The Breeding Season is Off to a Start With One Egg in the Box

For the first time in nearly a year, we began the day with an egg in the nest box. Astrid had remained in the box all night long. Just before 6 AM, Ares flew up to the box perch with his usual introductory screech. He had a Woodcock in his talons, but just as he was about to hand it off to his mate, something in the darkness caused him to issue an alarm call. He dashed out of the box taking the prey with him. He reappeared on the State Building a little while later and we still have no idea what spooked him. Was it an intruder? He returned to relieve Astrid about an hour later and we believe this was his first opportunity to see the new egg. He fussed over it for a short time and even settled down on it as if he was going to incubate. Of course, leaving the egg uncovered for extended periods is normal at this time. Full incubation doesn’t typically begin until half the clutch has been laid. This helps insure that the intervals between the hatches will be smaller than those between the egg layings. This means that the differences in size of the nestlings won’t be so great, and that serves to lessen competition for food in the nest and increases survival chances for the younger nestlings.
At around 10:45 Ares retrieved the same Woodcock from storage and brought it to Astrid. This time she was quick to accept it and flew over to the hotel to feed.
Generally falcons prefer windy, sunny days and this afternoon they were able to do some effortless sailing around the canyon, but only rarely were both out of view of the nest box. Our monitoring of the falcons was somewhat lacking during the latter part of the day, but as far as we know, at least one ledge display and three matings took place. Astrid was also seen making two trips to the hotel ledge in order to drink water from a puddle. At 3:45 Astrid was back at the box and seemed to be semi incubating and semi shading the egg. As evening came the pair converged at the hotel for more drinks from ledge puddles. Ares tried again to give Astrid a food tribute, but she wouldn’t accept it and he stored it instead. Astrid ended her day where it began – at the nest box. We expect a second egg to be laid sometime tomorrow night or Tuesday morning.
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Ares brings an early breakfast for Astrid but then gives an alarm call and dashes off
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A ledge display over the new egg

 

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Mating at the box in the afternoon

 

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Ares on duty at the box

 

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Astrid half-incubating and half-shading the egg
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The egg was left alone several times today. Full incubation won’t start until half the clutch has been laid

One thought on “The Breeding Season is Off to a Start With One Egg in the Box”

  1. I wondered if the young falcon coming around could be one of the chick’s from last year that disappeared so soon.
    It was not banded, but would anyone monitoring last year recognize it if they saw it? Obviously it has grown since last year but it would be interesting to know that they found their way back to let everyone know they were ok even though they can’t stay.

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