Dear Tweeters:

As with many of these threads, they lead to many interesting points. Stan
Kostka enlightened us about Martins nesting in bridges, which is apparently
a tolerable scenario and a good one for Martins.
One wonders if the use of human structures is always a boon to birds, or if
they can cause problems in the way of a local population sink if things go
wrong.
I work as a habitat biologist for the province of BC. Here, as elsewhere,
Cliff & Barn Swallows nest under highway bridges & overpasses. Our agency
had to negotiate a special bridge cleaning protocol with the Department of
Highways who were constantly blasting the nests from the structures during
the breeding season, despite the obvious contravention of the International
Migratory Birds Convention Act and our local Wildlife Act.

The problem has been solved, but to me, it points out one of the perils of
wildlife that choose to live very close to us. Redtails that love to hunt
our rodent-lush highway medians are another.
In the one case, wildlife that becomes a nuisance becomes a target for
destruction.
In the latter, mortality is not intentional but rather an unfortunate
by-product.
Incidently, almost all of the road-killed crows that I have examined are
juveniles of the year that have not learned how quickly to move away from
fast-moving objects.

We are all familiar with the success of Canada Geese in our urban
environments (I do not wish to re-open that thread), and of course Starlings
& House Sparrows on the more negative side. However, I like all of you, have
watched birds utilizing many of our structures as simply another piece of
exploitable habitat. The birds put no value-laden interpretation on the
structure, as it simply serves their needs.

I was fascinated this year as I watched hundreds of godwits roosting on a
wharf at Tokeland. Surely a suggestion to stick a wharf-like structure into
a natural marsh as a roosting platform for godwits would have been met with
howls of indignation. In other cases, we glory in the success of wooden
platforms as nesting structures for raptors, or high-rise buildings as
surrogate cliffs for Peregrines.
Rip rap bank protection can serve as escape habitat for fish, groins act as
stable habitat for starfish, barnacles and Rock Sandpipers and pilings as
roosting sites for Cormorants. Barbed wire catches low-flying raptors, but
the posts serve as hunting and resting perches in treeless environments.

Often, I attempt to look at wildlife use of artificial environments with an
unbiased view, and ask "what does the bird think it is using?" Is it merely
a dry perch out of reach of rising tides, a safe ledge high above a hunting
environment, or a dry overhang under which a nest of mud can be attached?
Then I wonder about the future of those niches and whether they can cause
problems for the species using them.

The actions of our expanding human populations remove or alter some
irreplaceable habitats and the specialist species that go along with those
places. Alternatively, we create a diversity of other niches that can be
exploited by some species. Often, those are the adaptable and the ubiquitous
species that may not always need more habitat.
However, as long as they live with us in ways that we can tolerate, we enjoy
their links to our industrious ways.
However, heaven help the deer that invade the orchards too frequently, or
the Robins that descend on the vineyards that replaced the bunchgrass that
once supported Burrowing Owls.

Well, back to Dennis's original thread notion, I have often wondered if the
rare birds that occur at feeders represent all the individuals that arrived
in the area, attracted by the flurry of activity around the feeder? Or are
there others of the same species that are trying to tough it out in some
patch of native habitat that has not been searched by birders ?

So like the rest of the animals that populate the planet, we alter the world
to meet our needs and other species respond to our impacts. As far as we
know, we are likely the only species that worries about what we do, and who
is responding to it.

So at once, we suffer the glory and the burden of the human intellect.

Rick Howie
Kamloops, BC
rick.howie at shaw.ca