Balsam Mountain Drifters

A male Appalachian (Type 1) Red Crossbill feeding in a Fraser Fir during a surplus cone crop year. Carver's Gap, TN.

A large, blood-red finch, the Red Crossbill, Loxia curvirostra, is built to withstand the harsh, subalpine canopy of coniferous forests. Crossbills feed almost solely on the seeds of spruces, firs, pines and hemlocks. Seldom found outside of cool, mature stands of conifers due to this restricted diet, it is very convenient in these suitable habitats to specialize; if an animal can harvest the seeds quickly and in large quantities, they can be among the few survivors of these environments. Crossbills have evolved to take on this challenge. Due to the constant variation in cone crop abundance, crossbills are constantly on the move. Often, they gather in large flocks, calling in more birds with the a two-note call in order to increase their chances of locating cone-laden spruces from the sky. This nomadic behavior is truly astounding. Much like Cedar Waxwings and goldfinches, crossbills spend a lot of time passing through the sky and canopy searching for very seasonal food sources.

However, in order to make use of the seed-filled spruce and fir cones, crossbills rely on their namesake bill. The Red Crossbill’s lower mandible actually curves around the upper mandible, causing the beak to cross over itself. This allows the bird to close its mouth under the scales of spruce, pine, etc. cones with powerful biting muscles, exposing the seeds to be dislodged and scooped up by the bird’s long tongue. But as complex and stressful as their search for food is, water is just as important to crossbills. Since they fly at such high elevations, there are few (if any) permanent water sources at which they can stop to drink on their journeys. Consequently, puddles and bird baths are almost sacred to crossbills, and they can often be tracked down while making a stop at one of these vital temporary water sources. Grit evokes the same necessity, and the birds frequently "chill out" on rock outcrops, logging roads and gravel parking lots.
   

A pair of Red Crossbills in a red spruce.

The Red Crossbill is a widespread species and occurs almost anywhere there are boreal conifer forests worldwide. Due to this large range, crossbills exhibit variations in almost each different forest type. Roan Mountain’s breeding crossbills, for example, are part of the “Type 1 Red Crossbill” population, and are affectionately known as “Appalachian Crossbills,” or the Loxia curvirostra pusilla/minor group. These mountain crossbills are generalists compared to other localities, feeding on not only spruce and fir cones, but those of hemlocks, pines and other seeds lying on open ground. In order to efficiently harvest such a variety of food, they have short, stocky bills with a prominent overlap. There are two groups of birds in this complex that could potentially prove to be separate species; one is considerably larger and noticeably variable in morphology and song, the other extenuates the description of Appalachia's smaller, generalist crossbills.

Appalachian Crossbills also have a beautiful, complex song and unique call notes. In fact, they won’t respond to the calls of conspecific flocks from other populations when they cross paths. Since crossbills are so nomadic, many varieties (particularly from western North America) irrupt throughout the mountains when their regions undergo poor cone crops or harsh winters. Appalachian Crossbills will also irrupt in other regions when the trees here in the southern mountains don’t produce adequate cone crops, and our crossbills have been documented as far west as California! Due to their imposing presence and indisputably unique appearance, crossbills are pretty easy to distinguish from any other mountain bird (even though White-winged Crossbills have made appearances as rare vagrants in Tennessee). Although, be forewarned of the much more common cedar waxwings which also frequent spruce treetops in the same habitats as crossbills appear.
 
Male crossbills range from a deep, blood red to a pale vermillion with yellow blotches. Females are typically more subtle in coloration, and are usually yellowish-green to rich, caramel brown with darker wings. Juveniles, however, often bear a heavily-streaked breast. While the observation of  most passerine juveniles  indicates breeding in the immediate area, crossbills seldom follow this trend. Instead, juveniles are launched from canopy nests only a few weeks after hatching to fly with the rugged, nomadic flocks of adults. Juveniles can be seen miles away from their nesting territory only days after fledging! Rather than nesting seasonally, crossbills nest whenever and wherever there is an abundant food source. In fact, Appalachian crossbills are well-known for nesting in the middle of winter, sometimes miles from the high-elevation forests where they typically reside.

The remarkable movement of the Red Crossbills draws my mind to the Appalachian Trail as it crosses the spruce-fir forest of Roan Mountain, Mount Rogers and the Great Smoky Mountains National Park. Red Crossbills move along these ridges just like the hikers who come from Maine or Georgia. Both the crossbills and the hikers are searching for something out here in the wilderness. The crossbills are looking for food, and the hikers are often searching for time to think, answers or simply a good time in some amazing places. Before hikers, Native Americans and mountain men roamed these ancient hills, likely alongside many more crossbills than we see today in search of game (pine cones), new lands and prosperity. And much like the centuries of humans going across the mountains, crossbills embrace a sense of community, a lifestyle of freedom and adventure, and a tendency to always return to their home in the mountains; no matter how far they roam. Crossbills even manage to do so without a regimented hierarchy. Maybe these mountain ecosystems have an importance that stretches beyond ecology alone, directly shaping the human culture of the mountains in addition to the plant and animal communities which call them home. Regardless, it's amazing to watch Appalachian Crossbills work together in order to survive the harsh mountain weather in what is debatably the world’s most beautiful habitat. There is a lot to be learned from their example.

Sources:

Brooks, Maurice. “Red Crossbills Summering in the West Virginia Mountains.” The Wilson Bulletin. Vol. 52, No. 1. (p. 36). March 1940.

Groth, Jeffrey G. “Resolution of Cryptic Species in Appalachian Red Crossbills.” The Condor. Vol. 90, No. 4. November 1988.

Heinrich, Bernd. “Winter World.” Harper Collins Publishers. 2003.

Red Crossbill Life History.” Cornell Lab of Ornithology All About Birds. https://www.allaboutbirds.org/guide/Red_Crossbill/lifehistory

Vanner, Michael. “The Complete Encyclopedia to North American Birds.” Parragon Publishing. 2005.

(Local eBird observations and reports to the Bristol Birds email list were also reviewed to determine the status of the birds in the immediate Roan Mountain area.)