ing hummingbirds it made in a live ponderosa pine, Riverbend Business Park, as to be a signifi- Fort Collins, CO, 12 February 2017. Photo by David cant determinant in Leatherman the timing of their

170 Colorado Birds Summer 2017 Vol. 51 No. 3 Fig. 3. Sap wells made by Downy Fig. 2. The unordered network of holes Woodpecker in live ponderosa pine in created by this female Downy Wood- Fort Collins. Note the mostly random, pecker is apparent in this image. River- widely spaced pattern of holes. The only bend Business Park, Fort Collins, CO, alignment of wells is over certain small 12 February 2017. Photo by David lengths horizontally. Photo by David Leatherman Leatherman north–south movements. That is to say, the hummingbirds move north or south after the north or south movements of sapsuckers in order to take advantage of sapsucker-prepared “fuel stations” along their route. Apart from the mutualism that exists between sapsuckers and other fauna, this brief account simply is intended to document initiation of sap wells for the purpose of self-indulging by woodpeckers other than those we call sapsuckers in Colorado. I have seen both Downy Woodpecker and Hairy Woodpecker do this in our state, which has been reported for both species elsewhere (Short 1982). One other species common here, American Three-toed Woodpecker, engages in similar activity (Villard 1994). On several occasions I have noted Downy Woodpeckers pecking live trees to get the resultant sap. Conifers serving as hosts for this activity have been ponderosa (Pinus ponderosae) and Scots pine (P.

Colorado Birds Summer 2017 Vol. 51 No. 3 171 sylvestris). Along the Poudre River in Fort Collins, Siberian elm (Ulmus pumila) has been used. Early in the history of our country, whether Downy Woodpeckers do this and whether it was damaging to the tree was hotly debated. Conclu- sions have been that it is not for the purpose of eating cambium (i.e., for sap only), that the holes are shallow and seldom revisited, and that it is not serious to the health of tree. I would disagree about the wells not being revisited, but generally agree with the rest. Perhaps the lack of interest in cambium is why there does not seem to be a lot of hole enlargement when Downy Woodpeckers engage in live tree sap sucking. Fig. 4. Sap wells made in live aspen by The situation where I most studied sapsucker species, probably Red-naped. this occurred in Fort Collins on the Note the holes are ordered both horizon- Poudre River’s west side just north of tally and vertically. Photo by David Prospect Street. The tree was a pon- Leatherman derosa pine installed as landscaping at the Riverbend Business Park. The same individual female was noted in this 20-foot tall tree drinking sap over a few-month period in late winter/early spring 2017 from wells presumably she made. Unlike what occurs with sapsuckers utilizing a particular tree over a period of weeks or months, flow-sustaining enlargement of the initial Downy-made trunk wells was not significant. The only indication any modifications had been done at all was the different color (reddish brown) of newly worked bark versus that of bark around the original holes (gray-brown). Another way in which the injury of the Downy differed from typical sapsucker pecking was the more random, unordered, rather widely spaced pattern of holes. Also, the size of the holes and subsequent working around their edges indicated the bird that made them used a smaller chisel (aka, beak) than a sapsucker (see Figs. 1, 2, and 3 in comparison to Fig. 4). I have seen Hairy Woodpeckers visiting sap wells made by Yellow- bellied Sapsuckers at Grandview Cemetery in Fort Collins on several occasions. But the only time I have witnessed them initiating holes for the purpose of drinking sap involved a lodgepole pine (P. contorta) in Coal Creek Canyon. Of course, my real reason for being at this site

172 Colorado Birds Summer 2017 Vol. 51 No. 3 was to view the special Magnificent Hummingbird female visiting Adam Jack’s feeder in early November 2014. A review of Cornell University’s extensive “Birds of North Amer- ica” database indicates it is likely that most, if not all, members of the woodpecker genus Picoides peck on live trees to obtain sap. In addition to the three Colorado species mentioned, it is also known for Black-backed Woodpecker, White-headed Woodpecker, and Nut- tall’s Woodpecker (Miller and Bock 1972, Raphael and White 1984, Cramp 1985, Villard 1994). Other members of this genus for which it has not been recorded are Ladder-backed Woodpecker, Red-cockaded Woodpecker, and Arizona Woodpecker.

