The Curious Case of the Red Crossbill

Nature Bummin’ with MCHT Steward Kirk Gentalen     

I mean, they’re Red Crossbills. Loxia curvirostra. Where do we begin? Better yet, when do we begin?

Full disclosure here (and I think we’ve had this conversation before) but when it comes to nature observing, birds tend to be the “first hook” when exploring a new place for me. Unless, of course, I am at a place like the Grand Canyon, Niagara Falls, or North Perry Creek.

I’ve got a lot of great memories with birds, but there are a handful of moments that really stick out (some memories as early as pre-college). As a kid, I always appreciated leaving my natural habitat (the suburbs of New Jersey) to check out the birds while visiting my aunt and uncle’s feeders in upstate New York. During the summer, before my last year of high school, I participated in the Hardwood Island program off Mount Desert Island where I saw Bald

Red-winged crossbill

Eagles for the first time—I was totally and completely humbled. That same week, I was introduced to a bird called the Black-throated Blue Warbler—I pretty much thought that was the coolest name ever. Still do.

But if we’re really going to go back down memory lane, I would be remiss if I didn’t give some nature bummin’ props to the professor in Gilligan’s Island. He wasn’t just the coolest guy on the show, he was the only cool guy on the show (no one ever wanted to be Gilligan, the Skipper, or the dreaded Thurston Howell III).  One of the best things about the professor was that he knew everything about nature (or at least he seemed to) and he could invent anything out of coconuts. The professor set me up to observe nature at an early age with eyes wide open.

Fightin’ Banana Slugs, class of 1993!

I had two major bird watching epiphanies towards the end of my college years at the University of California at Santa Cruz. The first epiphany was that I could take my binoculars with me wherever and whenever. At the time, I had a cheap-o, micro pairs of binos—so why not stuff them in a backpack? Why not have them live there? That’s a lovely, convenient home for observation tools and resources. Why is it that some of my favorite epiphanies are so, so obvious?

It was the realization that I didn’t have to wait for organized Saturday morning bird walks to look at birds!

The second epiphany was just as obvious and just as huge as the bino thing. It was the realization that I didn’t have to wait for organized Saturday morning bird walks to look at birds! Heck, you never have to wait at all—birds are pretty much everywhere (especially in Santa Cruz), you just had to look and listen . So, you might as well have your binos with you so you can check out whatever feathered creature you crossed paths with—at any and all times! That was when “tweeter watching” turned from a hobby into a very important form of entertainment for me—eyes wide open.

Bird watching as entertainment is cheap (cheapo-binos, bird book, and a bike), diverse (birds are like that, so many niches, so many adaptations), and relatively easy. It’s even easier if you aren’t in a hurry (which I certainly wasn’t at the time). And so, on an hour or two bike ride on West Cliff Drive along Monterey Bay through Natural Bridges State Park and to the UCSC Marine building complex I could see dozens of avian species and a handful or more of marine and terrestrial mammals. And a ton of Monarch butterflies (who wouldn’t be entertained by that?). And it could be done by bicycle. And all there for free! Birding by bike was huge for me then and remains huge still. Whatever gets you out there.

“You can observe just by watching” – Yogi Berra

It’s an amazing adaptation that allows Crossbills access to their favorite food—seeds from cones, or cone-seeds.

During my last trimester of college (Spring ’93), I took an Ornithology class, and the timing was perfect (eyes and ears wide open). I was already into it, so the learning was smooth, and it felt great to be forced to learn stuff and get tested on things. Even better was to have friends in the class (a wonderful graduate assistant named Dawn and a visiting professor named Craig Benkman) at every turn to help, assist, correct, and keep me in my lane during those early bird watching years.  

Professor Benkman was cool in that while being a total dork about birds he also had a passion, and he would talk about that passion whenever he got the chance. His passion was Crossbills, and at the time Crossbills came in two easily recognized flavors, Red-winged and White-winged. Not all Red Crossbills are red, but all White-wingeds have white on their wings. And all Crossbills, except the youngest of fledglings (who eventually go crossed), have misaligned bills. When closed, a Crossbill’s top and bottom mandible literally cross each other. It’s an amazing adaptation that allows Crossbills access to their favorite food—seeds from cones, or cone-seeds.

