Sunday, July 08, 2007

Blakeman raises a question, I ask a question back, and Jan sticks up for me

In response to yesterday's letter by D.B. who wants to kill a redtail eating "his" bluebirds, John Blakeman, our Ohio hawk expert, writes:

There is a very good possibility -- baring the discovery of a tail that is red on the bird -- that the villain in question was a Cooper’s hawk, a species much more capable (and likely) to capture bluebirds.
Bluebirds, especially those just fledged, are scrumptious, easy pluckings for a neighborhood Cooper’s hawk.
I just don't think a red-tailed hawk can take anything but an incidental bluebird, one that is somehow handicapped, or a still-flightless fledgling. A Cooper’s hawk, however, can take both fledgling and adult bluebirds with frightening ease.
And (if the Cooper’s is the real culprit) this raises a very interesting development. Here in Ohio, and elsewhere in the Midwest and East, where wooded habitat abounds, American kestrel populations have markedly declined in the last decade. The species is still not rare. But even casual kestrel watchers have noted their reduced numbers in recent years.
Here in my area, to reverse this decline, a Boy Scout, for his Eagle Scout Project, erected about 10 kestrel nest boxes, all on tall utility poles. I oversaw a similar project 30 years ago here, and within two years virtually every box had a nesting kestrel pair. This year, with the new boxes, in prime kestrel habitat, not a single one was occupied.
In fact, I see only a scattered, low number of perched kestrels hunting from roadside utility lines. The species is decidedly declining, while virtually all other raptors are stable or increasing. How so?
It’s becoming ever more obvious that as Cooper’s hawk numbers have increased, along with their recent invasion into small cities and suburbs, kestrel numbers have declined. An experienced adult kestrel can usually avoid a Cooper’s hawk attack. But kestrels right out of the nest cavity don't fly well for several weeks. As they flap around trying to learn how to fly with agility, they give themselves away to any marauding Cooper’s.
So, kestrel reproduction in areas with increased Cooper’s hawk has been greatly suppressed by these bird-eating accipiters.
Cooper’s hawks eat almost nothing but birds, and they've recently learned that large, vulnerable concentrations of small birds can be found and easily preyed upon in numerous backyards, at urban and suburban bird feeders.
Cooper’s hawks are proliferating so successfully that I believe that it’s only a matter of time before bird feeders begin to notice reduced populations of dickey birds at the feeders. It’s a glorious time for Cooper’s hawks, who have now learned to come into cities that have backyard bird feeders.
This may have been the case with the unfortunate bluebirds that prompted this note.

John Blakeman

My question in return:
Dear John, Does your letter mean that if the hawk eating R.B.'s bluebirds proves to be a Cooper's Hawk, then it would be OK for the guy to try to trap or kill it, because Cooper's Hawks are proliferating like mad, killing kestrels, etc.? Somehow you leave this question hanging. Though the question of the hawk's correct species is an interesting one, it obscures the larger question of whether R.B's desire to kill the marauding hawk, whether it's a redtail or a Cooper's, is justified.
I tend to agree with another correspondent, Jan Lipert, who writes:

You tell 'em, Marie! It drives me crazy when people want to isolate one particular element from nature and plop it into their yards -- and then get furious when nature takes its course. It amazes me that people try to orchestrate their back yards the way they do their own lives. Inside, humans may have their way, but outside, Nature Rules!
Jan Lipert