Oregon

The Evening Grosbeak is a fascinating finch: completely absent from most birders’ visibility some years, and at every feeder in its range in others. Even more noteworthy is that, like Red Crossbills, Evening Grosbeak populations have different flight calls. We know from studies of Red Crossbills and the recent elevation of Type 9 Red Crossbill to Cassia Crossbill that these calls are important for flock cohesion and likely play an important role in speciation, but more research is needed to better understand Evening Grosbeak call types. We review what is known about the distribution of Evening Grosbeaks as well as provide descriptions of the known call types. Your eBird observations and audio recordings help us better understand the distribution of call types and their taxonomic significance.

Historical changes in Evening Grosbeak distribution

The Evening Grosbeak has one of the more interesting past and present stories of any species in North America. Beginning in the late 1800s to the 1950s people began noticing large, periodic winter flights of Evening Grosbeak in the northeastern United States. From the 1960s to the early 1990s, Evening Grosbeak irruptions occurred almost annually, with flights involving massive numbers of individuals. These irruptions corresponded with significant spruce budworm outbreaks in 1945–1955 and 1968–1988 across the boreal forest in eastern Canada (Bolgiano 2004).

Not only did Evening Grosbeaks numbers fluctuate in the Northeast in response to spruce budworms, but Bent (1968) noted their eastward expansion as well:

“…Facilitating their eastward extension has been the widespread planting in the east during the past few decades of the box elder (Acer negundo) as a shade tree (Allen, 1919). The seeds of the box elder, which hang on the trees all winter, are preferred by the evening grosbeak to anything else, when available, and Taverner (1921) calls the situation a “baited highway” along which the grosbeaks have been able to travel.” 

Some individuals that followed the eastward “baited highway” of box elder plantings also encountered spruce budworm outbreaks that provided them with ample resources and eventually they stayed in the area to breed. By the 1940s Evening Grosbeaks were breeding in New York, Vermont, Massachusetts, New Hampshire, and Maine, with a few nesting records in Pennsylvania and Connecticut (Young 2008). The species’ expansion was also supported by the proliferation of pin cherry (Prunus pensylvanica) and a fondness for sunflower seeds at a growing numbers of bird feeders across the East (Bonter and Harvey 2008). In fact, for a few decades Evening Grosbeaks were one of the most common species seen at bird feeders across much of North America in the winter. In areas as far south as the Carolinas and even farther south to the mountains of Georgia, Evening Grosbeaks occurred in large numbers biennially. Now, however, Evenings Grosbeaks appear to have experienced a significant population decline and are now listed as species of special concern in Canada. Population declines are due, in part, to habitat loss of mature diverse forests and forest management practices aimed at reducing spruce budworm numbers (Bonter and Harvey 2008).

Evening Grosbeak diet

Evening Grosbeaks tend to eat seeds of maples, ashes, apples, box elder, cherries, Russian olive, and occasionally pines (Gillihan and Byers 2001). They also eat sunflower seeds at bird feeders, but due to their beak and body size they only take sunflower seeds from hopper and platform feeders.

Potential differences in food preference according to call type are poorly known. Mexican birds (Call Type 5) tend to frequent coniferous forests, suggesting that they may feed on pines more frequently than other call types farther north, but more study is needed.

Evening Grosbeak call types

Evening Grosbeaks have several call types in their repertoire; in this article we focus on the variation in flight calls. Their other common call, the “trill call,” is not identifiable to type with current knowledge. The function of the other quiet, plastic calls of Evening Grosbeaks is unknown.

Flight calls in social finches are the main contact call used for flock cohesion and several finches have different flight calls. In the Red Crossbill complex for example, 10 different flight calls have been identified in North America, one of which (Type 9) is now a new species—the Cassia Crossbill (Loxia sinesciuris).

Sewall, Kelsey, and Hahn first described Evening Grosbeak call types in 2004 (Sewall et al. 2004). They described 5 call types and found that like Red Crossbills, grosbeak call types are geographically restricted. During eruptions, however, grosbeaks with different call types may occur in the same area. Different call types may also associate with different tree species as in Red Crossbills, but more study is needed.

In 2009, Aaron Haiman, a student of Tom Hahn, studied the Evening Grosbeak complex in greater detail and found that bill morphology differs among call types, especially among females. These differences he suggests could affect mate selection and speciation. Haiman also examined call type distribution across North America and created a generalized distribution map of the 5 call types. Below, we’ve laid out full descriptions of each of the call types.