To pry a cone open, Crossbills wedge their open bills in between scales of a cone (largely spruce cones in mid-coast Maine). They then close their bills, and it’s this crossing of the bills which separates the scales and allows a Crossbill to use their sticky tongues to pull exposed seeds out and the feast is on. I remember Professor Benkman talking about a study he had done on Crossbill efficiency, and how many cones with how many seeds were required for a Crossbill to spend time on a tree. That kind of esoteric passion is fun to be around and so naturally, I developed a special fondness for Crossbills and their super bill adaptation early on in my bird watching “career”.

Back then I would see Crossbills so infrequently, there could be years between sightings. That made for memorable moments when I actually did cross paths with them in the Sierras or Santa Cruz Mountains. My Crossbill luck started to change with a summer in Homer Alaska (2004). It was a summer filled with showing people epic tide pools and loads of scope-views of White-winged Crossbills. This was a time to learn White-winged Crossbill bubbly in-flight chip calls, which is key (in my experience) to seeing them. Very seldom is a Crossbill seen before heard.

Irruption—a sudden sharp increase in the relative numbers of a natural population usually associated with favorable alteration of the environment.

We moved to Vinalhaven that fall (2004), and little did we know that we would soon frequently cross paths with both kinds of Crossbills. For perspective, we note that White-winged and Red Crossbills are lovingly lumped into a group of birds referred to as winter finches. Beyond Crossbills this group includes Redpolls, Pine Siskins, Pine and Evening Grosbeaks, Purple Finch, and Goldfinches. These winter finches are irruptive species, along with Snowy Owls Bohemian and Cedar Waxwings, in that their numbers can increase dramatically in southern North American during winter depending on the status of their food in northern North American.

A bad cone year to the north can mean lots of Crossbills along the Maine coast and beyond. And they’ll stay as long as there are cones. A concrete pattern to this irruptive behavior can be tricky to pinpoint, but as a general rule of thumb, a large irruptive event occurs every ten years or so, with smaller irruptive happenings in-between. You never know what finches you might find in the maritime spruce forest in winter.

Those first few winters in Maine (05-08) weren’t necessarily “big irruptive” years for winter finches in mid-coast Maine per se, but White-winged Crossbills, Pine Grosbeaks, and Redpoll sightings were fairly common depending on where you went on Vinalhaven. You learned to go to the Huber Preserve to see Pine Grosbeaks, and that the Basin Preserve was reliable for sizable groups (15+) of White-winged Crossbills. That was good enough for me.  Amongst the dozens of sightings of these species, only (maybe) twice in those years did I see Red Crossbills, and both times the flocks were just a handful of birds (if I was lucky).

Things changed (they always are changing) during the summer of 2008, which goes down as the summer of the White-winged Crossbills on Vinalhaven and beyond. My friend Big Al Jones was living with us, and when I told him in late June I had seen some Crossbills, Big Al mentioned that he had never seen one before. Well, he went from zero to a gagillion in a matter of weeks. Big flocks (25-75) descended onto the island and roamed freely all summer. They were the first bird I would see every day that summer, and always the most numerous. Sweet, sweet white winged crossbill summer of 2008.

But still, Red Crossbills were few and far between on Vinalhaven. Absent from my records and memories from that summer, but they may have been around in small numbers and undetected. The white-wingeds stayed strong through the fall and winter (‘09) and when they finally headed off in early spring what was left behind was a sprinkling of Red Crossbills in select locations. Their bubbly flight chip calls, however, had been replaced by singing. With songbirds, singing means mating.

