Tuesday, February 22, 2005

Destruction of Suburban Woodlands

Marilyn Fifer sent the following letter, which I forwarded to John Blakeman. He sent a reply, which follows the letter.

Dear Ms Winn:

...Recently, you and John Blakeman discussed an increase of the urban RTH population; however the issue of encroachment by development /destruction of suburban woodlands had not been represented as a cause and effect. This loss of habitat /food supply forces the RTH to search for new territory. NYC may be to hawks what the Americas were to Columbus.

My husband and I are aware of raptor population in (Northern) Queens, Nassau and Bronx county. The newest resident in our neighborhood is a red tail who considers the Ft. Totten woodlands as part of his territory. While driving on the parkways/expressways in Nassau county, we are on 'hawk patrol' looking for raptors perched on top of lamp posts or trees. We have espied red tails (including a mated pair) and what appear to be Cooper's and/or Sharp-Shinned hawks. We are members of the WCS and visit the Bronx Zoo every weekend. A few red tails consider the zoo's 265 acres as part of their territory.

They're out there!

Thank you for your wonderful web site, and a thank you to John Blakeman for sharing his wealth of knowledge with us.

Best wishes,
Marilyn Fifer

Dear Marie and Marilyn,

The destruction of suburban woodlands and forests is not a significant population stress for red-tails for the following reason. RTs simply can't and don't live in extensively forested areas. The big birds absolutely require large, open hunting areas. Any area that is much more than 50% forest is not ideal. Too little meadow rodent habitat, and too many trees, around which the red-tail has difficulty flying when hunting.

In presettlement times, before European destruction of the great forests of the East (including my Ohio), red-tailed hawks were very rare, living only on the edge of a few forest openings. In Ohio, about 4% of the state was open prairies (as was much of Long Island). The red-tail lived only on the edges of these large grasslands. Tens of thousands of square miles of closed forests had no red-tails. (And heavily-wooded central Pennsylvania to this day has few nesting red-tails.)

In short, there are more red-tails today than ever before. In early times, the birds were rare in the East because most of it was dense forest. When the forests were converted to meadows and pastures, the red-tail population quickly expanded into these new areas (much as the species has in NYC recently). But because everyone had free-ranging chickens, and hungry immature red-tails would kill these easy delights, the hawks were shot.

Only recently has the shooting and trapping of hawks essentially ended. The only major human killers of red-tails today are motor vehicles, and then usually only clumsy immatures out on initial summer hunting adventures.

The thought that moderns continue to destroy wildlife habitat, thereby forcing the extirpated animals into marginal or urban areas seems reasonable. But whether it's white-tailed deer, or our red-tailed hawks, this virtually never happens.

First, how long does it take to convert a rural district to shopping malls and housing developments? It's not the 3-5 years deer commonly live out their lives, nor even the 10-15 years adult red-tails live. And with both deer and red-tails, most offspring never live through their first years.

The thought that suburban development drives animals into marginal habitats seems reasonable, but it's wrong for this reason. The concept presumes that out in nature there is a generally fixed number of animals.When the areas they live in are destroyed, the animals no longer have a place to live and must try to survive in remaining, degraded habitats.

But nature never has fixed numbers of animals. The size of animal populations is always a result of the amount of available habitat. If that declines (as it does with development) the number of animals simply declines. The animals don't move somewhere else. They die. If new habitats are created (or found, as with Central Park), populations will expand there. Massive development has certainly led to a decline of many species, and sprawl reduces locally-available habitat. But by itself, development and sprawl haven't forced animals to take up residence elsewhere. Most of the displaced animals, whether voles or red-tailed hawks, have simply died off. Our Central Park hawks haven't moved there because someone built a new mall over in Jersey. That mall, by itself, is one thousandth the area needed by a wild rural pair. Even a new 100-acre housing development isn't a massive portion of a pair's territory. Urban sprawl is decidedly detrimental to wildlife populations, but primarily because they destroy habitat, not that they drive away wildlife residents.

Marilyn, I'm afraid that you've acquired the same habit the rest of us have, who frequently travel hawk-populated roadways. Red-tails just love to sit on utility poles and other perches overlooking highway rights-of-way. These grassy swards are prime habitat for meadow voles, and red-tails are habitual hunters in these areas. They tend to take the same hunting perches at the same time of day for extended periods, often several weeks or more. For me, it's just such a pleasure to see perched red-tails along highways. They make travel a bit more interesting. My wife and I just returned Saturday afternoon from a Cleveland Playhouse show 50 miles away. We counted five red-tail nests and close to a dozen birds perched nearby. Shouldn't we feel sorry for the hundreds of other motorists who passed by without seeing any of these regal birds? Glad to hear that others are seeing local red-tails in the greater New York area. I like your term, "Hawk Patrol." I'll continue my patrols.


John A. Blakeman