Colorado Birds the Colorado Field Ornithologists’ Quarterly

Vol. 48 No. 4 Fall 2014 Colorado Birds The Colorado Field Ornithologists’ Quarterly

Loggerhead Shrikes The Five Seasons Double Clutching Wrens Colorado Field Ornithologists PO Box 643, Boulder, Colorado 80306 cfobirds.org

Colorado Birds (USPS 0446-190) (ISSN 1094-0030) is published quarterly by the Colo- rado Field Ornithologists, P.O. Box 643, Boulder, CO 80306. Subscriptions are obtained through annual membership dues. Nonprofit postage paid at Louisville, CO. POST- MASTER: Send address changes to Colorado Birds, P.O. Box 643, Boulder, CO 80306.

Officers and Directors of Colorado Field Ornithologists: Dates indicate end of current term. An asterisk indicates eligibility for re-election. Terms expire 5/31.

Officers: President: Bill Kaempfer, Boulder, 2015; [email protected]; Vice Presi- dent: Christian Nunes, Boulder, 2015*; [email protected]; Secretary: Larry Modesitt, Greenwood Village, 2015; [email protected]; Treasurer: Tom Wilberd- ing, Boulder, 2015*; [email protected]

Directors: Jim Beatty, Durango, 2014; Christy Carello, Golden, 2016*; Lisa Edwards, Falcon, 2014*; Ted Floyd, Lafayette, 2014*; Mike Henwood, Grand Junction, 2015*; Brenda Linfield, Boulder, 2016; Joe Roller, Denver, 2015; David Gillilan, 2016*.

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

Chair: Doug Faulkner, Arvada, 2016; [email protected]

Secretary: Rachel Hopper, Fort Collins

Committee Members: John Drummond, Monument, 2016; Brandon Percival, Pueblo West, 2015*; Bill Schmoker, Longmont, 2016; David Silverman, Rye, 2014; Glenn Wal- bek, Castle Rock, 2015. Mark Peterson, Colorado Springs, 2016*

Colorado Birds Quarterly:

Editor: Peter Burke, [email protected]

Staff: Christian Nunes (Photo Editor), [email protected]; Tony Leukering (In the Scope Editor), [email protected]; Ted Floyd (Conversations Editor), tfloyd@ aba.org; Peter Gent (News from the Field Editor), [email protected]; Christy Carello (Sci- ence Editor), [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 $6.50. Send requests for extra copies/back issues, change of address and membership renewals to CFO, P.O. Box 643, Boulder, CO 80306; make checks out to Colorado Field Ornitholo- gists. Contributions are tax deductible to the extent allowed by law.

258 Colorado Birds Fall 2014 Vol. 48 No. 4 The Colorado Field Ornithologists’ Quarterly Vol. 48 No. 4 Fall 2014

PRESIDENT’S MESSAGE...... 260 Bill Kaempfer

ABOUT THE AUTHORS...... 261

CFO BOARD MEETING MINUTES...... 263 Larry Modesitt

MOVEMENTS, MIGRATION AND BREEDING BY LOGGERHEAD SHRIKES IN EL PASO COUNTY..... 266 Susan Craig

THE FIVE SEASONS...... 272 Ted Floyd

Male Rock and Canyon Wrens Evince their Fitness as Single Parents...... 276 Nat Warning

NEWS FROM THE FIELD: fall 2014...... 282 Peter Gent

CFO BIRDING TRIP REPORT...... 294 Ted Floyd

IN THE SCOPE: IDENTIFYING CURVE-BILLED THRASHER SUBSPECIES: WHY AND HOW...... 296 Tony Leukering

THE 70TH report OF THE CBRC...... 305 Doug Faulkner

THE HUNGRY BIRD: Canyon Wren, White-lined Sphinx Moth...... 312 Horsetooth Dave Leatherman Reservoir, Lar- imer County, 30 May 2014. BOOK REVIEW: THE SIBLEY GUIDE Photo by Dave TO BIRDS SECOND EDITION...... 316 Leatherman Christian Nunes PRESIDENT’S MESSAGE

My Patch

Bill Kaempfer We all enjoy the birding tales and reports we hear from colleagues about familiar and not-so-familiar birding spots; for instance, Dave Leatherman’s ongoing exploration of Mountain View Cemetery in Ft. Collins, Ted Floyd’s frequent reports on the Greenlee Preserve near his home in Lafayette or Brandon Percival’s monitoring of Chico Basin Ranch just outside Colorado Springs. More recently, we’ve learned quite a bit from David Suddjian’s reports from Park County. Dave, Ted, Brandon and David have all discovered that a long standing, frequently repeated birding experience is yet another way to maximize one’s birding experience. You may recall that last year I reported in this column my New Year’s Resolution to report all of my observations to eBird; and since January 1 I’ve kept that Bill Kaempfer up. This year I’ve picked a patch! As parks go, Smith Park on Gilbert Street (aka 5th Street) between Euclid and Aurora in Boulder is not much of a park. While it is an official Boulder City Park, complete with a picnic table and bench, it is actually just an old, overgrown house lot. I try to get up there a few times each month for a quick lunch break. As of Au- gust 17, I’ve tallied 22 visits and 41 species! I’ve seen first hand just how much vegetation can grow in a wet year, too. It’s a nice spot, nestled between pricy houses at the foot of Flag- staff Mountain. It has views of the Flatirons and the east side of the property is actually the bed of Gregory Creek flowing down from a more famous and popular birding site, Gregory Canyon in Boulder Mountain Parks. The location and extensive vegetation has made for quite a few pleasing and unexpected observations. In July there was a singing Red-eyed Vireo, and back in May I had a Broad-winged Hawk fly over. Now my patch is telling me that fall migration has be- gun with Western Wood Pewee, Black-headed Grosbeak and Yellow- breasted Chat among the new visitors popping in. Even more valuable and interesting is what I’ve learned through repeated visits. For instance, a Cordilleran Flycatcher didn’t show up until May 28, but it has been present and singing right here in Boul- der ever since, now joined by a couple of presumed youngsters. The Lesser Goldfinch pattern is just the same while Ruby-crowned King- let is just the opposite—one was singing away at Smith Park from

260 Colorado Birds Fall 2014 Vol. 48 No. 4 April 28 until June 13 after which it departed for its spruce breeding ground several thousand feet on up in the mountains. So that is my advice—find your own patch and bird it regularly. No matter what birds you discover, I suspect you’ll ultimately find that you’ve learned something new and enjoyed the experience. Bill Kaempfer, [email protected]

ABOUT THE AUTHORS

Loggerhead Shrikes in El Paso County Susan Craig received a Master Banding Permit in 1976. She learned to band raptors and owls, and worked as an owl bander at Whitefish Point Bird Observatory in 1988. She has published several pieces in Colorado Birds and North American Bird Bander. Currently she focuses on songbird and shrike banding.

The Five Seasons Ted Floyd is editor of Birding, author of the Smithsonian Field Guide to the Birds of North America and serves as a director on the CFO board. He has a B.A. in Ecology and Evolutionary Bi- ology from Princeton University and a Ph.D. in Ecology from Penn State University. An expert in avian nocturnal flight calls, husband and father of two children, Ted gets very little sleep.

News From the Field Peter Gent has lived in Boulder and worked at the National Center for Atmospheric Research since 1976. At NCAR, some people think his real job is birdwatching and going on birding trips. He has twice been the President of CFO, twice been the Chairman of the CFO Bird Records Committee and was a co- editor of the CFO Journal in the mid 1980s.

Parenting Behavior in Male Rock and Canyon Wrens Nat Warning is an amateur birder, but has been privileged to study Rock and Canyon Wrens for the past three seasons (supported by a research grant from CFO in 2012). He obtained his B.S. from the University of Wisconsin and his M.S. from the University of Northern Colorado. Before moving to Colorado, he worked as an aviculturist at the International Crane Founda- tion where he assisted with Whooping Crane reintroductions. He continues to study Rock Wren nesting behavior and currently is seeking gainful employment.

Colorado Birds Fall 2014 Vol. 48 No. 4 261 Nora Covy is currently pursuing a Master’s degree in Biology from the University of Northern Colorado. She obtained her B.S. from Miami University in Ohio and her NABC training and banding certification through Point Blue Conservation Sci- ence in California. She has worked at the National Aviary in Pittsburgh, the Kalamazoo Valley Bird Observatory and most recently has worked with White-winged Swallows in Venezuela as part of the Golondrinas de las Americas Project. Nora currently studies cliffs, and the birds that climb around on them.

Lauryn Benedict is an assistant professor of Biology at the Uni- versity of Northern Colorado. She obtained her B.S. from Cor- nell University, and her Ph.D. from UC Berkeley. Lauryn studies bird song and behavior. You can often find her in Colorado parks and natural areas tracking little brown birds.

Dave Leatherman is a photographer, entomologist and expert on Colorado birds. He is a regular contributor to Colorado Birds as author of The Hungry Bird. His photographs of birds carrying food are of such high quality that many of the invertebrates can be identified to species. He obtained his B.S. from Marietta College and his M.S. from Duke University. When not birding, Dave has been known to occasionally enjoy a night on the town listening to live jazz.

In The Scope: Identifying Curve-billed Thrasher Subspecies Tony Leukering is a freelance ornithologist currently based in Florida. His primary interest in birds is migration, and his work has included nearly 14 years at the Rocky Mountain Bird Ob- servatory. He is a recipient of CFO’s Ron Ryder Award and has authored virtually all of the In The Scope columns for Colorado Birds.

Book Review: The Sibley Guide to Birds Second Edition Christian Nunes began birding as a youngster in his native state of Rhode Island. His passion has directed him to a B.S. in En- vironmental Science from Northern Arizona University and to his current position as a Wildlife Ecology Technician for the City of Boulder. He is the photo editor for Colorado Birds, and he also fills the position of Social Media Director and Vice Presi- dent of the Colorado Field Ornithologists.

262 Colorado Birds Fall 2014 Vol. 48 No. 4 CFO BOARD MEETING MINUTES

19 July 2014 C.U. Mountain Research Station, Nederland, CO

Larry Modesitt President Bill Kaempfer called the April quarterly meeting to order at 11:37 a.m. Other officers present were Vice President Chris- tian Nunes, Secretary Larry Modesitt and Treasurer Tom Wilberding. Directors Peter Burke, Lisa Edwards, Doug Faulkner, David Gillilan, Mike Henwood, Joe Roller and Ted Floyd were present. Christy Carello and Jim Beatty, whose term as a director expires at the convention, sent their regrets. A representative of our customers, a Cordilleran Flycatcher, was also present to ensure all interests were represented properly, ably inspiring our discussions.

Secretary’s Report: Larry Mode- listservs and in national publications, sitt. Directors approved the minutes resulting in 21 registrants outside of of the 12 April 2014 board meeting. Colorado so far. Banquet: We agreed to a policy of Treasurer’s Report: Directors ap- allowing award recipients to attend proved Tom Wilberding’s financial the banquet at no charge. The Ster- statements. Having the convention ling mayor will attend our picnic. in fall rather than spring has made Other Meals: We discussed meth- financial comparisons difficult. Dues ods and made assignments to make are up, reflecting new members join- it more likely that every person will ing in order to attend the convention. receive the meals ordered. Field Trips: We agreed on a policy Sterling 2014 Convention Details— to compensate field trip leaders for Bill Kaempfer this and future conventions. If there Registration. Six weeks prior to is a fee for any field trip, the leader of the convention, we have 163 res- that trip will not be charged. Leaders ervations, the fourth highest ever. of two or more trips will be compen- This is especially encouraging as we sated with an amount equal to the are experimenting both with a fall non-banquet part of the convention convention and with online registra- fee, currently $45. Those leaders will tion, saving approximately $1,200 in receive a T-shirt provided they sign postage. There is also the fact that up prior to the deadline for order- Sterling was the sight of a spring con- ing the shirts. We also formalized our vention not that long ago in 2006. previously unwritten policy to donate Special efforts were made to attract one-half the fee income to landown- attendees from other states by making ers who make their properties avail- announcements on adjoining state able for field trips. We intend to offer

Colorado Birds Fall 2014 Vol. 48 No. 4 263 a variety of special trips (such as pho- continues to review 2013 records, as tography, bird food sources, birding by last year had the largest number of ear, botany, butterfly trips, etc.) that documentations ever submitted, over may collect fees, which would remain 300. Several birds that have become with CFO. For 2014, Bill Kaempfer less unusual recently were eliminated and Ted Floyd will develop a script from the list requiring documenta- to aid leaders in communicating with tion. This will make 2014 easier, as participants. Peter Burke offered to set the committee strives to be closer up a text network to help trip leaders to completion within one quarter of communicate news and sightings in submission. The backlog of scanning real time. 2,500 old paper documents is being whittled away. Other Activities Paper Sessions. Christy Carello CFO Website: David Gillilan re- has lined up seven speakers and estab- ported that Brenda Linfield and Ann lished guidelines for speakers. Johnson are wrapping up the techni- Team ID Challenge and Prizes: cal aspects of webmaster work, so that Christian Nunes announced the 2014 future maintenance will not require format will be “Jeopbirdie,” a game extreme technical skill. that will involve identification chal- lenges but also seeks to involve every- Social Media Communications: body. Christian Nunes reported that Face- Ramada Liaison: Joe Roller has re- book continues to work well. cruited volunteers from the board to serve as greeters (identified by their Convention Planning for Salida “Ask Me” tags) to be on hand to an- 2015—Bill Kaempfer swer questions and help convention Facilities: Tom Wilberding scouted attendees get where they need to be possible locations in Salida and ar- on time. ranged for a banquet site located on Registration Packet Assembly: the Arkansas River as well as hotel The packet will contain valuable in- discounts. Salida is a popular tourist formation to participants, including location for whitewater rafting, camp- meals ordered, T-shirt (if purchased) ing and hiking so advance reserva- size, a CFO checklist listing all 498 tions are necessary. birds that have been accepted by the Trips: There are many excellent Colorado Bird Records Committee, in- field trips located within one hour of formation on Jeopbirdie, a list of field Salida in all directions. trips with times and a welcome letter. T-Shirts: Lisa Edwards announced that Sherrie York will provide artwork, Colorado Bird Records Commit- and is open to suggestions regarding tee: Doug Faulkner reported that our which bird(s) to showcase. upgraded website is working well, with Speaker: Several potential keynote no unresolved issues. The committee speakers were discussed.

264 Colorado Birds Fall 2014 Vol. 48 No. 4 Nominating & Convention Awards: COBBA II: Bill Kaempfer recom- Joe Roller announced that his nomi- mended, and directors agreed, that nating committee, which also includes CFO will contribute funds for expens- Larry Modesitt and Maggie Boswell, has es of publication of COBBA II. We proposed offering the slate at the con- will consider further contributions, vention of continuing existing officers. based upon fundraising progress and Directors agreed with Joe’s recommen- need. dation for convention awards. New Business: Bill Kaempfer not- Colorado Birds: Peter Burke re- ed that CFO makes contributions in ported that many readers have ex- five key areas: pressed interest in continuing the • Providing a respected journal, News from the Field section. Peter Colorado Birds Gent has agreed to act as temporary • Communicating about birds NFTF compiler until a new volunteer through COBirds, Facebook and our is found. website • Supporting the formal state list Publicity: Ted Floyd will include of accepted birds through the Colo- information on our Facebook page rado Bird Records Committee that CFO is the organization sponsor- • Holding annual conventions, ing the page. Sterling being the 52nd continuously held gathering Membership: Lisa Edwards an- • Sponsoring research through nounced 39 new memberships be- grants in furtherance of our mission. tween April 1 and July 1, 30 of which Beyond these specific contribu- were totally new members. We now tions, since education and youth are have record all-time membership, important to the board, and since con- which has exceeded 500 for the last servation also is a part of our mission, four quarters. Bill asked if we should begin to have more focused discussions on these top- CFO Field Trips: Bill Kaemp- ics as part of our quarterly board meet- fer noted the success of these special ings. It was agreed to include October trips, and we discussed possibilities for agenda items for education & youth upcoming trips, particularly for No- and for conservation. vember of this year. Mike Henwood reported that several people saw mul- The next meeting will be October tiple lifers on his winter rosy-finch 18, 2014 at 11 a.m. in Salida. trip. On August 12, Ted Floyd will lead a nocturnal trip for CFO mem- President Kaempfer adjourned the bers. meeting at 3:29 p.m.

