SSttaattuuss aanndd ddiissttrriibbuuttiioonn ooff TTyyppee 11 RReedd CCrroossssbbiillll ((LLooxxiiaa ccuurrvviirroossttrraa )):: aann AAppppaallaacchhiiaann CCaallll TTyyppee?? MATTHEW A. YOUNG • CORNELL LAB OF ORNITHOLOGY • 159 SAPSUCKER WOODS ROAD, ITHACA, NEW YORK 14850 • OMAY6NCORNELL.EDUP KEN BLANKENSHIP • 2400 BARRETT CREEK BOULEVARD #827, MARIETTA, GEORGIA 30066 • OKENHBLANKENSHIPNCOMCAST.NETP MARILYN WESTPHAL • P. O. BOX 1427, HENDERSONVILLE, NORTH CAROLINA 28793 • OMJWESTPHNRET.UNCA.EDUP STEVE HOLZMAN • 349 JEFFERSON ROAD, BISHOP, GEORGIA 30621 • OSTEVE_HOLZMANNYAHOO.COMP records of our own, and also adduce the broad - er natural history of this Type, using primarily recent records of calling birds that have been identified by audiospectrographic analysis. We review evidence that Type 1 is not a specialist on a single species of conifer (as some Types appear to be), and from that we infer that wan - derings away from the core breeding range in Appalachia are driven by cone crop failures of several species. We further suggest that wan - dering Type 1 birds, which have medium-sized bills among the Red Crossbill Types, settle most readily in areas where cone sizes and types are most similar to those found in core range. We urge observers to audio-record Red Crossbills wherever they are detected and to note the species of conifer in which they are observed, to increase our understanding of their complex natural histories. Background: Red Crossbill Types and their natural histories Red Crossbill ( Loxia curvirostra ) has been di - vided into ten “call types” (hereafter Types 1- 10) in North America; in addition to differ - ences in flight calls, small but significant dif - ferences in bill morphology, ecology, and ge - netics distinguish these Types (Groth 1993c, Benkman 1999, Parchman et al. 2006, Irwin 2010). Groth (1993c) was the first to assert that the Types meet criteria for full-species sta - tus under both phylogenetic and biological species concepts and that they should there - fore be recognized as taxonomic species. More recent studies continue to inform discussion of Red Crossbill’s taxonomic status. Sewall (2009, 2011) and Sewall and Hahn (2009) present ev - idence to support the ideas that Red Crossbill This Red Crossbill was audio-recorded and confirmed as Type 1, a Type that appears to be predominantly an Appalachian bird. flight calls are an example of reliable signaling This individual was photographed along Persimmon Road, Clayton, Georgia on 5 July 2008. Photograph by Darlene Moore. and that adults show limited learning of vocal - izations. Benkman (2007) and Benkman et al. Abstract Northwest have at times called this association (2009) argue that Types are effectively repro - Red Crossbill ( Loxia curvirostra ) of Type 1 has into question. In this paper, we review evi - ductively isolated. Interbreeding between been considered chiefly an Appalachian bird, dence in support of this association (n=186 Types seems to be relatively rare, despite sym - though detections of this Type as far away from Appalachian recordings of Type 1, n=14 non- patry of several Types and widespread wander - Appalachia as New England and the Pacific Appalachian recordings of Type 1), including ing by many Types. In several published stud - 554 NORTH AMERICAN BIRDS STATUS AND DISTRIBUTION OF TYPE 1 RED CROSSBILL: AN APPALACHIAN CALL TYPE? ies, interbreeding between various Types has been estimated at up to 5% (Groth 1993b, Summers et al. 2007, Benkman et al. 2009). In the South Hills of Idaho, where the resident population (Type 9) occurs sympatrically with Types 2 and 5, interbreeding was found to be less than 1% among 1704 paired crossbills (Benkman et al. 2009). Similarly, in a Euro - pean study of sympatrically occurring Red (or Common) Crossbills ( L. curvirostra ), Parrot Crossbills ( L. pytyopsittacus ), and Scottish Crossbills ( L. scotica ), Summers et al. (2007) Figure 1. A male Type 1 Red Crossbill with a fledgling visible in the left part of the frame (at left); the same male is shown found evidence of hybridization in approxi - feeding a different fledgling (right). These birds were audio-recorded and photographed in Rabun County, Georgia on 25 mately 5% of pairs, mostly between the larger- April 2009. Images from video by Ken Blankenship. billed Parrot Crossbill and Scottish Crossbill. Benkman (1993a) further predicted the exis - conclusively documented for a few; definitive In a study of sympatrically occurring Types 1 tence of a Sitka Spruce ( P. sitchensis )-associated evidence of specialization for a primary and 2 in the mountains of Virginia and North Type—and indeed Irwin recently (2010) de - conifer is lacking for Types 1, 6, and 7. Carolina in the 1980s, Groth (1993b) found scribed Type 10 in the coastal Sitka Spruce Benkman (2007) suggested that Type 1 