{"id":66681,"date":"2025-10-01T11:09:01","date_gmt":"2025-10-01T15:09:01","guid":{"rendered":"https:\/\/www.allaboutbirds.org\/stagaabnews\/?p=66681"},"modified":"2025-10-01T12:50:55","modified_gmt":"2025-10-01T16:50:55","slug":"craig-benkmans-40-year-fascination-with-crossbills-and-conifers","status":"publish","type":"post","link":"https:\/\/www.allaboutbirds.org\/stagaabnews\/craig-benkmans-40-year-fascination-with-crossbills-and-conifers\/","title":{"rendered":"Craig Benkman's 40-Year Fascination With Crossbills and Conifers"},"content":{"rendered":"\n<p class=\"toc-link\">From the <a href=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-autumn-2025-table-of-contents\">Autumn 2025<\/a> issue of Living Bird magazine. <a href=\"https:\/\/join.birds.cornell.edu\/page\/14522\/donate\/1\">Subscribe now<\/a>.<\/p>\n\n\n<div class=\"wp-block-group sidebar-alignright order-bottom\"><div class=\"article-list list-style\"><h2 class=\"article-list-header\">More From Living Bird<\/h2><ul><li class=\"article-item\"><div class=\"article-item-container\"><div class=\"article-item-media  content-living-bird-toc\" data-link-to=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-autumn-2025-table-of-contents\/\"><figure class=\"article-item-media-ratio\"><img decoding=\"async\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-1280x720.jpg\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-720x405.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-1280x720.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-768x432.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-1536x864.jpg 1536w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77-480x270.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/20200307C_390-nef-forsberg-1.77.jpg 1800w\" sizes=\"(max-width: 1280px) 100vw, 1280px\" alt=\"a group of tall white cranes stands in front of smaller white pelicans in water lit by pink dawn or evening light\" loading=\"lazy\" \/><\/figure><\/div><div class=\"article-item-body\"><a class=\"article-item-link\" href=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-autumn-2025-table-of-contents\/\"><span class=\"article-item-header\">Living Bird Autumn 2025\u2014Table of Contents<\/span><\/a><\/div><\/div><\/li><li class=\"article-item\"><div class=\"article-item-container\"><div class=\"article-item-media  content-living-bird-toc\" data-link-to=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-autumn-2025-table-of-contents\/\"><figure class=\"article-item-media-ratio\"><img decoding=\"async\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-latest.png\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-latest.png 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-latest-240x180.png 240w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-latest-480x360.png 480w\" sizes=\"\" alt=\"Living Bird-latest issue\" loading=\"lazy\" \/><\/figure><\/div><div class=\"article-item-body\"><a class=\"article-item-link\" href=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-autumn-2025-table-of-contents\/\"><span class=\"article-item-header\">Living Bird Magazine\u2014Latest Issue<\/span><\/a><\/div><\/div><\/li><li class=\"article-item\"><div class=\"article-item-container\"><div class=\"article-item-media  content-article\" data-link-to=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-magazine-archives\/\"><figure class=\"article-item-media-ratio\"><img decoding=\"async\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-acrhive.png\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-acrhive.png 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-acrhive-240x180.png 240w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2023\/07\/living-bird-acrhive-480x360.png 480w\" sizes=\"\" alt=\"Living Bird archives\" loading=\"lazy\" \/><\/figure><\/div><div class=\"article-item-body\"><a class=\"article-item-link\" href=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/living-bird-magazine-archives\/\"><span class=\"article-item-header\">Living Bird Magazine Archives<\/span><\/a><\/div><\/div><\/li><\/ul><\/div><\/div>\n\n\n<p>The rest of Craig Benkman\u2019s life began on a snowy late-winter morning in 1982. As the first-year graduate student prepared to attend a seminar on ecology at the State University of New York at Albany, a classmate burst into his office with an urgent message: \u201cCraig, Craig! There are crossbills coming to the ground outside!\u201d<\/p>\n\n\n\n<p>Benkman\u2019s heart leapt. For months, he had searched around the Hudson Valley for the strange red finches, thinking they could be a perfect study subject for his dissertation. But so far, he\u2019d had no luck finding any crossbills.