During my hummer study in the early 1980s and in observations in Discovery Park since that time, I have found no evidence that Anna's Hummingbirds are replacing Rufous. Rather the two species appear to intersperse themselves. Anna's first-nest in February and March, while Rufous are still arriving. Then it is Rufous turn to breed. In fact at feeders, Rufous appeared to dominate Annas while they are in-migrating, just by pure numbers. Furthermore, while Rufous may certainly use feeders - as like most at least northern latitude hummingbird species -they are opportunistic.

Rufous, whose migration routes and feeding patterns have evolved over thousands of years, breed based on the availability of forest understory & edge plants, such as Salmonberry, Orange Honeysuckle, Red Columbine etc , with which they have co-evolved so that these plants are hummingbird pollinated. While I do not say that Rufous do not feed in gardens and that Annas do not feed at native plants, I am sure that the majority of Annas Hummingbird sightings in Greater Seattle are in backyards with a diversity of ornamental flowering plants - more opportunism at work here!

Funnily enough, while I am sure that day length and hormonal development are triggers for Annas breeding season, it also is true that the bloom of Red-flowering Currant, as early as the beginning of February, may also stimulate them.

I do know that some Annas double clutch, though I do not know the story for Rufous, though it is quite possible. Certainly Rufous males start clearing out as early as the beginning of July, perhaps while their females re-nest. Again their second nesting must surely follow Annas' second nesting, avoiding competition, though perhaps more by accident than by resource competition.

Again in the spirit of opportunism, there are a surprising number of flowers that both species visit throughout the summer months. My sense was that feeders were not necessarily important for hummers in those months. Now I have a question for y'all.

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David Hutchinson, Owner
Flora & Fauna: Nature Books
Discovery Gardens: Native Plants
3706 Corliss Ave North
Seattle,WA.98103
http://www.ffbooks.net/
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