Anytime, anywhere

Crossbills tend to nest in late winter/early spring which is on the “early” side of all things North American songbird mating-wise. In reality they can breed any time of year as long as there is enough food (cones) to support such activity, and of course a willing mate.  Red Crossbill singing/courtship behavior on Vinalhaven began in early March (09). This mating pattern would be repeated yearly through 2021 and resulted in large flocks of freshly fledged young Red Crossbills (and adults) each May. There would be a week or so where chatty (and sizable) Red Crossbill flocks would gather and scour the island, decimating cone crops with their funky mandibles. And then they’d be gone (snap of a finger emoji here), before any wave of neo-tropical migratory songbirds could reach Maine. Poof! Ain’t nobody gunna tell Crossbills how or when to raise their young. Nobody puts Crossbills in a corner. Nobody.

red-winged crossbill

Each winter, the Red Crossbills would return to start the process over. They would be joined by White-wingeds most winters—some years a lot of white-wingeds, other years not-so-many—and bubbly Crossbill chatter was appreciated on almost all winter work days and any random walks through spruce woods along the mid-coast. Those were nice times.

Times they are (always) a-changin’

This last winter–2022–was different (of course) with no Crossbills showing up on my radar, even though I was in the spruce as much as ever. It got me thinking about Professor Benkman and his Crossbill efficiency studies. Had the mid-coast Maine spruce cone crops dropped to such levels as to leave Crossbills saying, “such small portions!” as they flew to conier-pastures? Or maybe they struck it rich somewhere else—north, south, west, who knows (probably not east)—and stayed to raise young somewhere else. What was clear was that there were few (if any) Crossbills around, making me appreciate the stretch of years they were here. Didn’t ruin any days though, never ran out of stuff to see.

Solstice party ‘22

By late June, most local songbirds have settled down a bit on the singing front. I’m not saying they are completely silent by any means, but the cacophony of bird song that marks late May and early June courtship season dwindles a bit as energy shifts from mating to stuffing insects in nestling’s mouths. No way to avoid it—happens every year.

With that in mind, it was even more noticeable when the bubbly call of Red Crossbills returned to mid-coast Maine on June 20th. In the backyard (Tenants Harbor), while changing out trail cameras in the “back woods”, I could hear them coming—bubbly flight chip calls—and saw the classic undulating flight of a finch (flap-flap-glide, flap-flap-glide). A flock of six or seven landed on the tops of a clump of spruce trees next to me—chatty silhouettes in marginal, afternoon light,  emphasizing the crossing of bills that much more. “Cool,” I think is what I said.

Continual crossbills

There were more in the neighborhood the next day, allowing for wonderful scope views from the front yard picnic table. All week, I saw Red Crossbills wherever I went, and as June rolled into and through July the mid-coast Maine Red Crossbill scene was getting kinda silly.

On Vinalhaven Red Crossbills were at the Huber, the Basin, and the Barney Point preserves, as well as Lane’s Island, in town, at the shed, and a handful even flew over the docked ferry while I was on it! Red Crossbills were on Calderwood Island, at the Bamford, Clark Island and Weskeag preserves on the mainland and were the auditory accompaniment for any bike ride I went on. The only day I didn’t see or hear Red Crossbills was the day I mostly spent in line at the Rockland Ferry Terminal. And looking back I am sure some flew over, but just missed out on timing. Along with Cedar Waxwings, Red Crossbills became the most numerous bird species I would hear any day in July. As the song goes, “It’s a Red Crossbill Summer”… a song I made up in my head anyway.

Red Crossbills were becoming the most numerous bird I would cross paths with.

I reached out to my birder friend (some would even say bestie) Kristen Lindquist to see if she had been seeing any up in Camden. Not only had she not seen any Crossbills, she hadn’t seen any reports of them in the mid-coast (she’s one of those birders, that pays attention to what other people see which makes her not only a great friend but also a great resource). The lack of reports was surprising because not only was I seeing them every day, Red Crossbills were becoming the most numerous bird I would cross paths with.

Female Crossbill

Kristen gently tossed out the idea that maybe I was mistaking goldfinch for crossbills. Now, I’m always up for doubting (hey, I am from Jersey remember), and goldfinch flight calls are somewhat similar to Crossbills, but Goldfinch calls often have a “po-ta-toe chip” pattern. Crossbill calls are way more bubbly (have I mentioned that yet) and after hearing them for over a decade I dare say they sound pretty different than Goldfinch to me. Plus I wasn’t just hearing them, I was seeing them and photographing them. So after a few moments, I wrote back, “maybe you are confusing Crossbills for Goldfinch.” “Haha,” was her response. That’s the way we roll.