<\/p>\n\n\n\n<p>When he proposed studying the birds for his PhD, he knew it wouldn\u2019t be easy. Red Crossbills and White-winged Crossbills, so named for the overlapping tips of their bills, are notoriously nomadic, wandering vast distances across North America\u2019s remote evergreen forests in search of their only food source: the seeds of conifer trees, such as spruces and firs and pines.&nbsp;<\/p>\n\n\n\n<p>Unlike other birds that reliably nest in the same place year after year, crossbills will breed anywhere and at any time\u2014even in the dead of winter\u2014so long as they find an abundant supply of conifer seeds. All the while, they remain high in the treetops, making crossbills notoriously difficult subjects for ornithological research.<\/p>\n\n\n\n<p>One faculty member on Benkman\u2019s dissertation committee simply laughed at the thought of studying the birds.&nbsp;<\/p>\n\n\n\n<p>\u201cI kind of got discouraged,\u201d Benkman says. \u201cI almost quit.\u201d<\/p>\n\n\n\n<p>Still, Benkman was convinced that crossbills had potential. That same dependence on a single, unreliable food source that made the finches so tricky to study also raised a host of fascinating questions to explore: How had the birds adapted to the challenges of accessing conifer seeds? Why did different crossbills have different bill shapes?&nbsp;<\/p>\n\n\n\n<p>So when Benkman\u2019s classmate informed him of the crossbill flock on campus, he didn\u2019t hesitate.&nbsp;<\/p>\n\n\n\n<p>\u201cA group of us said, \u2018No class today!\u2019\u201d recalls Benkman. By the end of the day, Benkman had netted about 10 Red Crossbills\u2014more than enough to probe how the curious finches carve into conifer cones.&nbsp;<\/p>\n\n\n\n<p>\u201cI thought, \u2018Well, I guess I\u2019m going to study crossbills!\u2019\u201d he recalls.<\/p>\n\n\n\n<p>And so he did\u2014for the next 40 years.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"897\" height=\"673\" data-id=\"66869\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33.jpg\" alt=\"\" class=\"wp-image-66869\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33.jpg 897w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33-720x540.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33-240x180.jpg 240w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33-768x576.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-White-winged-Crossbill_CROPPED-1.33-480x360.jpg 480w\" sizes=\"auto, (max-width: 897px) 100vw, 897px\" \/><figcaption class=\"wp-element-caption\">Craig Benkman\u2014pictured here with a White-winged Crossbill in Quebec, in 1988\u2014has studied crossbills for more than four decades. <\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1064\" height=\"798\" data-id=\"66871\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33.jpg\" alt=\"\" class=\"wp-image-66871\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33.jpg 1064w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33-720x540.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33-240x180.jpg 240w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33-768x576.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Craig-Benkman-with-Cassia-Crossbill-1.33-480x360.jpg 480w\" sizes=\"auto, (max-width: 1064px) 100vw, 1064px\" \/><figcaption class=\"wp-element-caption\">Thirty years later, in 2018, Benkman holds a Cassia Crossbill in Idaho. The previous year, as a result of research by Benkman and others, the Cassia Crossbill had been officially recognized as a full species. <em>Photos courtesy of Craig Benkman.<\/em><\/figcaption><\/figure>\n<\/figure>\n\n\n\n<p>Over a decorated research career that has netted him honors from the American Society of Naturalists and American Ornithological Society, Benkman\u2019s influential work expanded not only how ornithologists understand crossbills, but also how evolutionary biologists understand the relationship between species and their environments. He chronicles his life\u2019s work studying the finches of the <em>Loxia<\/em> genus and more in his thorough and wide-ranging book <a href=\"https:\/\/pelagicpublishing.com\/products\/crossbills-and-conifers\">Crossbills and Conifers: One Million Years of Adaptation and Coevolution<\/a>, published in summer 2025 by Pelagic Publishing.<\/p>\n\n\n\n<p>\u201c[The book] touches on so many different dimensions of what we think of in terms of avian biology and ecology and evolution,\u201d says Irby Lovette, director of the Cornell Lab of Ornithology\u2019s Center for Biodiversity Studies. Lovette says reading about Benkman\u2019s work on crossbills is almost a crash course in ornithology. \u201cIt\u2019s like everything in one bird.