Barn Owl (CA) — 2008

Jan 01, 2008 -
It may be a new year, but these owls appear to be up to the same old thing!

Jan 14, 2008 -
The male is observed delivering prey items to the female.

Jan 28, 2008 -
An example of the male grasping the female's neck for balance prior to copulation.

Feb 04, 2008 -
Here's a good picture of the barn owl's eyes. They are characteristically dark and relatively small compared to other owl species.

Feb 09, 2008 -
Another shot of the owls mating. The male spreads his wings for balance while mounted on the female.

Feb 15, 2008 -
Barn owls stretch frequently. This is one example of the body bowed with both wings flexed upwards.

Feb 17, 2008 -
A nest cam viewer sends in this nice image showing the heart-shaped facial disk.

Feb 25, 2008 -
Here's a daytime image of the owls in their typical mating posture.

Feb 29, 2008 -
It seems as if the frequency of mating has increased in the past couple days. It takes about a month from the onset of mating until the first egg is laid. The first mating picture was captured in late January so hopefully it won't be long!

Mar 02, 2008 -
The female was seen crouching as shown for several minutes at a time sporadically throughout the day. This could mean an egg is on the way!

Mar 03, 2008 -
A precopulatory picture of the female crouched before the male who is about to mount her. Both the male and female may solicit copulation.

Mar 03, 2008 -
Barn owls hunt by night using their remarkable vision and hearing ability.

Mar 05, 2008 -
In this image, one of the barn owl appears to be eating. Barn owls mainly hunt for small mammals, most of which are rodents.

Mar 06, 2008 -
In the far left corner of this image, a significant accumulation of prey can be seen. About a month before egg laying begins, the male barn owl will often bring prey items to the female to solicit copulation. It is not unusual for there to be more food than the female can possibly eat!

Mar 08, 2008 -
Like most barn owls, this pair will probably remain together for their entire life. However, if a barn owl's mate disappear, it will find another.

Mar 09, 2008 -
Here is a beautiful image of the male barn owl's expansive wings which he uses for balance during copulation. Barn owl's wings are set relatively low on their body, making them ideal carrying heavy prey.

Mar 09, 2008 -
The barn owls seem to have spent quite a bit of time looking at the camera today!

Mar 11, 2008 -
Barn owls commonly nest in trees, cliffs, man-made structures, caves, and outcrops. The type of site a barn owl was raised in strongly influences its choice of nest site. Once a site has been chosen, the couple will often reuse it for multiple seasons.

Mar 13, 2008 -
The barn owls continue to mate. Hopefully we'll see some eggs soon!

Mar 14, 2008 -
These two barn owls have been preening each other quite frequently for the past two days. This behavior is more specifically called allopreening. The owls mutually preen each other in hard to reach areas, like the head, as shown in the picture.

Mar 17, 2008 -
The female has not moved off the nest long enough for us to see the egg, but we know she laid the first one on March 16th!

Mar 18, 2008 -
At around 5:30 pm, we get our first glimpse of the second egg.

Mar 18, 2008 -
The male and female are seen here with sizeable meals. It is rare, however, for the male to eat inside the box.

Mar 21, 2008 -
Shortly after 1pm, we got our first look at the third egg.

Mar 22, 2008 -
Even though eggs have already been laid, the barn owls will continue to mate throughout incubation.

Mar 23, 2008 -
Sometime between 5:00 and 7:00pm this evening the fourth egg was laid!

Mar 26, 2008 -
The female leaves her post for brief moments throughout the day. We finally see the five eggs here.

Mar 28, 2008 -
In this image, the female is holding a prey item brought to her by the male in order to initiate copulation. Remember, she is also incubating 6 eggs!

Mar 28, 2008 -
The female moves off her clutch to expose a newly laid sixth egg!

Mar 29, 2008 -
Here's an image of the male barn owl casting a pellet. On average, barn owls cast two pellets per day.

Mar 30, 2008 -
The seventh egg was laid sometime between 7:45pm and 8:20pm on the night of the 30th!

Mar 30, 2008 -
The seventh egg was laid sometime between 7:45pm and 8:20pm on the night of the 30th!

Apr 02, 2008 -
The incubation period lasts for approximately 29-34 days. This means that the first egg should hatch sometime around April 17th!

Apr 04, 2008 -
The female rarely leaves the nest during incubation. That means lots of stretching and pacing!

Apr 07, 2008 -
In the 1950's and 1960's, the widespread use of chlorine-containing pesticides led to a decrease in many bird populations. These pesticides decreased the thickness of eggshells by a significant amount, making them more likely to break under the weight of the female. Since then, these types of pesticides have been banned in North America.

Apr 08, 2008 -
Barn owls are one of the most widely spread birds in the world.They are found on every continent except for Antarctica.

Apr 09, 2008 -
Nest boxes have successfully increased barn owl populations in many areas where they were in decline!

Apr 12, 2008 -
The female barn owl is significantly bigger than the male in a number of ways, such as in body mass, beak length, and foot width. However, the male has a longer tail and longer wing span. Females also usually have darker plumage than males.

Apr 13, 2008 -
These particular barn owls have been pair-bonded for at least five years. In first year couples, courtship begins one month prior to egg laying.

Apr 15, 2008 -
The owls mated multiple times today! Here's a picture of the female preening the male post-copulation.

Apr 16, 2008 -
Around 3:15pm on the 16th, the first egg hatched!