As far as I knew, I was the only person on Vinalhaven seeing them for the first few weeks. Then my friend Janet Ghores, who basically lives in the spruce on Vinalhaven, reported hearing them often and seeing them infrequently. Another “bird-aware” friend on island, Patience Chamberlin, was reporting them from most walks she was taking. I finally reached out to Trevor Persons (bird and herp freak, amongst other passions) to see if he had been seeing any Crossbills in central Maine (or wherever he lives) and while he hadn’t been seeing any Crossbills himself, Trevor did mention seeing scattered reports on a bird listserv for mid-coast Maine. This all made me feel better about things—not because I was doubting my sightings (already been through that)—it just didn’t make sense that others weren’t enjoying this summertime Red Crossbill event, that literally started about the first day of Summer! Crossbills can be so under the radar.

This all got me thinking, Crossbills live that nomadic, irruptive lifestyle, I wonder if there is a way to tell where these summer visitors might have started from. This is where the fun began…

The Research/Dangerous Kitchen

Male and juvenile Crossbill 

A little simple Red Crossbill research turns up info on 10 or so “call types” of the species. These are not subspecies, but rather groupings within the larger “Red Crossbills umbrella” based on the differences and similarities of their calls. The differences in calls correlate to differences in preferred food and cone types, and the differences in cone correlates to differences in bill size and structure. Take “type 5” Red Crossbill for instance, which lives mainly in the western United States and Canada and seeds from Lodgepole Pine and Engelmann Spruce. This particular type has adapted a large bill to open up such hardy cones. It also sounds unique.

On the other hand, Red Crossbill ‘‘Type 3’’ feeds largely on Western Hemlock in western North America. Hemlock trees generally have smaller cones with easier access than Lodgepole Pines and thus “type 3” has adapted, over time, a smaller bill required to access such seeds. Both types have distinctive calls to match their distinctive bills. And while these two types are largely found out west, both types (3 & 5) have been recorded as far east as New York (type 5) and through north eastern Maritime forest (type 3). Bottom line is when the food runs short in their regular turf they could show up just about anywhere! This begs the question—which type showed up in mid-coast Maine this summer?

So are they subspecies or something?

Much is still to be learned about Red Crossbill diversity, and I certainly have not kept up with the knowledge gained over the years. One type—type 9—is now officially recognized as its own species! It’s called the Cassia Crossbill (Loxia sinesciurus), and is actually a non-wondering species of Crossbill only found in Idaho. It turns out the Cassia Crossbill is endemic (only found there) to Idaho. They live in a handful of specific Lodgepole Pine forests in Southern part of the state (Twin Falls and Cassia counties), never straying too far from the habitat (total range of roughly 67 square kilometers).

What makes these Lodgepole Pine forests special is a complete absence of squirrels (dream world, huh?). With no squirrel pressure, the Lodgepole Pine cones in these forests have grown larger and tougher to access, and in response the Cassia Crossbill’s bill is larger to open up such cones. While other Red Crossbill types may irrupt and visit these forests they cannot efficiently access the cone seeds and thus don’t stick around for too long, where the Cassia is right at home. And who “discovered” this as a unique species in 2009? Professor Craig Benkman of course! How cool it must feel to identify a “new” species of Crossbill that has been around (in Idaho of all places!), but no one has noticed! How has this happened in the relatively heavily birded United States of America?

In the end, each of the Red Crossbill types may very well end up eventually being recognized as distinct species (or subspecies) as we continue to understand and learn more about them. The variety of Red Crossbill bill structure adaptations reminds me of Darwin’s Finches of the Galapagos. You know, the group of “finches” (not really finches) Darwin collected that turned out to be different species on different isolated islands as the birds adapted their bills and behaviors depending on different food on said different isolated islands.

