Introduction to Differences in Crossbill Vocalizations

Further complicating matters is the idea that there are several different “vocal types” of Red Crossbills in North America, and each appears to make a different call when in flight. Since Jeff Groth’s landmark work in 1993, the idea of recording crossbills for identification has slowly gained in popularity. Groth’s work laid out the idea that each type gives a unique, identifiable call when in flight. These call types correspond with slight differences in morphology and ecological specialization. As many as nine “vocal types” of Red Crossbill can be found across North America (Groth 1993, Benkman 1999), each of which may represent a different species, or more likely, an evolving species (Young 2008). To be able to identify most of the vocal types with certainty, audiospectrographic analysis is needed. Computer programs like Raven Lite can be used to do the audiospectrographic analysis. What this analysis gives you is a computer printout of the bird's voice – a signature of the species so to speak.

In this article I will give a brief description comparing the vocalizations of the White-winged Crossbill and the four most widespread Red Crossbill “vocal types” (types 1,2,3, and 4). In each section I will try to describe the differences between their vocalizations. Do not fret, with much practice one can identify some or most of the types in the field. With a just a little practice, the various Red Crossbill “vocal types’ can be distinguished from the White-winged Crossbill fairly easily. Examples of each of these vocalizations are presented in the form of quicktime movies, which can be downloaded from the bottom of the page.

Lastly, the Macaulay Library of Natural Sounds has an archive of 100 different White-winged Crossbill recordings that can be listened to online. You can also make comparisons to Red Crossbills, redpolls, goldfinches, and a variety of other finch species.

White-winged Crossbill Vocalizations

In the first White-winged Crossbill recording (see White-winged Crossbill Call -- Example 1) there are two different calls. The first call sounds much like a squeakier, harsher call that an American Goldfinch would make. The second call could be easily confused with the call of various Red Crossbill vocal types; however, it’s a sharper, quicker and thinner veet-veet-veet than any of the Red Crossbill vocal types. Some practice is needed to avoid misidentification when hearing this call. Additionally, it’s a call that is often given by perched birds and not by birds in flight.

The main flight call given by the White-winged Crossbill is a chattering "chyet-chyet" or “chet-chet” call, usually doubled or tripled, and repeated once every second or two (see White-winged Crossbill Call -- Example 2). This White-winged Crossbill flight call is a louder, harsher (or twangy) version of a redpoll flight note. Audiopsectrographic analysis of the White-winged Crossbill is of somewhat less importance as long as you get the basic gist of their calls down. With some practice, the calls of the White-winged Crossbill can be fairly easily distinguished from any Red Crossbill vocal type or other finch species.

Type 1 Red Crossbill Vocalizations

The Type 1 Red Crossbill flight call sounds much like a Type 2 Red Crossbill. In both vocal types the spectrographs are dominated by a downward component. To be able to identify these two types with complete certainty, audiospectrographic analysis is essential. The Type 1 spectrograph will start with an initial upward component the vast majority of time, and the downward part descends more quickly than that found in the Type 2 (see Red Crossbill Type 1 Call). Overall, the Type 1 flight call is a quicker, dryer and sharper flight call than the Type 2, which sounds like chewt-chewt-chewt. This type also appears to be more frequent in the East than the other vocal types (Parchmen et al. 2006) and it likely utilizes hard pines such as lodgepole, red and ponderosa very infrequently. This is probably the least common of the “widespread” Red Crossbill vocal types in North America.

Type 2 Red Crossbill Vocalizations

Type 2 flight calls are a bit more powerful and husky than those of Type 1.  The downward component of the spectrograph is more gradual, and the initial upward component found in the Type 1 is absent (see Red Crossbill Type 2 Call). Additionally, the call (as it appears on the spectrograph) will often level out a bit before continuing its downward trend. The call sounds like cheewp-cheewp-cheewp. Both types often have secondary ending components (see recording and spectrograph). More than any type, this type will readily feed on hard pines like red, lodgepole and ponderosa. However, like the other vocal types, it will also feed on spruces. This type has perhaps the most varied diet and is the most widespread Red Crossbill vocal type in North America (Groth 1993). The flight calls of the Type 1 and Type 2 Red Crossbill are probably the least likely to be confused with the veet-veet-veet of the White-winged Crossbill. 

