June 20 2012. We went back to the same old-growth forest this morning to continue with our study and point counts. It was very warm at the start and the mosquitoes were happy to see us. For a while I felt as though I was conducting a one-man study on mosquito attraction. I know they’re are drawn to carbon dioxide, so for a while I tried not to exhale, but couldn’t keep it up. Body heat, lactic acid and octenol are also appealing to them and to quote from an on-line source: “ When people and animals breathe, they exhale a mixture of carbon dioxide and octenol, which is actually a type ofalcohol. Octenol is sometimes described as ‘cow’s breath in a can’, and is a remarkable lure for mosquitoes…. I’m not sure how I feel about that; but comforted that we’re all in it together.
Evidently different mosquito species find different cues more compelling and I was intrigued that a few seemed to believe that my auditory canal was the choicest place to find a meal. Perhaps for them it’s the most obvious point source of body heat; but whatever the reason it’s one thing to swat a mosquito on your jaw-line but banging away on your ear does little except aggravate tinnitus.
Mosquitoes aside, today’s Birds of the Day were Black-throated Green Warblers. Although I couldn’t see any of several territorial males in the forest canopy above, I solved a piece of the endless birding jigsaw puzzle by experiencing how the dense forest affects their song. In spring migration we listen for the Black-throated Green’s deliberate and buzzy signature song: “Zee zee zee zee Zoo Zee”- with the emphasis on the last two notes. Today I could quite distinctly make out this song in its entirety – but only when the bird was fairly close. With distance the softer notes vanished until all I could pick out were the last two, which when isolated from the introduction notes, came out as “doo deet” repeated over and over. This was something of a breakthrough for me as I know I’ve heard that repetitive two-note song many times before, but could never figure out whose it was. So a minor achievement today. Here’s a shot of a Black-throated Green Warbler taken just six weeks ago.