Project Fund and Scholarships— Respectfully submitted, No news at this time. Larry Modesitt, Secretary

Colorado Birds Fall 2014 Vol. 48 No. 4 265 Movements, Migration and Breeding by Loggerhead Shrikes (Lanius ludovicianus) in eastern El Paso County, Colorado

Susan H. Craig Abstract Loggerhead Shrikes (Lanius ludovicianus) are classed as predatory songbirds, primarily consuming terrestrial insects and their larva, plus spiders, lizards, small snakes, mice and small birds (Yosef 1996, Pruitt 2000). As such, they help control insects harmful to the short grass prairie. Opening the plains to cattle and agriculture as settlers moved west in the late 1800s allowed shrikes to expand into Colorado from desert areas to the south (Cade 1997). There were few trees when settlers came here, so they brought in western red cedar and lilac bushes to decorate their homesteads, thus providing additional nesting habitat for shrikes.

Introduction In eastern El Paso County, shrikes are found in cattle pasturage with scattered trees, or near farms or abandoned homesteads where trees were planted. As part of their environment, they prefer short grass cropped by cattle, plus barbed wire fencing for use as hunting perches and to impale prey for display. Utility wires are also heavily used as hunting perches. Small (10’-20’), isolated Russian elm trees undisturbed by cattle, or bushes of Western Red Cedar are preferred nesting habitat. Nesting success is heavily influenced by adverse spring weather (rain, hail). Migration may be delayed by lingering winter cold/late spring. The species has declined significantly across the continent, including eastern El Paso County (EPCo). Ongoing drought in recent years has killed many trees in EPCo, which reduces nesting opportunities for shrikes. In the past four years, I found only about half as many nests as during the previous decade. (Craig 2007, Craig 2002). Loggerhead shrikes can be found in eastern EPCo in every month of the year. However, over-wintering on the high plains of Colorado is risky business for this species. In mild winters, some adults and young-of-the-year may be found near nesting sites occupied during the previous breeding season. However, in harsh, cold winters, many die. The ones who leave in time likely move south into southern

266 Colorado Birds Fall 2014 Vol. 48 No. 4 Colorado, but survivors soon drift back north into EPCo. For example, episodes of Polar Vortex during the winter of 2013-14 killed numbers of over-wintering shrikes. Of the dozen shrikes I found during fieldwork on January 5, 2014, all disappeared from my study area during late January/early February. One of my banded birds was found dead in mid-February, completely intact and uninjured, but apparently starved or killed by the cold. The bulk of breeding birds arrives in April (Porter et al 1975), and nesting commences in mid-May. Peak of egg-laying is May 16 (Kingery 1998). Nests are bulky cups of twigs lined with softer strips of bark or grasses. Eggs number from 4 to 9; incubation begins with the penultimate egg, and averages 16 days. Hatching to fledging averages 17 days. Young remain near the nest, taking short flights and gradually learning to forage. Adult shrikes are diligent caregivers and aggressive defenders (Porter et al 1975).

Methods Beginning in 1993, I began capturing shrikes from alongside quiet back roads in eastern EPCo using a round, walk-in trap baited with a small pet-store mouse. (I do not band nestlings.) The mouse is protected from the shrike in its own small-mesh cage. The trap is 95% effective, and is safe for both shrikes and bander. Once removed from the trap, the bird is inserted into a closed-end, ventilated black plastic tube to reduce stress and to protect the bander from being bitten. One leg is banded with a USFWS/USGS individually num- bered metal band, notes and measurements are taken, and the bird is released at the site. A GPS reading denotes the 10’ block in which the bird was captured. My recapture rate is approximately 8%. My primary study area is basically the eastern half of El Paso County, extending east to the Lincoln County line, north to Elbert County and south to Pueblo County. I’ve worked this area for over 20 years, capturing and banding nearly 1,500 shrikes. Studying shrikes in hand has enabled me to view plumage and molt characteristics, monitor health and breeding condition, and refine sexing and aging techniques. Fieldwork has also provided opportunity to view behavior during nesting, foraging and migration.

Results Years of observation in the field indicate there are probably four distinct populations of Loggerhead Shrikes wintering/breeding/migrating through EPCo. With careful observation, these movements are discernable but somewhat overlapping. The pathway followed by migrating and breeding shrikes along the Front Range of the Rockies

Colorado Birds Fall 2014 Vol. 48 No. 4 267 is also a zone of overlap for several subspecies. Although morphomet- rics for shrikes are not totally reliable, I’ve identified with confidence at least two subspecies: L. l. excubitorides and L. l. sonoriensis Most of the shrikes breeding in EPCo are subspecific intergrades, likely among L. l. migrans. L. l. nevadensis and L. l. excubitorides. Shrikes I’ve banded in eastern New Mexico during the winter appear to be the same subspecific types as those that breed in Colorado. On the western slope of New Mexico, L. l. sonoriensis predominates as the wintering subspecies. Several winter trips to south Texas indicate many shrikes are longer-distance migrants, likely belonging to Group 4 (see below). In December of 2010, I captured a shrike banded in south Texas in 2006 by Dr. Chabot. Isotopic and DNA analysis done at the time indicated that bird had originated in the Dakotas. Group 1 includes the shrikes that may overwinter after breeding in EPCo. If they leave the county because of winter weather extremes, I believe they travel only a short distance into southern Colorado or northern New Mexico and quickly move back into their territories when weather conditions permit. Few in number, these birds are the earliest breeders; I have twice found nests with eggs in late March, most recently on March 26, 2014. Hatching date for this recent nest was April 17; the chicks fledged on May 2 and May 3. (photos by Bill Maynard) Group 2 includes a mysterious population that passes through EPCo from early February through mid-March. Infrequently encountered or captured, these include some very young birds, some only 40 to 50 days old, some still showing feather sheaths at the base of flight feathers. Some still wear fledgling plumage on the head or upper back; their feathers are pristine, without wear. I believe these birds are the product of winter breeding in southern Texas or the Gulf Coast of Mexico (Craig, unpub. data). Group 3 are birds that breed in EPCo, but do not over-winter. They are medium-distance migrants, travelling in late summer south into north and central Texas and New Mexico. (I’ve had one winter recovery from central Texas, a bird banded near Ramah, CO.) This group represents a large portion of the shrikes found defending or loafing on breeding territories in late April. Typically they nest in mid-May, with fledglings first appearing in the third week of June. These birds migrate out early; in many years most nest sites are va- cated by mid-July. They may travel through EPCo in family groups including fledglings and one or both parents, which may continue to feed the youngsters as they move along. However, captures of these young birds often show some to be rather thin; at this age, they’re still learning to forage while migrating.

268 Colorado Birds Fall 2014 Vol. 48 No. 4 Figs. 1 & 2. One of very early hatching-year shrikes from the population (Group 1) that breeds and occasionally winters in El Paso County. This fledgling was photographed by Bill Maynard on 6 May 2014.

Fig. 3. This bird represents one of the “mysterious” hatch-year birds (Group 2) who show up in low density from late February to early March. Photo by Su- Fig. 4. An adult male Loggerhead san Craig Shrike. Photo by Susan Craig

Group 4 are long-distance migrants. They pass through the state in May into early June. These birds come from much farther south: south Texas and Mexico. Birders report heavy shrike migration through the southern tip of Texas (McAllen and Brownsville) in mid-April. Since most suitable nesting territory in EPCo has been taken by the time Group 4 arrives, these shrikes are likely headed for the northern tier of states and possibly southern parts of Canadian provinces.

Discussion Group 2 is somewhat hypothetical, since evidence is partly circum- stantial. I have, however, found strong supportive evidence of winter

Colorado Birds Fall 2014 Vol. 48 No. 4 269 breeding in south Texas. On four occasions during winter trapping in south Texas (December 1998, January/early February 2000), I caught young shrikes with incompletely-grown bills and with flight feather bases still in sheaths, indicating age less than 40 days. The eggs from which they came would have been laid in November or December. It was only after reading a paper about double breeding in winter (Ro- hwer 2009) that I understood the significance of these young birds. While it is true that Texas resident shrikes breed early, the argument here might be that these birds were hatched by early-breeding Texas shrikes. However, if this were the case, young Texas birds would not be migrating through or captured in EPCo in February and March. Furthermore I have never encountered any of these young specimens as local breeders, so my hypothesis is they do not breed in Colorado, but somewhere further north, possibly southeast Alberta (Chabot, pers. com.). In the spring of 2013, Groups 3 and 4 were significantly delayed by a very cold, late spring; some shrikes were still migrating through EPCo well into June (pers. obs.). Nesting and migration were delayed into late August; I was still finding family groups at nesting sites with fledglings less than 40 days old in mid-August.

Conclusion Twenty-two years of fieldwork with Loggerhead Shrikes in eastern El Paso County reveals complex migration and breeding strategies by several populations. Weather extremes play a significant role in timing of spring arrival, breeding success, departure and over-wintering success. Without conservation efforts shrikes will continue to decline in number in eastern EPCo and elsewhere in Colorado. Supplementing breeding habitat for Loggerhead Shrikes may help to stem the decline. In the Comanche National Grasslands (USDA-FS), some experimental exclosures (“cribs”) were built around a few small trees in 2005. These were relatively small, square structures made of stacked poles designed to prevent cattle from rubbing trees. Subsequent monitoring (Wiggins 2005) indicated that these cribs are quite attractive to breeding shrikes and increase nesting success. Since shrikes like to forage along mowed roadsides looking for stunned insects or other road-kill, they are often struck by passing cars. A very simple solution for reducing shrike fatalities is practiced near the Carden Plains in Ontario, Canada. In shrike breeding areas, roadsides are not mowed; the weeds and grasses are allowed to grow tall, which discourages foraging shrikes, thus keeping them away from roadsides. Proactive efforts to preserve and perhaps create nesting habi-

270 Colorado Birds Fall 2014 Vol. 48 No. 4 tat will increase Loggerhead Shrike breeding success so that these unique songbirds may continue to prosper in eastern El Paso County.

LITERATURE CITED Cade, T. J. and C. P. Woods. 1997. Changes in distribution and abundance of the Loggerhead Shrike. Conserv. Biol. 11:21-31. Chabot, A.A. 1994. Habitat selection and reproductive biology of the Logger- head Shrike in eastern Ontario and Quebec. M.Sc. thesis, McGill Univ. Craig, S. 2002. The Shrikes of Dearing Road, El Paso County, CO. Journal of the Colorado Field Ornithologists, 36:1 Craig, S. 2007. Loggerhead shrikes in El Paso County, Colorado: a history of local abundance versus continental decline. Colorado Birds, 41:2. Kingery, H.E. (ed). 1998. Colorado Breeding Bird Atlas. Colorado Bird Atlas Partnership and Colorado Division of Wildlife, Denver, CO. Porter, D. K., M. A. Strong, J. B. Giezentanner, and R. A. Ryder. 1975. Nest ecology, productivity, and growth of the Loggerhead Shrike on the short- grass prairie. The Southwestern Naturalist 19:429-436. Pruitt, L. 2000. Loggerhead Shrike status assessment. U.S. Fish & Wildlife Service, Ft. Snelling, MN. Wiggins, David. A. 2005. Loggerhead shrike (Lanius ludovicianus): a technical conservation assessment. Prepared for the USDA Forest Service, Rocky Mtn. Reg. Species conservation project. Yosef, R. 1996. Loggerhead Shrike (Lanius ludovicianus). In The Birds of North America, No. 231 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists’ Union, Washington, D.C.

Susan Craig, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 271 The Five Seasons

Ted Floyd I wonder how long it would take you to notice the regular recurrence of the seasons if you were the first man on earth. What would it be like to live in open-ended time broken only by days and nights? You could say, “it’s cold again; it was cold before,” but you couldn’t make the key connection and say, “it was cold this time last year,” because the notion of “year” is precisely the one you lack. —Annie Dillard, Pilgrim at Tinker Creek

Practically everything in our heads is received wisdom. We didn’t discover any of it on our own. Evolution, relativity, the round earth, the heliocentric solar system...not a one of us figured out those things by ourselves. We didn’t discover those things, and there’s something else: We accept them on faith. Have you ever conducted experiments to confirm evolution or prove relativity; performed calculations to establish the relative orbits of planets; or gone out far enough into space to observe the roundness of the earth? I’ve met relatively few people who have done any of those things, and I doubt I’ll ever meet anybody who’s done all of them. Even something so simple as the cycling of the seasons is received wisdom. Not a one of us figured it out on our own. We learned it from our parents and teachers, or maybe we read about it in a book. Unlike relativity and evolution, though, the cycling of the seasons, once learned, is easily grasped and easily proved: Just go out for ten or twenty years, and you’ll sure enough corroborate the discovery of Annie Dillard’s hypothetical first man on earth. Spring, summer, fall, winter...spring, summer, fall, winter...spring, summer, fall, winter... Now wait a minute. Dillard didn’t say anything about that particular quater- nion scheme. Who’s to say there are precisely four seasons? Why not two, or five, or eleven? I’m being serious. In certain places on earth, we do in fact speak of a rainy season and a dry season, so just two. In the deserts of southern Arizona, the monsoons of late July and August certainly are different from the searing heat and drought of June and early July; so do they have five seasons down there?

The four seasons are arbitrary. They’re engrained in our thinking. And that’s especially so, I believe, in the case of birders. Like many of you, I started birding in the eastern U.S. Let’s face it: So many of our American birding traditions are of Atlantic Seaboard origin. Like the tra- dition of the four seasons: warbler migration in the spring, breeding bird surveys in the summer, geese flying south in the fall followed by Christmas Bird Counts and feeding stations in the winter. Over and over again, for all one’s years as a birder.

272 Colorado Birds Fall 2014 Vol. 48 No. 4 As a teen birder, I was addicted to the journal of ornithological record then known as American Birds. The mainstay of that journal was—and still is—quarterly, seasonal reports. There were—and still are—four seasons, but they depart a bit from the sidereal reckoning of equinoxes and solstices. Instead, the seasons go like this: December–February (winter), March–May (spring), June–July (summer), August–November (fall). It works so well in the mid-Atlantic re- gions and in New England, where I lived and birded until I was 30. Then I moved to Nevada, and I started to question the conventional wisdom. March and even April are pretty darned wintry in Reno; June is a great month for vagrants; and the whole idea of seasonality is completely messed up by the mountains and desert oases. What happens in Vegas, stays in Vegas. And what happens bird-wise at the summit of Mt. Charleston is so out of synch with what’s happening bird-wise at Corn Creek. Seasons, schmeasons. After my tour of duty in Nevada, I came to Colorado—where I had an epiphany during the overnight hours of Sunday–Monday, July 29–30. At 1:00 a.m., my son Andrew, seven months old at the time, and I were out prowling the mean streets of Lafayette, eastern Boulder County, taking in all the sounds and smells and (limited) sights of a warm summer’s evening: crickets chirping, bullfrogs groaning and the neighbor’s dog yapping; the pleasing aroma of skunk spray and the barely discernible whiff of outgassing from a small marsh down the street and a Great Horned Owl gliding silently by. All those things, plus something surprising and wonderful: Chipping Sparrow flight calls, 17 of them during the course of a half-hour ambled through suburban Lafayette.

