Red Crossbill Flight Call

[Heike Fallago]

Below is a thorough summary of the ten North American Types of Red Crossbill. Please note that additional Types occur in Europe, Africa, and Asia, and that we welcome insight into that puzzle as well.

It must be said that while much has been learned in recent years about Red Crossbills, there is still much to learn. Our understanding of how these populations interact and to what extent they are evolutionarily divergent and reproductively isolated is still not well understood. Birds that give certain call types appear to preferentially mate with others that give their own call type, but the big question is, is this what happens under all environmental conditions?

Red Crossbills are on the move this year, and in September some remarkable high counts were tallied at migration locations along the Great Lakes and elsewhere. We expect Red Crossbills to continue to turn up in new areas this fall. Back in June and July large numbers of Red Crossbills (Type 3, based on a few recordings received) were moving down the west coast. In July 2012 Red Crossbills appeared on the Farallon Islands off the coast for the first time since 1998 (Alvaro Jaramillo pers. comm.), and these were very probably Type 3s. Type 2s have also moved in small numbers out into the Plains of Kansas.

Then in mid-August, a very significant west to east Red Crossbill movement occurred into the Great Lakes, Midwest, Ontario, and Northeastern states. This was a large movement and was much earlier than usual, which has made it particularly interesting to try to determine what Types have been involved. Recordings obtained so far (North Dakota, Wisconsin, Minnesota, New York City, Pennsylvania, Maryland and Quebec) have all involved the small-billed Type 3, which has its core range in the Pacific Northwest where it is most efficient at feeding on Western Hemlock. The Western Hemlock crop this year is reported to be poor, which is likely what has caused these birds to irrupt southward along the Pacific coast and eastward to the Atlantic coast. If anything, this flight has highlighted the remarkable dispersal abilities of Red Crossbills, since this movement has literally occurred from coast to coast.

Taxonomy: Subspecies unknown; could match type specimen for L. c. pusilla, but has also been referred to as L. c. neogaea. This population most likely needs a new name but has yet to be formally described.

Known range: Primarily in the Appalachians from s. New York to Georgia; occasional in Adirondack Mts., NY, and central Mass northward into New England, and perhaps Great Lakes, Maritimes, and s. Ontario; rare to very rare in West. [eBird map]

The Type 1 Red Crossbill flight call sounds much like a Type 2 Red Crossbill. In both call types the spectrograms are dominated by a downward component. To be able to identify these two types with certainty, audiospectrographic analysis is essential. The Type 1 spectrogram above is typical, starting with an initial upward component the vast majority of time, and a downward part that descends more quickly than in Type 2. Overall, the Type 1 flight call is a more attenuated, dryer and sharper flight call than the Type 2 and it sounds like chewt-chewt-chewt. Like the Type 5, Type 1 can produce sound polyphonically (see Type 5 for more on polyphony), meaning they use separate parts of their syrinx like a Catharus thrush.

Status: West: Type 1 appears to be rare, maybe only occurring in irruption years, in the coastal Sitka Spruce and Western Hemlock forests of the Pacific Northwest (Young et al. 2011). East: The core zone of occurrence (area where a type occurs most commonly) for Type 1 is the Appalachians from southern New York to northern Georgia (Young et al., 2011). In the Appalachians they are most commonly encountered in areas of both red spruce (and other spruces) and Eastern White Pine, and to lesser amounts Eastern hemlock and various hard-coned pines (i.e., Pitch, Red, Virginia and Loblolly pines). The Type 1 Red Crossbill appears to be more of a generalist and is probably the least common of the more widespread call types found in North America. It is also perhaps the most genetically distinct of all the Types (Groth 1993, Parchman et al. 2006), and might warrant species status.

Taxonomy: Might be most appropriately assigned to subspecies L. c. benti, but, in part, has also been assigned to L. c. benderei. This is another case where nomenclatural issues have created confusion that needs to be resolved.

Preferred trees: Hard-coned pines. Most efficient at feeding on Ponderosa Pine in the Intermontane West, but will use other hard pines as well, including Lodgepole and Jeffrey pines (West), Red, Jack, Pitch, Virginia and Table Mountain Pines (East). Uses spruces and soft-coned pines as well.

