Wisconsin's 2017-18 Red Crossbill Irruption

By Ryan Brady February 7, 2018
Red Crossbill (Ponderosa Pine or type 2) Loxia curvirostra (type 2)

Snowy Owls may have stolen the show again in 2017-18 but another species has also irrupted in a big way across Wisconsin this year. Red Crossbills began moving into the state last summer, increased greatly throughout fall, and continue to show very well this winter wherever pines and other conifers are prevalent. Best of all, there’s always more than meets the eye with this fascinating species.

The thing is, not all Red Crossbills are quite the same. Scientists recognize at least ten different “types” based on distinct call notes, preferred tree species, areas of occurrence, and movement patterns. It’s possible these types are even different species, as demonstrated by recent work in southern Idaho that led to recognition of Type 9 as its own species, the Cassia Crossbill. Read the authoritative guide to all the types here.


Here in Wisconsin, only three types had been confirmed prior to this year’s irruption, including Types 2, 3, and 10. Types 2 and 10 occur here regularly and are known to breed. Type 3, which is typically found in coastal areas of western North America, irrupts periodically and made a big flight eastward into the region in 2012-13.

This year’s irruption, however, has proven to be the most diverse on record, yielding at least five types statewide and establishing first state records for Types 4 and 5. Type 2 has been most widespread, while Type 4 has made its best-documented eastward push in nearly 50 years. Remarkably, Bayfield County has hosted all five types and is the only county with records of Types 5 and 10 this year.

Photo by Ryan Brady


Type 2

This type appears to be the most abundant and widespread in this year’s irruption. It occurs annually and is known to breed here but this year’s flight has clearly been augmented by an influx of birds from farther west.

View a map of this year’s sightings
Listen to a sample of this call type

Type 3

This type from Pacific coast regions of western North America was well represented in the north woods during fall but appears to have largely continued eastward into the northeastern U.S. and Canada, leaving only a few scattered records in northern Wisconsin in recent months. Its last big irruption here occurred in 2012–13.

View a map of this year’s sightings
Listen to a sample of this call type

Type 4

This type, also with origins in the Pacific Northwest, is making its biggest known eastward flight since 1969–70! Wisconsin had no confirmed records of this type prior to this year yet as of mid-winter it appears to be the second most abundant and widespread type in the state.

View a map of this year’s sightings
Listen to a sample of this call type (first 0:18)

Type 5

Wisconsin’s only two state records were recorded during this year’s irruption by Ryan Brady in Bayfield County, the first in his yard on August 20 and later in the Chequamegon National Forest on January 20. These furnished two of just a handful of records east of the Mississippi River, although several have also been recorded recently in Iowa and Minnesota. Most eBird records of this type come from the Rocky Mountains westward, particularly from central Colorado to southern Wyoming and northern Utah.

View a map of this year’s sightings
Listen to a sample of this call type

Type 10

This type is often the most regularly detected in Wisconsin but has been especially scarce during this year’s flight. It has been recorded only from Bayfield County, and even there in much smaller numbers than Types 2 or 4. Northern Minnesota is the only other location away from the east or west coasts with confirmed observations since July.

View a map of this year’s sightings
Listen to a sample of this call type

Spectrogram samples for the five types of Red Crossbills known to occur in Wisconsin. All recordings from Bayfield County by Ryan Brady.

Unfortunately, exact patterns of distribution and relative abundance among types are hard to decipher because most recordings/data are coming from far northern Wisconsin, even though Red Crossbills are being seen to some degree throughout much of the state. The good news is that you can help!


As you may have gathered by now, Red Crossbills can only be identified to type with audio recordings, not photos. The recordings can be brief and low quality, meaning your cell phone or other inexpensive device is often good enough. One key, however, is to be prepared and fast-acting. Often the best way to detect the birds is via overhead flight calls, leaving you with just seconds to get out your device and make a recording. Another key is to be sure you are recording actual “kip-kip” flight calls, not “toops”, alarm calls, song fragments, or other vocalizations that can’t separate the types. Usually birds flying overhead yield the best results but perched birds often can be typed and thus are very much worth recording.

Once you have your recordings, you should send the file(s) to crossbill experts Matt Young (may6@cornell.edu) or Tim Spahr (tspahr44@gmail.com) for identification to type. Audio files may be small enough to send as attachments but consider Dropbox, Google Drive, or some other file sharing system for video files more than just a few megabytes.

The last step is to get your observation and recording into eBird! Audio files such as .wav and .m4a can be directly uploaded into your checklist using the “media” button near the species comment field. Video files, however, need to be converted first to audio because eBird does not accept videos. At least 3 options for doing this are: (1) use software for editing video/audio, (2) use free web-based converters (e.g. this one); or (3) ask Matt or Tim to convert it for you. Please note that crossbill observations submitted to eBird at the type level without mention of a field recording will not be validated due to the difficulty of separating them by ear alone.

Photo by Ryan Brady


  1. Will we score our first state record of Type 1? This type’s core range lies in the Appalachian Mountains to our east. Because this year’s flight is decidedly west-to-east and the northeast U.S. generally has an excellent cone crop it may be unlikely. But it also may just be a matter of time given the nomadic tendencies of most crossbill types.
  2. What types will nest in Wisconsin and when? Crossbills are known for ignoring the traditional calendar and nesting at any time of year whenever a sufficient cone crop is present. In past years fledglings have been out of the nest by April, and recent field observations in the north strongly suggest some courtship activities are underway. So it’s just about time to get out there and document breeding for the Wisconsin Breeding Bird Atlas, and in the process assess what types are breeding here. Only Types 2 and 10 have been documented as nesting previously.
  3. A big flight back? All signs suggest the bulk of this year’s flight stems from the western U.S. So they’ll have to head back at some point, right? If so, we could see another pulse of Type 3’s and an uptick in observations, especially at concentration points like Lake Superior’s south shore. Time will tell but be on the lookout as we head into spring!

This year’s flight, combined with the technology and expertise available today, offers tremendous opportunity for in-depth study of this species and its variations. Let’s take advantage of it, and enjoy the crossbills!