To make a long story short (and it’s one I’ve previously told on the pages of this journal), Andrew and I were listening in on the amazing mid-summer nocturnal flight of Chipping Sparrows migrating east from the Rockies to molting grounds on the High Plains. It makes all the sense in the world. There’s one thing every Colorado bird has to do at least once per year. I’m not talking about breeding, as many birds— especially young birds, but also some adults—forego breeding for one or more years. Neither am I talking about migration, as some Colorado birds are ef- fectively sedentary for their whole lives. Rather, I’m talking about molt. Some birds do it twice a year, but all of our birds do it at least once per year. The timing of each bird’s annual, or prebasic molt, is variable, but, for most residents and short-distance migrants, it commences during the summer, typically right after breeding. With long-distance migrants, it happens on the wintering grounds in the tropics. There are exceptions, but that’s the general picture. Back East, where I grew up, molt is easily overlooked. That’s because the annual molt tends to occur either on or near the nest site or on the distant wintering grounds. One day, the birds are on their breeding grounds; the next day, they’re packing up and heading south for fall migration. For residents and short-

Colorado Birds Fall 2014 Vol. 48 No. 4 273 distance migrants, the whole phenomenon of molt is elided in the Dog Days of August. For long-distance migrants, it happens in Ecuador or somewhere; out of sight, out of mind. Here in Colorado, though, we are able to appreciate that the annual molt is a discrete phenomenon, quite distinct from either the nesting season that precedes it or the fall migration that follows. That’s because many of our birds are what we refer to as “molt migrants.” That term means pretty much what it sounds like: It signifies that a bird goes somewhere to molt. In general, the phenomenon is considerably more pronounced in western birds than in their eastern counterparts. Birds like Bullock’s Orioles, Lazuli Buntings and Western Tanagers are molt migrants, but their eastern counterparts—Baltimore Orioles, Indigo Buntings and Scarlet Tanagers—are not. Same thing with populations we don’t treat as separate species: Interior West populations of Warbling Vireos and Chipping Sparrows are molt migrants, but their eastern counterparts are not. How come?

Earlier this summer, I was in a forest in northern New Jersey. Even though I was lathered in DEET, I was bitten, stung, and chomped on by every arthropod imaginable. Then I came back to Colorado and enjoyed a most delightful romp in the pinewoods in the foothills of the Rockies. No bugs! I could have birded butt-naked with impunity. Lowland deciduous woods in New Jersey vs. montane pine forests in Colo- rado in summer. Puh-leeze. From the human perspective, it’s no contest. Same with birds, but the result is precisely the opposite. There’s not enough food in the woods in Colorado for birds to complete their energetically costly annual molts. So they bail out. They go elsewhere to molt—to rivers, marshes, or just low seeps and swales, generally to our south and east. Some of them don’t go very far. Others make it all the way to the desert oases of New Mexico and northern Mexico. They molt there, then carry on in fall to their wintering grounds. I need to be clear about something. I’m talking here in generalities. Molt— like breeding and migration—is a somewhat “plastic” life history trait. If conditions warrant, birds will dramatically alter their migratory and breeding sched- ules. Drastic decisions—raise a second brood, don’t bother migrating—are heavily influenced by the weather. And they differ from individual to individual. The same caveats apply to the question of when and where to molt. A user-friendly introduction to molt migration is given by Michael Donahue in an article in Birding (“Migrants, Mono Lake, Monsoons, and Molt”), May/ June 2007, pp. 34–40. The article is available as a free PDF download from the American Birding Association: tinyurl.com/Donahue-Birding.

As I type these words, I’m sitting outside in my back yard pondering the ar-

274 Colorado Birds Fall 2014 Vol. 48 No. 4 bitrariness of the idea of the four seasons. According to the calendar, it’s “July” (whatever that means), but the night sky says otherwise. Capella is rising in the Northeast, the Pleiades are way up there and Fomalhaut is nearing the merid- ian. I’ve just described the night sky in autumn—unless you’re out in the hours before sunrise in mid-summer. As if on cue, a Chipping Sparrow just flew over, at 2:29 in the morning. It was up there a ways, but it’s a still night, with no traffic yet on Baseline Road, and the sparrow’s little voice pierces the dark sky. [There goes another.] To refer to the bird as an “early fall migrant” is a stretch. The bird’s southward fall migration will come much later. For now, the bird is heading east. I wonder how far it will go. Given the hour, I suppose the bird could make it all the way to the Kan- sas border or beyond. Or maybe it will stop flying at the Brett Gray Ranch in Lincoln County or in one of the lush, buggy groves out along the South Platte River east of Denver a bit. Or maybe it won’t make it any farther than the mis- erably mosquito-ridden cattails of Greenlee Preserve, just down the road from where I type. Birds are symbols of freedom, we all know. But what does that really mean? [Pardon the interruption, but there goes another Chipping Sparrow.] Freedom from want and worry, from the workaday routine of life? Maybe that’s a part of it, but, for me, they symbolize, more than anything else, a freedom to think outside the box, to go beyond the arbitrary dictates of received knowledge and conventional wisdom. [Two more Chipping Sparrows.] Say it out loud: “Summer migration.” And: “The five seasons.” You almost have to force yourself to do so. Those phrases don’t exactly roll off the tongue. But those things are real. They’re dynamic and exciting. They’re thrilling and wonderful, and they’re happening right now, in real time, on quiet nights and in buggy marshes all across eastern Colorado.

References and Resources I’ve already mentioned Michael Donahue’s article. [I just heard two more Chipping Spar- row flight calls.] A few other resources that have helped me acquire a better appreciation of the fifth season, molt, include Steve Howell’s Peterson Reference Guide to Molt in North American Birds, Peter Pyle’s two-volume Identification Guide to North American Birds and Howell’s two-part series, “All you ever wanted to know about molt but were afraid to ask,” published in Birding in 2003, and available online: tinyurl.com/Howell-molt-part-1 and tinyurl.com/Howell-molt-part 2.

Ted Floyd, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 275 Male Rock and Canyon Wrens Evince their Fitness as Single Parents

Nat Warning, Dave Leatherman, Nora Covy, Lauryn Benedict

The speed of nestling development in birds is unrivaled by other animal groups (Dial 2003). For most songbirds nestling size and survival increase steadily from hatching to fledging, and one or both parents are challenged during this time to provide sufficient food to sustain such rapid development in multiple offspring (Dinsmore et al. 2002, Grant and Shaffer 2012). Considering the need to coordinate successful nesting with high food resource availability, nesting birds are under very strong selective pressure to maximize reproductive output during a limited period of time (Schmidt and Whelan 2010). Females are typically thought of as providing a greater nesting investment than males. Additionally, females bear the cost of lower annual survival than males due to increased risk of being preyed upon while incubating (Low et al. 2010). In spite of, or perhaps because of, this high female investment, males of many avian species are integral to successful reproduction well beyond ensuring fertile eggs. In fact, theory suggests that the social monogamy observed in over 80 percent of avian species is driven by the need for two parents to provide enough food to ensure offspring survival (Emlen and Oring 1977, Cockburn 2006). Among monogamous bird species, two parents typically provision young during the nestling phase and for up to weeks or months post-fledging. For these parents, the duration of nestling provisioning represents a balance between ensuring survival of those offspring and the ability to invest in additional offspring in future broods (Trivers 1972). One way for parents to increase overall reproductive success is to raise multiple broods (Mulvihill et al. 2009). Double brooding is common in songbirds, and occurs when a pair has two successive broods in a single season (Monroe et al. 2008, Gow and Wiebe 2012). The second clutch typically is laid after the nestlings from the first brood are fledged, and both parents can tend to the new brood (Ingold 1987). In many species, double-brooding is the norm for all pairs, but in others it may depend on seasonal timing, resources or individual ability. In Mountain Bluebirds, for example, females that initiated clutches earlier in the season were significantly more likely to double brood (O’Brien and Dawson 2012). In Eastern Kingbirds older females on higher-quality territories initiated their first clutches earlier in the season, and were most likely to lay multiple clutches per season (Murphy 2004).

276 Colorado Birds Fall 2014 Vol. 48 No. 4 If pressed for time, birds may use nesting strategies that allow them to raise more young quickly. Double clutching is one category of double brooding in which a female lays two clutches, which each parent cares for separately, and often simultaneously (Blomqvist et al. 2001). Double clutching has been well described in Mountain Quail, Mountain Plovers and Sanderlings, but has not been documented in passerine songbirds (Parmalee and Payne 1973, Gutierrez and Delehanty 1999, Blomqvist et al. 2001). Nesting patterns that fall between double clutching and successive double brooding have been described as “compressed breeding attempts” (Gow and Wiebe 2012), or overlapping broods (Walsh and Bock 1997). In these cases, a second clutch (in a different nest) is laid before the first brood has fledged. In species where females are the sole incubators, this leaves males to provision the first brood. Both double clutching and overlapping broods can occur in monogamous species, but these breeding strategies are somewhat surprising since they require that a single parent is able to provision nestlings. Overlapping broods have been described in a few Colorado songbird species, including Cedar Waxwings (Putnam 1949), Rose- breasted Grosbeaks (Rothstein 1973) and American Robins (Rowe and Weatherhead 2007). In House Sparrows, overlapping broods are occasionally taken to the extreme with a second brood initiated in the same nest while it is still occupied by young from the first brood (Lowther 1979). When broods overlap, the female invests her energy in laying and incubating a second clutch of eggs while the male invests his energy in provisioning the first brood. Thus, successfully carrying out overlapping broods depends upon male investment, skill and fervency. Rock Wrens (Salpinctes obsoletus) and Canyon Wrens (Catherpes mexicanus) are two monogamous Colorado species in which females are the sole incubators, with both parents helping to provision young (Jones et al. 1995, Merola 1995, Lowther et al. 2000). Both species are known to commonly attempt multiple successive broods (usually two) per season, thereby increasing reproductive output. Such an arrangement puts time pressure on females to lay, incubate and provision multiple clutches. It also puts pressure on males who invest heavily in provisioning young and in bringing food to their incubating mates even before eggs hatch (Fig. 1). Typically, both parents provision nestlings from multiple broods in both species, but there is one account of overlapping broods in Rock Wrens described for a Colorado pair from Gregory Canyon (Boulder County; Walsh and Bock 1997). In our studies of Canyon and Rock Wrens we have con- firmed that most pairs attempt to raise two broods per season. We

Colorado Birds Fall 2014 Vol. 48 No. 4 277 Fig. 1. (a) Rock Wren male feeding his mate just outside the nest cavity during incubation (14 July) (b) male delivering a cicada to the nest (4 Aug) (c) male inspecting four hungry nestlings (d) male delivering a large insect, possibly a mantid, to nestlings (9 Aug). Photos by Nat Warning

have usually observed both sexes caring for each set of young, but several exceptions indicate that males alone can provision a brood of chicks. We monitored a Rock Wren pair in Larimer County which nested and hatched chicks on 23 July 2013, after their first two nesting attempts failed. From 28 July to fledging on 8 Aug, only the (color banded) male was observed feeding the four nestlings. In this solo effort the male Rock Wren completely provisioned the four young in the nest for 11 days leading up to fledging (Fig. 1), and continued to feed and tutor the fledglings out of the nest. We monitored the nest using a motion-activated camera with a custom 1 m focal length (Re- conyx, Holmen, WI) placed 1 m from the nest cavity entrance from 25 July to 8 Aug 2013. The camera was triggered during 334 separate nest visits in which we could determine the sex of the visitor, and the last documented female visit to the nest was 27 July at 14:00. During this time we infrequently observed an unbanded wren, presumably the female, on the territory. Her behavior suggested that she

278 Colorado Birds Fall 2014 Vol. 48 No. 4 Fig. 2. Male Canyon Wren provisioning nestlings with (a) a centipede (27 May) and (b) a mayfly (30 May) (c) male feeding a grasshopper to a day 1 fledgling (1 June). Photos by Dave Leatherman may have been incubating at another nest, in an attempt to overlap broods, but we were unable to locate a second nest. Canyon Wrens can also be successful single parents. From 24 May to 28 May 2014 we made daily observations of a Canyon Wren pair in Larimer County feeding nestlings, but from 29 May onward, the female was no longer detected on the territory. This left the male to solely provision the nestlings from 29 May to fledging on 1 June (Fig. 2). On five subsequent visits we observed only the male (identified by song) feeding the three fledglings, until at least 16 June (Fig. 2). The sustained effort of this male, in the face of a missing mate and multiple invasions into the nest by Cliff Swallows, was remarkable. It is not unusual for a single songbird parent to successfully fledge chicks (Griggio et al 2005). In many species of birds single parenting is the norm (Cockburn 2006). Single parents are more often females, but male songbirds can successfully raise chicks on their own. Breed- ing is one of the most dangerous annual periods for songbirds, and

Colorado Birds Fall 2014 Vol. 48 No. 4 279 partner loss is relatively common during this time. If females die, or direct their energy elsewhere, males can maximize their reproductive success by ensuring that existing clutches survive. This might have costs down the road since parents that invest heavily one year can be at a disadvantage in future years (Nilsson and Svensson 1996). Nev- ertheless, both Rock Wren and Canyon Wren males seem willing and able to make the investment required of a single parent.

Acknowledgments We thank the City of Fort Collins Natural Areas Program and the Colorado Division of Parks and Wildlife for access to the study sites. Funding for the motion activated camera was provided by the Denver Audubon Society - Lois Webster Fund.

LITERATURE CITED Blomqvist, D., J. Wallander, and M. Andersson. 2001. Successive clutches and parental roles in waders: the importance of timing in multiple clutch systems. Biological Journal of the Linnean Soceity 74:549-555. Cockburn, A. 2006. Prevalence of different modes of parental care in birds. Proceedings of the Royal Society B: Biological Sciences 273(1592):1375- 1383. Dial, K. P. 2003. Evolution of avian locomotion: correlates of flight style, lo- comotor modules, nesting biology, body size, development, and the origin of flapping flight. Auk 120(4):941–952. Dinsmore, S. J., G. C. White, and F. L. Knopf. 2002. Advanced techniques for modeling avian nest survival. Ecology 83:3476–3488. Emlen, S. T. and L. W. Oring. 1977. Ecology, sexual selection, and the evolution of mating systems. Science 197(4300):215-223. Gow, E. A. and K. L. Wiebe. 2012. An Unusually Synchronous Double Brooding Attempt by a Northern Flicker Pair. Wilson Journal of Orni- thology 124(2):389-392. Grant, T. A. and T. L. Shaffer. 2012. Time-specific patterns of nest survival for ducks and passerines breeding in North Dakota. The Auk 129(2):319-328. Griggio, M., G. Matessi and A. Pilastro. 2005. Should I stay or should I go? Female brood desertion and male counterstrategy in Rock sparrows. Be- havioral Ecology 16(2):435-441. Gutierrez, R. J. and D. J. Delehanty. 1999. Mountain Quail (Oreotyx pictus). The Birds of North America. Ingold, D. J. 1987. Documented double-broodedness in Red-headed Wood- peckers. Journal of Field Ornithology 58:234-235. Jones, S. L. and J. S. Dieni. 1995. Canyon Wren (Catherpes mexicanus). The Birds of North America. Low, M., D. Arlt, S. Eggers, and T. Pärt. 2010. Habitat specific differences in adult survival rates and its links to parental workload and onnest preda- tion. Journal of Animal Ecology 79(1):214-224. Lowther, P. E. 1979. Overlap of House Sparrow Broods in the Same Nest. Bird-Banding 50(2):160-162.

