Crossing Paths with Crossbills

Author: NCWRC blogger/Tuesday, May 4, 2021/Categories: Blog, Conservation, Wildlife Management, Wildlife Watching

Crossing Paths with Crossbills

NCWRC staff blog post by:
Clifton Avery, Wildlife Diversity Technician, NCWRC
Chris Kelly, Wildlife Diversity Biologist, NCWRC

In the fall of 2020, we headed to the field in search of a unique and rather uncommon bird – the red crossbill. This unusual finch uses its asymmetrical bill to extract seed from the cones of conifer trees. The species is further divided into “types” which differ according to bill sizes adapted to varying size and hardness of conifer species’ cones. For example, the Type 2 crossbill has a large bill that is most efficient at prying open bracts of ponderosa pine cones. In contrast, our local Type 1 crossbill of the Southern Appalachians has a medium sized bill and will feast on seed from a variety of conifer species.

Here in North Carolina, the red crossbill is listed as a species of special concern, indicating a need for monitoring. But monitoring this species presents a unique challenge because flocks don’t stay put. Red crossbills are nomadic, covering long distances in search of the next big conifer cone crop. The cones of local conifer species ripen at different times of the year – red spruce and white pine in autumn, and shortleaf and pitch pine from late autumn to winter – and bumper crops only come along every few to half dozen years depending on the species. In North Carolina, most red crossbills are associated with the high elevation red spruce and
Fraser fir forests, where they feast on spruce seed from summer through autumn. We know to look for and monitor them there. However, in years when red spruce has a poor cone crop, the crossbills must search elsewhere for food and we must search far and wide for them.

This was one of those years. Crossbills had been reported by birders in the autumn feeding on the abundant white pine cone crops some 500 to 1,000 feet below the spruce zone along the Highlands Plateau region and Blue Ridge Escarpment. One of those sites was DuPont State Recreation Forest, which features a variety of conifers. Crossbills had been spotted near Guion Farm in the planted stands of white pines that were bursting with ripe cones, but crossbills have even more choices of conifers at DuPont. The so called “yellow pines”, including table mountain, pitch, shortleaf, and Virginia pines, feature harder cones that hold seed longer than soft cones of spruce and white pine. Having spotted a small flock of crossbills in the white pine plantation, the search fanned out to the surrounding forests and granitic domes dotting DuPont. The dry forest of tall pitch pines, gnarly table mountain pines, and fire-scarred oaks felt a world away from the cool, foggy spruce forests of the high mountains.

On his first day of searching, Clifton found not only crossbills, but an active nest! He walked quietly and kept his ears trained to the sky. As he stepped gingerly across a granite dome he heard the distinct “chewt, chewt” call of a crossbill overhead. A male and female crossbill flew into a tall pitch pine rooted at the base of the dome. Scanning the pine, he noticed a clump resembling a nest in the bow of two branches near the top of the 50-foot-tall tree. The female crossbill then flew directly into the clump, prompting faint calls from presumed nestlings. After a few minutes, the female alighted in another branch and the male joined her for a brief visit. He suspected these were food deliveries to nestlings.

The next day we met at the nest site to observe the nest and record their calls to examine the audiospectrographs that are useful for distinguishing between crossbill types. Not only did the crossbills return to the nest, but we also witnessed the female removing a fecal sack from the nest. This confirmed the nest was active and there were nestlings. A fecal sac is the bird version of a diaper and allows the parent bird to easily pick up the self-contained droppings and remove them from the nest.

On October 17, Chris visited the nest at dusk and could barely make out the movements of one fully feathered nestling. The rest of the nest’s contents were obscured by branches and clumps of pine needles. All was over and done a few days later when the young fledged between October 18 and 20.

Finding the nest of any of our target species, be it a golden-winged warbler or a peregrine falcon, is a thrill. But this one was particularly exciting because the last confirmed red crossbill nests in North Carolina were in 1986. Marcus Simpson documented a nest in Linville Gorge that year and Douglas McNair reported nests in Highlands during a bumper crop of white pine cones. Birders’ crossbill sightings took Clifton back to Highlands in fall 2020, some 34 years later. While most songbirds nest in the spring and early summer in the western part of the state, red crossbill nests have been documented from the spring well into late autumn. In years of bumper cone crops, such as 2009 and 2013, crossbills can raise four broods. Whether those broods are all produced locally remains unclear. Chris described a memorable crossbill sighting in August of 2009 in the spruce-fir forest along Bald Knob Ridge in the Black Mountains. Early one morning, she watched the adult males feed fledglings. The fledglings’ bills had not yet crossed, indicating their age at less than a month old. Among them, stripy-plumaged older juveniles with crossed bills fed independently. Adult females only appeared after 10 a.m. Their appearance in late morning, according to some accounts, suggests they had been tending another clutch of eggs in the cooler morning hours. Let’s hope those bumper cone crops keep coming!

We knew the North Carolina Museum of Natural Sciences in Raleigh would want this unique crossbill nest for their collections, but there was the matter of getting to it. Clifton returned to Dupont nearly a month later with Andy Whittier, a research forester and certified tree climber from NC State University’s Camcore, an international group focused on tree improvement and gene conservation. Unfortunately, the nest was nowhere to be found. Along with everything else 2020 was, it was an active year for hurricanes. The nest was probably blown apart or out of the tree from a storm and was nowhere to be found around the tree’s base. Andy climbed the 50 feet up the tree to make sure the nest had not been shifted out of site or fallen into another branch. He did not find the nest, but got an enviable crossbill’s view of the world!

Next time you are around a large grove of pines or spruce, look up into the crowns to see if there are ripening cones. If so, keep your ears trained on the distinctive “chewt, chewt” call of the red crossbill. Perhaps you will find the next nest in North Carolina!

Photo credit: Clifton Avery and Chris Kelly, NCWRC


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