Species Spotlight: Red Crossbill

By Amber Wiewel 15 Feb 2024
Red Crossbill (Northeastern or type 12) Loxia curvirostra (type 12)

Red Crossbills are one of the rarest, and strangest, breeders in Pennsylvania. The most unique physical feature of this finch species is in its name: the tips of the upper and lower bills cross in opposite directions. This adaptation allows crossbills to pry open the cone scales of conifer species like pine, spruce, hemlock, and Douglas-fir, and extract the seeds with their tongue. (See a very cool video of this behavior below.) They even feed regurgitated seeds to their young. Red Crossbills have a relatively large range, but because of this dependence on conifers, are found only where the habitat is right: boreal forests of northern North America and montane coniferous forests in the U.S. down through Mexico. Furthermore, they are a nomadic species, vacating the core of their range when cone crops fail and finding their way to conifer forests where food is more plentiful.

Red Crossbills in Pennsylvania

In Pennsylvania, Red Crossbills are most commonly found in high elevation, mature coniferous forests. There is considerable historical evidence suggestive of breeding in the state, especially in the northern counties, but there have only been about a dozen confirmed nests in the state. During the first and second PA atlases, there were only six and 11 total reports, respectively, of potential or confirmed breeding of the species in the state.

Atlas blocks with possible, probable, and confirmed breeding records for Red Crossbill during PA’s first (yellow) and second (blue) breeding bird atlases.

To the excitement of many Pennsylvania birders, poor cone crops in boreal forests combined with above-average crops of Eastern White Pine cones and possibly other pines in Atlantic and Great Lakes states this winter (2023-24) has resulted in an irruption of crossbills in Pennsylvania. Most of this winter’s reports of crossbills are coming from central (including north-central and south-central) and eastern PA, but many areas of the state are under-surveyed, especially in winter. See the eBird map for Red Crossbill here. (Zoom in to PA, and keep zooming in until you see location pins appear. You can either filter by date to only see recent reports or click on a pin to see the most recent reports at that location.)

Undoubtedly the biggest surprise of the third Atlas so far was the discovery of a Red Crossbill pair building a nest at R.B. Winter State Park (Union County) in early January! Since then, there have been at least two more confirmations made of breeding in the species in north-central PA as well as a number of probable and possible reports.


How to Find Red Crossbills

Red Crossbills often nest during January to April, feeding their nestlings conifer seeds from the previous year’s cone crop, and may nest again in July to August to take advantage of the season’s new cone crop. Right now, with so many reports of crossbills in the state and especially with confirmation that some of them are breeding, we need birders out looking for breeding behaviors in crossbills and submitting their observations to the PA Bird Atlas eBird portal. We don’t know what to expect during subsequent years of the third Atlas, but we most likely won’t get another chance to experience so many crossbills breeding in the state!

Look for crossbills in stands of conifers with a large cone crop (i.e., look for a lot of cones). Listen for their distinctive “kip kip kip” flight calls to cue you in to their presence. They are often in small groups and call frequently, so they can be quite noisy. Crossbills spend most of their time in the canopy eating seeds, but can also be found on roads eating grit to help digest seeds. They prefer more open woodland for nesting.

Common Breeding Codes for Red Crossbills

  • H (In appropriate habitat for breeding) – Crossbills that you observe in conifer stands, foraging on cone seeds or eating grit on roads.
  • P (Pair in suitable habitat) – Looks for males and females interacting in conifer habitat. Males are dull red. Females are yellow-olive to grayish, with a pale throat (distinguish from immature birds which do not have a pale throat).
  • C (Courtship, display, or copulation) – Look for males courting females by chasing, bill-touching, and food sharing.
  • CN (Carrying nesting material) – Males and females carry material including conifer twigs and needles, grasses, and lichen, to the nest site.
  • NB (Nest building) – Nests are built primarily by females. Nests are well-concealed on horizontal branches in conifers about 2-20 m high.
  • ON (Occupied nest) – Only females incubate and may be seen from the side or below in incubation position. Males may feed incubating females on nest, especially during cold weather.
  • FY (Feeding young) – Both males and females feed regurgitated seeds to nestlings and fledglings. You are unlikely to see this behavior at the nest but may see it with fledglings. Listen for “chitoo” calls from young crossbills begging to be fed by adults.

Extra Credit

The most important thing for the Atlas is to document the presence of crossbills breeding in the state. That said, you can take a simple step to provide additional information to increase our understanding of the distribution of the different call types in Pennsylvania. The call types are distinct enough that, in most cases, short sound recordings can identify birds to type.

Whenever possible, make a recording of any crossbills you encounter. Here’s how:

  • Make a recording on your smartphone in .WAV format.
  • Upload the recording to your eBird checklist as “Red Crossbill” (with no type designation).
  • Send a copy of your checklist to the Finch Research Network for identification (info@finchnetwork.org).
  • If an expert identifies your recording type, change your eBird entry to include type.


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