Wednesday, December 15, 2004

Concerns About the New Structure - 12/15/04

12/15/04 -- A FASCINATING LETTER FROM J. BLAKEMAN, THE RED-TAILED HAWK EXPERT IN OHIO WHOSE PREVIOUS LETTER IS REPRINTED SOMEWHERE BELOW. NEEDLESS TO SAY I FORWARDED THIS COMMUNICATION TO VARIOUS PEOPLE AT THE NYC AUDUBON. I HOPE BLAKEMAN IS PUT IN THE LOOP!

Marie,

Glad to see that positive steps are being made to reinstall the pigeon spikes.


I’m a bit concerned about the proposed guard rail or fence, or whatever it is called. The device, as I read the piecemeal news, is being developed by an architect and it is intended to keep carcasses and sticks from plunging off the ledge.

My concern is this. If this structure extends above the finished level of the nest, above its finished rim, the birds won’t like it. If it extends six inches or more above the rim, this will mean that the birds will have to land on the new artificial rim, then drop down onto the real nest. This is not behavior the birds will want to do. This is a real issue when eggs are being laid and incubated. Because of the delicate nature of the eggs and newly-hatched young, the adults instinctively curl their talons under their feet when the land on the nest's rim. If they are forced to first land on some elevated pipe or fence, they will not be able to easily drop down onto the nest with their retracted talons.

Secondly, this new rim must extend away from the edge of the nest. The birds are sensitive to any structure that interferes with the folding and extending of wings when landing and taking off. If new spikes or prongs extend more than 4-6 inches above the cornice, they will protrude above the new nest and can injure the soft developing wings of the eyasses when they start to flap their wings.

Lastly, I’m concerned about the design of the new carcass-catching device, what ever it might be. If the ejected food items merely accumulate in the device, it's only a matter of time before the device becomes overwhelmed. Sooner or later, the carcass-catcher will become filled. Do the designers understand the nature and quantity of rejected items?

The device, ideally, will be below the rim of the nest, but I’m a landscape designer and understand the aesthetic considerations the architect is likely to address in his solution. If appropriate, I’d be delighted to quickly review the proposed design, if possible. A CAD design could be emailed to me as an email attachment. My professional CAD program can open any drawing used by architectural professionals.

I wouldn't want all of what's happened go for naught, to have the proposed solution turn out to be rejected by the birds. If everything stays low and below the nest rim, all should be well (except for possible carcass accumulation problems). But nest-holding rim devices could cause nest site rejection by the pair. Or, they might elect to stay at the same site, but attempt to pile up enough sticks so the rim rises above whatever new structures are installed. That's the kind of nest that could, indeed, fall off and create a problem. The normal flat, bushel-basket sized and shaped nest presents no problems. A tall columnar one built to get the rim high in uncontaminated airspace could be a problem.

I hope that all of these concerns are immaterial.

Sincerely,

John A. Blakeman