\u201d<\/p>\n\n\n\n<p>Starting with that one snowy day in Albany, Benkman made his life\u2019s work out of chasing crossbills from New England to Canada\u2019s Maritime Provinces and out west to the Rocky Mountains and isolated South Hills of Idaho. Along the way, he developed fascinating insights into the relationships between birds and their habitats, challenged traditional notions about how bird species and their food sources evolve, and even discovered <a href=\"https:\/\/allaboutbirds.org\/guide\/cassia_crossbill\">a new species of crossbill<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Uncovering the Crossbill&#8217;s Seed-Eating Secrets<\/h2>\n\n\n\n<p>After Benkman captured his first crossbills,&nbsp;he shuttled them to a makeshift aviary on campus. In the wild, it would be impossible to watch crossbills forage at the level of detail necessary to understand how they efficiently slip seeds from cones. But from behind a one-way mirror in the aviary, Benkman had an unprecedented close-up to the subtleties of feeding crossbills.<\/p>\n\n\n\n<p>\u201cThe birds are so tame in captivity,\u201d he says. \u201cOnce you put them in a cage, they\u2019ll start feeding on cones within a couple of minutes.\u201d<\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<p>He spent hundreds of hours observing the Red Crossbills forage on amply provided pine cones\u2014watching and taking notes as they contorted and flipped every which way to extract and husk seeds in seconds\u2014before releasing them back into the wild.&nbsp;<\/p>\n\n\n\n<p>\u201cMore than once, I had to catch myself from clapping in admiration at what these feeding birds could accomplish,\u201d Benkman writes in his book.<\/p>\n\n\n\n<p>Benkman\u2019s front-row seat in a lab aviary was perfect for understanding the details of crossbill feeding. <\/p>\n\n\n\n<p>But to understand how the birds interact with their environment, he needed to venture out into the vast boreal forests that crossbills call home. He scoured the outer reaches of Ontario, Quebec, and New England for flocks of White-winged and Red Crossbills, even skiing down snowy forest roads on frigid midwinter days.&nbsp;<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<div class=\"wp-block-group has-sand-neutral-tint-background-color has-background is-layout-constrained wp-block-group-is-layout-constrained\">\n<h3 class=\"wp-block-heading\">How Crossbills Crack Open a Cone<\/h3>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped columns-3-mobile wp-block-gallery-2 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" data-id=\"66872\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a-1280x1280.jpg\" alt=\"\" class=\"wp-image-66872\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a-1280x1280.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1a.jpg 1389w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1281\" data-id=\"66873\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b-1280x1281.jpg\" alt=\"\" class=\"wp-image-66873\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b-1280x1281.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b-720x721.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b-768x769.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1b.jpg 1418w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" data-id=\"66870\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c-1280x1280.jpg\" alt=\"\" class=\"wp-image-66870\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c-1280x1280.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CassiaCrossbill1c.jpg 1346w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" data-id=\"66947\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-1280x1280.jpg\" alt=\"\" class=\"wp-image-66947\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-1280x1280.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-1536x1536.jpg 1536w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull1.jpg 1826w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><figcaption class=\"wp-element-caption\"><strong>Resting Position. <\/strong>A crossbill&#8217;s bill tips are naturally offset, with the upper bill overlapping the lower bill. <em>Graphics by Jillian Ditner.<\/em><\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" data-id=\"66945\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-1280x1280.jpg\" alt=\"\" class=\"wp-image-66945\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-1280x1280.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-1536x1536.jpg 1536w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull2.jpg 1826w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><figcaption class=\"wp-element-caption\"><strong>Bill Open. <\/strong>As the crossbill bites into the cone, the bill tips align and squeeze in between the cone scales, creating a gap.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"1280\" data-id=\"66946\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-1280x1280.jpg\" alt=\"\" class=\"wp-image-66946\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-1280x1280.