Type 3 Red Crossbill Vocalizations

The flight call of the Type 3 is weaker and squeakier sounding than the other types. The spectrogram (see Red Crossbill Type 3 Call) looks a bit like a lightning bolt with its zig-zag appearance – it starts out with a downward component followed by a short upward component connected to a second downward component. In some ways it’s a thinner call and could be confused with the veet-veet-veet callnote of the White-winged Crossbill. However, the flight call of the Type 3 is much squeakier than the veet-veet-veet. The Type 3 flight call is as fast as a Type 1 Red Crossbill, but again, its flight call is squeakier and weaker than the Type 1. Additionally, this vocal type will use hemlock more than any of the other vocal types, except in years when birds are eating what they can to just survive. All Red Crossbill vocal types, and the White-winged Crossbill, will feed on almost any conifer during years they’re trying to survive.

Type 4 Red Crossbill Vocalizations

The flight call of the Type 4 is perhaps the easiest to recognize. It’s a very bouncy, almost musical whit-whit-whit. The whit-whit-whit sounds much like the “whit” call of an Empidonax flycatcher (e.g., Least or Dusky Flycatcher). The spectrograph (see Red Crossbill Type 4 Call) is dominated by an upward component that is often preceded by a weaker and highly variable downward component. The spectrograph of some individuals will show a strong initial downward component, while in others it’s barely discernible.  The spectrograph often looks like checkmark. Again, the flight call of this type is very recognizable with some practice.

Differences in the songs of Red and White-winged Crossbills

The differences in the songs are quite evident. The song of the White-winged Crossbill (see here) is often quite long and powerful with a combination of staccato trills, chitters, and chatters, usually lacking intermixed call notes, warbles and whistles.  The song of the Red Crossbill can be quite variable, which is to be expected from a species with several different vocal types (see here and here).  Songs are often a much weaker series of whistles and callnotes, warbles and callnotes, trills and callnotes, or some combination of the these depending on the vocal type involved.

Potential for Breeding White-winged Crossbills in the Southern Part of its Range

Here I will largely address only the White-winged Crossbill, since they are the focus of this year’s crossbill invasion across much of the United States. I will note however, that there appear to be a few scattered Red Crossbill reports in the southern Great Lakes states and some nesting could occur there as well. Furthermore, a larger invasion of this species could still take place.

This could be the year that states like Pennsylvania, Connecticut and New Jersey could add this delightful boreal nomad to their breeding lists. Already in 2008 the White-winged Crossbill has been confirmed nesting in one southern NY location approximately 10 miles from the Pennsylvania and New Jersey state lines.  Additionally, numerous White-winged Crossbill reports from Illinois, Iowa and Ohio have also been noted. In wilder forested areas of the above-mentioned states, a few birds could nest while utilizing plantation Norway and white spruce, and European Larch-–if the cone crop holds up. This has occurred south of the boreal zone at several southern NY sites over the years, including this year. Additionally, areas of native boggy black and red spruce should also be checked. The site where they nested in southern New York 10 miles from the Pennsylvania and New Jersey state lines was a boggy area of black spruce with plantation Norway spruce in the general vicinity (Haas personal communication 2008). Times to look for potential nesting are from January to April.

In the western and southern Rockies (i.e., Idaho, Colorado, Utah and perhaps even New Mexico and Arizona) where this species is rarely detected as a breeder, nesting could also take place in mountain Engelmann spruce or perhaps even blue spruce.  Moreover, even northern coastal areas of Sitka spruce could attract a few nesting pairs. Come February and March, while we’re all out searching for crossbills, also watch for widespread nesting Pine Siskins south of their usual breeding zone, including in residential areas.

Literature Cited

Benkman, C. W. 1999. The selection mosaic and diversifying co-evolution between crossbills and lodgepole pine. American Naturalist, 153, S75–S91.

Groth, J. G. 1993. Evolutionary differentiation in morphology, vocalizations and allozymes among nomadic sibling species in the North American red crossbill (Loxia curvirostra) complex. Univ. California Publications in Zoology 127: 1-143.

Parchman T. L., C. W. Benkman, and S. C. Britch. 2006. Patterns of genetic variation in the adaptive radiation of New World crossbills. Molecular Ecology 15: 1873-1887.

Young, Matthew A. 2008. Red Crossbill (Loxia curvirostra). Pages 612-613 in The Second Atlas of Breeding Birds New York State (K. J. McGowan, and K. J. Corwin, Eds.) Cornell University Press, Ithaca, NY.

Please address comments or questions on this article to the author.

*Matt Young, Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, NY 14850.