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Tag: Loxia curvirostra

New Crossbill Compendium

New Crossbill Compendium

Red Crossbill, type unknown.  Larimer County, CO.  Photo by Andrew Spencer
Red Crossbill, type unknown. Larimer County, CO. Photo by Andrew Spencer

Ken Irwin is a household name — at least among the bedlamites who think untangling the mysteries of Red Crossbill call types is a fun and worthwhile activity.  Ken has haunted the seaside spruces of California’s Patricks Point State Park for years, tracking the Red Crossbills that wander in and out of the park, recording their vocalizations, capturing and measuring them, and following their nesting cycles.  According to a couple of people I talked to, he may know the individual birds by name, and rumor has it that he is close to being accepted among the crossbills as an adopted member of their tribe.

Ken is best known for discovering a new call type (Type 10), and his paper describing it is coming out in the next issue of Western Birds (which, incidentally, will also include an article on phoebe vocalizations by Arch McCallum and me — more on that later).  When I talked to Ken on the phone last year, he was also hard at work on a website that would include sound files of all the types, their excitement calls, their begging calls, their songs, etcetera.

Now that website is up, and everyone interested in crossbills should go see it.  It’s a work in progress — but even in its current form, at about 14,000 words, it’s more than a little overwhelming.  Nevertheless I recommend girding your loins and wading in.  Irwin’s site is the most important addition to the web-based crossbill literature in years.

The recordings are probably the most important contribution made by the site, and they are both good and bad.  Here’s the good news:

  • there are a lot of them;
  • they put Type 6 and Type 7 on the web for the first time (outside Jeff Groth’s original site from 1996, where all the recordings are so short and so heavily edited that they don’t really count in my opinion);
  • there are several nice head-to-head comparisons of different types;
  • most of them include lots of examples of individual birds, so that you can quickly get a strong sense of the limits of individual variation within the types;
  • they include many recordings of lesser-known vocalizations like excitement calls or “toops”, chitter calls, and songs.

Here are some things I liked less about the site:

  • The organization is confusing, and it got more so as the page went on.  The information on this one page should have been split onto several linked pages, and was apparently intended to be.  This may improve with future revisions.
  • Personally, I feel that Irwin’s word descriptions of the different calls are uneven in quality and ultimately unsuccessful, but then I have this reaction to most word descriptions of crossbill calls.
  • The recordings have been a little too heavily edited for my taste, so that the birds sound too mechanical, not quite like they would in the field.  Since Irwin typically includes 2-3 calls per individual bird, the overall effect is much better than that of Jeff Groth’s site, but if he had included longer cuts with less editing, I think his recordings could have been even more useful.
  • The spectrograms are full-contrast — bicolored black-and-white instead of grayscale — and therefore less informative than they should be.

When it comes to the science — the validity of Type 10 in general, Irwin’s boundaries for Type 10, and his conclusions regarding crossbill song — I’m going to have to postpone judgment for a while.  When I see his Western Birds paper, I’ll post again.  Until then, when you’ve got a little free time and extra brainpower, head over to his page and start the long process of digesting the enormous amount of information that he’s published — and thank him for it if you get the chance.

AOU Checklist News!

AOU Checklist News!

The North American Checklist Committee of the American Ornithologists’ Union has published the results of its deliberations on the first round of proposed changes from 2009, and it has updated the slate of proposals currently under consideration.  Here’s a quick summary of the changes that affect species splits north of Mexico.  (I won’t get into all the changes to scientific names, even though those topics are just as interesting in my opinion — you can click through to read about those yourself.)

Proposal accepted

This split will become official once the next checklist supplement is published in the July 2010 issue of the Auk.

  • Split Pacific Wren from Winter Wren. As I reported earlier, this split did indeed pass, and unanimously at that.  However, note that the names “Pacific Wren” and “Winter Wren” are not final.  The committee is considering an addendum to the proposal that would split eastern North American birds from Eurasian birds and change the names of the American species to “Western Winter-Wren” and “Eastern Winter-Wren.”  Stay tuned.

