Interesting nesting development

I just received an interesting e-mail from my friend Gayle regarding the park hawks. Either there is a third pair or one of the nesting pairs is moving into new digs:

"Hi Rob hope the arm is getting better fast.

Question for you...Every morning this week around 9am [...] I have been watching a large female red-tail hanging out in a tree south of the Band Shell where there is a little valley. She is often there looking out over Prospect Park West to the movie theatre where all the yummy pigeons hang out. Both yesterday and today I saw both a male and a female (big difference in size!) perched in a tree right across the street from the bus station on Prospect Park Southwest. Twice the male took twigs and flew over to the horse riding ring into the top of a pine tree right there on West Drive. I also saw both of these hawks fly into the pine tree yesterday. So...who are they? Are they the Ravine hawks? Are they newbies to the Park? Am I just imagining this? Have you seen this? [...]

-Gayle"

Just by their size difference it sounds like Big Mama and Split-tail. The Ravine pair are pretty close to each other in size. I have read that red-tails sometimes build more than one nest before settling on one. I have watched Mama & Split working on the same nest as last year a few times this winter (could have changed their mind for whatever reason). Maybe the Ravine male found a new mate as he does seem to prefer pine trees. I'll have to check it out.