LITERATURE CITED Cramp, S. 1985. Handbook of the Birds of Europe, the Middle East and North Africa, Vol. 4. Terns to Woodpeckers. Oxford University Press, New York. Daily, G. C., P. R. Erlich, and N. M. Haddad. 1993. Double keystone bird in a keystone species complex. Ecology 90:592–594. Ehrlich, P. R., and G. C. Daily. 1988. Red-naped Sapsuckers feeding at wil- lows: Possible keystone herbivores. American Birds 42:357–365. Miller, A. H., and C. E. Bock. 1972. Natural history of the Nuttall Wood- pecker at the Hastings Reservation. The Condor 74:284–294. Nickell, W. P. 1965. Birds and insects feed at sapsucker trees. Bird-Banding 36:192–193. Raphael, M. G., and M. White. 1984. Use of snags by cavity-nesting birds in the Sierra Nevada. Wildlife Monographs 86:1–66. Short, L. L. 1982. Woodpeckers of the World. Monograph Series 4, Delaware Museum of Natural History, Greenville. Villard, P. 1994. Foraging behavior of Black-backed and Three-toed Wood- peckers during spring and summer in a Canadian boreal forest. Canadian Journal of Zoology 72:1957–1959.

Dave Leatherman, [email protected]

Colorado Birds Summer 2017 Vol. 51 No. 3 173 Exchanging an Active Barn Owl Nest Box

Scott Rashid In February 2014, members of the Colorado Avian Research and Rehabilitation Institute (CARRI) built and placed ten nest boxes for Barn Owls (Tyto alba) in suitable habitat in Boulder County, Colora- do. This species readily accepts nest boxes (Bent 1938, Taylor 1994, Chandler 2011); the boxes we use are made of ¾-inch plywood and assembled with wood screws. One particular box was placed on the west side of a barn at a turkey farm in the town of Berthoud (Fig. 1). The box was 15 inches (38.1 cm) high, 15 inches deep, and 30 inches (76.2 cm) long. It had a 6 inch (15.2 cm) entrance hole on the left side of the front, two inches (5.1 cm) from the top and three inches (7.6 cm) from the left side. A door 15 inches (38.1 cm) high and 12 inches (30.5 cm) wide on the front right side of the box enabled us to extract the owlets for banding and to clean the box. I chose to make the boxes this size after searching online for Barn Owl nest box sizes. I settled on a box design that I found on the Cape Romain Bird Observatory’s website (https://www.crbo.net). I chose that box design because many years ago I dug a hole in a sandstone cliff for Barn Owls. The hole was approximately 14 inches in diameter and extended about three feet back into the cliff. When I checked the hole several weeks later, I found a pair of Barn Owls nesting in it. Either the birds enlarged the hole or it was enlarged due to erosion. The cavity turned to the right at the end, which is where the owls were nesting. Since the owls decided to make their nest cavity a bit of a long horizontal, it made sense to me to make nest boxes hori- Fig. 1. Joe Heyen standing under the original, zontal instead of square or smaller nest box. any other shape.