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Evening Grosbeak (Type 1) Coccothraustes vespertinus brooksi (Grinnell, 1917)

Known range: Commonly breeds across the Pacific-Northwest, its core range.  Type 1 is the most widespread type in the west, from the northern Rockies and the Cascades to at least British Columbia and south to Oregon, northern Wyoming, and the Black Hills of South Dakota. Wanders to the northern Sierra Nevada and to San Bernardino California, and to Colorado, Arizona and New Mexico. Recordings by Aaron Bowman recently confirmed Type 1 in north coastal Alaska. Known to occasionally overlap in range with Types 2, 3, and 4, including during the breeding season. Might also overlap in range with Type 5 in Arizona. Type 1 likely occurs across more of the west, but more recordings are needed to accurately reflect its actual range. eBird map

Flight call: Descending chee-er; said to have a more pure-tone that begins at a high frequency, rises slightly, and then descends rapidly (Sewall et al. 2004). Its call is more thin and whistled. The other call types described as tee-er, keeer, peeer, p-teeee, p-teer and clee-ip, among other variations.

On a spectrogram, Type 1’s flight call is clear and descending with an initial quick rise in pitch. Spectrographically it is quite similar to Gray-cheeked and Bicknell’s Thrush flight calls. Type 1 starts with a narrow uptick from 2 to 5+ kHz, followed by a sharp drop, a slight leveling off, and another sharp drop. No harmonic banding is evident in spectrogram. The peak is up above 5 kHz and higher than other Evening Grosbeak flight calls, but much of the energy is in the lower frequency part of spectrum making Type 1 sound slightly lower-pitched than Types 2 and 4. Separating Types 1 and 2 where they overlap in primarily California and Oregon can be quite challenging.

Additional Notes/Irruptions: Bill thick, but slightly less slender than birds in Central Rockies and Mexico (Grinnell 1916). Most irruptive and widespread type in the West, and quite likely the most abundant too, often irrupting to foothills areas throughout much of the West. If a western type were to show in the east with Type 3, it would likely be Type 1. Modest numbers of Type 1 moved during the fall and winter 2017, but so far in 2018 there has been no discernable sign of a significant movement. However, movements could still occur in October–December.

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Evening Grosbeak (Type 2) Coccothraustes vespertinus californicus (Grinnell, 1917)

Known range: Core breeding range is largely restricted to the Sierra Nevada of California where it commonly breeds; occasional to Oregon in s. Cascades and rarely to Washington and amazingly a record in North Dakota. eBird map

Flight call: tee-er; thinner in quality and tends to sound higher pitched (Sewall et al. 2004). Begins with a pronounced rise followed by a gradual and steady drop in frequency. Type 2 is similar to Type 1, but is a bit more explosive, whistled, and piercing.

Type 2 flight calls are high and clear-sounding. Spectrographically Type 2 is similar to Type 1 with a distinctive inverted “V” shape. However, Type 2 flight calls spend more time and deposits more energy near the apex of the inverted “V” around 5 kHz, thus producing a higher sound on average than Type 1. These flight calls are similar in appearance to Gray-cheeked and Bicknell’s Thrush calls, but without modulation or banding evident in spectrogram.

Additional Notes/Irruptions: Bill intermediate in thickness between boreal/eastern birds and Mexican birds (Grinnell (1916). Wanders, at least, rarely north to southern Washington where it overlaps with Call Type 1. In 2017 it moved in very small numbers to southern California, but this type generally is not known to move much outside of the Sierra Nevada. Type 2 is quite possibly one of the least common (Hahn pers. comm.).

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Evening Grosbeak (Type 3) Coccothraustes vespertinus vespertinus (Cooper, W, 1825)

Known range: Core breeding range is boreal forests of Canada east of the Rockies to Newfoundland and in the northeastern United States; wanders southward to the southern Appalachians and historically rarely to the Gulf Coast, but such events have become much less common the last 25 years. eBird map

Flight call: clee-ip; begins with a harsh trill and then only slightly descends. Burry and resembles call of House Sparrow.

Type 3 flight calls look most like Type 5, but overall are quite distinctive spectrographically. The rough and burry-sound is plainly evident in spectrograms. Type 3 flight calls show an initial “down-up-down” component around 3–3.5 kHz followed by several bands between 2 and 4 kHz. The strength of this banding feature appears unique to Type 3.

Additional Notes/Irruptions: Bill is the shortest and thickest of all the types (Grinnell 1916). Most irruptive of all the types as well. Wanders south in the mountains in the East, but irruptions have been much smaller and infrequent south of Pennsylvania in the last 15+ years. Prior to the 1980s wandered as far south as Georgia with some regularity, but in recent decades it is very rare south of the Northeastern states. From 1967-1991, Evening Grosbeaks showed up every year during the Ithaca, NY Christmas Bird Count. A small movement out of the Maritime Provinces into the New England states took place in 2017. A small to perhaps even modest movement could take place in the Great Lakes and Northeastern States this fall-winter 2018. See Ron Pittaway’s winter finch forecast.

