The Crossbill Story: Part 2
By Tom Hahn
I first started trying to catch Red Crossbills in the fall of 1987, my second year in graduate school. I hoped to get a handle on how crossbill reproductive physiology changed seasonally and relative to conifer seed supply. But to study this, I needed to get my hands on them via mist netting.. and they were nomadic, nest in the dead of winter, hard to find, and lived in the tree-tops.
I had poured over Ludlow Griscom’s 1937 monograph and found his plethora of named crossbill subspecies largely mystifying, but I was not yet aware of Jeff Groth or his discovery of 8 different call types / ecomorphs; his first paper describing types 1 and 2 from the Appalachians didn’t come out until the following year. So I was just looking to catch “Red Crossbills.”
In September, after I finished my first-year summer coursework at Friday Harbor Labs, I headed straight back to the Fish Lake area of the eastern Cascades, where I had found lots of developing Douglas-fir cones and crossbills earlier that summer. Crossbills were still common, but my first mist netting efforts were dismal failures. I had read a little paper by Curtis Adkisson (who had been Jeff Groth’s masters advisor at Virginia Tech) about catching finches using live decoys with mist nets set in a “vee” around them, but I didn’t have any decoys. I instead played vocalizations through a loudspeaker next to the mist nets, hoping these would draw birds down.
The recordings I used at first were from the Cornell Laboratory of Ornithology (Lab of O). Technology at that time was primitive compared with now, so I put snippets of audio just a few seconds long onto the endless-loop cassette tapes that people used for the greeting message in their telephone answering machines (note to young people…this was back in the days way before cell phones, so to talk on a telephone, you used a land line). We used small Pignose electric guitar amps/speakers for playback, and of course the little cassette player had to be directly connected via a cable to the speaker (that’s right, no such thing as Bluetooth speakers back then). The crossbills around Fish Lake occasionally seemed to show some interest in these recordings, but I never had even a single bird come down close to the playback speaker. After another completely unsuccessful all-day attempt using these Lab of O recordings on 7 November, I decided to go back to the recordings I had made at Fish Lake back in early July. I had avoided trying these because they were really bad, with lots of background noise and mostly just distant flight calls. The best snippet I had of the “tseedl tseedl tseedl tsee” song was marred by a big fly ricocheting around in the parabolic reflector during the recording. I decided to give it a try anyway, and started using it on my next trip.
Tuesday, 10 November 1987, was a chilly, foggy day near Fish Lake, and did not seem promising. I set up nets in a “vee,” with rock salt (crossbills and other finches crave salt), the playback speaker, a red bandana, and a live male song sparrow in a cage—the lab had a couple of male song sparrows in captivity at the time for use in behavior experiments on the role of testosterone in year-round territoriality. I had everything set up by about 9:00 am, started the endless loop playback of the “tseedl tseedl” song with the distracting loud buzz of the fly on it, and scampered about 50 yards up the hill to hide in a thicket of ocean spray bushes in case my standing too close to the nets was putting the birds off. After about 15 minutes, the sun started burning through the fog, and about 9:30 am, a group of four crossbills came quietly in and perched low in the trees, looking down toward the speaker, the salt, the bandana, and the song sparrow decoy. After a little while, all four came down, two going into nets right away, and two others landing on the ground and picking up grit and salt. I had an enormous adrenaline rush when the first two hit the nets, and I dashed down the hill to get them out of the nets immediately, lest they manage to untangle themselves and escape. The two birds on the ground simply hopped away from me as I approached, and didn’t actually fly up until I actively tried to shoo them into the nets. So much for the idea that I had been alarming the birds by being too close to the nets; these birds couldn’t have cared less about my presence! In fact, I’ve subsequently had crossbills land on my back while taking another bird out of a net!
These four became my decoys. They lived in a big outdoor aviary on the roof of the Zoology building at the UW, and came with me on all my subsequent trips that fall. I had much better success catching birds with them as field assistants, though it still never was guaranteed by any means. Raptors, especially Accipiters and pygmy owls, often hung around when I had the decoys out in the raptor-proof cage I had made for them. This definitely dampened the crossbills’ willingness to come to the ground, so each day’s outcome was impossible to predict. But I caught quite a few crossbills during the rest of November 1987 at several sites in the east Cascades Douglas-fir forests. I still didn’t know about the call types, and I consistently ran into trouble when I tried to catch birds over in the Puget Sound basin—turned out the Type 3s I was encountering there were not very interested in my Type 4 decoys.