174 Colorado Birds Summer 2017 Vol. 51 No. 3 The nest box was placed approximately 11 feet, 4 inches (3.5 m) from the ground and an inch (2.5 cm) of wood shavings was placed inside the box. I always place shavings on the bottom of the boxes to ensure the eggs won’t roll around. It is real- ly not needed, as the adult birds produce so many pellets that by Fig. 2, Barn Owl eggs in the smaller nest box. Note there the time the owlets are eight of them. have hatched there is plenty of stuff on the bottom of the box for the owlets to stand on. If young birds stand too long on bare wood there is a chance that their legs will grow out sideways. If that happens, the bird will never survive, as they won’t be able to stand properly (Sigrid Ueblacker, former president of the Birds of Prey Foundation in Broomfield, pers. comm.). I checked the box on 12 March 2015, but nothing was in it. How- ever when I checked again on 3 April 2016, I was pleasantly surprised to find two adult Barn Owls and five eggs in the box. Checking a Barn Owl nest box can be a bit tricky. I always check my nest boxes during the day, quietly placing a ladder under the box and climbing to the entrance to look inside. Most times the owls remain within and just hiss or click their bills at me. If the box has been used in previous years, or if I can see any evidence that there may be birds within, I will place an 18 inch (45.7 cm) diameter fishing net, mounted on the end of an aluminum ex- tension pole, over the nest box opening in case the adult birds exit the box as I climb to look inside. If the birds exit I will catch them in the net, then age and band them and place them back in the box. Every time I have checked a nest box that had an adult bird in it the male has exited first, followed sometimes instantly by the female. Other times the male exits and the female remains within. Members of CARRI returned to the farm on 26 May 2016. I was able to band five healthy owlets. Due to Barn Owls laying one egg every 2–3 days and beginning incubation as the first or second egg is laid, it is hard to determine the age of every owlet within a nest box.

Colorado Birds Summer 2017 Vol. 51 No. 3 175 However, the oldest owlet was approximately 30 days old. I returned to clean out the box in late October, to find that the birds had double-clutched, or laid a second set of eggs, and raised another family. Barn Owl nests are quite the messy affair. The box often has several inches of pellets and animal remains within. Fig. 3. Only four of the original eight eggs produced When I began cleaning out young. All of the eggs had hatched, however I only the box, I found three dead found four owlets inside the box when I returned to owlets that were just a few band them. weeks from fledging. Due to that box being small (for Barn Owls), this year (2017) I decided to replace the box with a larger one. The larger box is 15 inches (38.1 cm) wide, 18 inches (45.7 cm) high, and 40 inches (1.0 m) long; as with the other box, it had a 6 inch (15.2 cm) entrance hole on the top left front. The reason that I wanted to replace the nest box with a larger one is that in 2014, Fig. 4. The same four owlets in the larger box just a pair of Barn Owls nested after the owlets were banded and placed inside the in one of our boxes and the box and the box was erected. female laid 10 eggs. All the eggs had hatched but due to the small box size the three youngest owlets died—they were seem- ingly inadvertently trampled by the older owlets (Rashid 2017). We arrived at the box on 7 May 2017 to find both parents in the box along with eight unhatched eggs (Fig. 2). Not wanting to disturb the owls too much I decided to return to the site after the eggs had hatched to change out the box. I wanted to wait until the owlets were old enough that I could catch and band the adult female and the young at the same time. That way I would only have to return to the

176 Colorado Birds Summer 2017 Vol. 51 No. 3 nest one more time to handle the birds; this would cause less stress on the owls. We returned to the nest on 27 May to find the adult female and at least two owlets that were just a few days old. Due to the owlets being so small, I did not want to try picking up the female to band her as she could have acci- dentally stabbed her Fig. 5. The same four owlets in the box on 15 July. When owlets with her sharp this photo was taken, they were just a few days from fledging. talons. On 17 June, members of CARRI arrived at the nest site to band the owlets and replace the nest box. I positioned the net in front of the entrance hole. I then gave the pole to David Neils, a longtime CARRI member, who held it against the hole as I placed the ladder under the box and began climbing. As I climbed the ladder, the female flew out and landed in the net and was captured. I quickly climbed to her and removed her from the net. I then climbed down the ladder with her in my hand. I placed an aluminum US Fish and Wildlife Service leg band on her left leg and placed her in a cardboard pet carrier, with a towel over the carrier. Placing a towel over the pet carrier keeps the owls calm and quiet, as they are unable to see what is going on around them. Another CARRI volunteer and photographer, Jon Rayeski, placed the box in the shade a few feet away. I climbed back up the ladder, opened the door and looked inside to find four young fluffy owlets that were about 15–20 days old, looking at me (Fig. 3). There was also about 8 inches (20.3 cm) of pellets and debris at the nest entrance under the hole. When the debris within the box gets too deep, the female will kick it away from the owlets toward the entrance. This can make a box that is 15 inches (38.1 cm) deep only 7 inches (17.8 cm) deep near the nest entrance, ultimately making the box very small and presumably uncomfortable for the owlets. Another CARRI volunteer, Brian Trout, climbed up the ladder behind me with a pet carrier enabling me to place the owlets into the