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-1536x1536.jpg 1536w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3-480x480.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/CrossbillSkull3.jpg 1826w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><figcaption class=\"wp-element-caption\"><strong>Bill Moves Laterally to Open Cone. <\/strong>The crossbill moves its lower mandible side-to-side to spread the cone&#8217;s scales apart, repeating the action until its tongue can retrieve the seed inside. <\/figcaption><\/figure>\n<\/figure>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<p>\u201cI have indelible memories of stunning red, black, and white male White-winged Crossbills singing while flying over snow-ladened spruce when temperatures hovered at \u201320\u00b0F,\u201d Benkman writes.<\/p>\n\n\n\n<p>Once he found crossbills in the wild, Benkman vigilantly recorded as much information as he could about their habitat and behavior: what trees were around, how many cones they carried, what the crossbills ate, how many seeds they consumed. He also became adept at noticing the formation of tiny conelets in the spring, a sign of a crossbill-attracting cone crop that he could study the next year.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<div id=\"video-ml\" class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<iframe src=\"https:\/\/macaulaylibrary.org\/asset\/309251731\/embed\" width=\"640\" class=\"ratio-ml\" frameborder=\"0\" allowfullscreen><\/iframe>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p>Upon earning his doctorate in ecology in 1985, Benkman authored a series of papers that greatly enriched the scientific literature on crossbills. Across seven studies, he explained how crossbills use their elongated bills to pry open tough cone scales; discovered that a crossbill\u2019s crossed bill was essential for consuming large amounts of conifer seeds, but a hindrance to eating other kinds of seeds; and described how the small bill of the White-winged Crossbill makes it well suited for exploiting tiny spruce and tamarack cones, while the larger bills on Red Crossbills can more easily break into hefty pine cones.<\/p>\n\n\n\n<p>Along the way, the once-mysterious birds became more familiar to Benkman, both scientifically and personally. He began to feel as though he knew the crossbills as well as they knew themselves\u2014their personalities, tendencies, and whims.&nbsp;<\/p>\n\n\n\n<p>\u201cIt\u2019s kind of like bonding with a dog,\u201d he says. \u201cBeing able to feel almost at one with an organism is a marvelous thing.\u201d<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Happening Upon An Evolutionary Classroom in the Idaho Hills<\/h2>\n\n\n\n<p>In subsequent stints&nbsp;as a postdoctoral fellow at Princeton University and the University of British Columbia, Benkman continued to build his bond with crossbills as he explored how they adapt to their environment. But after accepting a faculty position at New Mexico State University, he found himself surrounded by desert, far from his familiar finches.<\/p>\n\n\n\n<p>\u201cI wasn\u2019t convinced I was going to continue to study crossbills,\u201d he says. \u201cI started thinking about studying lizard communities.\u201d<\/p>\n\n\n\n<p>He still had time to explore one last hypothesis, though. Benkman suspected that since crossbills harvest millions of conifer seeds every year, the conifer trees might in turn be adapting to better defend their seeds from predators. He wondered about a coevolutionary arms race\u2014two species, a bird and a tree, becoming increasingly intertwined as they adapt in response to one another.<\/p>\n\n\n\n<div class=\"wp-block-group sidebar-alignright sidebar-space order-bottom\"><!--HubSpot Call-to-Action Code -->\r\n<span class=\"hs-cta-wrapper\" id=\"hs-cta-wrapper-096b8ce3-0e2d-46c5-bbf7-12de3323c8da\">\r\n    <span class=\"hs-cta-node hs-cta-096b8ce3-0e2d-46c5-bbf7-12de3323c8da\" id=\"hs-cta-096b8ce3-0e2d-46c5-bbf7-12de3323c8da\">\r\n        <!--[if lte IE 8]><div id=\"hs-cta-ie-element\"><\/div><![endif]-->\r\n        <a href=\"http:\/\/cta-redirect.hubspot.com\/cta\/redirect\/95627\/096b8ce3-0e2d-46c5-bbf7-12de3323c8da\" ><img decoding=\"async\" class=\"hs-cta-img\" id=\"hs-cta-img-096b8ce3-0e2d-46c5-bbf7-12de3323c8da\" style=\"border-width:0px;\" src=\"https:\/\/no-cache.hubspot.com\/cta\/default\/95627\/096b8ce3-0e2d-46c5-bbf7-12de3323c8da.png\"  alt=\"subscribe to Living Bird magazine\" loading=\"lazy\" \/><\/a>\r\n    <\/span>\r\n    <script charset=\"utf-8\" src=\"https:\/\/js.hscta.net\/cta\/current.js\"><\/script>\r\n    <script type=\"text\/javascript\">\r\n        hbspt.cta.load(95627, '096b8ce3-0e2d-46c5-bbf7-12de3323c8da', {});\r\n    <\/script>\r\n<\/span>\r\n<!