Eventually I started noticing that not all the crossbills I was encountering sounded alike. I vividly remember the first time I definitely noticed birds being a different call type. On my way over to the Devils Table area east of Mount Rainier in mid November, I had stopped for a bathroom break along the Chinook Pass highway, and some totally different-sounding crossbills flew over. I later encountered a mess of ones sounding just like them when visiting my parents in NW Wyoming at Christmas; they were Type 5.
By March 1988 I was convinced there were at least 4 different “call types.” The birds I’d been dealing with around Fish Lake since summer I referred to as Type 1 (Groth’s Type 4). Different ones that were common in the Puget Sound Basin that fall had these very nasal-sounding calls they sometimes made—these turned out to be toops—and were my Type 2 (Groth’s Type 3). The ones I first heard along the Chinook Pass highway I called Type 3 (Groth’s Type 5). And some very mellow-sounding ones that first showed up during late winter around Fish Lake I called Type 4 (Groth’s Type 2). But I was still very much struggling with this variation. When I talked with Jeff Groth for the first time that winter and sent him some of my recordings, it was legitimately electrifying to have him say that I had independently noticed what he was calling Types 4, 3, 5 and 2, respectively. He was thrilled, because people had been pooh-poohing his “call types” as some figment of his imagination, and he was looking forward to being able to tell them that others were starting to notice the same thing. Jeff generously sent me a cassette tape of Type 2, 3, 4 and 5 call exemplars, and my (substantial) lingering confusion about telling these types apart rapidly dissipated.
Looking back on the fall/winter of 1987/88, it was one of the most exciting experiences I’ve had as a biologist. I was starting to get an inkling that something really interesting was in the process of being discovered, and having Jeff Groth draw aside the clouds of confusion gave me a clear path forward. I could now be confident about what different forms of crossbills I was dealing with as I embarked on my own attempts to understand their reproductive and migratory schedules.
Tom Hahn was around when the whole crossbill call type story started to get off the ground. This is the 2nd part of the Crossbill Story. Tom has several more of these to share…..so stay tuned!
For Part 1 of the Crossbill Story — the Early Years, click here: https://finchnetwork.org/the-crossbill-story-the-early-years-2
The Finch Research Network (FiRN) is a nonprofit, and was granted 501c3 status in 2020. We are a co-lead on the International Evening Grosbeak Road to Recovery Project, and have funded almost $13,000 to go towards research, conservation and education for finch projects in the last couple years. FiRN is committed to researching and protecting these birds like the Evening Grosbeak, Purple Finch, Crossbills, Rosy-finches, and Hawaii’s finches the honeycreepers.
If you have been enjoying all the finch forecasts, blogs and identifying of Evening Grosbeak and Red Crossbill call types (20,000+ recordings listened to and identified), redpoll subspecies and green morph Pine Siskins FiRN has helped with over the years, please think about supporting our efforts and making a small donation at the donate link below. The Evening Grosbeak Project is in need of continued funding to help keep it going.
Donate – FINCH RESEARCH NETWORK (finchnetwork.org)
Book Link
For help with Finch ID and much much more, here is a link to the exciting and newly released Stokes Guide to Finches of the United States and Canada: https://www.amazon.com/Stokes-Finches-United-States-Canada/dp/0316419931
Shirt Link
For a commemorative Winter Finch Forecast shirt where proceeds will go towards the study and conservation of finches and their habitats globally, see here: https://finchnetwork.org/shop
Please think about joining Finch Research Network iNaturalist Projects:
Winter Finch Food Assessment Project/Become a Finch Forecaster: https://finchnetwork.org/the-finch-food-assessment-become-a-finch-forecaster
Red Crossbill North American Foraging Project: https://finchnetwork.org/crossbill-foraging-project
Evening Grosbeak North American Foraging Project: https://finchnetwork.org/evening-grosbeak-foraging-project