Colorado Birds Summer 2017 Vol. 51 No. 3 177 carrier to be lowered to the ground. Once the owlets were safely on the ground, I began taking the nest box down so we could replace it with the larger box. As with the other box, this one had a door on the front left side, 18 inches (45.7 cm) high and 12 inches (30.5 cm) wide. Once I had removed the old box and lowered it to the ground, Brian and I climbed onto the barn roof and David placed the larger box on the ladder and pushed it up to us. We attached the new box to the barn using an electric drill to drive screws. I took each owlet from the pet carrier and attached an aluminum USGS leg band to the right leg. I band all adult birds on their left leg and nestlings on their right leg. That way, when I see one of my banded owls, I will instantly know whether the bird was an adult or juvenile when it was banded. I climbed up the ladder, opened the door and placed each owlet into the nest box (Fig. 4), then closed and latched the door. After- wards, I opened the pet carrier to find the adult female owl lying down. I reached in and placed my hands around her and lifted her from the box. I climbed the ladder and put her headfirst into the box through the entrance hole. I placed a dark towel over the entrance hole until the owls inside relaxed. All owls remained within the box and seemed to like their larger home. I returned to check on the owls on 15 July and all four owlets were still in the nest box (Fig. 5). They were only a few days from fledging.

Acknowledgments I would like to thank Larry and Kristin Ramey, for allowing us to place the nest box on their property. I would also like to thank Gina DiGiallonardo, Joe Heyen, Larry Kilgore, Lance and Jill Morrow, David Neils, Jon Rayeski, and Brian Trout for their assistance with this project.

Literature Cited Bent, A. C. 1938. Life History of North American Birds of Prey. Part Two. Dover Pub- lications, New York. Chandler, D. 2011. Barn Owl. Firefly Books, Richmond Hill, ON, Canada. Taylor, I. 1994. Barn Owls: Predator–Prey Relationships and Conservation. Cambridge University Press, Cambridge, UK. Rashid, S. 2017. Barn Owls nesting in nest boxes in Boulder County. Colorado Birds 51:45–50.

Scott Rashid is Director of the Colorado Avian Research and Rehabilitation Institute (CARRI), Box 3351 Estes Park, CO 80517. [email protected]

178 Colorado Birds Summer 2017 Vol. 51 No. 3 The Colorado Field Ornithologists’ Quarterly

Instructions for contributors to Colorado Birds Colorado Birds is devoted to the field study of birds in Colorado. We invite you to submit articles of general or scientific interest for publication. Authors are encouraged to submit materials that contribute to the enjoyment and understanding of birds in Colo- rado. The preferred submission method is via email attachment to the Colorado Birds editor, [email protected]. Submissions may be edited for length and content. Photos or other art may be submitted in black and white or color. Files should be saved as high-resolution jpeg or similar format and must be a minimum of 900 x 750 pixels. Potential cover images must be at least 2625 (vertically) x 1725 (horizontally) pixels. For cover photos, it is also important to remember that there needs to be space at the top of the image for the journal title, etc. Please DO NOT save photos in MS Word or oth- erwise embed within a document. Include photo captions along with the photographer’s name, where and when taken, and other relevant information. All photos should be sent to the Colorado Birds editor, [email protected]. Contributors who are not members of CFO will, upon request, receive a complimen- tary copy of the issue of Colorado Birds in which their articles appear. The articles in this journal reflect the research and opinions of the individual authors. As such, the articles do not necessarily reflect the opinions or positions of the Officers, Directors, or other representatives of CFO.

Colorado Birds Summer 2017 Vol. 51 No. 3 179 Fig. 1 Fig. 2

Fig. 3 Fig. 4

Fig. 5 Fig. 6

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