-- end HubSpot Call-to-Action Code -->\r\n\r\n<\/div>\n\n\n\n<p>But studying his hunch would be complicated by squirrels. Across the Red Crossbill\u2019s range, red squirrels are seemingly everywhere, and they are voracious cone predators. Benkman suspected that in the presence of squirrels, any crossbill-induced adaptations would likely be few and far between.<\/p>\n\n\n\n<p>To observe conifer trees armed with defenses specifically against crossbills, Benkman would need to find a swath of forest free from squirrels. He pored over red squirrel range maps and local bird surveys for clues.<\/p>\n\n\n\n<p>After a few failed efforts, a conference in Boise in 1996 gave Benkman a chance to visit another potential site: the South Hills, a small island of mountains rising from southern Idaho\u2019s Great Basin.<\/p>\n\n\n\n<p>It was a long shot.&nbsp;<\/p>\n\n\n\n<p>\u201cNo ornithologist had ever suggested anything special about the crossbills in the South Hills,\u201d Benkman writes. But upon arriving in the forest, he was immediately struck by the abundance of crossbills that appeared like Reds, with large bills and strange calls. The crossbills fed with glee atop lodgepole pines, and there was not a squirrel in sight.<\/p>\n\n\n\n<p>\u201cIt was no understatement that I was euphoric,\u201d Benkman writes. He had found a living evolutionary laboratory. And if the South Hill crossbills were as different as he suspected, he may have discovered a new species.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"719\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-1280x719.jpg\" alt=\"\" class=\"wp-image-66887\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-1280x719.jpg 1280w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-720x404.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-768x431.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-1536x863.jpg 1536w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77-480x270.jpg 480w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/cassia-crossbill-craig-benkman-idaho-96727111-1.77.jpg 1934w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><figcaption class=\"wp-element-caption\">In 1996, Benkman found a distinctive population of Red Crossbills in Idaho, living in an isolated area where squirrels did not occur. After an additional 20 years of research into the birds&#8217; evolutionary relationship with the local lodgepole pines, the crossbill was recognized as a distinct species, the Cassia Crossbill. <em>Image by <a href=\"https:\/\/macaulaylibrary.org\/asset\/96727111\">Craig Benkman \/ Macaulay Library<\/a>.<\/em><\/figcaption><\/figure>\n\n\n\n<p>Over the decades that followed, Benkman\u2014and a bevy of graduate students from New Mexico State and the University of Wyoming, where Benkman was hired in 2004\u2014examined the South Hills and their crossbills from every angle. Approaches ranged from the high tech\u2014like sequencing portions of crossbill DNA\u2014to the creative, including snipping cones from unreachable branches using 30-foot-long clippers, and even using dental equipment to make molds of the insides of the birds\u2019 bills.<\/p>\n\n\n\n<p>At every turn, the research confirmed Benkman\u2019s initial suspicions. The cones in the South Hills were unusually large and had unusually thick scales at their outer ends, where crossbills prefer to feed\u2014a clear sign of tree evolution driven by crossbills. Accordingly, the local South Hills crossbills had abnormally large bills and, unlike typical roving crossbill behavior, tended to stick around the mountains year-round. When birds from other crossbill lineages wandered in, they typically moved on quickly after finding the hefty lodgepole pine cones that local birds were far better at harvesting.&nbsp;<\/p>\n\n\n\n<p>Benkman and his collaborators discovered that the interloping crossbills rarely bred with the Idaho natives, making the South Hills birds more and more distinct as they continued to adapt to their own unique environment and food. The local crossbills even had different vocalizations than Red Crossbills elsewhere in the West.&nbsp;<\/p>\n\n\n\n<p>These findings indicated to Benkman that the finch was evolving into a new species. The proposed name for the new bird was Cassia Crossbill, after the county in Idaho where it resides; its Latin species name, <em>sinesciurus<\/em>, means \u201cwithout squirrels.\u201d&nbsp;<\/p>\n\n\n\n<p>In 2017, the American Ornithological Society\u2019s North American Classification Committee accepted Benkman\u2019s proposal. After a career full of discovery, he had his crowning achievement\u2014not that Benkman is one to boast.