An EASTERN SCREECH-OWL continues to spend days in our nest box in northeast Ithaca. Here are some recent highlights and notes.
* The owl appears regularly for a few minutes just after sunrise, and then for an hour or two before sunset. I've seen the owl at length at midday only once (Monday, when it was warm and bright outside). The owl has been exiting the box reliably at right around 5 PM, before it gets really dark. We've seen this owl perched out of the box just twice. Usually, I lose sight of it even though it doesn't seem to go far. * On that sunny Monday, the owl spent much of the time with its face half-shaded by the overhanging eave of the box. I saw that the owl's pupils were of different size. A quick web search indicates that Barn Owls have independent pupillary response to light too. My understanding is that in contrast, normal pairs of human eyes have a consensual reflex that causes them to be the same size even if one eye gets more light. * Earlier this month I wrote that owl pupils seem to dilate and contract more slowly than ours do. My recent observations refute this notion. A few times, I have seen the owl's pupils contract very rapidly when it redirects its gaze from ground to sky, and also dilate quickly upon a quick shift back. I have found one published paper that confirms very quick pupillary light reflex in screech-owls. But I am not sure whether the changes I saw resulted entirely from light reflex, or whether they also (or instead) arose from pupillary accommodation, which is another reflex whose purpose is focusing, not limiting the passage of light into the eye. (And despite all this, I still can't shake the strong impression that this owl's pupils are much more dilated in the morning than under equal or lesser light conditions at dusk.) * This afternoon, Tilden and I got to watch the owl calling at least twenty times (!!!), issuing both whinnies and short trills. It was his first time seeing a vocalizing owl, and my first time watching one whinnying. The owl leaned forward just a little and flexed its throat slightly when sounding forth, with a neutral facial expression. This visual subtlety stands in contrast to owls I've seen intoning long trills, with deep conspicuous breaths and eyes nearly shut as if in an intense, almost ecstatic meditative state. Sticking my head out the window, I might have heard a distant second owl, whose presence could explain why our owl was so vocal. But everything in the half-in-half-out soundscape was so weirdly elusive that I couldn't tell direct sounds from echoes from possible imaginary owl voices in my own head. Mark Chao -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/[email protected]/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
