[cobirds] Possible Plumbeous Vireo mate guarding, Hecla Junction, Chaffee

Okay, if you have a Chaffee County list, you probably already have Plumbeous Vireo listed. They're just not that hard to find there, but this behavior was interesting. At Hecla Junction Monday, I was attempting to record a singing Plumbeous Vireo. I was excited because I had a singing vireo in a pair of junipers very close. When you're recording with a smartphone, getting close to the bird can be really important. (For Pluto.Living fans, make that really, really, really, really important. https://www.youtube.com/watch?v=D01iBJwXNKQ)

As I pointed my Rode external microphone at the spot the vireo song came from, I spotted the bird - or thought I did. But the song seemed to be higher up. At the same time, I realized there was a softer chattering call. As the bird I was watching fed among the low juniper branches I could see it was a Plumbeous Vireo. Then higher up, I spotted the singing bird, another Plumbeous Vireo. As I watched the birds, it was clear the lower bird was doing the chattering, while the upper bird was shadowing the movements of the lower bird. 

Because the human brain is programmed to find patterns whether or not they are there, I concluded I  was watching a pair. I suspect the lower bird was the female and the chattering was probably providing contact information. The male was possibly mate guarding, making sure the female didn't get distracted by another male. Cornell Labs Birds of the World species account notes "Male accompanies female closely during nest-building, but does not guard female during egg-laying…" https://birdsoftheworld.org/bow/species/plsvir/cur/behavior#sex If that's the case this pair was probably at the nest building stage. 

The recording of the pair can be found in this eBird checklist https://ebird.org/checklist/S70703885. The much softer chatter of what I take to be the female can be heard between the louder phrases of the familiar male song. 

I used the word "chatter" to describe the female call because that was the term Nathan Pieplow used in the Peterson Field Guide to Bird Sounds of Western North America. (Isn't it amazing how many authors of great birding resources we have in Colorado?) On the companion website to the field guide, Nathan offers to Chatter calls. The first, by Andrew Spencer, most closely matches the call I heard. Interestingly, Spencer's recording also has chatter calls interspersed with phrases of the typical male song. This leads me to wonder if Andrew was also recording a pair.

Birding just never gets old. In A Guide to Bird Watching, a book that shaped my birding path 55 years ago, Joseph J. Hickey wrote of birding, "It is unquestionably a hobby that can be thoroughly enjoyed for an entire lifetime." So far, so good.

Chuck Hundertmark

Lafayette, CO