&nbsp;<\/p>\n\n\n\n<p>\u201cI\u2019ve been privileged just to kind of bumble along and answer questions that, \u2018gosh, this seems interesting\u2014hopefully other people will be interested,\u2019\u201d he says. \u201cIn some cases, other people were interested.\u201d<\/p>\n\n\n\n<figure class=\"wp-block-image alignright size-full featured\"><img loading=\"lazy\" decoding=\"async\" width=\"1200\" height=\"1200\" src=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Cassia-Crossbill_USA_Kirk-Gardner_242828451-1x1-1.jpg\" alt=\"\" class=\"wp-image-66874\" srcset=\"https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Cassia-Crossbill_USA_Kirk-Gardner_242828451-1x1-1.jpg 1200w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Cassia-Crossbill_USA_Kirk-Gardner_242828451-1x1-1-720x720.jpg 720w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Cassia-Crossbill_USA_Kirk-Gardner_242828451-1x1-1-768x768.jpg 768w, https:\/\/www.allaboutbirds.org\/stagaabnews\/wp-content\/uploads\/2025\/09\/Cassia-Crossbill_USA_Kirk-Gardner_242828451-1x1-1-480x480.jpg 480w\" sizes=\"auto, (max-width: 1200px) 100vw, 1200px\" \/><figcaption class=\"wp-element-caption\">Cassia Crossbills have deeper bills than Red Crossbills that feed on lodgepole pines in other regions. This bill shape allows Cassia Crossbills to penetrate the thicker scales of lodgepole pine cones in the South Hills, and access the seeds inside. <em><a href=\"https:\/\/macaulaylibrary.org\/asset\/242828451\">Image by Kirk Gardner \/ Macaulay Library<\/a>.<\/em><\/figcaption><\/figure>\n\n\n\n<p>With Benkman\u2019s discovery of the Cassia Crossbill,&nbsp;the once-overlooked South Hills area became a prime birding destination, with birders eager to add a potential new species for their life lists. A recent study by an economist at Mount Holyoke College documented that wildlife tourism in the region has boomed since the Cassia Crossbill was designated its own species, with the annual number of birder visits nearly doubling over the last decade.<\/p>\n\n\n\n<p>\u201cWith my birder hat on, I\u2019ve made sure that I\u2019ve seen them,\u201d says Lovette, who planned a trip to Cassia County specifically to see Benkman\u2019s birds.<\/p>\n\n\n\n<p>Evolutionary biologists were also fascinated by the ways Cassia Crossbills have shaped their environment.&nbsp;<\/p>\n\n\n\n<p>\u201cAs a scientist, I love it because it\u2019s a little bit of a window into how species form,\u201d Lovette says. \u201cIt\u2019s kind of the textbook example of coevolution between birds and their diets.\u201d<\/p>\n\n\n\n<p>In fact, it\u2019s too good of a textbook example. When Lovette edited the Cornell Lab\u2019s <em>Handbook of Bird Biology <\/em><a href=\"https:\/\/academy.allaboutbirds.org\/product\/ornithology-comprehensive-bird-biology\/\">ornithology textbook<\/a>, he had to ask contributing authors to avoid using so many crossbill examples.&nbsp;<\/p>\n\n\n\n<p>\u201c[The crossbill research] is not just about dietary ecology or foraging\u2014it\u2019s also about evolution and about contact calls and coevolution and community ecology,\u201d Lovette says.<\/p>\n\n\n\n<p>Benkman retired as a University of Wyoming faculty member in 2022. But even after four decades spent chasing and studying crossbills, he\u2019s not done exploring the <em>Loxia<\/em> finches. Familiarity has not bred contempt\u2014far from it.&nbsp;<\/p>\n\n\n\n<p>\u201cTake an astronomer: The more they learn about space, the more they marvel at it when they look up,\u201d Benkman says.<\/p>\n\n\n\n<p>Next summer, he will be waiting in his home near Fort Collins, Colorado, for the Red Crossbills to return to the forests nearby. The uncertainty of his younger self is gone. He knows the crossbills will come back.&nbsp;<\/p>\n\n\n\n<p>\u201cI can\u2019t wait,\u201d he says. \u201cThey bring me tremendous joy every time I see them.\u201d&nbsp;<\/p>\n\n\n\n<div class=\"wp-block-group well-gray is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading\">About the Author<\/h2>\n\n\n\n<p>Benjamin Hack is a freelance writer based in Arlington, Virginia. A former student editorial assistant at <em>Living Bird<\/em> through the Cornell Lab of Ornithology\u2019s Science Communications Fund (made possible with support from Jay Branegan [Cornell \u201872] and Stefania Pittaluga), Hack has also written for <em>Audubon<\/em> and <em>Smithsonian<\/em> magazines.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>In a recent book, Benkman reflects on his research career studying the evolutionary interplay between\u00a0crossbills\u00a0and the cone-bearing trees where they feed.<\/p>\n","protected":false},"author":2,"featured_media":66807,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_tec_requires_first_save":true,"_birdpress_living_bird_toc":66671,"_birdpress_living_bird_toc_title":"Living Bird Autumn 2025&mdash;Table of 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