280 Colorado Birds Fall 2014 Vol. 48 No. 4 Lowther P. E., D. E. Kroodsma and G. H. Farley. 2000. Rock Wren (Salpinc- tes obsoletus). The Birds of North America. Merola, M. 1995. Observations on the nesting and breeding behavior of the Rock Wren. Condor 97:585-587. Monroe, A. P., K. K. Hallinger, R. L. Brasso, and D. A. Cristol. 2008. Oc- currence and implications of double brooding in a southern population of Tree Swallows. Condor 110:382–386. Mulvimll, R. S., S. C. Latta, and F. L. Newell. 2009. Temporal constraints on the incidence of double brooding in the Louisiana Waterthrush. Condor 111:341-348. Murphy, M. T. 2004. Intrapopulation variation in reproduction by female Eastern Kingbirds Tyrannus tyrannus: the impacts of age, individual per- formance, and breeding site. Journal of Avian Biology 35(3):252-261. Nilsson, J. A. and E. Svensson. 1996. The cost of reproduction: a new link between current reproductive effort and future reproductive success. Pro- ceedings of the Royal Society of London. Series B: Biological Sciences 263(1371):711-714. O’Brien, E. L. and R. D. Dawson. 2013. Experimental dissociation of individual quality, food and timing of breeding effects on double-brooding in a migratory songbird. Oecologia 172:689–699. Parmelee, D. F. and R. B. Payne. 1973. On multiple broods and the breeding strategy of arctic Sanderlings. Ibis 115:218-226. Putnam, L. S. 1949. Life history of Waxwings. Wilson Bulletin 61:141-182. Rothstein, S. I. 1973. Extreme overlap between first and second nestings in the Rose-breasted Grosbeak. Wilson Bulletin 85:242-243. Rowe, K. M. and P. J. Weatherhead. 2007. Social and ecological factors af- fecting paternity allocation in American robins with overlapping broods. Behavioral Ecology and Sociobiology 61(8):1283-1291. Schmidt, K. A. and C. J. Whelan. 2010. Nesting in an uncertain world: information and sampling the future. Oikos 119(2):245-253. Trivers, R. L. 1972. Parental investment and sexual selection. In: Sexual Se- lection and the Descent of Man, ed. B. Campbell, pp. 136-179. Chicago: Aldine. Walsh, J. J. and C. E. Bock. 1997. Likely occurrence of overlapping broods in the Rock Wren. Western Birds 28(4):223-224.

Nat Warning, Nora Covy, Lauryn Benedict, School of Biological Sciences, University of Northern Colorado, Greeley, CO 80639

Dave Leatherman, 612 Stover Street #7, Fort Collins, CO 80524

Nat Warning, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 281 NEWS FROM THE FIELD

Spring 2014 (March–May)

Peter Gent Overview of the Season “News from the Field” contains reports of rare birds sighted in Colorado. These reports are compiled from the COBirds listserv ([email protected]), eBird (ebird.org) and the West Slope Birding Network ([email protected]). Very rare species seen this spring included: Red-faced Warbler and Hooded Oriole (one accepted record each), Zone-tailed Hawk (two accepted records), Painted Redstart (five accepted records), Yellow- bellied Flycatcher and Black-chinned Sparrow (six accepted records each), White Ibis (seven accepted records) and Swainson’s Warbler (eight accepted records). The monthly average temperature in Denver was just above normal in both March and May, but the April average of 49.0F was 1.6F above normal. Precipitation in Denver was about normal in March and 0.47 inches below normal in April, but the 3.51 inches received in May was 1.39 inches above normal. In addition, the snowpack in nearly all of Colorado’s mountain ranges was well above normal, making for excellent skiing conditions nearly everywhere. 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 http://cfobirds. org/CBRC/login.php. This is the preferred method to submit your documentation. However, a hardcopy form is located on the inside of this journal’s mailing cover. The documentation should be sent to CBRC chairman Doug Faulkner (address on form). Abbreviations: CFO - Colorado Field Ornithologists; CG - campground; CR - County Road; m.ob. - many observers, Res. - Reservoir.

BRANT: One was at Redstone in Franktown, Douglas, on 15 and 16 Park in Highlands Ranch, Douglas, Mar (UK, HK). from 1-17 Mar (m.ob.). Red-necked Grebe: A pair was Trumpeter Swan: Two were at observed building a nest at Lake John Boyd Ponds, Morgan, on 2 Mar (SM), in North Park, Jackson, on 30 May and one was seen at Nee Granda (CH, PS). Much more on this obser- Res., Kiowa, on 22 Mar (BK). vation in the Summer Report. EURASIAN WIGEON: A NEOTROPIC CORMORANT: beautiful male graced the Walker Pit One was seen at Denny Lake in Cor-

282 Colorado Birds Fall 2014 Vol. 48 No. 4 Least Bittern, Chico Basin Ranch, Pueb- Little Blue Heron, Drake Pond, El Paso lo County, 22 May 2014. Photo by Bill County, 25 April 2014. Photo by Bill Maynard Maynard

Laughing Gull, Lamar Truck Plaza, Great Black-backed Gull, Wood Lake, Prowers County, l6 May 2014. Photo Weld County, 4 March 2014. Photo by by Dave Leatherman Dave Leatherman tez, Montezuma, on 3 May and perhaps ZONE-TAILED HAWK: One earlier (MBa, m.ob.). This is the first was well observed at Lamar Com- record for this county. munity College, Prowers, on 10 May Least Bittern: One was at Chico (MPe, DM, CFO field trip). There are Basin Ranch, Pueblo, from 20-26 May two previously accepted records for (BM, BKP). this species from Colorado. White Ibis: An excellent find was RUDDY TURNSTONE: Very an adult photographed at the Akron rare on the West Slope of Colorado golf course, Washington, on 25 May was one seen near Craig, Moffat, on 18 (GW). There are seven previously ac- May (VZ, FL), which is the first record cepted records of this species in Colo- for this county. rado, with the last two seen in 2006. LAUGHING GULL: An adult

Colorado Birds Fall 2014 Vol. 48 No. 4 283 Lewis’s Woodpecker, Fowler Trail, Boul- Eastern Phoebe, Chatfield State Park, der County, 28 May 2014. Photo by Douglas County, 19 April 2014. Photo Jane Baryames by Mark Chavez

White-eyed Vireo, Chico Basin Ranch, Gray-cheeked Thrush, Crow Valley Pueblo County, 26 April 2014. Photo Campground, Weld County, 13 May by Bill Maynard 2014. Photo by Mark Chavez

McCown’s Longspur, southwest of Worm-eating Warbler, Cherry Creek Pierce, Weld County, 11 May 2014. State Park, Arapahoe County, 6 May Photo by Dave Leatherman 2014. Photo by Mark Chavez

284 Colorado Birds Fall 2014 Vol. 48 No. 4 Northern Waterthrush, Crow Valley Kentucky Warbler, Crow Valley Camp- Campground, Weld County, 14 May ground, Weld County, 20 May 2014. 2014. Photo by Mark Chavez Photo by Mark Chavez

Hooded x Yellow Warbler, Roxborough Northern Parula, Tinsletown, El Paso State Park, Douglas County, 17 May County, 9 May 2014. Photo by Bill 2014. Photo by Mark Chavez Maynard

Blackburnian Warbler, Stulp Farmyard, Black-throated Blue Warbler, Fountain Prowers County, 26 May 2014. Photo Creek Regional Park, El Paso County, by Jane Stulp 18 May 2014. Photo by Bill Maynard

Colorado Birds Fall 2014 Vol. 48 No. 4 285 Bay-breasted Warbler, Stulp Farmyard, Summer Tanager, Crow Valley Camp- Prowers County, 21 May 2014. Photo ground, Weld County, 21 May 2014. by Jane Stulp Photo by Dave Leatherman

Scarlet Tanager, Chico Basin Ranch, Pueblo County, 21 May 2014. Photo Townsend’s x Black-throated Green by Bill Maynard Warbler, Chico Basin Ranch, Pueblo County, 21 May 2014. Photo by Bill Maynard

Indigo Bunting, Enchanted Mesa, Boul- Hooded Oriole, private residence, Mesa der County, 31 May 2014. Photo by County, 1 May 2014. Photo by Brenda Jane Baryames Wright

286 Colorado Birds Fall 2014 Vol. 48 No. 4 White Ibis, Akron, Washington County, 25 May 2014. Photo by Glenn Walbek

White-rumped Sandpiper, Chico Basin Ranch, Pueblo County, 26 May 2014. Photo by Bill Maynard

Rufous Hummingbird, Stulp Farmyard, Prowers County, 27 April 2014. Photo by Jane Stulp

Northern Flicker intergrade, Grandview Northern Saw-whet Owl, Forbes Park, Cemetery, Fort Collins, Larimer Coun- Costilla County, 18 May 2014. Photo ty, 20 April 2014. Photo by Dave by Polly Wren Nelder Leatherman

Colorado Birds Fall 2014 Vol. 48 No. 4 287 Blue-headed Vireo, Last Chance, Wash- Prothonotary Warbler, Fountain Creek ington County, 15 May 2014. Photo by Regional Park, El Paso County, 17 May Glenn Walbek 2014. Photo by Bill Maynard

Black-and-white Warbler, Crow Val- Golden-winged Warbler, Brett Gray ley Campground, Weld County, 9 May Ranch, Lincoln County, 16 May 2014. 2014. Photo by Mark Chavez Photo by Glenn Walbek

Blue-winged Warbler, Welchester Tree Mourning Warbler, Crow Valley Camp- Park, Jefferson County, 27 May 2014. ground, Weld County, 21 May 2014. Photo by Mark Chavez Photo by Glenn Walbek

288 Colorado Birds Fall 2014 Vol. 48 No. 4 Chestnut-sided Warbler, Fountain Creek Blackpoll Warbler, Martinez Park, Fort Regional Park, El Paso County, 19 May Collins, Larimer County, 17 May 2014. 2014. Photo by Bill Maynard Photo by Dave Leatherman

Prairie Warbler, Belmar Historic Park, Jefferson County, 15 May 2014. Photo by Glenn Walbek

Yellow-throated Warbler, Chico Basin Townsend’s Warbler, Fairmount Cem- Ranch, El Paso County, 23 May 2014. etery, Lamar, Prowers County, 25 April Photo by Bill Maynard 2014. Photo by Dave Leatherman

Colorado Birds Fall 2014 Vol. 48 No. 4 289 Black-throated Green Warbler, Chey- enne County, 5 May 2014. Photo by Glenn Walbek Hepatic Tanager, Lamar Community College Woods, Prowers County, 30 April 2014. Photo by Dave Leatherman

Fox Sparrow, Red Rocks Trading Post, Jefferson County, 6 April 2014. Photo by Mark Chavez

Northern Cardinal, Willow Creek Na- Rose-breasted Grosbeak, Powers County ture Trail, Prowers County, 3 March yard, 10 May 2014. Photo by Jill Smith 2014. Photo by Jill Smith

290 Colorado Birds Fall 2014 Vol. 48 No. 4 was at the truck stop in Lamar, Prow- at Chico Basin Ranch, El Paso, (BKP, ers, on 6 May (DL), and another adult DS), and one was seen at Crow Valley was seen at DeWeese Res., Custer, on CG, Weld, on 24 May (NK). 22 and 23 May (RMi). Vermilion Flycatcher: A male was ICELAND GULL: A second year at South Fork in the San Luis Valley, bird was at Woods Lake, east of Sever- Rio Grande, (3rd record there) between ance, Weld, on 2 Mar (SM). 6 and 8 Apr (VS, JR). Arctic Tern: One was seen at Boyd BLUE-HEADED VIREO: One Lake in Loveland, Larimer, on 14 May was at Last Chance, Washington, on 15 (NK). May (GW), a second on 15 May was LESSER NIGHTHAWK: Be- at the Neenoshe Locust grove, Kiowa, tween two and five birds were seen (SM), and one was seen at the Mc- at the Nucla sewage ponds, Montrose, Murry Natural Area in Fort Collins, between 26 and 31 May (BW, CD, Larimer, on 16 May (RS). m.ob.). This might be the most reli- PHILADELPHIA VIREO: One able location in Colorado to see this was seen at Stalker Lake, northwest very unusual species. of Wray, Yuma, on 23 May (SM), and Acorn Woodpecker: One was another was seen in Gregory Canyon, nicely photographed at the Perennial Boulder, on 28 May (PB). Frontier Nursery in Colorado City, Bohemian Waxwing: A flock of Pueblo, on 21 May (DC). more than 200 was seen in Steamboat EASTERN WOOD-PEWEE: A Springs, Routt, on 4 Mar (LW, MPa). very good season for this species with This species was not seen anywhere six reported. One was in Carrizo Can- else in the state this spring. yon, Baca, on 22 Apr (SR), and one Blue-winged Warbler: A male was seen at the Lamar Community was seen at Welchester Tree Park, Jef- College, Prowers, on 16 May (DM). ferson, between 22 and 31 May (SJ, One was seen at Two Buttes, Baca, on m.ob.), and will be discussed more ex- 21 May (AS, TB), and another was at tensively in the Summer Report. Duck Creek SWA, Logan, on 24 May Golden-winged Warbler: A male (SM). One was seen at Crow Valley was seen at the Lamar Community CG, Weld, on 29 May (CSh), and an- College, Prowers, on 26 Apr (NL, DL), other was at the Stulp farm, Prowers, and single males were at the Melody on 31 May (JS). Temple Grove, Bent, on 5 May and 23 YELLOW-BELLIED FLY- May (JS, DN, JT). CATCHER: One was at the Lens SWAINSON’S WARBLER: One farm, north of Wray, Yuma, on 14 of this rare species was seen at the May (SM, NM). Melody Temple Grove, Bent, on 5 Alder Flycatcher: One was seen May (DN, JS, GK). and heard at the Greenlee Preserve, LUCY’S WARBLER: Four birds Boulder, on 17 May (TF), and one were seen in the known nesting loca- was north of Wray, Yuma, on 22 May tion of Yellowjacket Canyon, Mont- (SM). Another on 22 May was seen ezuma, on 15 Apr (SM).

