Tuesday, March 23, 2010

Arizona Raptor and Couldn't That Plastic Bag in the Bowl of the Nest Suffocate an Eyass?

Photo by Paul Anderson

Wisconsinite Paul Anderson and wife Marian, have been on a trip in the west and saw this bird which they couldn't identify. They are not as yet birders. But as they noticed her and asked, I think an interest has been kindled.


I took these on Saturday near Prescott AZ. I'm standing under a high tension line and you can see the wires in one shot, that gives you a perspective how high he is! Sorry it isn't any finer but that was max optic zoom to get what I did.


Photo by Paul Anderson


What you've got here is a big western Red-tailed Hawk. See the patagial bar, the dark patch on the "shoulders"? Also see the wrist coma and of course the signature orange tail. Also look carefully and you can see just the shadow of a belly band. She does look big doesn't she?


A while back Brett Odom, who has the office overlooking Pale Male Jr. and Charlotte’s nest, expressed concern about a plastic bag that they had placed in the bowl of the nest. I sent it along to John Blakeman who had originally been concerned by plastic in previous nests that he’d observed but after watching, saw that water did not puddle and interfere with the gas exchange of the eggs and that a plastic bag lining worked just as well as the more natural materials hawks usually use.

Brett then sent me this email in response, he said—

This is good news. But I was mostly concerned with suffocation once the eyass has hatched. The bag isn't woven into the nesting material. It is in there fairly loosely, and whenever the wind blows, the bag blows around also. Is it possible for the bag to blow over the eyass and suffocate it?

I thought about that too...the whole thing about not putting plastic in a baby’s crib for fear of them suffocating, right? I'd say it was a possibility though probably freakishly rare. A problem in particular, if the plastic was blown completely over a very young eyass totally obscuring him.

One thing about Charlotte though, she is pretty savvy and thinks on her feet. She is absolutely the only female I've seen that stopped a youngster just up off his haunches from falling out of the nest. She calculated he was not going to stop in time and not being able to use beak or feet/talons to stop him she strode over and sat on him. Problem solved.

She is a very observant mom, who will also pull something they've swallowed whole that's too big out immediately if the eyass actually have their airway covered. If it's just stuck and they can breath she lets them learn the lesson by waiting before pulling it out--when they then invariably do it a couple more times with the same rat before it sinks in. Charlotte is very patient but also watches very carefully for possible problems for the eyasses.

My fear with the plastic bag over the eyass though is that without the visual cue of the eyass itself she won't realize he's under there and therefore won't be cued to do anything about it. Or what if the youngster just became covered up and then was trod on? Being an experienced mother perhaps she'd see the eyass wiggling, or realize she was missing one, and do something. I don't know.

Now there's a question. Would she know she was missing one if he were covered with plastic?

The common wisdom is that raptors can't count and that is the reason an orphaned eyass of common age can be put into a nest and readily nurtured. I'm not sure the parents don't know there is another one, my thought is that it is possible that they just don't care that another has appeared. An eyass is begging; the eyass gets fed. Parrots can tell you "How many?" so it is a concept that some avian species have, so shouldn't necessarily be discounted as a possibility at least in my opinion.

Also Red-tails learn from experience and a mature pair, like Junior and Charlotte, are just better parents than a couple of first nest parents. I wonder if that is why in the hawks that have lost mates lately, the replacements have been quite young.

Pale Male did not have a successful nest until he mated with an older more experienced female. Then after some year of successful nests with various mates Pale Male chose Lola who's eyes were light, very likely a first time mom. One experienced parent raises the possibility of successful young exponentially.'

Another thought. eyasses though used to being sat upon, perhaps similar to being covered with a bag if he wasn't being directly stifled, if experiencing discomfort vocalizes. If the eyass got hungry he would fidget and beg, if being pressured physically by something on the other side of the bag, he'd squawk and this would get the parent's attention. Hawk parents investigate when they hear their offspring in distress..

Besides it is probably much more likely that debris of whatever kind may collect to hold the bag down or the parents themselves will lay some other materials on top of the bag and hold the plastic down by the time it could become a danger to the little guys.


I’d asked about the status of Junior and Charlotte’s nesting activities and received this note in response from Brett—

I have not noticed any eggs yet, or brooding behavior from Charlotte. And with the weather not cooperating today, it will probably be hard to tell if any eggs or a sitting Charlotte is behind the panes of glass. Also, with a white plastic shopping bag now lining the nest, it will probably be hard to know if there are any eggs. But I will keep you informed if I see either parents sitting on the nest for long periods of time.

Brett B. Odom

Thanks Brett!

Donegal Browne

1 comment:

Karen Anne said...

All that free floating plastic, what's the matter with people. Thinks of giant trash islands in oceans, too.