Wednesday, May 26, 2010

When does the mother leave the nest, then? - added to

This is in answer to one of the commenters, Evelyn, who noticed that in the webcam boxes she's watched, the mother has left the nest when the babies were around 2-3 weeks old. She wondered if maybe I was mistaken when I stated that in most successful nests that I and the scientists I know have studied, the mother stays with the babies until they are branching and often all the way through until they're independent, with the male continuing to feed the babies and the mother. Why is she not seeing this, then?

I will answer your statement about the owls you've watched on web-cams. First, these are all not entirely wild environments w/ cameras and possible other disturbances. Second, I have never said that it's not possible for the 2 parents to hunt.

I was not mistaken about anything I said, BUT there may be changes at work. Barn Owls are famous for their adaptability and we may be seeing this now. When I say that the mother generally tries to stay w/ the babies all the way through, I'm not speaking just for myself and my own observations, but I'm talking about the collective observations of dozens of barn owl biologists who have dedicated their entire lives to watching barn owls in the wild, not just on webcams. BUT.....

Having said that, however, i will say that I have only studied barn owls in Southern California, up near the Angeles Crest Forest and in Carlsbad and its surrounds. AND, I've been sick for several years, so I have not been out in the "field" like I was before - so perhaps during this time of so much increased urbanization of our empty spaces, a change has been taking place among the barn owls being observed. Evelyn may be on to something here.

Let's start with what I do know or what I have said: I'm aware of other studies that state that barn owl females have been known to go out hunting when the babies have gained enough fluff to stay warm on their own. However, that has not been OUR observation, in general. By that I mean that STATISTICALLY, it was more likely, according to our studies, that the female, IN SUCCESSFUL NESTS, will stay with the babies until well into branching and continue to stay with them until they are hunting on their own.

So, it's important to really parse through the intricacies of what's really being said. English is the best language for science because you can express things in terms of the exact meaning, meaning I can express to you that I'm talking about a statistical probability according to the observations of the people I've worked with and according to my own observations. I am NOT Saying it's impossible for the mother to act as we have seen on a few of these cameras.

In cases where hunting is not as good as it is in a great season, the female may be compelled to help w/ the hunting.

In general, though, she is not eager to leave her babies. The babies are more likely to thrive if the mother stays with them through branching and fledging (that is a statistical probability - so there are going to be successful nests where the mother did leave, such as Molly's nest). But, as you saw with OO nest, the nest was NOT a successful nest (by that we mean all the babies survive to adulthood and independence - ALL the babies).

I know that there are times when I have made a general educated, probability based guess when asked a question on the very fast moving chat, but I don't have time in those situations to explain the caveats, if ands and buts, that go with my "in general" statements.

Then I get misquoted and "people" say "AHA! Scientists were WRONG!".

It can be frustrating when it's not been explained well in our education system, how scientists use statistical probability to inform their "quickie" answers in cases where they're answering questions in "general".

It makes a person not want to answer any questions sometimes! Lol.

So, you're seeing one of the probabilities at work, but you're also seeing a smattering of unsuccessful nests (OO).

But here's the other factor that Evelyn may be pointing out, that needs serious consideration:

I have to wonder if, because of the continual urbanization of our neighborhoods, hunting has gotten worse and worse until now the mothers are more and more compelled to have to go out when the babies are 3 wks old.

This may be a pattern that scientists need to look into! It will be the grad students and post docs who do these studies - it's a perfect subject for someone working on their PhD - to compare data from a particular area from 20+ yrs ago compared to now, when there are less vacant lots, more rodent poisons, less hunting grounds.

Even the La Costa owls no longer nest at this wonderful nesting site I talked about in my book. Why? The nearby fields are all covered w/ cement now, made into a library (don't get me wrong, I love libraries!).

Perhaps we are seeing some behavioral changes due to changes in the environment caused by man - meaning increased urbanization!

This is fascinating to me because Barn Owls are great at adapting to subtle changes in environment, unlike most other species of owl (which is not to say that they adapt quickly to big changes, meaning they would not adapt to having no branches to hop to and suddenly take up flying straight out of the box or nest).

This ability to adapt is why you do find Barn Owls in the suburbs. We've seen some pretty incredible adaptation w/ hawks and falcons, too, with them nesting on tall buildings and hunting pigeons. Who would have predicted this?

There's a famous red tailed hawk who has made his nest on the balcony of a ritzy apartment building for many years, even starting to run into decades, I think. His name is "Pale Ale". He has raised many clutches of babies there, and it's right next to central park, so it's the perfect setup for birders/birdwatchers from all over the world to sit on a bench w/ their cameras and binaculars and watch the raising of the chicks all the way to fledging. There's always a dedicated group of birders at this bench during nesting season.

May 26, 2010 11:58 PM

NOTE! On THIS blog, I use all caps for EMPHASIS ONLY! They do NOT indicate an overexcited state, anger, or anything other than just emphasis. I get lazy and don't want to go up and italicize things. Heck, it took me a year to notice that they had a little doohhicky for italicizing on this blog. LOL.

-Stacey

Evelyn has offered some other links to other barn owl webcams in the comment section of this post, and I'll copy them here so you can all see them:

From Evelyn:

in case you or anyone else is interested, here are some neat barn owl cams.



http://www.free-live.org/web/cams/cam_schopfguggerli_s.php


nicasio owls, on ustream

the 2 above are about the same age:


http://www.beleefdelente.nl/kerkuil these owlets are about a week or 2 younger

and

http://www.starrranch.org/blog/?page_id=2

the female there is starting a second batch, 3 eggs so far

the hatch dates for the schopfuggerli owlets are may 2nd 3rd, 5th, 8th

the 5th hatch was either the 9th or 10th and the 6th hatch was probably between the 12th and 14th

itacri said...
Eveyln, here's another you will enjoy. Tawny Owls in a real wild nest (hollowed out tree). It says 2009 on the page but it isn't, they just didn't change that from last year. 



http://www.eoy.ee/kodukakk/kakukaamera

From Kathlene:
http://www.youtube.com/watch?v=9glyi3LA_d4&feature=related

5 comments:

Evelyn said...

ahh ty

in case you or anyone else is interested, here are some neat barn owl cams.

http://www.free-live.org/web/cams/cam_schopfguggerli_s.php

nicasio owls, on ustream

the 2 above are about the same age

http://www.beleefdelente.nl/kerkuil these owlets are about a week or 2 younger

and http://www.starrranch.org/blog/?page_id=2

the female there is starting a second batch, 3 eggs so far

Evelyn said...

forgot to add...

the hatch dates for the schopfuggerli owlets are may 2nd 3rd, 5th, 8th

the 5th hatch was either the 9th or 10th and the 6th hatch was probably between the 12th and 14th

Evelyn said...

I've seen multiple barn owls either bring a rat or a rabbit, or seen the leftovers

What I'd like to know is.... how do they get the rabbit through the hole in a barn owl box!

itacri said...

Eveyln, here's another you will enjoy. Tawny Owls in a real wild nest (hollowed out tree). It says 2009 on the page but it isn't, they just didn't change that from last year.

http://www.eoy.ee/kodukakk/kakukaamera

Kathlene said...

http://www.youtube.com/watch?v=9glyi3LA_d4&feature=related