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Evening Grosbeak (Type 4) Coccothraustes vespertinus warreni (Grinnell, 1917)

Known range: Breeds in a core area from central to southern Rockies of Utah, Colorado and New Mexico; occasionally wanders and likely breeds north to the vicinity of Jackson Hole, Wyoming and rarely to central Montana. eBird map.

Flight call: “p-teer;” a very rapid frequency drop followed by an abrupt rise. Similar to Type 2, but huskier or burrier sounding.

Type 4 flight calls sound intermediate between Type 2 and 3 in the field, and are separable spectrographically based on the “down-up-down” feature at the beginning of the call, as well as the slight banding evident in the longer portion of the call near 4 kHz. This banding is also what gives Type 4 the slightly burry sound that helps separate it from Type 2 in the field; though not as burry sounding as Type 3 though.

Additional Notes/Irruptions: Bill intermediate in thickness but slenderer than birds found in the boreal and east (Grinnel 1916). Not thought to be very irruptive, but does occasionally irrupt to foothills areas of the Rockies. Small numbers were seen in the lowlands of the Rockies in 2017, and numbers could move again this year October–December. Bryant Olsen reports that Type 4 seems to prefer to feed on Russian Olive (Elaeagnus angustifolia) in Utah in winter.

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Type 5 Evening Grosbeak Coccothraustes vespertinus montanus (Ridgway, 1874)

Known range: Core range appears to be the Sierra Madre of Mexico, north to southeastern Arizona and the bootstrap of sw. New Mexico. All knowledge of this Call Type is based on two recordings by R. Hoyer from the Huachuca Mountains. eBird map.

Flight call: The long-sounding “cheeeerr” Type 5 flight calls are quite ringing, burry, and piercing, with a strong descending sound evident in the field.

Type 5 spectrograms are fairly complex with the main component around 4kHz and slowly descending. A secondary component is visible around 9kHz. Type 5 flight calls also show a short initial downward component around 4–5kHz. Close inspection of spectrogram reveals fine rapid modulation, similar to what is seen in Gray-cheeked and Bicknell’s Thrush flight calls. There is a somewhat buzzy, ringing quality similar to Type 3, but these two types don’t appear to overlap in range.

Additional Notes/Irruptions: Appears to be among the least common of the call types, even in its core range. Rarely encountered even in apparently ideal habitat, though the area around Cofre de Perote, Veracruz does seem to offer the best chance of finding it. Seemingly rare and highly erratic in the United States. Bill much slenderer in Mexican birds (Type 5) than any of the other forms (Grinnell 1916). 

HELP US LEARN MORE ABOUT CALL TYPES
The Macaulay Library has 359 recordings of Evening Grosbeak, most of which can be assigned to call type. However, even for call types with the most recordings, a larger sample size covering a wider geographic area can help clarify the wider occurrence and distribution picture of the species.

Of the 359 recordings in the collection, Type 1 is the most well represented with 89 recordings, followed by 49 of Type 3, 28 of Type 2, but only 13 of Type 4 and 2 of Type 5. The remaining recordings are either recordings still in need of identification or are trill calls, possible songs, or various quiet vocalizations that with current knowledge are not identifiable to call type.

Please be sure to record any Evening Grosbeak you hear. If you are new to recording check out the resources in the Macaulay Library. Even if all you have is a smartphone, you can still make a valuable contribution (Learn more about recording with smartphone and apps that record in .wav format). Each grosbeak recording adds an important piece to the puzzle, especially when accompanied by notes on behavior. If you think you hear two different call types, please be sure to make a recording as information on call types overlap, is greatly needed. The conservation of grosbeak call types will depend in large measure on our understanding of their complex distributions and ecological associations. Birders can make critical contributions to their conservation by recording grosbeak calls and by reporting their findings.

REPORTING YOUR EVENING GROSBEAKS
If you record an Evening Grosbeak, please enter it as “Evening Grosbeak” in eBird, upload the recording to your checklist, and send the link to the checklist to the authors (contact information below) for assistance with identification to specific call type. If identification to Type can be confirmed via the recording, you can easily use the new Change Species feature in eBird to search for the correct grosbeak type and revise the identification. If you try to identify the type yourself, do not worry if you misidentify the proper call type; one of the authors will contact you after listening to your recording. Keep in mind that many grosbeaks can be typed from poor recordings, so we encourage you to make a recording, even with your smartphone (Learn about smartphone recording). However, as with Red Crossbill, please be conservative, especially with observations that are not supported by a recording. Please do not assume call types based on range.

