Western Screech OWLET UPDATE and Photo Essay!

#1! Lots of down but some contour feathers appearing

#2 of the two owlets

It was time to band the owlets after peeking into the box last week, I determined they were old enough, ~ 3 weeks to 1 month old and getting ready to "fledge." Typically owls leave the nest cavity and are called "branchers", because that's what they do, sometimes falling clumsily to the ground, climb up a tree, and perch on a branch. Their growing flight feathers are heavy with blood and they beg for food and begin to persistently follow their parents around before they are capable of even moderate flight. I wondered about this being a successful strategy because it seems safer remaining in a protected cavity. But after seeing and smelling the remains of this nest box, I think I figured out why it's best to get out of there (see below!)

At least 3 prey remains in this nestbox

Here is more evidence of the male being a good provider with three different prey remains that might be a deer mouse, vole or gopher and the tiny remains of a pocket mouse or other tiny rodent.

Ken climbs the ladder and hands me the mom for
weighing and checking the band we put on last week.
You can see the plug in the nest hole.

We begin with Ken removing the female from the box (the nest hole is plugged to ensure she doesn't flush out of the nest) and handing her to me. She is held in a bag until the nestlings are banded. As typical for screech owls, she is very calm through this process.The female has a lot invested with two owlets, so would unlikely abandon a nest at this stage. Both owlets were plump at 135-145 grams (the same weight as some adult males).  We banded and weighed them separately, so owlet #1 remained in the bag quietly waiting for the sibling.The mom was also well-fed, weighing in at 190 grams!

One owlet banded and held in a cloth bag until the second owlet is processed

The owlets are returned to the nest box, then mom is returned. We wait about five minutes to remove the plug before leaving the owls safely in their box. I have no doubt the male is roosting somewhere nearby, but we were unable to find him.

OWLS and OWLETS!

Today Ken and I checked the boxes on the Reserve. We were particularly interested in Nest Box #15 (sort of like an address) where we discovered a nesting Western Screech Owl, 37 days ago in April. Today May 27, we saw a mom owl with her two owlets and a nice meal for the chicks, a deer mouse (peromyscus sp.)

A view from above: 3 screech owls and breakfast. Note the larger owlet on the left.
Owl eggs hatch asynchronously, so one will be a little older than the next.

Ken removed the female and lowered her down to me for banding. She remained still and calm through the process.We returned her to the box after taking some measurements and examining her condition.

Here I am taking the wing chord measurement of the owl.
Note the band on her right leg.

Then I looked at her brood patch. Hormones help release breast feathers providing direct heat exchange for incubating eggs and brooding young,until owlets can thermoregulate on their own. This female's brood patch is already getting pin feathers (two dark lines under her bare skin), because the owlet's feathers now keep them warm. By fall her breast will be feathered, which will help keep her warm for the winter months.

The brood patch, well past its use for warming chicks. Because the
chicks now have feathers they no longer need warming by the adult.

Leftover prey shows the male is a good provider. He was likely roosting in a cavity nearby, and maybe observing us. Stay tuned for the rest of the story!

A view with the mom removed. The owlets are about the size
of an adult deer mouse (right corner), and too small to band.

The Cornell Lab of ornithology is a great resource for bird natural history including screech owls. Also click here for a nice overview of owl courtship and reproductive behavior.

OWL IN THE NEST BOX!

Western Screech Owl inside a nest box

Can you see the the owl in the box?  You are looking at the head and back of a Western Screech Owl inside nest box # 15. We believe she is incubating eggs due to her flattened posture and absolute stillness when we peeked the camera into the box. If she is incubating and all goes well, we can expect to see 2-7 nestlings within the next month.

So how did we see her? This winter Ken and crew installed nest boxes to determine potential use of the BCCER as breeding site for Northern Saw-whet owls, a cavity nesting species. To check the nests Ken attached a flexible cable with tiny camera and LED light to a bamboo pole, plugged in to his tablet. He can feed the camera quietly into the cavity entrance, see what is inside on his screen and then take a photo. We have conducted two box checks,

Ken's nest-cam set up. The camera is at the end of the pole
inside box #4. He is viewing the inside of the box on his tablet.

one on March 11 and one on April 19. In March, we found bird feces in two two boxes but no birds were present. We guessed the boxes were used by Northern Flickers roosting in the boxes at night. In April, we found identifying flicker feathers in the same boxes, and then we found the screech owl in a third box, What a fun surprise! Learn more about Western Screech Owls here.

ATTENTION SAW-WHET OWLS - Nest Boxes Available!

Ken Sobon and team have installed over 15 nest boxes on the Big Chico Creek Ecological Reserve (BCCER). He is hoping that the boxes will attract saw-whets, perhaps those wintering on the Reserve or moving through in spring, will stay and nest. If a pair does-it would be the first documented saw-whets breeding on site! We haven't done any summer surveys so we can't say they don't breed here. Generally I think the Reserve is too low in elevation (and hot) for Sierra Nevada breeding habitat, but these owls are shown to be nomadic, meaning they will breed where conditions are right (good prey, micro-climate) and don't often return to the same breeding area.

Locations of seven nest boxes on the Reserve. Also see our two banding sites, OWL2 and OWL3. The structures include barn workshop, office and old ranch house.The forests provide cover and good roosting habitat for owls and the meadows are great habitat for foraging for rodents.

You can see the boxes are distributed around, mostly under good canopy cover and near meadows for foraging and all boxes face NE (cooler). Some are on different tree species, some near small drainages, some with a different slope aspect.  It will be really exciting to check these boxes. Other cavity nesters that might find the boxes homey are western screech owl, ash-throated flycatcher, northern flying squirrel, wood rats and???  Monitoring begins in early March. Stay tuned!

This box #8 will be under a fairly dense cavity when the oaks leaf out.
You can see the canopy closure in the aerial google earth photo above
taken in late May.