To further this thought, migration is hereditary in songbirds, not learned...unlike in geese, cranes and swans where young follow adults on migration paths. Thus, if a bird survives wintering in an area and returns to its normal breeding grounds and is successful breeding, there is a good chance that migration routes will be passed on genetically to its offspring. This is believed to be the case with the increasing number of Rufous Hummingbirds now wintering in the southeastern United States instead of making their more traditional fall migrations to Mexico.

Jeff Kozma

J c r underscore 5105 at charter dot net

Yakima

-----Original Message-----
From: tweeters-bounces at mailman1.u.washington.edu [mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Mike Patterson
Sent: Monday, November 16, 2015 7:09 AM
To: Tweeters <tweeters at u.washington.edu>
Subject: [Tweeters] Re: Question About Site Fidelity in Tropical Kingbirds

One might postulate that, if all northward ranging Tropical Kingbirds are doomed to death before reproduction, then the behavior would be non-adaptive and should be either remain rare or eventually extinguish itself. There is, however, pretty convincing trend data that suggests Tropical Kingbird occurrences in the fall are increasing and that individuals are remaining later. This would be the opposite of rare or eventually extinguished...

I have seen 6 different Tropical Kingbirds this season on the lower Columbia. Back in the 90's, they were not even annual in this area.

I explored some of the data last season at:
http://www.surfbirds.com/community-blogs/northcoastdiaries/?p=2506

--
Mike Patterson
Astoria, OR
The history of photons
http://www.surfbirds.com/community-blogs/northcoastdiaries/?p=3005
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