At 01:01 PM 9/23/2009, "Rob Sandelin" <floriferous at msn.com> wrote:
>I have many questions which apparently have no
>answers, such as,
>
>Are feeders a natural selection factor for species in an area. For example,
>over time do seed eaters become more numerous?

I'll go out on a limb here, and try to answer from my own
observations (sans data), and say probably, but that would be a tiny
part of a region's population, thus not likely significant. In a
local area (town), one can readily see that if House/English sparrows
are fed, they will become more numerous; ditto starlings and
cowbirds, especially at cattle and horse pens/corrals where food
wastes to ground constantly...

>Do feeders reduce the amount of natural foraging enough to impact
>populations of local insects.

Not likely with seed feeders, because "finches" [goldfinches and
house finches (purple and Cassin's?)], being often the most numerous
species at feeders, eat few insects, and rarely if ever feed their
young anything but regurgitated seed, wild-caught or hunted at feeders...

>For example, do more insects survive predation as eggs or larva
>because the birds are foraging less?

same answer as above; very few insectivores eat seeds from feeders,
usually in winter if at all...

>Do feeders increase the survival of nestlings? If yes, are the
>increased populations dependant upon the feeder for survival Does
>a feeder alter the carrying capacity of an area?

Probably neutral, since seed feeding birds tend to wander about in
loose flocks, or solo during nesting, looking for natural foods as
well. Winter and/or migration have greater impact on population
survival than isolated bird feeding stations, overall...

>If feeders increase populations of feeder birds, does this also
>increase survival and populations of predators such as Coopers Hawks?

Cats, let loose by well-meaning owners, probably do more damage to
local birds as a direct result of feeders than they would
otherwise... Probably makes NATURAL/NATIVE predators a bit healthier
in that they find a few more easy targets, and can stake out a
feeder. But, overall, not likely to have positive impact on
populations, since there are myriad other ecological factors that
impact on them, whether or not fattened in someone's yard.

I would say that Turkey populations can be radically altered,
especially if they are allowed to feed in cow pens, and since they
are protected [one is not allowed to shoot or otherwise chase them,
even where "unnatural", unlike what one can do with English/House
sparrows and Starlings, in most states]... BUT, with game animals,
since they get hunted by humans eventually, the increase impact of
feeding sites is probably minimal [and many states forbird "baiting"]...

>The ecological questions around feeders are many, the answers are unknowns.

I think answers are known. For instance, I know sickly birds tend to
stick near feeders because they are weak to begin with (some obtain
sickness from dirty water sources set up near feeders, another
issue), then either die soon, or as I saw last spring, Sharpie,
Merlin, or Shrike gets a slightly fatter meal...

In Montana, birding groups were successful in exempting bird feeding
from a new law against feeding wild animals. Thus, we passed an
unequal law to protect one class of people over another, but that's
another issue for another listserv...

-- Jim Greaves, Thompson Falls MT