Greetings All

The entire concept of populations sinks is rather complicated. Sinks seem
like a slam dunk negative, attracting birds into habitats that won't/can't
support them causing them to not breed, or breed suboptimally when they might have
done better elsewhere.

This is very true for ag fields where birds start breeding, hatch their
broods, only to have the field cut, killing the otherwise viable young.

However, it has been argued that some population sinks (the talk I heard was
re: smallish woodlots in the midwest) actually aren't as bad as they seem.
They tend to host birds that are not able to establish territory in fully
suitable habitat, and so "settle" for these lesser habitats. And even though their
reproduction would be insufficient to replace losses, some reproduction is
better than none. So, sinks in some circumstances give birds a chance to breed when
they otherwise might not.

Now, I can hear Dennis thinking... if we maintained a higher quality suburban
habitat, then these areas wouldn't be a sink at all. Can't argue with that.
The tendency for our populace to insist on neatly trimmed yards, excluding
bushes, dead snags, etc is unnecessarily detrimental. I don't know precisely what
changes would be necessary to turn things around, but I think some simple
things would work... like a less tidy yard. I know that by letting undergrowth
regenerate on our property (after previous owners) has led to a vast increase in
bumblebees, for instance.

Now, there is also the issue of late season wanderers. These are birds, most
often, that failed to find a mate, or had an unsuccessful nesting. They then
wander about, hoping against the odds, to find success elsewhere. It is not
unusual for me to have birds that hold territories .5 miles away up Powdermill
Gulch, but not down where I live lower on the gulch, to wander into my yard and
sing for several days late in the season. I suspect these are birds that
couldn't establish a territory, and are down in the suboptimal habitat in my
immediate neighborhood (thanks Ramon for cutting down those huge maples) hoping that
they might still attract a mate.

Enough ramblings.
Sleep calls
Steve Mlodinow
Everett WA


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