Legendary breakthrough observations on adaptive bill radiation shares many traits with what’s being learned about Red Crossbills.  What we have is a Red Crossbill scene that can be described as potentially multiple (double digits!) speciations of a not uncommonly seen “mother” species that have not yet been formerly recognized individually (by humans) just yet? Not an exact match, but similarities make them feel similar.

White-winged crossbillA difference from Darwin’s Finches is that each Red Crossbill type (minus type 9) may mix with other types through the magic of irruption. From my understanding Darwin’s Finches stayed on their island to promote “island biogeography” and thus split and speciated. Apparently the different Red Crossbill types will hang, but don’t breed with other types (type-ist solidarity?).  In a way, each type has their own “islands” of breeding habitat, and many of those “islands”  are amorphous and fluid. Man, I love thinking about this stuff.

So uh… now what?

Juvenile Crossbill 

Now it’s August and the Red Crossbills are still around. Their numbers and sightings have stayed steady, but their groups seem to have become more “pair based”. Chip calls have blended into song, giving this bald observer the hope that mating has already happened and that fledglings will follow! I realize that there’s a strong possibility that this is false hope, but it’s fun to dream. Having Red Crossbills around in the summer is beyond any dreams I had before. It’s okay to dream.

As for me, I am hoping I can start adding to the knowledge and understanding of Red Crossbills and all their types. Apparently it’s not all that hard to help. In fact, it’s as simple as recording Crossbills in the yard, in the travels, and then sending the recordings to Finch Research Network (FiRN). Never recorded audio wildlife before, just got to do it I guess.

And in conclusion (I guess)

I didn’t see it coming, but Red Crossbills have really been the story for me this summer. A consistent (and constant) layer on top everything else that’s been going on. Only once before have I felt that I knew something that others didn’t (weird feeling) and that was when the coyote showed up on Vinalhaven back in 2010. But this has been different, and I’m so glad others have been able to share the joy. As far as I am concerned (and from my experience) Red Crossbills in summer (before this summer) was rarer than Stellar Sea Eagles in Maine. Leave it to nature and the solstice to change that narrative.

I’m pleased to note that albeit being thousands of miles away, I’m still learning from Professor Benkman!

Oh, and P.S. Kristen Did see red Crossbills at Clark Island on August 11th!

Addendum 

(8/21/22) I headed to Clark Island early in hopes of seeing a River Otter that I have been tracking for years. It was the first time I had ever, actively and purposefully “tried” to see River Otters “in the flesh”, as they say, and sure enough I had a day to remember with a group of five of them. While waiting for the otters to re-emerge (they were taking minute + long dives), and with a huge stroke of luck, a flock of chatty Red Crossbills landed low in the tree I was using as a blind. They were so low–if I was standing, they would have been eye-level–and maybe only 10 feet away. I was camera ready (ready for otters) and had a clear view of the head and torso of one of the crossbills. I raised up my lens and snapped a few as it appeared to be checking me out (oh how the tables have turned!). It took a few moments, but after a bit the crossbill flew back a branch, joining a second Crossbill and the two looked to be chilling–taking a break from the cone feasts at the tops of trees.

Let’s cut to the chase–the crossbill that landed close to me was a juvenile–from this summer summer’s–which would account for the extra chattiness of the group, as well as the slightly different notes I had been hearing from crossbill flocks the for the few days prior. A few weeks ago I had been seeing couples. Now there were groups of three to four birds, and they were starting to merge into larger flocks of up to eight. Destiny was upon them. Mid-late June they arrived in groups, paired up within a few weeks, started singing (courtship), and now the fruits of their activities were in plain view. If (my observed) history with Red Crossbills maintains, they will most likely be on their way shortly, in search of conier forests to help fill all the new bills. We are prepared for this, and either way they’ll be on their way sooner or later. Whatever plays out, 2022 will go down as the “Summer of the Red Crossbills” in my book, which speaks of the power of a finch with a funky bill. Because let’s face it, only crossbills could have made river otters the 2nd coolest thing I saw that morning. And that says something.

See more Nature Bummin’ stories from Kirk