[obol] Regarding Tree Swallow fall date

[Kevin Spencer]

OBOL,

Interesting question about Tree Swallow exit date.

If Tree Swallows leave by August on the coast, that is quite different than eastside. My observations in August and September in the Klamath Basin has been that it is a time for large staging numbers, especially near water. 

They congregate on wires (mostly Tree and Bank,but also Barn and some Violet-green )  in the late afternoon. I've seen thousands in the Tulelake area in late August and early Sept., within 4-5 poles with 3 wires. And that's just in one location.  I checked some of the NAMC fall counts for Klamath County, and though the numbers vary from year to year, one count in '97 had at least 1500 Tree Swallows alone, and that was for 20 September, 1997. Other years had around 100 or so. It depends upon the weather. If cold temps persist then bug activity and numbers is reduced and so the swallows move on, or, I may have missed where they actually were hanging out. If the days are consistently warm then they tend to linger in large numbers. So, likely the temps during the '97 count were favorable for greater numbers during that 3rd week in Sept. But in general, the numbers of swallows drops sharply after Sept., on the eastside.

Kevin Spencer
rriparia at charter.net