Subject: [Tweeters] Winter Annas females
Date: Dec 16 11:53:54 2009
From: David Hutchinson - flora.fauna at live.com



There are at least two answers to this intelligent question and maybe, because I am getting rather out of date with my info stream, several more: . Firstly Annas' females, according to my original study at least, winter in the same way and in the same places as males. But there were two qualifiers.
This species like some, perhaps all West Coast hummers, have a sex ratio that is skewed in favour of males. So perhaps there are 20% more males in any case.
Also from observation, in hard weather when resources are more critical, males were more dominant at feeders tending to duke it out with each other to territorialise a feeder. So females tended to use the "sneaky acquisition of resources method'" by dodging aggressive males to reach feeders and perhaps also available flower patches e.g. fatsia, winter jasmine, members of the Heath family.
The sex ratio part of the equation may be related to their polyginous breeding system. Therefore:
A smaller number of females than males manage to keep the population stable and, in fact, substantially increase it in our region.
They also raise two young without male help.

Rather than me disgorging old date, anyone interested in hummers should read the Trochilid section of Volume 5 of the Handbook of the Birds of the World,ed Del Hoyo. This gives a terrific overview of the breeding systems and behaviours of hummers and hermits.
It was a real eye-opener for me.DH

--
David Hutchinson, Owner
Flora & Fauna: Nature Books
Discovery Gardens: Native Plants
3212 W.Government Way
Seattle,WA.98199
http://www.ffbooks.net/
206-623-4727



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