I apologize if I kicked off an avalanche here about bird feeding. To
summarize the posts thus far I'd say there are lots of opinions, not a lot
of documentated study. I was looking for facts about impacts of feeding one
type of bird (Anna's hummingbird). Ecological study is rather difficult,
and I was hoping somebody might have found a study which showed changes in
populations between feeder and non-feeder groups. Since local population
monitoring is not very precise, it would be pretty hard to understand even
first order impacts, much less third order. For example, does attracting and
feeding Anna's, who then presumably utilize other available flower nectar
sources have an impact on nectar availability to hover flies, or other
winter active nectar seeking insects? For example, honey bees drive away
and cause local depletion of native pollinators because they dominate the
nectar sources. Does Anna's, which is a relatively new winter resident, and
is widely observed to be highly territorial, have an impact on other winter
nectar users? Who are the other winter nectar users, what are the sources of
winter nectar. Many wintering plants produce chemicals to provide sort of an
antifreeze whent the temperature drops below freezing. Does the supply of
nectar in a given plant change when the temperature drops below freezing?
How does this reduction affect energy needs of Anna's or other nectar users
during what would most likely be critical energy need periods? Could Anna's
survive the past three weeks of temperatures here without being supported by
feeders?

So many lovely questions, so little time. If only there were patrons who
would support me for a decade so I could play with these questions. Sigh,
Charles Darwin I aint.

Rob Sandelin
Naturalist, Writer
The Environmental Science School
HYPERLINK
"http://www.nonprofitpages.com/nica/SVE.htm"http://www.nonprofitpages.com/ni
ca/SVE.htm
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