[Tweeters] Wintering Anna's Hummingbirds... from retired University of Oregon ornithology instructor

Wild Birds Unlimited of Eugene eugenewbu at gmail.com
Fri Dec 14 23:41:23 PST 2018

This is part 1 of an article, written by Daniel Gleason, retired University
of Oregon Field Ornithology instructor, in response to the forwarding of
remarks on Tweeters that recently were published.

*Anna’s Hummingbirds: Surviving Winter*…At one time, Anna’s hummingbirds
ranged from northern Baja California north to the San Francisco Bay area.
Over the past 100 years, their range began to expand north and east, and
they are now found as far north as southern British Columbia and along the
coast into southern Alaska. The eastward expansion has taken these birds
into western Texas. Northern populations (Oregon and north) have slowly
expanded eastward in recent years, and are now found in Boise, Idaho, in

*Range Expansion:* It is not known for certain all factors that prompt
birds’ range expansion but it is thought that, begun, an increase of exotic
plants aided the Anna’s Hummingbirds’ expansion. They were already seen
year-round in California but much of the land east of California did not
have supportive plants and habitat. As white settlers moved into these
lands, they planted exotic plants, many which proved attractive to Anna’s
Hummingbirds, both in terms of providing nectar as well as attracting
insects that the birds could also eat. Much later, it people began to put
out and maintain hummingbird feeders.

*Food Needed:* But, all hummingbirds need more than just nectar to survive.
They need proteins and other micronutrients that they get from insects,
eggs on plants, and spiders, all an important part of their diet.

People mistakenly assume that insects and spiders are not available during
the cold winter months, but that is *not* the case. Actively *flying* insects
are dramatically reduced during long cold periods, but many other insects
can be found, and birds find over-wintering egg masses and larvae. We large
humans are not good at noticing such small insects.

Studies of captive Anna’s Hummingbirds show that they can exist on pure
sugar water for 10 days, but they show significant weight loss. So more
than sugar is needed and these other nutrients come from insects, spiders
and their eggs throughout the year.

Recently, in Washington, a couple of individuals have tried adding all
manner of unresearched and untested products (baby formula!) to hummingbird
feeders. Unless you have conclusive, scientifically-researched, proven data
to support the beneficial use of such products, do not use them!* If you
care about hummingbirds, attempting to provide extra nutrients besides
nectar is to possibly put the birds at risk!*

Why? Hummingbirds have very tiny bodies and providing even small amounts of
micronutrients could be far in excess of what is needed. The quantity of
such nutrients (boron, copper, etc.) would have to be measured in
10-thousandths of a gram. To weigh out such a small amount requires an
analytical balance costing several thousand dollars—not something you have
around home. Such small quantities are easily obtainable in a hummingbird’s
daily diet, even in winter’s cold. Proteins are also obtained daily from
the insects and spiders. Providing more is completely unnecessary and the
excess could put the birds at risk. These products contain food ingredients
humming birds would never come in contact with, and could in fact, cause
poisoning to the birds due to their tiny bodies being unable to process
these substances.

Dan & Barbara Gleason
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