Proposals rejected

In most cases, a 2/3 vote of the committee is required for a proposal to pass.  These proposals failed to muster that level of support:

  • South Hills Crossbill. The proposal to split South Hills Crossbill (Type 9) from Red Crossbill failed on a vote of 6 “yes” votes to 5 “no” votes, with three of the “no” voters indicating that they would be open to changing their minds if presented with more data.  Two of those voters preferred to deal with the North American Red Crossbill complex as a whole, rather than splitting one type at a time, piecemeal.  Thus, most of the committee appears to accept that the different call types of Red Crossbill are likely good species, but I think it may be a while before those species appear in your field guide.
  • The split of Western Scrub-Jay. The proposal to split the interior “Woodhouse’s” Scrub-Jay (woodhousei) from “California” Scrub-Jay (nominate californica) failed on a vote of 7 “yes” votes to 5 “no” votes.  Many members of the committee felt that more data were needed from contact zones.  The tagalong proposal to split the southern Mexican subspecies sumichrasti into yet a third species gained even less committee support.  Vocal differences between woodhousei and californica have been reported, and you can expect those differences to be discussed in a future post on this blog.

New proposals

The checklist committee never sleeps.  The following splits of North American species are now under consideration:

  • Split Black Scoter (Melanitta americana) from Common Scoter (Melanitta nigra).  I wrote about this split recently.  This proposal was originally submitted in 2006 and failed to pass at that time, but the recent publication of Sangster (2009) has revived it.  Personally, I think it’s a clear-cut split, but we’ll see if the committee agrees.
  • Split Curve-billed Thrasher (Toxostoma curvirostre) into two species: the western palmeri group and eastern curvirostre group.  The proposal makes no recommendation regarding the resulting English names.  The proposal cites various genetic data, which I won’t comment on, but it also cites vocal differences, including differences in calls.  I’m a little skeptical of these differences, but I’ll investigate them in the future and report back on what I find.
  • Split Whip-poor-will (Caprimulgus vociferus) into a nominate eastern species and the southwestern arizonae species, on the basis of subtle but easily diagnosable differences in song, differences in egg coloration, and (most importantly) a hot-off-the-presses study demonstrating that the vociferus and arizonae groups may be as genetically distinct from one another as either is from the Dusky Nightjar (C. saturatus) of Costa Rica and Panama.  I haven’t been able to track down the article text yet, so I can’t say what I think of it.

As you can see, vocal differences are playing an ever-more-prominent role in taxonomic decisions.  Look for more on this topic from me in the future.

The Crossbill Quiz: Answers

The Crossbill Quiz: Answers

Here are the answers to the quiz from the last post:

a. Type 4

Type 4 is believed to specialize on the cones of Douglas-fir.   It is widespread but somewhat irregular in its distribution: it is usually common in moist forests of the Pacific Northwest and can be frequently found in dry forests there also.  It is regular in southeast Arizona, and indeed this particular recording was made at Barfoot Junction in the Chiricahuas in May 2009.  It appear to be absent some years from Colorado, but fairly common in other years; 2009 saw a decent influx of this type into the state.

Ken Irwin (unpubl.) has proposed that hidden inside Type 4 there is another call type,  Type 10, that specializes on sitka spruce in coastal California.  It’s still unclear to me whether Type 10 is a separate call type or just a variation on Type 4.  Whatever the case, Type 10 seems to wander widely, at least across the northern states, out to New England and Maryland.

The Type 4/10 group, as a whole, sounds very distinctive because of its upslurred calls.  It may be a little hard to hear that they are upslurred because they are delivered so fast, but the rising, flicking quality of the calls is pretty distinctive, reminding some people of the “whit” calls of Empidonax flycatchers.

b. Type 9, the South Hills Crossbill

This type is sedentary and restricted to the South Hills and Albion Mountains of Idaho, where it feeds on the local variety of lodgepole pine.  It sounds kind of like Type 2, clear, simple, and downslurred, but it is noticeably low-pitched.  I think it is kind of “dull-sounding,” without much ring or resonance, but I’d be interested to hear how other people describe the difference.  I recorded this in the South Hills in September 2009.

c. Type 2

Here’s a Type 2.  This is probably the most numerous crossbill in North America; it is common almost everywhere Red Crossbills can be found.  It is surmised to specialize on ponderosa pines.  Across its range its calls are variable, but the high-pitched, clear, downslurred quality is fairly distinctive.  This recording was made in Boulder County, Colorado, in July 2007.

d. Type 3

This is one of the smallest crossbills (only Irwin’s proposed Type 10 is similarly small) and is one of the most common crossbill types in moist northwestern forests, apparently specializing on western hemlock.  It also can be found across the boreal forest, occasionally into New England, and it wanders rarely into the southern Rockies — there are now two certain records for Colorado and more in the “probable” category.  There are also recordings from Arizona.