Colorado Birds Fall 2014 Vol. 48 No. 4 291 MOURNING WARBLER: A Prairie Warbler: One was seen male was seen north of Wray, Yuma, at Belmar Park, Jefferson, on 14 May on 14 May (SM, NM). One was seen (MC), and one was at Fountain Creek at Crow Valley CG, Weld, on 15 May Regional Park, El Paso, on 19 May (TD), and another was at the same (SG). One was seen at Chico Basin location on 21 May (GW). One was Ranch, Pueblo, on 23 May (BKP, DS). seen at Melody Tempel Grove, Bent HERMIT WARBLER: A male on 23 May (DN, JS, JT), and one was was seen at the Melody Temple seen in Pueblo, Pueblo, on 26 and 27 Grove, Bent, on 25 Apr (DN, DL), May (VT, BKP). and another was seen in Pueblo City KENTUCKY WARBLER: A Park, Pueblo, on 17 May (PS-S, CSm). very good spring season for this spe- RED-FACED WARBLER: One cies. A male was seen at Melody Tem- was observed below McPhee Dam on ple Grove, Bent, on 4 May (JS, DN, the Dolores River, Montezuma, on 10 JT) and another male was found at the May (DG). There is only one accept- house of Pam Piombino near Hygiene, ed record of this species in Colorado, Boulder, on 12 May (PP). A female which was seen at the Wheatridge was banded in nearby Lykins Gulch, Greenbelt, Jefferson, on 3 May 1993. Boulder, on 13 May (MBo), and one PAINTED REDSTART: One was seen at the Durango Fish Hatch- was seen at Crow Valley CG, Weld, ery, La Plata, on 16 May (RMo). One between 1 and 3 May (CSh), and was at Crow Valley CG, Weld, on 20 gave excellent views to many observ- May (GW), and the last was seen at ers. There are five previously accepted Tamarack Ranch, Logan, on 25 May records of this species in Colorado, (GW). and a submitted record of a bird seen Bay-breasted Warbler: Very un- during the CFO Convention last May. usual in the San Luis Valley was a fe- EASTERN TOWHEE: One was male at Home Lake, Rio Grande, on 12 reported from Crow Valley CG, Weld, May (VS). One was seen at Crow Val- on 3 May (GL), a female was observed ley CG, Weld, on 17 May (TS), and at DePorter Lake, Sedgwick, on 24 another on 17 May was seen below May (SM), and a male was at Tama- the dam at Two Buttes, Baca (DM). A rack Ranch, Logan, on 25 May (SM). male was observed at the Stulp farm, Canyon Towhee: The first record Prowers, between 21 and 23 May (JS). of this species on the West Slope of Pine Warbler: A female was seen Colorado was one seen in Yellowjack- at Pastorius Res. southeast of Duran- et Canyon, Montezuma, on 15 Apr go, La Plata, on 4 May (JB). This is (SM). the first sighting of this species on the BLACK-CHINNED SPARROW: West Slope of Colorado. One was at Two birds were seen at the usual loca- Crow Valley CG, Weld, between 15 tion in the Colorado National Monu- and 18 May (KP, TS), and another ment, Mesa, on 24 Apr (JC). was seen at Prewitt Res., Washington, Golden-crowned Sparrow: The on 23 May (GW). two individuals that have spent the

292 Colorado Birds Fall 2014 Vol. 48 No. 4 last several winters in Colorado re- on 15 May three males were seen at turned this year and stayed on into the the same location (JM). Another male spring season. One was at the Trading was seen in Sand Canyon, Kiowa, on Post in Red Rocks Park, Jefferson, be- 21 May (AS, TB). tween 1 Mar and 12 Apr (m.ob.), and Eastern Meadowlark: One was the second was at the North Teller seen on CR 21 north of CR G, Baca, parking lot, Boulder, between 1 Mar on 21 May (AS, TB). and 24 Apr (m.ob.). HOODED ORIOLE: A female Hepatic Tanager: Out of its usual was seen at the home of Brenda range was a female seen at the Lamar Wright and Coen Dexter in Nucla, Community College, Prowers, on 30 Montrose, on 1 and 2 May (BW, CD). Apr and 1 May (SS, SEM, m.ob.), and The only accepted record is of a male a male was seen along Rouse Road, that spent a month 18 miles west of Huerfano, on 30 May (RMi). Cortez, Montezuma, in the summer of SCARLET TANAGER: One was 2006. seen at Chico Basin Ranch, Pueblo, on Baltimore Oriole: A female was 21 May (BM, LE, BKP). seen in Nucla, Montrose, on 8 May Painted Bunting: A pair was seen (BW, CD). in Picture Canyon, Baca, on 10 May Scott’s Oriole: One in a rather un- (CN, CFO field trip), and continued usual location was seen in Sand Can- through the end of May. In addition, yon, Kiowa, on 21 May (AS, TB).

ACKNOWLEDGMENTS Many thanks to the volunteer regional compilers: Jim Beatty (southwest), Coen Dexter (west central), John Drummond (southeast), Forrest Luke (northwest), and Brandon Percival (Pueblo area). Special thanks to Tony Leukering for extracting all the data from eBird, and preparing a table of all the reports from Colorado.

CONTRIBUTING OBSERVERS MBa: Ms Bartlett; JB: Jim Beatty; MBo: Maggie Boswell; TB: Tayler Brooks; PB: Peter Burke; DC: Diana Capen; MC: Mark Chavez; JC: Jacob Cooper; TD: Todd Deininger; CD: Coen Dexter; LE: Lisa Edwards; TF: Ted Floyd; DG: Dennis Garrison; SG: Steve Getty; CH: Charles Hundertmark; SJ: Stephanie Jones; BK: Bill Kaempfer; HK: Hugh Kingery; UK: Urling Kingery; GK: Gary Koehn; NK: Nick Komar; DL: Dave Leather- man; GL: Gary Lefko: NL: Norm Lewis; FL: Forrest Luke; BM: Bill Maynard; DM: Dan Maynard; RMi: Rich Miller; JM: Jeannie Mitchell; SM: Steve Mlodinow; NM: Nick Moore; RMo: Riley Morris; SEM: SeEtta Moss; DN: Duane Nelson; CN: Christian Nunes; MPa: Marilyn Palmer; KP: Ken Pals; BKP: Brandon Percival; MPe: Mark Pe- terson; PP: Pam Piombino; JR: John Rawinski; SR: Sue Riffe; PS-S: Pearle Sandstrom- Smith; SS: Scott Severs; CSh: Cathy Sheeter; VS: Virginia Simmons; PS: Paul Sling- sby; TS: Tim Smart; CSm: Clif Smith; RS: Rob Sparks; AS: Andrew Spencer; DS: Dan Stringer; JS: Jane Stulp; JT: Janeal Thompson; VT: Van Truan; GW: Glenn Walbek; LW: Lisa Williams; BW: Brenda Wright; VZ: Vic Zerbi.

Peter Gent, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 293 CFO FIELD TRIP REPORT

Meteors, Molt Migration and More with Ted Floyd

August 12, 2014 Fifteen hardy birders convened early on the morning of Tuesday, August 12, for three-plus glorious hours of the rich sensory and psy- chological experience of being out at night. Where to start? I know, let’s start with astronomy. We were fortunate to have with us Dan Durda, a professional astronomer who helped us identify double stars, gas nebulae, the galaxy in Andromeda, the planet Uranus, various constellations, several star clusters, stars with every manner of Arabic name, a near conjunction of Jupiter and Venus, an iridium flare, The Great Watermelon (how the moon looks late at night a day or so after full), and, oh, yes, meteors. The Perseids were, all things considered, rather humdrum. The Great Watermelon blew out all but the bright- est meteors. Still, we saw several dozen. One induced a wonderful shriek from some of the participants. I love it when that happens. We learned cool stuff about asteroids, extrasolar planets and what the moon’s surface is made of. We heard coyotes and bull frogs, crickets and cicadas, a squeaky rodent, fish thrashing about and maybe a red fox. A highlight was seeing a big foraging flock of bats, mainly big

CFO Fall Field Trip: Saturday November 8th

Join CFO President Bill Kaempfer and Vice President Christian Nunes on this trip to east-central Colorado. Reserve a spot by emailing [email protected]. We will depart from the King Soopers parking lot at the Bennett exit off I-70 (about 15 miles east of I-70 and 470) at 7:00 a.m. on November 8. The trip will visit birding hotspots along the I-70 corridor in eastern Colorado including Flagler State Wildlife Area, Bonny State Wild- life Area and Hale Ponds. Expect to find late migrants, shorebirds and waterfowl. Sandhill Cranes are likely and we may be able to try for Sprague’s Pipit. Bring food, water and appropriate dress for the weather. Carpooling will be required. This trip is open to CFO members and non-members.

294 Colorado Birds Fall 2014 Vol. 48 No. 4 brown bats, but also at least one hoary bat. The bats were working the buggy airspace in the treetops that line Greenlee Reservoir. The Chipping Sparrow flight was good. During the times when I wasn’t gabbing, I heard them going over at a rate of 30-40 flight calls per hour, from our start time at 2:45 a.m. to the end of nauti- cal dawn, about three hours later. Sharp-eared listeners like To- piltzin Martinez, Elena Klaver and Mark “The Minnesota Mys- Chipping Sparrow, CR 17 north of SR 14, tic” Alt heard more than I did. Weld County, 11 May 2014. Photo by (They have better ears, and they Dave Leatherman talk less.) We also heard a few Lark Buntings, a couple of Wilson’s Warblers and a few short, high, clipped notes that I think could have been Brewer’s Sparrows. So things were definitely on the move, with just the slightest breeze out of the west-southwest. At 3:58 a.m. we heard something amazing: a loudly trumpeting, high-flying Western Grebe, winging its way from northwest to southeast. It’s unusual to even see a Western Grebe in sustained flight. Hearing one at night was awesome. We also got to hear a lot of calling from Black-crowned Night-Herons flying about. The resident Barn Swallows were on the wing, twittering in the moonlit, doing whatever it is they do on summer nights. We also heard a flight call that I think was likely that of a Semipalmated Plover; not positive of that ID. Oh, and a few Killdeer. We also heard a female Great Horned Owl singing a subdued, sort of whiny, nasal version of the typical series of hoot notes.

Ted Floyd, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 295 IN THE SCOPE

Identifying Curve-billed Thrasher Subspecies: Why and How

Tony Leukering and Nathan Pieplow Curve-billed Thrasher is typical of semi-desert grasslands and moister deserts of the southwestern United States and northern Mex- ico. In Colorado, the species occurs as a breeder and (perhaps lower- density) permanent resident in southeastern Colorado from Fremont and southeastern El Paso counties south on the plains through Las Animas County and east to Prowers and Baca counties. In that area, its occurrence is strongly associated with that of Tree Cholla (Cylin- dropuntia imbricata) (pers. obs.). Curve-billed Thrasher, though nearly unreported from Lincoln, Kiowa and Cheyenne counties (eBird 2014) may be of regular occurrence in this grassland-transition zone of eastern Colorado. Occasional vagrants have occurred in northeastern Colorado (Jefferson, Boulder, Larimer and Weld counties) with individuals often being present for extensive periods (such as noted in Faulkner 2012a, pg. 58). Unfortunately, most reports of the species from the San Luis Valley and the West Slope lack firm details (see exceptions noted below).

Taxonomy In the United States, two subspecies have long been recognized in Curve-billed Thrasher. Eastern oberholseri is associated with the Chihuahuan Desert. It occurs from southeast Colorado southwest to southeast Arizona, south through southwestern Kansas and pan- handle Oklahoma to the Corpus Christi, Texas, area and south into Mexico. Western palmeri is associated with the Sonoran Desert re- gime and has a more restricted range, occurring in the southern half of Arizona and south into Mexico. Curve-billed Thrasher taxonomy in Mexico is not at all clear-cut, with various authors recognizing two to four additional subspecies (Pyle 1997, Zink and Blackwell-Rago 2000). Because palmeri Curve-billed Thrasher has been known for >100 years as “Palmer’s Thrasher” (e. g., Stafford 1912), we here use that name when referring to that taxon. Unfortunately, oberholseri has apparently not received any other epithet but Curve-billed Thrasher; even Pyle (1997) does not provide a common name. Because the taxon would require an English name if split, we considered many options for such, but found most that have been used in the gray literature as being somewhat misleading (particularly Eastern, which

296 Colorado Birds Fall 2014 Vol. 48 No. 4 heretofore has been an epithet restricted to species occurring regularly east of the Mississippi River). Thus, following the precedent set in this column (Leukering and Pieplow 2010a), we have opted here to use a name for this taxon without published precedent, although this one has recently been used informally by some birders, “Cholla Thrasher” (fide S. Mlodinow). Because the name reflects a consistent component of the taxon’s habitat, we find it somewhat more appropriate than Chihuahuan Thrasher, the next-best option. Hereafter, any use of “Curve-billed Thrasher” is meant to indicate both taxa, together.

Why Although knowledge’s sake is sufficient rationale to discern occurrence patterns of subspecies of Curve-billed Thrasher, the reason that most birders may be interested is that the species has been noted by Zink and Blackwell-Rago and others (2000; references therein) as perhaps consisting of multiple species. Unfortunately, the decision to split the species (if appropriate) awaits a rigorous study, particularly one that systematically samples the extensive contact zone of these taxa in southeast Arizona (genetically, phenotypically, vocally) to determine the actual relevance of the differing genetics of the two (V. Remsen, in litt.), as the study analyzed no contact-zone individuals. Curve-billed Thrasher has a slight propensity for long-distance vagrancy, with records scattered from Alberta south and east to Flori- da including Saskatchewan, Manitoba, Idaho, Montana, Minnesota, Wisconsin, Nebraska, Iowa, Missouri and Illinois (eBird 2014, Pyle 1997, Rosenberg 2006). There are also less-far-flung records from Nevada, Utah, northwestern New Mexico and northeastern Texas. Although we were unable to determine the referable taxon for most of these reports, some have been reported to subspecies. Records from Utah and Nevada are presumed to be referable to Palmer’s Thrash- er, though with few actual determinations, while California (where the species is of sporadic occurrence, with a recent “slight uptick” in frequency; P. Lehman, pers. comm.) records are considered to be of Palmer’s Thrasher (California Bird Records Committee 2007). As might be expected, most of the vagrant occurrences involving sub- specifically identified individuals east of the Rocky Mountains were of Cholla Thrasher. However, the Alberta record (eBird 2014) seems referable to Palmer’s, and individual records from Idaho (Rosenberg 2006), Nebraska (Pyle 1997) and Florida (Pyle 1997, B. Pranty pers. comm.; U. S. National Museum #340321) are reported as Palmer’s Thrashers. Additionally, Palmer’s Thrashers have been noted in western New Mexico on a few occasions (pers. obs., Feb 1998; M.