TAXONOMY
Astute readers will note that while eBird allows reporting to Evening Grosbeak call types, eBird does not match those to a scientific name as we do above. The main reason for this is that the eBird/Clements Checklist (2017 eBird/Clements taxonomy (v2017) has had a subspecies taxonomy in place for many years that includes three subspecies of Evening Grosbeak. Although there are 5 subspecies names that appear to match well with the distributions and appearance of Evening Grosbeak call types, a publication confirming this relationship has yet to be published. Our use of the subspecies names with the call types above should be considered a scientific hypothesis, yet to be established in peer-reviewed literature.

CONCLUSION
Understanding how these flight call differences relate to traditional taxonomy is fraught with complexity and requires more recordings of flight call types across a large geographic area, especially in the western mountains. Recordings paired with bird measurements may be even more telling as Haiman (2011) also found a significant difference in bill morphology that produce different flight calls.

You can make significant contributions to the research Tom Hahn and former students have conducted over the last 15 years by sharing your recordings of Evening Grosbeaks with eBird and the Macaulay Library.

LINKS
Learning to identify Evening Grosbeak call types is about as easy as learning your Red Crossbill types, which is to say, not that easy! All 5 types are represented in the Macaulay Library collection, but Types 4 and 5 are quite under-represented. Listen to more cuts here.

A couple of our favorite recordings where multiple types have been known to co-occur include:
1) Lance Benner’s cut of both Type 1 and 2 occurring together in southern California. https://macaulaylibrary.org/asset/72351751
2) Mike Hearell recording of both Type 1 and 4 in Weber, Utah. https://macaulaylibrary.org/asset/74142421
3) Type 1 and 3 can be heard well in this William W. H. Gunn Alberta, Canada cut at the 4-minute mark. https://macaulaylibrary.org/asset/43985

Lastly, there’s also evidence that suggests some or all Evening Grosbeak types sing a simple song mostly given around dawn. Notice the repetitive nature of the how the calls are given in the song in the examples below.
http://macaulaylibrary.org/audio/125382
http://macaulaylibrary.org/audio/111128
https://macaulaylibrary.org/asset/510291

For more on this subject and Evening Grosbeak call types in general, read Nathan’s Pieplow’s informative articles on the subject.

Download
Download all the grosbeak calls from this story

Acknowledgements
We would like to thank all of the eBirders and sound recordists who have contributed their Evening Grosbeak recordings to the Macaulay Library. We also thank Tom Hahn and his former students Kendra Sewall, Rodd Kelsey, and Aaron Haiman for getting us started down the grosbeak road—without their research, many of us wouldn’t even know that call types vary in this complex. Lastly, we’d also like to thank Lab staff Marshall Iliff, Kathi Borgmann, and Ian Davies for advice, editing, and contributions to this piece.

Literature Cited
Bonter, D. N., and M. G. Harvey (2008). Winter survey data reveal range-wide decline in Evening Grosbeak populations. Condor 110:376–381. http://www.bioone.org/doi/full/10.1525/cond.2008.8463.

Bent, A. C., and O. L. Austin, Jr. (1968). Life histories of North American cardinals, grosbeaks, buntings, towhees, finches, sparrows, and allies. 3 Parts. Bulletin of the United States National Museum: 237. 1889pp.

Bolgiano, N. C. (2004). Cause and effect: changes in boreal bird irruptions in eastern North America relative to the 1970s spruce budworm infestation. American Birds 58:26-33.

Gillihan, S. W., and B. E. Byers (2001). Evening Grosbeak (Coccothraustes vespertinus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.599

Grinnell, J. (1917). The subspecies of Hesperiphona vespertina. Condor 19:17-22.

Haiman, A. N. K. (2011). Levels of variation in evening grosbeak (Coccothraustes vespertinus) calls and morphology (Order No. 1502353). Available from ProQuest Dissertations & Theses Global. (909054837). Retrieved from https://search.proquest.com/docview/909054837?accountid=10267

Sewall, K., R. Kelsey, and T. P. Hahn (2004). Discrete Variants of Evening Grosbeak Flight Calls. Condor 106: 161-65. http://www.jstor.org/stable/1370527

Young, M. A. (2008). Evening Grosbeak (Coccothraustes vespertinus). Pages 620-621 In The second atlas of breeding birds in New York state (K. J. McGowan and K. Corwin, Eds.). Cornell University Press, Ithaca, NY.

 

Please address comments or questions on this article to the authors at may6@cornell.edu, tspahr44@gmail.com, or ajs535@cornell.edu

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