Here is what Dale had to say-
Last year I wrote...about the problem with Pale Male and Lola's nest. Some background info: I'm a member of the NJ Audubon (and an engineer) and noticed a problem with the nest support that you made for the nest. Talking to fellow members in NJ, we agreed that the most likely cause of the eggs not developing past the early stage is the lack of incubation since there was no evidence of chemical contamination or deformity of the fetus. The support on which the nest sits has the shape that could cause a venturi effect and accelerate the air flow under the nest. If this happens, the eggs will cool from the bottom and no amount of incubation by the birds will help.
The old support rested on the concrete and prevented this effect. Another clue can be found in the birds themselves. They tried to add a significant layer of nesting material after the eggs were laid which to my knowledge is not normal behavior. They seemed to realize the problem too late.
Last year you... stated that they [Red-tails] build nests on tree branches with open bottoms. Unfortunately, that is not an entirely true statement. They build the nest usually in a branch Y with the bottom supported. Even if there is an exposed portion of the nest, the tree branch blocks the wind. It's not like your nest support which channels the wind and makes the wind stronger. This year (for the third time), the same exact problem occurred with the same behavior. I was hoping that they would move their nest site but I guess that they are stubborn. As suggested last year, you can remedy the air flow problem by attaching something below the rack to block the wind such as hard plastic sheeting. leave enough room to allow water drainage or you will swamp the birds when it rains.
From a concerned member.
Pale Male and Lola's nest as of March 22, 2007 3:46PM
Is it only the lack of enough nesting materials even in the third year?
And for those that would like another look at the cradle while they muse over their theory, their fix, or their response to a previous theory. Here it is right before installation.
John Blakeman's visual aid to show the height of the spikes within the nest, to help explain his proposition that the pigeon spikes should be clipped within the bowl of the nest. He theorizes that they may be causing a disruption either by wicking heat away from the eggs or by interfering with normal egg manipulation by the hawks.
The Fordham installation of pigeon spikes. In my memory these are very similar spikes and installed the same way, on wood, flush against the building as was the foundation for Pale Male's original nest before it was destroyed.
The current spikes, original or not, no longer have the solid wooden foundation. (Look above you can see through the cradle, the solid buffer of the wood and the cornice itself are gone. That's a big change.) The spikes are now directly attached to the cradle, metal to metal, capable of wicking heat away from the eggs. Turning the cradle into a very large cooling device to dissipate heat. Similar to the coils on a refrigerator.
AND WHAT ELSE..?IF YOU DON'T WEIGH IN YOU DON'T GET TO COMPLAIN!