Colorado Birds Fall 2014 Vol. 48 No. 4 297 Fig. 1. This Curve-billed Thrasher shows most features typical of Cholla Thrasher. Photo by Bill Maynard

Fig. 2. The wing bars on this Cholla Thrasher, photographed in spring, are in the process of disappearing. Photo by Janeal Thompson

298 Colorado Birds Fall 2014 Vol. 48 No. 4 Complete captions on next page

Fig. 3. This Curve- billed Thrasher was photographed in Tuc- son near the western edge of the contact zone between Cholla and Palmer’s thrashers in southeastern Arizo- na. Photo by Steven G. Mlodinow

Fig. 4. Note the dark chest on this Curve-billed Thrasher and the near-lack of wingbars. Photo by Bill Maynard

Colorado Birds Fall 2014 Vol. 48 No. 4 299 Fig. 1. This Curve-billed Thrasher shows most features typical of Cholla Thrasher: yellow- orange eye, white throat, distinct underparts spotting on a whitish background and distinct white wing bars. This individual is still in fairly fresh plumage, with the relatively unworn wingbars. Note the white tips to the tertials, a sure sign of fresh plumage, because these tend to wear away quickly. Also note that the tertials are a bit darker and less worn than the brownish secondaries layered under them. This indicates that this bird is an immature hatched in the previous summer, because immatures often replace their juvenal tertials in the preformative molt in their first summer, but their juvenal secondaries are not replaced until the second prebasic molt the following summer/fall (Pyle 1997); adults would exhibit similar color and wear to these feathers. Chico Basin Ranch, El Paso County, CO, 24 December 2011. Photo by Bill Maynard

Fig. 2. The wing bars on this Cholla Thrasher, photographed in spring, are in the process of disappearing, with just two of the outer greater coverts still sporting obvious white tips. This bird exhibits very little orange in the eyes, and the gray back contrasts with the brown tertials, two features that suggest an immature (hatched in the previous summer). If true, then that could explain the virtual lack of wing bars, because the wing coverts would have been held for nearly a year (since being grown in the nest), unlike those of an adult, which would have been replaced in late summer or fall and might show more-extensive and – numerous white covert tips. All features exhibited by this individual are typical of Cholla Thrasher, particularly the whitish ear surround (a horizontal strip of whitish below the ear coverts) that is somewhat obscured by the dappled lighting. Southern Prowers Co., CO, 31 May 2014. Photo by Janeal Thompson

Fig. 3. This Curve-billed Thrasher was photographed in Tucson near the western edge of the contact zone between Cholla and Palmer’s thrashers in southeastern Arizona. Note the virtual lack of wing bars and no apparent white rectrix tips (although the tail tip is mostly obscured). However, also note the fairly bright throat and the pale ground color running down the middle of the underparts plumage with fairly contrasting and relatively distinct spotting. From the front, this bird could easily be identified as a Cholla Thrasher, whereas from the side it gives the appearance of Palmer’s Thrasher. In a suspected overlap zone, we would suggest calling this bird a Curve-billed Thrasher. Curve-billed Thrasher, Tucson International Airport, Pima Co., AZ, February 2013. Photo by Steven G. Mlodinow

Fig. 4. Note the dark chest on the Curve-billed Thrasher and the near-lack of wingbars. However, also note that the tertials have distinct white tips and that those feathers are grayer than the browner, worn secondaries layered below them. This bird is the same individual as depicted in Fig. 1. The fluffed-up side feathers obscure the bird’s wing bars and the bird’s more-scrunched posture compresses the chest plumage, causing it to appear more solidly dark. Were this bird found in southeast Arizona, it might have been pegged as one of the many intermediate-looking individuals there. Chico Basin Ranch, however, is probably as far from Palmer’s Thrasher and any overlap zone as the regular range of Cholla Thrasher range extends. As in all bird identification, arriving at the correct identification of this bird requires not only using more than one field character, but also in correctly assessing one’s ability to actually discern that character, taking into account various features as lighting, distance to the bird in question and the activity and posture of that bird. Chico Basin Ranch, El Paso Co., CO, 24 December 2011. Photo by Bill Maynard

300 Colorado Birds Fall 2014 Vol. 48 No. 4 Baumann in litt.; Williams 2010). Most importantly for Coloradans, the Colo- rado Bird Records Committee has accepted single records of Palmer’s Thrasher from Mesa (June 2004; Semo 2006) and Pitkin (December 2010 – April 2011; Faulkner 2012b) counties. Nearly all records of vagrant Curve-billed Thrasher have occurred in late fall and winter, with many being present for extended periods, often through the winter, so the aforementioned Mesa County record is somewhat anomalous. Interestingly, a Curve-billed Thrasher found 26 June 2014 near Colorado National Monument, Mesa County, may be referable to Palmer’s Thrasher, although the bird was not seen well enough to be certain (M. Foster pers. comm.).

How The following is intended to be read with reference to Figs. 1–6, the final two of which grace the back cover of this issue: Palmer’s Thrasher (above) and Cholla Thrasher (below). Curve-billed Thrasher plumage characters noted here were analyzed by Leukering from photos of >120 individuals and his extensive experience (n>250) with the species in Colorado, New Mexico, Ari- zona and Chihuahua, though admittedly light on Palmer’s Thrasher (n<20). Both forms of Curve-billed Thrasher share similar overall body coloration, having medium-brown upperparts and slightly paler underparts with contrastingly pale throat and cinnamon-buff vent region. Because there is little photographic documentation of differences between the two forms in juvenal plumage, we here treat just post-juvenal birds, that is, birds in either formative or definitive basic plumages (both taxa lack prealternate molts; Pyle 1997; see also Leukering 2010, 2011). The primary physical characters that differ between the taxa in the appearance of post-juvenal birds are as follows (in rough order of usefulness, more certain to less certain): Wing barring. In fresh plumage, Cholla Thrasher exhibits obvious white wing bars (Fig. 1) that, unfortunately, are often faded and worn to obscurity by spring (Fig. 2). Only in the freshest plumage does Palmer’s sport wing bars, and those are very thin and tend to be buffy or tawny, rather than white; these disappear by fall or winter. Tail tip. Although tail-tip pattern differs in the two taxa, correctly assessing that pattern in the field can be tricky, and requires good views of the spread tail from behind or unshaded views from in front. Cholla Thrasher has white tips to the outer 3-4 rectrices on each side, with the white being more extensive on the outer web than on the inner web of a given rectrix, and with tip size declin- ing on the tail inward. The outermost feather has the most extensive white tip, occupying about 10 percent of the unworn feather. In Palmer’s Thrasher, the three outer rectrices on each side are tipped thinly in sandy-buff. Because both forms spend so much time on the ground and in dense vegetation, their tail tips wear quickly and extensively, degrading both the contrast and extent of these pale tips, such that even Cholla Thrasher can apparently lack contrastingly pale

Colorado Birds Fall 2014 Vol. 48 No. 4 301 rectrix tips by summer. Beware also that these pale areas on juvenile rectrices of first-cycle birds average less distinct than on basic feathers of older birds within each taxon (Pyle 1997). Underparts color and pattern. Cholla Thrasher typically has relatively distinct spotting underneath on a noticeably paler background, often whitish, particularly down the middle of the underparts. Palm- er’s Thrasher has blurry spotting on a slightly paler brownish background, particularly across the chest; some individuals nearly lack obvious spotting. Although individual Cholla Thrashers can show quite blurry spotting and fairly dark chests, any Curve-billed Thrasher with the vertical middle of the underparts being contrastingly very pale is a Cholla. Conversely, any individual with nearly entirely brownish or brownish-gray underparts is a probably a Palmer’s. Throat contrast. This feature varies tremendously in both taxa. Some individuals have a white throat in striking contrast to the chest, while others have a dingier throat that provides little contrast to the chest. The very dingy and very white ends of the range are probably occupied solely by Palmer’s and Cholla thrashers, respectively. Ear surround. Although quite subtle, Cholla Thrasher tends to show a very thin, but often distinct, whitish ear surround (Fig. 2) that is more-or-less connected to the pale malar stripe, while Palmer’s Thrasher tends to lack this feature. In Palmer’s that express it, the color of it is pale buff or tawny and contrasts little with the rest of the face. Pale malar stripe. Despite the illustrated treatment in various field guides of both taxa, a thin, whitish malar stripe (proximal to the dark lateral throat stripe), when present, is often very short, at times indis- tinguishable in all but the best of views. This feature tends to be ab- sent in Palmer’s Thrasher, which enhances its hooded look, because the color of the lower face abuts the variably dark brown-to-blackish lateral throat stripe. Cholla Thrasher tends to show at least some expression of the feature, although often just the upper few millimeters, but even that creates a bit of a break in the dark coloration, providing a slightly different look. Overall color tone. Cholla Thrasher usually sports a gray aspect to its plumage, while Palmer’s Thrasher exhibits a ruddy tone. In fresh- plumaged individuals, this feature can be an excellent first clue to identity, however, individual variation is fairly substantial in both taxa, and wear and bleaching play a part in apparent plumage tone. Also, as with Catharus thrushes (Leukering 2007) lighting can impact apparent plumage tone, with shaded birds often appearing grayer and birds in full sun appearing ruddier. Eye color. Cholla Thrasher tends toward slightly oranger eyes than

302 Colorado Birds Fall 2014 Vol. 48 No. 4 the yellower-eyed Palmer’s Thrasher, though color overlap might be complete; beware that eye-color tends to be paler and yellower within taxa in first-year individuals.

Vocalizations The most common calls of Cholla and Palmer’s thrashers are loud and distinctive. Based on a visual review of spectrograms of 25 recordings from the United States and northern Mexico, they differ from each other in consistent but subtle ways. Cholla Thrasher (n=9) gives a series of 2-4 identical, sharply upslurred whistles in rapid series: WEET-WEET-WEET! All notes are equal in empha- sis. Some observers have noted a similarity between this call and the high alarm calls of Wood Thrush. The typical call of Palmer’s Thrasher (n=12) is very similar, but the first note is typically softer and ends on a much lower pitch, creating the impression of a strong accent on the second syllable: wit-WEET! or wit-WEET-wit! It is not known whether these calls are learned or innate, and it is not yet certain that call type always matches appearance. Chol- la-type calls are regularly heard as far west as Portal, Arizona, and they seem to be the dominant call type in Guadeloupe Canyon, near where Arizona, New Mexico and Mexico converge. A third call type is occasionally heard in southeast Arizona, at least from the Eloy area east to the New Mexico border (n=3). This call type resembles Cholla Thrasher’s call, but has the second note much reduced: WEET-wit, or WEET-wi-WEET. The significance of this call type is unknown. Rarely (n=1), Curve-billed Thrashers give a single upslurred “WEET!” Audio examples of these three call types can be heard at earbirding. com/blog/archives/2480.

A Cautionary Point From extensive perusal of pictures of Curve-billed Thrasher, particularly on Flickr (flickr.com), the situation in southeast Arizona seems muddled. This area is thought to host the contact zone between the two U.S. forms of Curve-billed Thrasher, and online pictures seem to support that contention. Many individual birds as far west as Tucson appear to be referable to Cholla Thrasher, whereas quite a few pictured birds are seemingly intermediate in appearance, tending toward birds showing little or no wing bars, yet quite pale underparts with fairly distinct spotting (Fig. 3). How much of this apparent intermediacy is due to photographic artifacts versus individual variation within subspecies or seasonal appearance differences caused by wear is unknown. However, keeping the thought of possible inter-

Colorado Birds Fall 2014 Vol. 48 No. 4 303 mediate individuals in the back of one’s mind when attempting identification of Curve-billed Thrashers, particularly West Slope Curve-billed Thrashers, would be apropos. Finally, some Curve-billed Thrashers in the typical Colorado range can present seemingly intermediate features (Fig. 4).

Acknowledgments Thanks to Paul Lehman and Bill Pranty for providing information on occurrence of Palmer’s Thrasher in their respective states. Thanks also to Paul, Peter Pyle and Van Remsen for providing excellent comments on previous drafts of this manuscript. We also gratefully acknowledge the assistance of Paul Buckley, Peter Gaede and Steve Mlodinow in our efforts to track down an English name for oberholseri. Finally, thanks to all those observers who have taken the time to enter their bird sightings into eBird (www.ebird. org), making it the superb information source that it is!

Literature Cited California Bird Records Committee (R. A. Hamilton, M. A. Patten, and R. A. Erickson, eds.). 2007. Rare Birds of California. Western Field Ornithologists, Camarillo, CA. eBird. 2014. eBird: An online database of bird distribution and abundance [web applica- tion]. eBird, Ithaca, New York. Available: http://www.ebird.org. (Accessed: 29 July 2014) Faulkner, D. 2012a. The 61st report of the Colorado Bird Records Committee. Colorado Birds 46:50-62. Faulkner, D. 2012b. The 62nd report of the Colorado Bird Records Committee. Colorado Birds 46:106-120. Leukering, T. 2007. In the scope: Gray-cheeked Thrush. Colorado Birds 41:59-62. Leukering, T. 2010. In the scope: Molt and plumage: a primer. Colorado Birds 44:135-142. Leukering, T. 2011. In the scope: Spring plumage change in passerines: prealternate molt vs. wear. Colorado Birds 45:154-157. Leukering, T. and N. Pieplow. 2010. In the scope: Pacific and Winter wrens. Colorado Birds 44:281-286. Pyle, P. 1997. Identification Guide to North American Birds, part I. Slate Creek Press, Bolinas, CA. Rosenberg, G. H. 2006. Mockingbirds and thrashers. In National Geographic Complete Birds of North America (J. Alderfer, Ed.). National Geographic Society, Washington. Semo, L. S. 2006. The 42nd report of the Colorado Bird Records Committee. Colorado Birds 40:133-156. Stafford, E. F. 1912. Notes on Palmer’s Thrasher (Toxostoma curvirostre palmeri). Auk 29:363-368. Williams, S. O, III. 2010. New Mexico. North American Birds 64:299-301. Zink, R. M. and R. C. Blackwell-Rago. 2000. Species limits and recent population history in the Curve-billed Thrasher. Condor 102:881-886.

Tony Leukering, 102A Delaware Avenue, Villas, NJ 08251, [email protected]

Nathan Pieplow, 4745-B White Rock Circle, Boulder, CO 80301, [email protected]

304 Colorado Birds Fall 2014 Vol. 48 No. 4 CBRC REPORT

The 70th Report of the Colorado Bird Records Committee

Doug Faulkner Chair, Colorado Bird Records Committee

Introduction This 70th report of the Colorado Bird Records Committee (hereafter CBRC or Committee) presents the results of deliberations of the CBRC involving 57 reports submitted by 47 observers and documenting 49 occurrences of five species (or recognizable forms) from the period November 2009 to April 2013. Per CBRC bylaws, all accepted records received a final 7-0 or 6-1 vote to accept. Each report that was not accepted received five or fewer votes to accept. This report highlights species with fewer than 10 state records, first state record of the Aleutian Cackling Goose, the phenomenal Com- mon Redpoll invasion of winter 2012-2013, and non-acceptance of a potential new species to the state list (Arizona Woodpecker). The focus on uber-rare species and events allows for more content per individual record than can be achieved using the previous all-records format. The CBRC will continue to publish all new records for the state and is considering other publishing venues, including online- only reports accessible through the CFO and CBRC websites. No new species have been accepted since publication of the 69th CBRC Report (Faulkner 2014) and the Colorado state list remains 498. Committee members voting on these reports were John Drum- mond (Colorado Springs), Doug Faulkner (Arvada), Bill Maynard (Colorado Springs), Brandon Percival (Pueblo), Mark Peterson (Colorado Springs), Bill Schmoker (Longmont), David Silverman (Rye), and Glenn Walbek (Castle Rock).

Committee Functions The Committee solicits documentation of reports in Colorado for all species published in its Main Review List (coloradobirdrecords. org/reviewlist.aspx), species with no prior accepted record in Colo- rado and sightings of regularly occurring species that are considered out-of-range or out-of-season. Documentary materials should be submitted online at the CBRC website (coloradobirdrecords.org). Alter- natively, one can fill out the form printed on the inside dust jacket of this journal and mail it to the CBRC Chair, or request an electronic Word document from the Chair or Secretary (see this journal’s inside front cover for contact information).