Apr 16, 2008 -

Apr 17, 2008 -
Hatching occurs in the same order as the eggs were laid.

Apr 20, 2008 -
The two nestlings are clearly visible in this picture.

Apr 21, 2008 -
The male barn owl will bring prey to the nest but only the female will feed the young.

Apr 22, 2008 -
The nestlings sleep huddled together to conserve heat.

Apr 23, 2008 -
The three unhatched eggs can be seen clearly in this image.

Apr 23, 2008 -
The nestlings are old enough now that mom doesn't have to eat their fecal sacs. Instead, they are able to go off the edge of the nest cavity.

Apr 24, 2008 -
The chicks are still at a stage where they only can crawl. By the 12th day, they will be able to hold up their heads without effort. By the 14th day, they will be able to walk, and by the 16th they will be able to swallow mice whole!

Apr 25, 2008 -

Apr 25, 2008 -
The owls keep at it even when the nestlings have already hatched! This is a way to reaffirm the pair bond.

Apr 26, 2008 -

Apr 27, 2008 -
When mom is gone the nestlings sleep together to conserve heat.

Apr 28, 2008 -
All but one egg has hatched!

Apr 29, 2008 -
The female barn owl will eat the nestlings feces until the youngest is about 10 days old.

Apr 30, 2008 -
In this picture, the female can be seen feeding bits of torn up prey to the nestlings. The nestlings will not be able to swallow prey whole until they are about 2 weeks old.

May 03, 2008 -
The nestlings will make their first flight at 50-55 days old but will not fledge until about 10 days later.

May 07, 2008 -

May 08, 2008 -
The female barn owl tears up prey into small chunks for the younger nestlings. The older ones are big enough now to swallow their meals whole.

May 16, 2008 -
At these high temperatures the chicks stand erect, sleek the feathers, and may use gular flutter. Studies also suggest that the chicks will accumulate a reserve of water as an insurance against dehydration when they are relying on evaporative cooling in hot nest box conditions.

May 23, 2008 -
The owls were able to swallow prey items whole by the time they were 16 days old.

May 28, 2008 -
These owls still have their juvenile plumage which is basically a grayish colored second natal down. This will be replaced by the basic I plumage following the prebasic I molt which will occur in the nest cavity when the nestlings are approximately 35-60 days old.

May 30, 2008 -
There are 46 described races of Barn Owls of which the North American race is the largest.

Jun 02, 2008 -
The nestlings sleep huddled together to conserve heat.

Jun 03, 2008 -
Females are more spotted than male Barn Owls. This may act as an indication of female quality to the male. In experiments it has been shown that the artificial removal of spots decreases a female's attractiveness.

Jun 06, 2008 -
Barn Owls have few predators, some of which include snakes, raccoons, and other raptors. However, human beings and their pets pose the greatest threat to Barn Owls.

Jun 08, 2008 -
The Barn Owl's eyes, like all owls, are fixed in their sockets. This means that they cannot change their field of vision without rotating their head.

Jun 11, 2008 -
Of all the animals who use sound to locate prey ever tested, the Barn Owl is by far the most accurate. One thing that does decrease this ability is rain.

Jun 12, 2008 -
Humans are not able to hear Barn Owl's in flight. Their flight is even silent on ultrasonic levels!!

Jun 14, 2008 -

Jun 16, 2008 -
Some sort of skeleton in the left corner of the picture.

Jun 17, 2008 -
Barn Owls have dark brown to black colored eyes.

Jun 19, 2008 -
On average, Barn Owls usually leave the nest at 65 days of age. These owls are 55-65 days of age, so we will be saying goodbye to them very soon!

Jun 21, 2008 -
Benicia, California, hit a high of 101 degrees today! The owls have assumed this position to expose as much surface air as possible to help cool them down.

Jun 24, 2008 -
One these birds fledge, they will randomly disperse and begin the search for a suitable nesting cavity. The search may last into the early winter or a site where they will eventually breed may be found by early November.

Jul 02, 2008 -
These owls are taking quite a bit of time to fledge!

Jul 08, 2008 -
Look at that wing span! No wonder barn owls are such great hunters.

Jul 16, 2008 -
The vole is the primary prey item of barn owls.

Aug 01, 2008 -

Aug 05, 2008 -
It is a little late in the summer to be starting a second brood. Usually, a second brood is started in mid-late July.

Aug 07, 2008 -
Barn Owls do not migrate. They remain in the same area for all four seasons. Barn Owls that live in areas with cold, snowy winters have to find a constant food source for they are not able to store large amounts of fat on their bodies.

Aug 10, 2008 -
Head shake!

Aug 11, 2008 -
Barn Owls usually hunt at night- beginning one hour after sunset and ending one hour before dawn. They will return to areas if they are successful in catching prey.

Aug 15, 2008 -
Normally, Barn Owls have a relatively short life-span with the average age expectancy somewhere around 2 years. However, there are exceptions- the oldest known wild Barn Owl in North America lived 11.5 years!

Sep 05, 2008 -
Barn Owls are able to recognize sounds of appropriate prey by memorizing prey noises. This ability is the most accurate of any animal tested, allowing capture of prey hidden by vegetation or snow.

Sep 05, 2008 -
Barn Owls are able to recognize sounds of appropriate prey by memorizing prey noises. This ability is the most accurate of any animal tested, allowing capture of prey hidden by vegetation or snow.