As many birders are aware, Minnesota is experiencing a Red Crossbill irruption. The majority of reports are coming from the western third of the state but there are also reports from the past few weeks of birds farther north and east.
For the past month I have been working with Matt Young of Cornell on identifying these birds to type. As of today we have identified four types from recordings sent to us: Types 2, 3, 4, and 5. Note that on August 13, Justin Watts recorded the first Type 4 in Minnesota on the North Shore; since then, many recordings from southwest Minnesota have been confirmed as Type 4. Type 2 has also been frequently recorded in western Minnesota since mid-August, and other reports from western Minnesota and elsewhere in the state have been confirmed as Type 3. Yesterday, Dennis and Barbara Martin recorded a flock of birds in Lincoln County that comprised three types, including as many as four birds confirmed as the first Type 5 in Minnesota. Only a handful of birds have been identified as Type 5 east of the Rockies, and according to Matt Young the four birds recorded by the Martins also represents the largest number of Type 5 to be found east of the Rockies. See eBird for current and confirmed reports of the various types in Minnesota and elsewhere. All of the above records refer to birds originating from western North America. The other type that has been confirmed in Minnesota, Type 10, may be our "regular breeder" in the state and has been confirmed in north-central Minnesota in June; elsewhere in the midwest Type 10 has also been associated with the current irruption (and note that Types 2 and 10 occur in both western and eastern North America). Cone production is apparently very poor in western North America this year, which is why these birds are roaming east. Although it is often possible to discern that more than one Red Crossbill type is present in a flock based on differing call notes, identifying those types without studying a recording of their calls via sonogram is extremely difficult and I would argue cannot be done with confidence. Thankfully the calls are quite distinctive when analyzed via sonogram...see Matt Young's 2012 article which remains an excellent source on the subject ( http://ebird.org/content/ebird/news/recrtype/). I'm happy to analyze any recordings of Red Crossbill calls sent to me. If you have such a recording and would like to learn more, please contact me by replying to this email. Bob Dunlap ---- Join or Leave mou-net: http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives: http://lists.umn.edu/archives/mou-net.html