Types 3 and 5 sound similar to my ear: they are more complex than the types we heard above, less clear and less obviously upslurred or downslurred.  Type 3 is the duller-sounding of the two, but I must admit I need practice with this identification.  This particular recording, the second-ever for Colorado (from the Grand Mesa, February 2009), was made by Andrew Spencer when I was right beside him–and I didn’t turn on my microphone because I thought they were “just” Type 5s.  To be fair, Andrew recorded them because he thought they were White-winged Crossbills.  🙂  He didn’t identify them until days later when he looked at the spectrogram.

e. Type 5

This is the “other” common crossbill in Colorado (besides Type 2), a widespread bird of high elevations in the West, apparently adapted to feed on lodgepole pine but also very fond of Engelmann spruce.  In direct comparison I think it sounds more “metallic” than Type 3, but it’s a tough call in the field.  A distant flock can sound a lot like a bunch of crickets.  This recording was made in Larimer County, Colorado, in June 2009.

The Crossbill Quiz

The Crossbill Quiz

Last week I facilitated the Sound Identification Panel at the Western Field Ornithologists Conference, which is a wonderful privilege I have been treated to for each of the last four years.  For those who don’t know, the Sound ID Panel is an annual WFO tradition started by Sylvia Gallagher. In front of a large live audience, a moderator (that’s me) quizzes an expert panel on the identification of mystery bird sounds.  This year our panelists were Ted Floyd, Oscar Johnson, Jon Feenstra, Rich Hoyer, and Tayler Brooks, and I must say they did an outstanding job.  In collaboration with each other, and notwithstanding the occasional wrong answer, they managed to identify almost every mystery sound in the end, and believe me, that’s not an easy feat.

In 2009 I decided to cross a line I’ve been reluctant to cross in the past.  I put Red Crossbills in the mix.  It seemed natural, since the conference was in Idaho, home to the endemic South Hills Crossbill, and our keynote speaker was crossbill guru Craig Benkman.  I gave the panel the following quiz:

Red Crossbill Call Types: Matching

In this quiz you’ll hear one example of each of the four most common and widespread crossbill types in the western United States, listed below with the tree species they are believed to specialize on:

  • Type 2 (Ponderosa Pine)
  • Type 3 (Western Hemlock)
  • Type 4 (Douglas-Fir)
  • Type 5 (Lodgepole Pine, Rocky Mountain variety)

Plus, given the location of the conference, we’re tossing in the sedentary and range-restricted South Hills Crossbill, endemic to Idaho, which has been proposed as a separate species, Loxia sinesciuris:

  • Type 9 (Lodgepole Pine, South Hills variety)

Here are the sound clips in random order.






How well can you do?  Answers will be posted in a subsequent message.

Macaulay’s Red Crossbill Types

Macaulay’s Red Crossbill Types

By popular demand, here’s a natural extension of my first post: an index to the Red Crossbill call types on some of the cuts in the Macaulay Library collection.  First, a couple of introductory notes and caveats:

  1. Typing Red Crossbills from recordings is not an exact science.  It’s not difficult if the bird is giving actual flight calls, but if the bird is singing, things can get confusing in a hurry, because the songs of Red Crossbills frequently contain strings of repeated sounds that resemble flight calls, but are really just notes in the song.  These song notes might be variations on the bird’s own flight call type, or they might somewhat resemble another flight call type, or they might just be something else entirely.   The point is that a solid identification to type requires a good string of call notes outside the context of song — and not all recordings provide such.
  2. In addition to song and flight calls, crossbills also give other calls, most notably the excitement calls (or “toops”) and the juvenile begging calls (or “chittoos”).  The excitement calls do vary from type to type.  It is not known whether the begging calls do too.  To avoid confusion, I’ve limited the examples in this post to cuts of flight calls only.

All identifications to type have been corroborated by Matt Young at Cornell.  Thanks for your help, Matt!

