Cooper’s Hawks Update 2: More Hatch, Racing to Eat

June 12

I had been starting to despare that we’d only have three chicks this year. Which is a perfectly normal of chicks for a Cooper’s nest, if a bit on the low side. But more would make this year’s observations more analogous to last year’s data, when we saw five successfully fledge. Cooper’s often have a day or two between hatching the first three and the remaining eggs, but this nest showed a 3-4 day holiday between hatchings. As it happens, we now have six of the little guys. Which is a very large brood, and will make this year’s journey to fledging pretty challenging, especially coming off a low mast period.

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Here is a picture of all six young huddling up for warmth, along with the adult female.

Other notes of interest in the past few days:

  • I believe I was able to observe the female deliberately favoring the newly hatched in feeding, reaching over the larger, begging young to get some meat into the little guys.
  • A red tail hawk was loitering about 100 yards away, on the edge of the nearby field. Two broad wing hawks made a big racket and chased him away. These two broad wings are likely the couple whose nest I identified over on a neighbor’s property. That nest is about a quarter mile east, so I thought it odd they were harassing a red tail this far away.

The runt (left in the picture at right) had a big piece of varmint dropped on him by parent who returned specifically for this deed. This wasuntitled_16-06-17_3939
after a big feeding where the little guy didn’t get any meat, and the biggest chick came over in the middle of the feeding and beat him up a little. The parent didn’t even land for this desert delivery, but rather just dropped a nice chunk on the side of the nest where the little guy was. Here he is trying to keep it from another of the smaller chicks.

The literature says that the parents will go out of their way to feed the smaller ones, but this is presented as a parentally-controlled process, where the chicks do not act aggressively toward one another. Last year’s nest and this year’s nest do not appear to operate like that. The big young are throwing their weight around. The literature says that the females are deferential to the smaller males, and while that doesn’t appear to be the case in this nest, we can’t be sure because we can’t be certain of genders. We can’t know yet if the size of the three big ones is a product of sex (females are much larger) or simply that they were the hatched first. After a few weeks the differences caused by the differences in time between hatchings will lessen relative to the effect of the dimorphism. We’ll know more later.

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Fiestiness

Some of the young are starting to get feisty. I most often cannot tell if it is the same bird or a different one, but periodically, one or another appears to get into a mood, calls frequently, and stomps around pecking at the others, usually singling one out. It’s a thrusting peck that lasts for about a second, often to a bird with its head down, the aggressor pushing his beak into the receiver’s upper neck. Very similar to what was seen last year. It usually doesn’t happen during feeding, but is frequently seen in that sleepy period after feeding, when some are asleep and some are awake.

PastedGraphic-2The lucky little guy on the left in the picture at right below was the recipient of one of those attacks just a few minutes prior to the meat mana falling from the sky.

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4:30 a.m.

One last behavioral note: the adult female sleeps on the west side of the nest, standing on one leg and flopping her head back and under some feathers. When she wakes, quite early, about 4:30 a.m., she preens her young, picking things out of their fluff before flying off. They remain asleep or at least adequately groggy to put up little resistance at this time of day. It reminds me of us putting sun screen on our kids

She does this at night too. She supervises a final bedtime around 9 p.m., and I cannot tell if her dipping her beak deliberately into the fluff pile of chicks is for preening, or some exertion of discipline, as some of the chicks are more cooperative than others.

 

June 15

The parents are supplementing their normal feedings – where the female parcels out pieces to each chick with some care, as below – untitled_16-06-17_3301are now throwing partially butchered prey into the nest (right), letting the young start to try to pull it apart. untitled_16-06-17_3894The parents first remove the head (seen on 2 chipmunks and at least one red squirrel today) and appear to make an incision in the abdomen and remove – or eat – the viscera. They also appear to remove about a third of the hair, perhaps a partial skinning.

The female will return after a few minutes and finish cutting up the prey into small bits to distribute. The chicks were actually getting some bits of meat out on their own. With a little tug of war, they managed to pull a chipmunk in two. Not bad for siblings ranging from 7 or 8 to 12 days old.

The chicks jostle for the carved and pulled pieces, with the bigger ones being more successful at ripping them from the mother’s mouth, but I untitled_16-06-12_3376think I’m seeing a pattern where the adult female is fending off the bigger ones by giving them large, inconvenient parts. Here, she just handed the 2nd biggest chick a big piece of gristle. The smallest is sitting to the right, having just had a nice little juicy piece of meat ripped from his/her mouth from the chick further to the right.

In the picture below right, the mother just gave a big furry piece of gristle to the biggest one, who is sitting mostly behind the tree. you can see his/her beak trPastedGraphic-4ying to snarf down what looks like the end of a chipmunk tail. That kept it busy for about the rest of the feeding. Note the mother appearing to stand on her head. She dips down with her legs stretched out in order to create leverage to rip strips of meat off the carcass.

You very much get the sense that the female is paying close attention to the interactions among the young. She’s not just flipping meat over to them, but observing them closely for some reason. It could be to keep track of how much nutrition each is getting, or perhaps there is reason for her to suss out the developing social order. All I can say is that she spends time and energy doing this.

The full Cooper’s series:

First Hatching

The Brood

Winnowing‎

Pre-Flight

Flight!

Epilogue

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