[cobirds] Red Crossbills: Type 2 and 4 recorded together (Boulder)

A week ago, while with my dog on his morning walk, I noticed two Red Crossbills perched atop a spruce tree in our front yard. They were calling and they sounded different from one another, so I pulled out my phone and used Merlin to record them.

I studied the sonograms today and think they were Type 2 Ponderosa ("pope-pope-pope") and Type 4 Douglas Fir ("whit-whit-whit").

This was the first time that I'd heard crossbills of different types calling together and it helped me appreciate how different their calls are. This flock of mostly Type 2 RECRs has been in and around the conifers within a block of the south side of the Boulder Community Gardens since August 28.  They were still there this morning.

You can hear the recording and see the sonograms at https://ebird.org/checklist/S150498144/media.

By the way, I recently read the fantastic book, "An Immense World" by Ed Yong.  In it, I learned that birds hear "faster" than humans.  While we may need a sonongram to see the details of a few milliseconds of bird calls, the birds apparently can hear the nuances quite easily.

Richard Trinkner

Boulder