Tuesday, March 13, 2007

Pale Male, Lola, and the Eggs

Pale Male on the 927 nest

As I'm still in the wiles of Wisconsin and not at my normal post at the Hawk Bench currently, I had a number of questions for Katherine Herzog to clarify some points brought up by her on the spot notes of Saturday and Sunday.

Here's what Katherine had to say:

Some answers to your many questions on Sat/Sun, Mar 10 & 11th Pale Male & Lola Observations:

When I arrived late afternoon on Saturday, Ric Davis informed me that Lola had been sitting high and mid-level in the nest...but by the time of my arrival at 3pm, she was sitting deep down into the nest for the first time that anyone had previously observed. The behavior of PM and L looking down into the nest did not happen standing on the edge of the "bowl" of the nest.... they were actually standing in the nest and looking down near their feet. And Lola from time to time seemed to be turning an egg/or eggs. Several people at the Bench noticed this too....that once the sunlight hit the nest fully and directly, Lola was moving something in the bottom of the nest and it did not look like she was rearranging nest material. I can't think of any other reason for both Lola and Pale Male to sit "disappearing" into the bottom of the nest unless egg/s were present....(I can't either. D. B.)

Especially Pale Male who previously had always been seen standing or sitting high on the nest or on the "bowl" rim. For him to take over immediately when Lola took a 20-minute break and disappear into the nest and remain until Lola came back to the nest was the strongest indication and argument for incubation. (Maybe you could run this past Blakeman.)

Could not determine the sex or age of the intruder RT Hawk but it was circling above the nest building and Pale was the first to fly toward it....a few seconds later Lola left the nest to assist. She flew directly back to the nest after only a minute or two....Pale landed on the railing of the Stove Pipe Building (the Satellite Dishes have disappeared, so that name has been retired). As Pale sat there, the intruder RT Hawk made a few lazy circles high over him and then headed north....not to be seen again that afternoon. The 3-hawk aerial ballet was not very aggressive....there was no stooping or battle just PM and L escorting the unwanted hawk out of their territory.

We certainly have seen Lola leave the nest alone, sometimes for 20 to 30 minutes at a time when eggs are in the nest. Other times waiting for PM to come to the nest before taking off. The element of behavior that I'm puzzled about it the continued mating? Does this happen between laying eggs and before a clutch is complete? (Yes, see below. D.B.)

About Lola sleeping overnight....well, unless you have a hearty sole to spend the night viewing her or a camera set up to record 'round the clock activity, no one really knows. We do know that Lola was seen on the nest both Sat & Sunday after sunset. Lincoln Karim observed her a little before 7am Saturday morning sitting on a tree at the 72nd St transverse but she could have been sitting on the nest, say until the first rays of the sun...but also that was before we believed she had begun to lay. What the Hawk Bench folks observe, myself included, is of course incomplete information....the operative word being "incomplete". And until a person or camera can be position over the nest we'll only be able to cobble fragments of observation into educated guesses. I don't give any credibility to "wishful thinking" and tend to call it--for better or worse--as it lays, so to speak.

All the best, Katherine

First of all, is Lola back on her feed? For me that's a possible indicator.

I just looked back at my notes from past seasons and as far as I can tell Pale Male only takes over the nest when Lola leaves if the clutch is complete. Or to be totally specific after I've been reasonably sure that the clutch was complete did that kind of switching take place. It may be an indicator for this particular pair. Though shouldn't be taken as an indicator for all Red-tails. I'm no expert but having watched three sets now, there is a great deal of variation in how-they-get-success, depending on the bonded pair.

In answer to your questions about copulation between eggs and second, copulation after the clutch is complete.

Yes, copulation is necessary to fertilize the next egg after one is laid. (Female turkeys may be able to store sperm for later, but as far as I know Red-tails don't.)

As with most hawk activities during breeding season, to my eye there seems to be a hormonal arc involved with copulation. Just as no eggs are produced immediately upon the first copulations of the season, no eggs are produced during the waning acts of copulation either.

According to what I've read, clutch size depends on prey density. Though as with many things that we originally put down to only one variable, I'm betting there are a number of variables that affect clutch size. Though I'm thinking that Pale Male and Lola are way ahead on the number of copulations needed to produce a sufficient number of eggs for any given season.

I'll look for the specific day in my notes but there was a rather spectacular case of copulation well after, I'm talking weeks after, we were convinced that the clutch was done. It's also the episode where Pale Male flew to guard the nest, hackles on end, then raked his talons back over the twigs repeatedly much the way roosters do.

The clutch was complete and incubation was underway. This day a pair of intruder Red-tails repeatedly invaded the space near the nest. One coming from the south while the other came from the north, then when one was chased the other would come in from behind the nest. There was variation upon variation of intrusion, Pale Male and Lola were having to use all their vigilance, teamwork, and experience to best these birds and by the third episode of this, Lola and Pale Male were no doubt drenched in their birdie version of adrenalin. The last bout was so confusing, for we observers anyway, there were screaming Red-tails everywhere it seemed, that though, four hawk watchers, Lincoln Karim, Stella Hamilton, Samantha, and I, attempted to make sense of what had gone on, who was who, what happened when, moment to moment, we couldn't. In fact when a hawk flew up and began to copulate with Lola only seconds after a bout with the intruders we weren't even sure for a moment that it was Pale Male doing the copulating.

It had been many days since the last copulation had been reported and there were none reported after this one that year either.

As danger is reputedly an aphrodisiac for some humans, perhaps it was for hawks on that day as well. So yes, there is definitely copulation after the clutch is complete, in my humble opinion anyway.

So was the incubation count begun Friday or Saturday? What's the consensus?

Donegal Brown

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