[CT Birds] Response to Question about the Blue-winged/Golden-winged hybirds
sgraesser13 at me.com
Wed May 9 15:26:39 EDT 2012
I have had a decent amount of experience with these birds in the past,
so here are my thought on them. I have seen the Hybrids establish
territories, but it seems that they do not come back to these
territories from year to year. This is also through banding
information collected. I have banded a number of Hybrid individuals
that were confirmed breeding, but was not able to obtain these birds
again in years following this. Now this is obviously not an exact
science due to some individuals possibly eluding nets, but is has
happened at multiple locations. I have banded a few hybrids here in CT
they are found during the breeding up in the northwest corner pretty
easily. It is also interesting to look at historic shifts in
populations. When you have a GWWA territory that has been slowly taken
over by BWWA you run across hybrids more frequently for the first few
years predominately F1 Brewster Warblers. Than you will see F2
Brewster with "pure" BWWA and a few LAWA. You than see the final shift
to "pure" BWWA with a few hybrids popping up every so often. This is
talked about in the Peterson's guide to warblers.
As mentioned about the genetic difference being very slight is almost
an understatement. When you have a Hybrid and want to know what its
potential parent species are, so far it has been found to be almost
undeterminable with using markers. They are very difficult bird to do
genetic work on.
Another thing to take note of in the region is most "Pure" birds in
regions were historic hybridization is occurring most likely are not
pure. When these hybrid birds breed with pure parents species or other
hybrids you run across individuals being born looking pure again.
There are sometimes small things you can look at to see seemingly pure
birds having recessive genes from earlier backcrosses. Some things to
look for in BWWA's is the appearance of spiked lores were the line at
the beginning has a small diagonal line that comes down. Also looking
at the white wing bars and if they are tipped yellow. Now this needs
to be done with some caution because of HY's having a yellow wash to
there secondary coverts. GWWA it has to do with the completion of the
white supercillium and if it makes it all the way across with out
meeting the yellow from the crown.
If you want to learn more about this Hybridization I suggest reading
The Genetics of the Golden-winged X Blue-winged Warbler Complex by
Kenneth C. Parkes it was published in Wilson and is easily found online.
I also have some degree of experience with them and can shed more
light on things if anyone is interested.
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