Colorado Birds Fall 2014 Vol. 48 No. 4 305 Report Format The records in this report are arranged taxonomically following the American Ornithologists’ Union (AOU) Checklist of North American Birds (AOU 1998) through the 54th Supplement (Chesser et al. 2013). We present the initials of the contributing observer(s), the official accession number and the vote tally in the first round and, if relevant, the second and third rounds (with the number of “accept” votes on the left side of the dash). The total number of state records is given in parentheses after the species scientific name. The initial observer of the bird is underlined, if known, and is presented first only if that person contributed documentation; additional contributors’ follow in alphabetical order by last name. If the initial observer is known with certainty, but did not submit documentation, those initials are underlined and presented last. Observ- ers submitting a photograph or video capture are indicated with a dagger (†); those who submitted video by a lower-case, italicized “v” (v) and those who submitted audio spectrograms or recordings by a lower-case, italicized “s” (s). In this report, county names are italicized. We have attempted to provide the full date span for individual records with this journal being the primary source of those dates. The Committee has not dealt with the question of full date spans as compared to submitted date spans when documentations cover only a portion of the reported dates (see the Costa’s Hummingbird record for additional discussion).

ACCEPTED RECORDS California and southwest Oregon). Aleutian Cackling Goose – Branta If Cackling Goose is to be split fur- hutchinsii leucopareia (1). The CBRC ther, current subspecies with isolated does not have a mandate to review breeding ranges and no to little genet- reports of subspecies, particularly for ic interchange with other subspecies those species common to the state. (like Aleutian Cackling Goose) stand However, it may consider doing so the best chance of becoming full spe- when a subspecies is of particular in- cies. Furthermore, Aleutian Cackling terest (e.g., may potentially be elevat- Goose was thought to be extinct until ed to full species status or whose oc- a remnant population was discovered currence in Colorado is thought to be on Buldir Island in 1962. Population rare). The Aleutian Cackling Goose’s estimates now exceed 100,000 (Mini relevance for review by the CBRC re- et al. 2011). Its small population size sides with the possibility of additional and coastal affinity suggests that va- splitting of Cackling Goose in com- grancy to Colorado should be consid- bination with its coastal distribution ered exceptional. pattern (breeding in the Aleutian The CBRC reviewed documenta- and Semidi Islands and wintering in tion of an Aleutian Cackling Goose

306 Colorado Birds Fall 2014 Vol. 48 No. 4 subspecies with any confidence. The reporting observer acknowledged that the dark plumage and white neck collar did not appear in the photos as seen in true life. The Chair has been unable to find any mention of this subspecies for Col- orado in the literature or online museum catalogs. This is not surprising given its limited distribution and near- extinction. Therefore, this individual represents the first record of Aleutian Cackling Goose in Colorado. Aleutian Cackling Goose, Union Reser- Costa’s Hummingbird – Calypte voir, Weld County, 25 November 2012. costae (7). A long-staying female at a Photo by Steve Mlodinow private residence in Grand Junction, Mesa, in November 2011 was docu- at Union Res., Weld, 25 November mented for just a single day (the 19th) 2012 (2013-12; SMl†; 6-1). This by a single observer (2013-39; JT†; individual was scrutinized for ap- 7-0). The photos left no doubt about proximately 20 minutes allowing the the identification of this individual. observer to extensively study body This bird represents the second record structure and plumage details that for Mesa and for the West Slope. could vary depending on posture and The CBRC (and most state bird light conditions. The tiny goose reli- records committees) consider the “of- ably showed diagnostic characteris- ficial” date(s) of occurrence as those tics (at least when considered col- which are supported by submitted lectively) of the Aleutian subspecies. documentation. Thus, the only date of These characteristics included a dark, occurrence for this individual will be bronzy breast, no indentation on the 19 November 2011 unless the CBRC narrow white cheek patch which ex- receives additional documentation for tended into a broad white gular stripe, the bird’s reported stay of 8-21 No- rounded head, and thin white collar vember 2011 (Such and Such 2012). at the base of the neck. The reporting However, perhaps state bird records observer included comments from two committees should consider that the outside experts, both well-respected first reported date is “official” and that birders from the West Coast, who documentation from subsequent dates agreed with the identification. The support that individual’s extended lone dissenting CBRC member was stay. Conceivably, if a bird is reported concerned that the bird’s bill was too on day X, then seen and documented large and that the digiscoped photos on days X+2, X+3, and X+6, and all did not show plumage characteristics documentation supports the identifica- well enough to identify the goose to tion, there is little reason to doubt that

Colorado Birds Fall 2014 Vol. 48 No. 4 307 the bird was correctly identified on day X. After all, what is the chance that a bird is incorrectly identified and then, by happenstance, that rare species is observed later at the same location? Then again, maybe it is too much of a reach and adds another possible source of error in establishing the scientific credibility that bird records portend to have. The Chair’s recommendation is that all observers should provide documentation so the entire duration of a rare bird’s stay can be vetted within a single inclusive record. Documenta- tion of this bird from other observers Costa’s Hummingbird, Grand Junction, on other dates would be appreciated. Mesa County, 19 November 2011. Pacific Wren – Troglodytes pacifi- Photo by Jackson Trappett cus (6). The CBRC recently accepted three new records of this species dou- only for the date of 27 December 2010 bling the total number of state records (2012-194; PH†, DM; 7-0). This in- to six. A calling Pacific Wren, found dividual was reported through at least along the Saddle Rock Trail in Greg- the 29th. Another Pacific Wren was ory Canyon, Boulder, 10 November observed along Greenhorn Creek 2009, was originally documented by near Rye, Pueblo, 2 November 2012 a single observer (2009-92; NPs, WS, (2012-168; DS; 6-1). This wren was NK; 5-2, 4-3, 6-1). This documenta- intensively studied which allowed tion did not include supporting physi- the observer to note and describe key cal evidence and the CBRC conserva- plumage details that satisfactorily dif- tively (although not unanimously) felt ferentiated it from Winter Wren for that physical evidence was necessary the majority of Committee members. to accept it as a state record. Subse- Common Redpoll – Acanthis flam- quent to that decision, the CBRC re- mea. The winter of 2012-2013 may ceived additional documentation con- always be known as the redpoll inva- taining a sound recording that swayed sion winter. Unprecedented numbers enough Committee members to vote of Common Redpolls descended onto in favor of acceptance. This bird rep- the state with initial reports streaming resents the first record forBoulder . in during the first weeks of November. Not to be outdone, Pueblo added Except for 35 at Granby, Grand, bird- two more Pacific Wren records to ers reported very few redpolls during bring its total to four for the county. the previous winter of 2011-2012. In One found on the Pueblo Res. CBC 2012-2013, 35 redpolls at a given lo- downstream of Pueblo City Park on cation were not unusual and the flock 18 December 2010 was documented coming to the Discovery Museum in

308 Colorado Birds Fall 2014 Vol. 48 No. 4 to garner one accept vote from the Committee (2013-136; 1-6). The bird was observed briefly by both observers, less than a minute by the primary observer who saw it perched on a tree truck and for only one second by the other observer who caught a glimpse of it as the bird flew away. The Hairy Woodpecker-sized bird had an all brown back, red on the hind crown, possible white barring on the lower right side (the side facing the observer and presumably meaning the flight Common Redpoll, Silverton, San Juan feathers), and rump and tail that were County, 5 February 2013. Photo by “more rufous” than the back. Except Jim Beatty for the tail and rump, the description is supportive of Arizona Woodpecker. Ft. Collins, Larimer, which included Dissenting CBRC members, however, a handful of Hoary Redpolls (see were concerned about the rufous col- Faulkner 2014), consisted of several oration (Arizona Woodpecker is not hundred Commons. In order to cap- rufous anywhere) and the lack of men- ture a snapshot of the magnitude of tion of a broad, white neck-patch that this massive irruption, the CBRC re- should have been readily visible. In quested documentation of Common addition to the description concerns, Redpolls away from their expected other Committee members expressed northeastern Colorado winter range. doubts that Arizona Woodpecker is This effort also resulted in 20 first likely to occur in southeast Colorado. county records. The list of accepted The species barely enters the United records is in Table 1. Not included States in southeast Arizona and south- in that table is the recently accepted west New Mexico. And, even within record of an individual at Flagler, Kit its normal montane range, the species Carson, 29 December 2011, which is rarely known to wander to lower el- represents the first for that county evations (Corman and Wise-Gervais (2013-173; BK†; 7-0). 2005). The Chair would like to point out that both observers did not believe Species Not Accepted— that their descriptions were adequate Identification Not to accept as a first state record. While Established it is rare for any (let alone both in this Arizona Woodpecker (Picoides ari- case) observer to state that his/her zonae). The reports submitted by two sighting of a possible rare bird should observers of a woodpecker in Cot- probably NOT be accepted as a record, tonwood Canyon, Las Animas, 26 it is refreshing that 1) they document- April 2013, was tantalizing enough ed the bird anyway, and 2) described

Colorado Birds Fall 2014 Vol. 48 No. 4 309 Table 1. Common Redpoll records from winter 2012–2013

Accession # # Birds Location County Dates Observers Vote 2013-237 1 La Veta Huerfano 10-12 Nov 2012 PN† 7-0 2012-184 1 Hayden Routt 15 Nov 2012 NM† 7-0 2013-87 1-2 Lamar Prowers 15-19 Nov 2012 JS† 7-0 2013-88 2 Fawn Brook Inn Boulder 17 Nov 2012 CH† 7-0 2013-107 60 Baseline Res. Boulder 24 Nov 2012 BSc† 7-0 2012-213 2-3 Manitou Springs El Paso 28 Nov – 28 Dec 2012 BM†, BKP†, NM 7-0 2013-24 1-2? Coaldale Fremont 8 Dec 2012 – 13 Jan TMi† 7-0 2013 2013-27 65 Steamboat Springs Routt 9 Dec 2012 – 22 Janu- TMo† 7-0 ary 2013 2013-52 2 Glenwood Springs Garfield 10 Dec 2012 TMc† 7-0 2013-82 1 Franktown Douglas 11 Dec 2012 HK† 7-0 2013-56 4 Pueblo Res. Pueblo 12 Dec 2012 – 3 Jan BKP† 7-0 2013 2013-85 30 Near CVCG Weld 13 Dec 2012 NL 7-0 2013-135 1 Denver Arapahoe 13 Dec 2012 MD 6-1 2013-57 2 Broomfield Broomfield 15 Dec 2012 EZ 7-0 2013-25 24 Granby Grand 15 Dec 2012 – 19 BC 6-1 Jan 2013 2013-7 1 Conifer Jefferson 18 Dec 2012 SMl† 7-0 2013-62 35 Sterling Logan 20 Dec 2012 KMD† 7-0 2013-58 6 Cascade El Paso 22 Dec 2012 – 17 JD†, SS 7-0 Jan 2013 2013-59 11 Black Forest El Paso 22 Dec 2012 JD†, HJR 7-0 2013-20 20 Fraser Grand 25 Dec 2012 – 6 Jan DF† 7-0 2013 2013-63 6 Sedalia Douglas 25 Dec 2012 – 18 BB† 7-0 Feb 2013 2013-23 65 Steamboat Springs Routt 28 Dec 2012 TLi† 7-0 2013-86 2 Aurora Arapahoe 28 Dec 2012 LB† 7-0 2013-76 20 East Vail Eagle 29 Dec 2012 – 15 AE† 7-0 Feb 2013 2013-28 10-22 Aspen Pitkin 30 Dec 2012 – 22 EB, JS† 7-0 Feb 2013 2013-100 25 Longmont Boulder 29 Dec 2012 – 15 BSc† 7-0 Mar 2013 2013-4 1 Tennessee Pass Eagle 30 Dec 2012 MD† 7-0 2013-21 30 Collbran Mesa 1 Jan 2013 NK† 7-0 2013-38 3-4 Mesa Mesa 1-5 Jan 2013 JT† 7-0 2013-60 6 Ouray Ouray 2 Jan 2013 KN 6-1 2013-22 27 Avon Eagle 3-6 Jan 2013 MV† 7-0 2013-111 3 Brush Hollow Res. Fremont 6 Jan 2013 TS† 7-0 2013-49 25 Walden Jackson 26 Jan 2013 TLe† 7-0

310 Colorado Birds Fall 2014 Vol. 48 No. 4 2013-44 8-35 Silverthorne Summit 27 Jan 2013 CT, SMl†, TLe† 7-0 2013-45 180-200 Kremmling Grand 27 Jan 2013 SMl†, TLe† 7-0 2013-137 20 Idaho Springs Clear Creek 3 Feb 2013 JH†, RDB 7-0 2013-46 3 Silverton San Juan 5 Feb 2013 JB† 7-0 2013-89 50 Aurora Arapahoe 6 Feb 2013 CP 6-1 2013-84 8 Monument El Paso 8 Feb 2013 – 18 Mar KS 7-0 2013 2013-90 3 Cortez Montezuma 21-24 Feb 2013 SMe 6-1 2013-123 16 Prewitt Res. Washington 3 Mar 2013 SMl 7-0 2013-91 8 Winter Park Grand 3-6 Mar 2013 BM† 7-0 2013-92 1 Aurora Arapahoe 11 Mar 2013 CT† 7-0 the bird just as they observed it without apparent influence or bias from field guides or personal knowledge of key field marks for that particular species.

REPORTERS AND CITED OBSERVERS The CBRC thanks the following individuals for submitting records of or discovering and reporting the rare species in Colorado discussed in this report: Brenda Beatty, Jim Beatty, Ernest Bradley, Linda Broeren, Brad Clements, Mario Davalos, Mary Driscoll, John Drummond, Ruth and Dan Brown, Anne Esson, Kathy Mihm Dunning (KMD), Donna Feldman, Joann Hackos, Chuck Hundertmark, Paul Hurtado, Bill Kaempfer, Hugh Kingery, Nicholas Komar, Nic Korte, Tony Leukering (TLe), Norm Lewis, Tom Litteral (TLi), Becky Marvil, Bill Maynard, Dan Maynard, Nancy Merrill, Tom McCon- nell (TMc), Tina Mitchell (TMi), Nick Moore, Suzy Meyer (SMe), Steve Mlodinow, Tresa Moulton (TMo), Polly Neldner, Kent Nelson, Brandon Percival (BKP), Cheri Phillips, Nathan Pieplow, Helen and John Reynolds, Bill Schmoker, Jacob Shorty, Da- vid Silverman, Susan Solyanis, Kristen Squazzo, Ruth Stewart, Tyler Stuart, Jane Stulp, Walter Szeliga, Cheryl Teuton, Jackson Trappett, Margaret Viens, and Eric Zorawowicz.

LITERATURE CITED American Ornithologists’ Union. 1998. Check-list of North American Birds. Lawrence, KS: Allen Press. Chesser, T.R., Banks, R.C., Barker, F.K., Cicero, C., Dunn, J.L., Kratter, A.W., Lovette, I.J., Rasmussen, P.C., Remsen, Jr., J.V., Rising, J.D., Stotz, D.F., and K. Winker. 2013. Fifty-fourth Supplement to the American Ornithologists’ Union Check-list of North American Birds. Auk 130(3): 558-571. Corman, T. and C. Wise-Gervais (Eds.). 2005. Arizona Breeding Bird Atlas. University of New Mexico Press, Albuquerque. Faulkner, D. 2013. The 69th Report of the Colorado Bird Records Committee. Colorado Birds 48(2): 163-179. Mini, A.E., D.C. Bachman, J. Cocke, K.M. Griggs, K.A. Spragens, and J.M. Black. 2011. Recovery of the Aleutian Cackling Goose Branta hutchinsii leucopareia: 10-year review and future prospects. Wildfowl 61:3-29. Such, J. and M. Such. 2012. News from the Field, Fall 2011 (August–November). Colo- rado Birds 46(2):139-158.