The flight call of the Type 4 is one the easiest to recognize even when compared to Type 10 (it was recently split from Type 10; see Type 10 below) and is a very bouncy, almost musical down up plick-plick-plick. The spectrogram (Red Crossbill Type 4 Call) is dominated by a down-up component with the ending section looking very similar to the Type 10 flight call.

Known range: Southwest U.S. to southern Mexico; possibly also Guatemala, Honduras, and El Salvador (recordings needed); in the U.S. it occurs in s. Arizona and s. New Mexico; museum specimens have been noted from Colorado and California. [eBird map]

The cheep-cheep-cheep flight calls of Type 6 are tonal with a slightly downward-modulated frequency and an abrupt terminal rising component (Groth 1993). Not much is known about Type 6, but by ear it does sound similar to the large-billed Type 8 of Newfoundland, although the spectrograms are obviously different. Type 6 is much less modulated than the m-shaped Newfoundland Type 8.

Status: West: Type 6 is most associated with Mexican pine species and its core zone of occurrence is the Sierra Madre Occidental (Benkman 2007) and north into the mountain ranges of southern Arizona and New Mexico. Recordings document this Type into southern Mexico, and it may be the form that occurs also in the highlands of Belize, Guatemala, Honduras, El Salavador, and Nicaragua. There is one record northward to California (San Diego Natural History Museum SDNHM 873; pers. comm. Lance Benner and Walter Szelinga) and Colorado has six specimens that match L. c. stricklandi (e.g., DMNS 4294, 4296, etc.; Spencer 2009). It has never been found in the East.

Taxonomy: The name L. c. percna is usually associated with this type and the subspecies percna is listed as Endangered by the Canadian Wildlife Service. Note however that some authorities (including eBird/Clements!) use the name L. c. pusilla as a synonym of L. c. percna. The nomenclatural confusion here still needs resolution.

Recent audiospectrographic analysis of recordings during 2005-2011 (n=30; 2 hr 37min of recordings) confirms the presence of a unique Red Crossbill type on the island of Newfoundland (presumably subspecies percna; see taxonomy below). These recent recordings were audiosprectrographically compared to the original two 4-second recordings used by Groth (1993), and much to our surprise, they did not match (Young et al. 2012). The most parsimonious explanation of the differences between the 1981 recordings and the 2005-2011 recordings, then, is that the more recent and complete set of recordings is typical of Type 8 Red Crossbill. Thus we adduce that the more recent recordings refer most reliably to Type 8 (Young et al. 2012).

The main frequency of sound is in the 3.25 to 4.0 kHz range. The flight call can be described as up-down-up-down cheet-cheet-cheet. Additionally, there are often very subtle modulated components attached on either end. Like Type 6, the sound of the flight call of these more recent Newfoundland recordings can be described as bell-like or ringing and clear, resembling the cheep call of the Evening Grosbeak. Type 8 flight calls are much more modulated than Type 6 though.

Taxonomy: Likely best matched by L. c. sitkensis, but many specimens identified as this form probably include other types of similar morphology such as Types 1, 3 or 4. Nomenclature in need of resolution.

Known range: Primarily the coastal Pacific Northwest of northern California to central Oregon, but uncommon year-round in the Northeastern U.S. and southeastern Canada. [eBird map]

The 2012 eBird/Clements taxonomy (v6.7) includes not only the nomenclature and taxonomy of species, but also of subspecies. Subspecies cannot be reported in eBird unless it is included as an identifiable group, but Red Crossbills can be reported to Type in eBird. In all cases except one (Type 9), those types are not linked to a scientific name.

Every crossbill recording adds an important piece to the puzzle, especially when accompanied by notes on behavior and ecology, including tree species used for foraging and nesting. The conservation of crossbill call types will depend in large measure on our understanding of their complex distributions and ecological associations, and birders can make critical contributions to their conservation by recording crossbill calls and by reporting their findings.

Since an understanding of conifer species is essential to understanding crossbills, the above article discusses conifer species at some length. Below is a list of the scientific names (with Wikipedia links) for the tree species mentioned in the article.

Pines can be broken down further into soft-coned pines (the two White Pine species listed below) and hard-coned pines (all the others listed below). At some points in the above article we refer to hard-coned or soft-coned species.

To hear a great comparison between Type 1 and Type 3 calls, try this link. In the first 10 seconds, the recording has a Type 1, followed by Type 3, and then Type 1 again, making for a particularly good chance to compare the calls side-by-side.

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