Thursday, March 03, 2011

Jane of Georgia's Screech Owls and Urban Raptor Explosion in New Orleans


This is red-phase Screech Owl Oscar having a bit of a nap with his head sticking out of the nesting box. As this is a house made out of sawn wood, as opposed to a cavity that might just have some irregularities to place his feet, just what is holding Oscar up?

Obviously Oscar's feet aren't touching the floor. Take into account there might be some nesting materials in the bottom of the box, then eggs, and then Olivia his mate. Could he be standing on Olivia's head or has he got his talons hooked in the flat wood side of the box?

Oscar has flown out for the night and this is Olivia poking her head out just a little. Note her "ears" aren't even showing and somehow she looks more disheveled than Oscar, and maybe a little, well, grumpy.

From Jane of Georgia--

Here's my first attempt at a picture of Olivia. We just had a bad
thunderstorm here, complete with tornado warnings. As the skies darkened, I saw Oscar fly out a smidgen earlier than has been his norm and this little face appear at the owl box door. A very poor picture with very poor lighting, but you can see her very light cheeks. Through the binoculars, and in the pictures on my screen here, she looks a lot redder than I initially thought she was.

But later--


I dragged a 6’ ladder down to the yard area closer to the owl house, just so they could get used to seeing it around. Oscar seems very comfortable with me being close by and sunned himself in my obvious presence for a long while. As dusk settled in, he dropped down into the box and Olivia peered out, saw me and dropped immediately out of sight. Seeing her a bit more close up, even for just a few seconds, reveals she is indeed much grayer in color than her man, with a very round scruffy face that reminded me right away of the Muppet, Animal, albeit not as red and without the raucous open mouth!

(The description of Olivia, makes me think of the always seemingly rumpled female Screech Owl in Central Park who we called, Unmade Bed.)

And from an earlier email---

Olivia is very very shy, so I have decided to keep my distance and observe the two owls only from my deck for a while. Again this evening, Oscar flew away right around 645pm, and Olivia immediately appeared at the doorway. She appears somehow smaller than Oscar, probably because I’m only allowed to see her head. So far, she hasn’t jumped up to the lip of the box’s door, so I can’t get a real handle on her relative size.

Actually Jane, you're right Olivia only appears smaller as you haven't ever seen all of her. In fact all raptors have what is called reverse sexual dimorphism. The females are to a greater or smaller degree, larger than the males. Olivia appears smaller because we aren't even seeing her whole head as she doesn't poke her head out all the way in your presence. So far all you have really seen is her face. We've not even gotten to see her "ears" yet.

Often in owls the female is a third larger than the male. Though in raptor pairs if you have a largish male for the species and a smallish female for that species, the size can look quite close.

Why are females larger than males in raptors? There lies one of the long standing questions in avian biology and the hypotheses have been studied and heatedly argued repeatedly. The hypotheses tend to come in three categories- ecological hypotheses, sex-role differentiation hypotheses, and behavioral hypotheses. So far no one has nailed it down to everyone's satisfaction.

But as everyone knows who has read the blog for any amount of time, we will eventually get to it as it is one of my favorite topics and I have a pet theory, which I think we saw a bit of an example of during Pale Male's latest courtship of first one female and then a second. But that's for later...


Can you see the nest box? The tree with the nest box is slightly right of center. Now? Okay see the first tree on the right side of the frame? It has a branch that goes to the left across about three quarters of the photograph. Follow that branch, and when you come to the first batch of deciduous leaves, look carefully and you will see the house.

More to come from Jane about the habitat in Oscar and Olivia's territory.

Next up-- why would Hurricane Katrina cause an explosion of urban hawks to New Orleans? From Sally of Kentucky--
Once endangered, the hawk makes an amazing comeback
FOX 8 News WVUE-TV City dwellers have been seeing a variety of urban raptors lately in places where they were not seen before. Since Hurricane Katrina, it seems as if hawks are more of a fixture in the New Orleans area than ever, especially downtown. ... http://www.nytimes.com/2011/03/02/us/02states.html?emc=eta1

1 comment:

Robert said...

Hi Donegal,

I suggest the use of a predator guard under the nest box.

Susan