Doug Faulkner, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 311 THE HUNGRY BIRD

White-lined Sphinx Moth

Dave Leatherman On a quiet Walsh, Colorado side street, a plain brown sparrow, its distant relatives probably within sight of a High Tea in the English countryside, happens upon a pretty green caterpillar. The stuff of a children’s book, right? Wrong. The bird, actually a non-native House Sparrow, is hungry. Like most birds presented with a feeding opportunity, it is eager to take advantage of its good fortune. Food is the precious legal tender of life in the wild. It is not to be shared, except rarely with a prospective mate or offspring. Escape happens. Theft happens. Messing around with prey has no evolutionary pay-off. As I fumble for my camera in the back seat, the drama unfolds. The female Passer domesticus, last-listed on the Colorado checklist and, therefore, supposedly our least-evolved species, demonstrates with anything but novice skill the fine art of subduing a live beast half your length. At 6.25 inches long, the Old World Sparrow is wrestling with a writhing 3-inch larva. Imagine yourself with one of those party subs that feeds 15, with the sandwich being alive and wanting in the worst way to escape. Out of the caterpillar’s mouth spews regurgitated, bright green plant juice. It rears back, displays its six claw-tipped true legs and shakes its horn-armed bootie like a breaching, ten-feet-out-of-the-water killer whale. The bird looks down at this display and seems to taunt, “Is that all you got?” Its man- dibles firmly pinch tight on the caterpillar’s head, and with a too-fast-for-the-naked-eye twist of its own head, slams the prospective meal to the ground. Only when I viewed my so-so photographs could I appreciate the violence of what happened right out the car window. Forget about the phony wrestling on TV. This unscripted take-down, on a rock-strewn mat with no give to it, no less, was repeated over and over. Presumably such impact served to both kill the caterpillar and, apparently by the looks of it, removed excess juice and plant material from its

312 Colorado Birds Fall 2014 Vol. 48 No. 4 digestive tract. Since I do not know what the caterpillar ate, it is possible some of the chemicals in the plant were toxic or distaste- ful to the bird, and best eliminated or at least thinned out. So what was Full-grown larva of White-lined Sphinx feeding on a white- the hapless cat- flowered evening-primrose (Oenothera sp.) along Larimer erpillar? It was CR5 north of Buckeye Road, 23 June 2014. Photo by Dave a “hornworm” Leatherman that turns into a moth I suspect we have all seen, the White-lined Sphinx (Hyles lineata). Known to many in their adult stage as “hummingbird moths”, they are abundant this year throughout many areas of Colorado. Female McCown’s Longspur capturing a White-lined Sphinx The White- caterpillar on Larimer CR5 north of Buckeye Road, 29 June lined Sphinx is 2014. Photo by Dave Leatherman native to North America and occurs from well south into Mexico north to northern Canada. It also occurs in Eurasia and Africa. Curiously it does not occur in the extreme northeastern portion of the United States. The insect undergoes multiple generations in the southern portion of its range, probably two here during most years. Population fluctuations are due to both local success/failure and adult flights that may involve hundreds of miles. Larvae of the White-lined Sphinx are quite variable in coloration, ranging from mostly yellow to mostly black, with many variations in between (including mostly green). Likewise, their diet is variable and

Colorado Birds Fall 2014 Vol. 48 No. 4 313 includes a wide array of plants: some considered “weeds”, orna- mental flowers and valuable crops. Among these are purs- lane (Portulaca), certain spurges (Euphorbia and Chamaesyce) , willow-herb (Ep- ilobium), fushcia, gaura (flowers Adult White-lined Sphinx (Linaria sp.) at Lake Estes, Larimer only), tomato County, CO. Photo by Dave Leatherman (Lycopersicon), evening primrose (Oenothera), apple (Malus), four o-clock (Mi- rabilis jalapa), grape (Vitis), elm (Ulmus) and others. Full-grown larva of White- lined Sphinx feeding on a white-flowered evening-primrose (Oenothera Say’s Phoebe with an adult White-lined Sphinx on the porch of sp.) along Lar- Stulp Farm 5 miles south of Lamar, Prowers County, CO on imer CR5 north 13 April 2014. Photo by Jane Stulp of Buckeye Road, 23June2014. Occasionally an aligning of supply and demand leads to “out- breaks” of larvae that denude local patches of food plants, followed by conspicuous movements of caterpillars across open terrain such as roads. Most of these mini-migrations are simply unfulfilled caterpillars seeking the additional food necessary to complete development, but some of this could also involve sated larvae seeking pupation sites. Just such a phenomenon occurred this past early summer in Lar-

314 Colorado Birds Fall 2014 Vol. 48 No. 4 imer and Weld Counties. Surely other areas of the eastern Colorado plains witnessed the same. In late June 2014 on Larimer CR5 east of the Rawhide Power Plant north of Fort Collins, literally thousands of White-lined Sphinx caterpillars crossed the road. I didn’t ask them why. Neither did the birds. I took pictures and the birds, prisoners. Included were House Sparrows, Western Meadowlarks, Horned Larks, Lark Buntings and McCown’s Longspurs. No doubt many other avian, mammalian, rep- tilian and amphibian species took advantage of the bounty. White-lined Sphinx moths nectar at many familiar plants. This adult stage is what catches many birders’ eyes, and is brought to our attention by friends and neighbors who want to tell us about their “hummingbird” or “hummingbird moth.” The moth DOES look like a hummingbird, as it hovers in front of a flower inserting its long pro- boscis. Common nectaring sites include the blooms of columbines, larkspurs, petunias, bouncing bet, lilac, clovers, thistles, jimson weed, moonvine and honeysuckle, among many others. Adults of the White-lined Sphinx fall prey to birds as well. Only three species accounts mention “sphinx moths” in Cornell Univer- sity’s massive and outstanding “Birds of North America” database (Elf Owl, Ferruginous Pygmy-Owl and Baltimore Oriole). This is not an accurate portrayal of reality, and simply serves to illustrate how woefully incomplete and imprecise our knowledge of bird food habits is at present. Most images that appear in online searches for “birds eating sphinx moths” seem to show flycatchers (Eastern Kingbird and Brown-crested) and owls (Flammulated and Eastern Screech). Sure- ly, many insectivorous passerines, raptors and perhaps other groups at least occasionally take these conspicuous and substantial morsels. I’ll end with my normal plea for readers to help fill in the blanks of our collective knowledge, as Jane has done above. Both the caterpillars and moths are easy to detect and identify. Digital cameras should make documenting bird-sphinx moth episodes, to use atlasing jargon, possible, probable and even confirmable. What are you seeing out there?

LITERATURE CITED Edinger, B. B. 1985. Limited hybridization and behavioral differences among sympatric Baltimore and Bullock’s Orioles. Masters Thesis. Univ. of Min- nesota, Minneapolis. Powell, Jerry A. and Paul A. Opler. 2009. Moths of Western North America. Univ. of CA Press, Berkeley. Weber, William A. 1976. Rocky Mountain Flora. Univ. Press of CO, Niwot.

Dave Leatherman, [email protected]

Colorado Birds Fall 2014 Vol. 48 No. 4 315 BOOK REVIEW

The Sibley Guide to Birds Second Edition

Christian Nunes On a shelf in my childhood bedroom there sits a book. Its binding is swollen and twisted, the cover dotted with sooty black mildew, all the irreversible result of water damage incurred during a summer backpacking trek up Vermont’s Camel’s Hump. While birding in my formative years, this blue-and-white tome adorned with brightly col- ored busts of eastern birds was my trusty key to deciphering the avian world. My Peterson was, for a time, the incipient textbook from which all the fundamental lessons of bird recognition seeped into my psyche. Stacked beneath various leaflets of mail on my coffee table, there’s another weary birding codex. Missing its cover and binding completely, the loose pages are now neatly stacked in a taxonomically suspect heap. This book has seen me through countless whimsical debates on the presence or absence of a hallux on a stint, or the particular geometry of a hawk’s nape. In the margins, notes on significant sightings are scribbled in an earnest form of database manage- ment. My Sibley has borne the weight of persistent, daily thumbing for more than 13 years. Prominently perched on my desk next to my computer is a sleek, glossy newcomer. At first glance it is clearly in the Sibley family. It demonstrates the general shape of a cigar box combined with a ram- bunctious array of bird illustrations, figures and succinct snippets of text that separate this taxon of field guide from all others. Unlike my other field guides, this book is perfectly fresh, without a page missing or a stitch of binding amiss. The perky Magnolia Warbler strutting on the cover clinches the ID as David Allen Sibley’s, The Sibley Guide to Birds Second Edition. For many years, birders across North America eagerly awaited the publication of Sibley II. In the first edition, there were inconsisten- cies in taxonomy and distribution maps that drew ire from fastidi- ous birders. Although the order of things changes annually, the new guide does its best to keep up with the split-happy times. By including illustrations of scores of regional variants, Sibley often preemptively highlights potential future splits, even if they aren’t on most birder’s radar. (In Sibley III, he’ll have to include a separate species account for the brand new Ridgway’s Rail, called out as the “California” Clap- per Rail in Sibley I & II.) Another positive change is the jettisoning

316 Colorado Birds Fall 2014 Vol. 48 No. 4 of the original’s representation of vagrant records with little green dots. Instead, he has generalized the situation by using larger gray areas that can represent single records or clusters of records across a geographic area. This approach more liberally alludes to the vagrant potential over larger areas. One fabulous addition is a checklist stashed at the rear of the book. Suddenly, my messy pen marks on each species account that represent a tick are unnecessary. I can simply do what most normal people do and fill in a checklist. Included in the checklist are a few boxes that will never get checked. The Dodos of North America are depicted on a plate in the introduction section, the artwork being a vivid reminder of errors past. With this in mind, the new guide is published on paper that is responsibly sourced and certified by the Forest Stewardship Council. Also included is contact information for the National Audubon Society, American Bird Conservancy and The Nature Conservancy, all of whom are major players in national, and international, conservation efforts. Involvement in these orga- nizations and their causes should make any birder more appreciative for every tick on the list. Unlike other popular field guides, such asThe National Geographic Field Guide to the Birds of North America, Sibley chose to leave out many vagrant species in an effort to save space in an already cumber- some “field” guide. In this new edition, 923 species are artistically rendered, an expansion of 113 species at the cost of only 54 more

Colorado Birds Fall 2014 Vol. 48 No. 4 317 pages. The addition of more vagrants offers the Sibley scholar numerous opportunities to withdraw fresh information from a familiar set- ting. Depictions of tantalizing morsels like Gray Silky-Flycatcher and Jabiru instill lucid daydreams of epic discoveries waiting to be made. Mixed in are even more examples of established non-native species, and several that at least have the potential to head that way. The descriptions of a small population of Black-throated Magpie-Jays in San Diego and the feral population of Red Junglefowl in the Florida Keys broaches the topic of non-native introductions and the validity of established populations. Beyond the regular taxonomic house-keeping that is to be expected from a second edition, the expanded coverage of this new edition will bolster any birder’s expertise. In preparing the second edition, Sibley recognized the value of including informative behavioral and visual cues as part of a holis- tic approach to bird identification—all under one cover. Focused on aspects of ornithology like behavior and ecology, Sibley’s Guide to Bird Life & Behavior was written as a companion to Sibley I. It digs deeply into the natural history of most North American birds, filling in many wonderful details, such as nesting behavior and migration strategies that the more image-centric field guide lacked. And in the years since its publication, an entire cohort of internet-savvy aficio- nados have taken to reading David’s blog in which he frequently delves into various topics of bird identification and behavior, while touching upon techniques for becoming a better birder. By adapt- ing bits of useful behavioral and ecological details from these two sources, David Sibley has created perhaps the single most useful field guide to the birds of North America. Of course, there are detractions. In an effort to fit in more artwork, the font size was reduced. This irks some readers, especially those with imperfect sight. Concerning the artwork, many of the plates appear a bit too dark and shadowed, and certain colors, especially reds, are not realistically depicted. The male Scarlet Tanager is almost a travesty, being shown as a dusky blood-red that’s quite off from its natural palette. To some these faults may be acceptable given the superior education gained from the more comprehensive artistic and editorial coverage. Those that purchased the book when it was first available will either have to adjust to these faults or wait until the first reprint- ing, scheduled for September 2014. As Sibley himself opines in the introductory section Variation in Appearance, “you should not expect any bird seen in the field to match exactly the picture of its species in this field guide.” Tell that to the Scarlet Tanager.

Christian Nunes, [email protected]

318 Colorado Birds Fall 2014 Vol. 48 No. 4 The Colorado Field Ornithologists’ Quarterly

Instructions for Contributors to Colorado Birds

Colorado Birds is devoted to the field study of birds in Colorado. Articles and short notes of general or scientific interest are welcomed; potential authors are encouraged to submit any materials that contribute to the enjoyment and understanding of birds in Colorado. The preferred submission format is electronic, via email attachment or on CD. However, typed or hand-written manuscripts are also accepted.

Photos or art: submit black & white or color material. Photos & graphics printed inside the journal will typically be printed in black & white; cover art is printed in color. Graphics can be submitted as prints, slides, or electronically. Electronic submissions can be sent in JPEG (*.jpg), PDF (*.pdf), PSD (*.psd) or TIFF (*.tif) format. Photos must be submitted in JPEG, PSD or TIFF; maps, tables and other non-photographic material may be submitted as PDF. Photos should be sent in their original format without editing, cropping or color correction. Cover art must be of the highest quality. Cover photos should be a minimum 5.75” wide by 8.75” tall at 300 dpi (1725 × 2625 pixels). Minimum size for interior photos is 3” by 2.5” (900 × 750 pixels or 750 × 900 pixels). For best reproduction, photos can be larger and higher resolution, but they cannot be smaller. Submit electronically via email or on CD. Include information about artist or photographer, subject, date, location and medium used.

Art and photos will be returned at your request; however, manuscripts and CDs will not, unless specifically requested. While your materials will receive the utmost care, the Colorado Field Ornithologists (CFO) or any representative thereof cannot be respon- sible for materials lost in the mail or due to other circumstances beyond our control.

Manuscripts reporting formal scientific research are sent out for peer review.

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.

Send journal contributions to:

Peter Burke 935 11th Street Boulder, CO 80302 [email protected]

Submissions of photos or graphics not accompanied by articles are welcomed. Send these to Christian Nunes, [email protected].

Colorado Birds Fall 2014 Vol. 48 No. 4 319 Fig. 5. In a fairly fresh-plumaged Curve-billed Thrasher (note the date and the pale-tipped tertials), this bird’s lack of wingbars is virtually definitive for an identification of Palmer’s Thrasher. Also note the dark chest and the relatively poor expression of underparts spotting. The location of this photograph is west of what is thought to be the contact zone between Cholla and Palmer’s thrashers in southeast Arizona, although Chol- la genes may extend into Palmer’s Thrasher populations this far west. Apache Junction, Pinal Co., AZ, 16 September 2012. Photo by Muriel Neddermeyer

Fig. 6. This Cholla Thrasher accounted for one of the few northeastern Colo- rado records of the taxon. The bird’s strong wing bars, distinct underparts spotting and whitish malar extending into an ear surround are typical characters of the form. The bird’s yellow eyes with little suggestion of orange and the contrast between the grayer median coverts and browner greater coverts suggest that the bird is an immature (hatched in the previous summer) which is typical of vagrants of most bird species. Red Rocks Park, Jefferson Co., CO, 24 December 2010. Photo by Glenn Walbek

In the Scope: Identifying Curve-billed Thrasher Subspecies: Why and How . . . 296

320 Colorado Birds Fall 2014 Vol. 48 No. 4