might that all 60 monitored birds paired with mem - forests of northern California. specialize on Red Spruce ( P. rubens ), a species bers of their own Types. The evolution of dietary specialization in largely confined to the Northeast (defined Types differ in bill depth and palate groove crossbill Types is readily understandable in here as the area from the Adirondack Moun - structures, and Benkman (1993a) proposed insular populations such as those of New - tains northward and northeastward to the that each Type is most efficient at feeding on foundland Red Crossbill (Benkman 1989, Canadian Maritimes). However, Red Spruce single key species of conifer, although not Benkman 1993b, Benkman and Parchman is also found in small isolated pockets along obligatorily. Other authors have proposed that 2009) or Hispaniolan Crossbill ( L. megapla - the spine of the central and southern Ap - certain Types have core zones of occurrence ga ) (Benkman 1994); it is also clear how is - palachians from Pennsylvania to North Car - where they regularly breed and are most com - land-like geography, such as Idaho’s South olina, and Groth originally thought that mon (Dickerman 1987, Knox 1992, Kelsey Hills, could give rise to differentiated cross - medium-billed Type 1 might be primarily an 2008, Young 2010a). While most Types do ap - bill populations, particularly where relatively Appalachian bird, but he later recorded two pear to forage most efficiently on a single stable cone crops are found (Benkman et al. Type 1 birds in British Columbia and set species of conifer when in their core zone of oc - 2009). Such specialization in other Types is aside the concept of an Appalachian Red currence (Benkman 1993a), they also feed on less clearly motivated and indeed is not yet Crossbill (Groth 1993c). seeds of multiple coniferous species and can be seen switching to those conifers that provide Table 1 . Estimated conifer seed usage through the cone cycle year (June through May) for Type 1 Red Crossbill, as well the highest energy yields throughout the cone as usage of insects and bird feeding stations. These estimates are based on our field observations, as well as on our un - derstanding of cone-ripening phenologies and Type 1’s bill morphology. Southeast (SE) and Northeast (NE) are abbrevi - cycle (Benkman 1987, 1988). In North Ameri - ated herein. ca, Benkman (1993a) indicates that Type 2 ap - pears to be most efficient at feeding on Pon - Conifer/Area Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May derosa Pine ( Pinus ponderosa scopularum ), Type White Spruce (NE) X X X X X-x X-x X-x x-o x-o x-o 3 on Western Hemlock ( Tsuga heterophylla ), Red Spruce (NE and SE) X X X X X-x X-x x-x x-o x-o x-o x-o Type 4 on Douglas-fir ( Pseudotsuga menziesii European Larch (Southern New York) x x x x x x x x x x x x menziesii ), and Type 5 on Lodgepole Pine ( Pi - White Pine (East) x X X X X-x X-x x-o x-o nus contorta ). Benkman (1993b) suggests that Type 8 feeds most efficiently on Black Spruce Eastern Hemlock (East) x x x x x x x x x x x (Picea mariana ). And Benk - Red Pine (NE) x-X X X X man et al. (2009) note that Virginia Pine (mostly SE) x-X X X X Type 9—which has already Pitch Pine (mostly SE) x-X X X X been proposed as a full Shortleaf Pine (SE) x-X X X X species, South Hills Crossbill (L. sinesciurus )—feeds most Loblolly Pine (Georgia) x-X X X X efficiently on an isolated pop - Norway Spruce (Southern New York) x x x x-X X X X X ulation of Lodgepole Pine. Insects x x Feeders o-x o-x o-x o-x x x Figure 2. Audiospectrograph of Type 1 Red Crossbill, considered diagnostic, KEY: recorded 19 June 1983 in Montgomery X = used often County, Virginia by Jeffrey Groth. The x = used less frequently dark horizontal marks on the right sides X-x = birds are using resource less and starting to transition to other conifers of image are for kHz lines 3, 5, and 7. x-X = birds are transitioning from other conifers to a new conifer Image used and adapted from Groth o-x = birds could start utilizing alternative resource (e.g., feeders), depending on availability of others (1993a) with permission of the author. x-o = birds have exhausted resource VOLUME 65 (2011) • NUMBER 3 555 STATUS AND DISTRIBUTION OF TYPE 1 RED CROSSBILL: AN APPALACHIAN CALL TYPE? Table 2 . Totals of Red Crossbills from Red Spruce areas of the Appalachians in North Carolina during mid- through late May surveys conducted by Mar - ilyn Westphal. Note the absence of Red Crossbills on most May surveys. Date / Location Black Mountains Balsam Mountains Buncombe May 2006 18 0 0 May 2007 0 0 0 May 2008 0 (no survey) 0 May 2009 0 0 0 May 2010 1 0 0 May 2011 32 2 0 History of Type 1 in the Appalachian Mountains McNair (1988) provides a thorough review of historical Red Crossbill breeding records from the southern Appalachians, from the Virginias to Georgia.