Type 1

#138304New York8/6/06
#138305New York8/6/06
#138306New York8/6/06
#138312New York8/6/06
#138320New York8/6/06
#138323New York8/6/06

Type 2


Type 3

#94205Maryland12/28/1997(with Type 10)

Type 4


Type 10

Groth’s (1993) monograph identified eight Red Crossbill types in North America.  Benkman (1999) identified a ninth type endemic to the South Hills of Idaho.  Ken Irwin (unpubl.) has proposed that there is a tenth type, which was actually recorded by Groth, but lumped with Type 4.  Ironically, my Colorado Birds article mentions this call type as a variant of Type 4 (the variant without the initial downslur).    Right now, expert opinions vary somewhat on whether this variant is actually separate from Type 4, but whatever it is, it seems to be relatively common and widespread, or at least widely wandering.

#94205Maryland12/28/97(with Type 3)
#130478New York5/17/98

I hope this post is helpful to those who want to try to sort these types out for themselves.  In conjunction with the Red Crossbill cuts on Xeno-Canto, the Macaulay cuts should get you off to a good start!

Getting started with crossbills

Getting started with crossbills

I think most birders know by now that Red Crossbills in North America sort into a number of different call types, each of which may constitute a cryptic species.  Identifying these types in the field promises to be a bugaboo of legendary proportions.  Where does one begin?

In this post I’ve collected links to some online resources that can get you started: a sort of Crossbill Q & A, if you will.

1) What are the crossbill types?  How did they evolve?  Are they for real?

A great source for beginning to answer these questions is Craig Benkman’s introduction to crossbill types in the July 2007 issue of Colorado Birds. Although it doesn’t discuss identification, the article’s overview of the research on crossbills is extremely valuable to anyone in North America, in spite of its nominal focus on Colorado.

When you’re ready to dig a little deeper, head to Benkman’s home page and look at the list of publications he has posted in PDF form.   The man is a scholarly publication machine.   Every important paper on crossbill types that has been published to date can either be downloaded from Benkman’s page or can be found referenced in the bibliographies of one or more of his works.

2) Where can I listen to online recordings of Red Crossbill types?

Your first stop should be Jeff Groth’s old page on the website of the American Museum of Natural History.   Although Benkman may be the current guru, Groth was the original discoverer of the call types.  The good news is that his page has audio files of the flight calls, excitement calls (“toops”), and alarm calls of types 1-7.  This makes it the most comprehensive collection of crossbill vocalizations on the web.   It also has range maps and basic natural history information for each of these types.

The bad news is that Groth’s site was, believe it or not, last updated in 1996, back when the Internet was in primary school.  Not all of the links still work.  There’s only a single audio file for each vocalization, and worst of all, because the files date from those dark days when 50 kB took a long time to download, they’ve been cut so short that they don’t sound like they do in the field–instead they all sound too much like each other.  Appreciate Groth’s site for what it has, but don’t let it intimidate you.  Crossbill identification is very hard, but it’s not hopeless.

Here are a couple of less comprehensive but more user-friendly resources:

  1. Matt Young’s crossbill identification paper on the eBird website.  This is the best identification article published to date.  It deals only with Red Crossbill types 1-4 (flight calls only) and White-winged Crossbill (which, interestingly, does not have multiple populations defined by call type).  These are the birds you are most likely to encounter if you live in the eastern United States.  If you live in the West, you are most likely to encounter Red Crossbill types 2-5, so this article will still be of great use to you.  It has much higher-quality (i.e. longer) recordings than Groth, including scrolling spectrograms in .mov format.  However, it has only a single example of each type, which makes it more difficult to get an idea of the variation within types.
  2. My Colorado Birds article on types 2, 4, and 5 in Colorado.  This was published along with Benkman’s overview in July 2007, and already I’m a little ashamed of the poor quality of some of the accompanying recordings (which you can listen to here: Fig. 1a, 1b, 1c, 2a, 2b, 2c).  Several people have pointed out that my spectrograms should have been zoomed in a little more, too.  Sorry about that.  On the bright side, this piece is a good supplement to Matt’s article, especially because it discusses Type 5, which is widespread in the West.
  3. Xeno-Canto’s Red Crossbill collection.  As of this writing you can listen to and download recordings of types 2, 3, 4, 5, 9 and 10.  I have posted a few mediocre recordings of Type 9, the South Hills Crossbill, which Benkman et al. 2009 have proposed as a separate species, Loxia sinesciuris.

In addition to the resources I’ve mentioned, there’s always the Macaulay Library, which is my favorite collection of online bird sounds.  In an upcoming post I’ll try to put together an index to the types heard on the Macaulay recordings.

More on crossbills soon!