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.\u00a0 Identifying these types in the field promises to be a bugaboo of legendary proportions.\u00a0 Where does one begin?<\/p>\n
In this post I’ve collected links to some online resources that can get you started: a sort of Crossbill Q & A<\/strong>, if you will.<\/p>\n 1) What are the crossbill types?\u00a0 How did they evolve?\u00a0 Are they for real?<\/strong><\/p>\n A great source for beginning to answer these questions is Craig Benkman’s introduction to crossbill types<\/a> in the July 2007 issue of Colorado Birds.<\/em> 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.<\/p>\n When you’re ready to dig a little deeper, head to Benkman’s home page<\/a> and look at the list of publications he has posted in PDF form.\u00a0\u00a0 The man is a scholarly publication machine.\u00a0\u00a0 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.<\/p>\n 2) Where can I listen to online recordings of Red Crossbill types?<\/strong><\/p>\n Your first stop should be Jeff Groth’s old page<\/a> on the website of the American Museum of Natural History.\u00a0\u00a0 Although Benkman may be the current guru, Groth was the original discoverer of the call types.\u00a0 The good news is that his page has audio files of the flight calls, excitement calls (“toops”), and alarm calls of types 1-7.\u00a0 This makes it the most comprehensive collection of crossbill vocalizations on the web.\u00a0\u00a0 It also has range maps and basic natural history information for each of these types.<\/p>\n 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.\u00a0 Not all of the links still work.\u00a0 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.\u00a0 Appreciate Groth’s site for what it has, but don’t let it intimidate you.\u00a0 Crossbill identification is very hard, but it’s not hopeless.<\/p>\n Here are a couple of less comprehensive but more user-friendly resources:<\/p>\n\n