[Tweeters] Predictability of Bird Movements - Lincoln's Sparrow

johntubbs at comcast.net johntubbs at comcast.net
Fri Apr 26 09:48:03 PDT 2013




Hi folks,



I've been keeping fairly detailed records on yard birds (at least those species  not seen all that often) for the last seven years and it's been interesting to note how consistent arrival dates are for various non-resident species.  There are pretty distinct time 'windows' that with enough years of data now seem to be highly predictable.  This has been the case with Townsend's Solitaire, for example, which I recently posted about (two visible from the yard flycatching from nearby trees, and one perched elsewhere in the neighborhood, within only a couple days of each other).  I just had the first Lincoln's Sparrow (LISP)  of the year show up in the yard foraging near our small recirculating stream, and after inputting the data, went back and reviewed arrival dates for the spring.  Here's what I found.



For the last six years, the first spring LISP showed up on the following dates in April: 11, 16, 22, 26, 27, 28 (arrival dates are not sequenced chronologically by year).  Considering I'm not watching the yard constantly, I suspect that the first arrival of a LISP might even be in a narrower range of dates and just weren't noticed.  This latest date I have logged for a spring LISP is May 10th, but only two data points are from May - all the rest from April.  So it seems they arrive in a pretty narrow range of time, don't stay very long and head off to breeding territories elsewhere. 



But as we also know with birds, not all of them follow the 'rules'.  In 2007, my first year record for LISP was in January.  That bird didn't stay around so I assumed it was probably heading down to lower elevations (we're at 800 feet in the foothills) to winter.  Otherwise, I have no yard  records at all from January 1st until April 11th.  September and October are when I see them in the fall, but I haven't looked at that data more closely yet to see how consistent the first fall arrival dates are.



As was discussed with Michael Hobbs' Thursday morning group yesterday regarding Say's Phoebe, Michael sees obvious short windows of time for various species passing through Marymoor as well (and has a treasure trove of data over many years  illustrating that phenomenon over almost two decades ). 





John Tubbs

Snoqualmie, WA

johntubbs at comcast.net



 








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