Dennis Paulson wrote:

>Alan Richards' posting prompts me to mention a good pair of essays in
>Birding 26 (4), August 1994. Brad Schram argues for "cowbird recipes,"

>and
>finishes "We need to act, and the sooner the more successful. The
>aforementioned cowbird control successes tell us it is not too late to be
>effective. How much longer that can be said, no one knows." Jamie Smith
>counters that cowbirds have been made convenient scapegoats and argues
>for
>more money spent in acquiring knowledge rather than killing cowbirds. He
>concludes "There is much to be done, but I believe that continent-wide
>cowbird control is far from the top of our priority list." I come down on
>Jamie's side (believe me, he's not a "cowbird lover"), after reading both
>of the arguments; one of the most convincing is that 15 years of cowbird
>control (surely at the expense of millions of dollars--yes, I know, it
>provides jobs for wildlife biologists essentially forever) has done
>nothing to increase Kirtland's warbler numbers, which happened only after

^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>a big fire provided adequate young jack pine habitat.

But this does not mean that cowbird control was ineffective. According to
Mayfield (1992; Birds of NA #19, Kirtland's Warbler), cowbird control was
successful in *halting the rapid decline* of the species, even though it
apparently took an increase in suitable habitat (the Mack Lake burn) for
the population to increase. This makes sense. Cowbird parasitism and
habitat loss are two distinct threats to Kirtland's (causally related, but
still distinct). Cowbird control simply prevented cowbirds from wiping
out the few hundred remaining Kirtland's. I'd call that a success.

Re the _Birding_ articles, while I think continent-wide cowbird
eradication would be a bit draconian, I found Smith's arguments against
cowbird control unconvincing. Yes, habitat loss *is* the ultimate
problem. But it is a proximate problem -- cowbird parasitism -- that
threatens to extirpate some local populations from their remaining
habitat. Smith's examples of populations that *are* able to cope with
cowbirds are irrelevant -- those are not the populations in question, and
it is obviously unecessary to consider cowbird control in those cases. No
one doubts that many healthy populations are able to cope with cowbird
parasitism -- how could cowbirds exist if this were not true? Likewise,
his analogy with the stock market (across North America, some bird
populations are down, others are up, and hey, it all evens out) is flawed.
To extend this analogy, we are not investors in an indexed mutual fund, we
are stockholders in discrete companies. We are concerned that certain
companies that are not performing well *not* go down the tubes. It will
give us no satisfaction at all to know that other companies are blossoming
while these companies fall apart. Perhaps we should sell our interest in
the losing companies and buy stock in the gaining companies (e.g., sell
Kirtland's and buy cowbird).


Another of Smith's arguments boils down to an emotional appeal to justice
[paraphrased]: "We humans did it by destroying habitat. Don't blame
cowbirds for doing what comes naturally. Why should they have to pay for
our mistake?" The other side of the coin is "Why should songbird
populations pay for our mistake." The mistake has been made, and some
birds will have to pay the price. Like it or not, we have the power to
choose whether it is cowbirds or warblers, vireos, etc. that pay the
price. Either we intervene and neutralize an immediate threat (cowbirds)
while working on the ultimate threat (habitat loss), or we do nothing
about the cowbird problem and hope that eventual increase in habitat (some
fine day...) will solve the problem. The latter approach will appeal to
those who find wisdom in the Prime Directive of Star Trek, but it will
leave us with an impoverished avifauna.


David Wright
dwright at u.washington.edu

>Parenthetically, my method of cowbird control actually *saves* money--I
>just stop putting millet seed in my feeders when the cowbirds arrive in
>my
>yard, and they go away!
>
>SAVE HABITATS INCREASE KNOWLEDGE SAVE HABITATS INCREASE KNOWLEDGE SAVE
>HABITATS

>(is my subliminal message clear?).
>
>Dennis Paulson