Tyto Alba — Another Non-Coyote Wildlife Adventure

Tyto Alba or Barn Owl (click on the individual photos to enlarge them)

Tyto Alba or Barn Owl (click on the individual photos to enlarge them)

It was dusk, and all was peacefully quieting down in the park until, “Clonk, clonk!” It sounded as though a clumsy big horse was having trouble getting back into its stall, knocking things over along the way. . . .  except that there are no horses or horse stables in San Francisco and haven’t been for decades, by law. This un-“natural” sound probably sounded all the more disparate because I was out in nature. Instead it was a young Barn Owl (Tyto Alba) waking up after a long days nap — banging against the sides of its own “barn” — a man-made owl box.

A few minutes later I heard loud wing battings. How could this be? Aren’t owls supposed to be silent flyers so as not to be heard by their prey? And then I heard what sounded like the complaints/warning cries of alarm of a bird such as a Stellar Jay — maybe a little different — and I figured some bird was warning-off these predator owls from encroachment. Wrong again. THAT was the sound of the Barn Owl itself! Barn owls don’t who, who, whoot, they screech in a bunch of different ways!

AUDIO: Notice there are a couple of distant coyote barks at the 34-39 second marker, and the owls get really intense at the 2:54 marker. The recording lasts 3:24 minutes.

As I sat there listening to their amazing shrieks, screeches, peeps, hissing and squawks, I saw one, and then THREE others — a total of four — fly off to a nearby tree — wow, there were that many here?! This was indeed a surprising night.

For years I’d seen one at a time at dawn and dusk, gliding and swooping in its silveriness, ever so silently through the dark. You could only see them as you do the bats — against the lighter night sky before total darkness set in. Once, I lay down on the ground and was able to capture, in a photo, an owl as it “mothed” right above me, from what seemed like five feet away, examining me out of curiosity — no, it was not courting me! It was only because that owl was against the lighter sky that the camera was able to capture its image — it was actually dark outside.

Why hadn’t I seen them here before? There were actually several signs that the owls were there, including the box itself. The old owl box has been empty for many years, or inhabited by squirrels, so there had been no reason for me to suspect that the box was rightfully occupied now, but there were other signs staring me in the face. Owl guano droppings had hardened along the length of a nearby tree trunk, and below another tree there were owl pellets and what looked like white splashes of paint — more guano, or owl poop which had been expelled away from the tree trunk and lay in individual blotches.

There was even a dead mouse which had been rejected. I pulled out my camera and took a few shots in the obscure nighttime lighting. I got home and processed the photos — nice photos except they were rather grainy due to the lack of light at 9:00pm. I decided that I would come back tomorrow and take photos with the aid of a flashlight, the way I had the raccoons years ago in Golden Gate Park.

2016-07-16 (11)The next evening, a little bit earlier than before — I didn’t want to miss anything — I arrived and plopped myself some distance away and waited. Soon a little face appeared in the hole of the box and I got a couple of shots. Then the face disappeared. The scenario repeated itself, only this time there was squawking from around me as the little feathery fella revealed himself. It was the adult owls — I thought they were chattering away. Several of the owls appeared on the branches in neighboring trees to gawk at me — like I suppose I was gawking at them.

I then focused the camera over on the owls in the branches and took some more pictures. The little fella in the box re-appeared in the opening. Suddenly the urgency in their shrieks intensified. And it is then that the tone of those intense squawks gained meaning: they were warning the little fella in the box: “keep down, keep down, danger, danger!!” All critters protect their nests and youngsters. Now a couple of the owls appeared on a nearby board/platform and right on the box itself, as those around continued their warning cries. They were distressed. And the youngster, too, looked worried, and cringed, and looked in the direction of the adults knowing that all the commotion signified danger.

Now I knew that the loud batting wings I had heard the day before also had been warning messages. I did not feel good about the distress.  I had the choice of returning the next day or lingering a moment longer to get a few more photos now. I decided on the latter course of action — it would be less disruptive than returning again. I grabbed a couple more shots and then left. I went home and processed the photos, looked up some tidbits of information which I’ve added below, and wrote up the encounter. I was totally distraught and upset that my presence had upset the owls which were in their nesting phase, and I vowed to never go back, and neither would I be the catalyst for others to disrupt these birds.

By extension, this situation is true for all wild animals anywhere, including coyotes in our parks: they just want to be left alone and not be noticed, but if they are intruded upon or threatened — even if it is just in their own perceptions — they will come forth with display messages and screeches — and more — if they feel a need to defend themselves, their territories, and especially their young.

I would write it up, but I would not reveal the nest location: the owls would not have wanted that. They are nocturnal, so if you want to see them you should begin your walk in the dark — and keep your eyes on the sky above the tree-line: you may see one floating silently by before returning to its roost at dawn, or as it begins its “day” hunting at dusk. Or, you could see them as a shimmer against the darker trees during those twilight hours. This experience of mine was so totally different from that with the famous Great Horned Owls in the Eucalyptus trees which many folks have observed, where the adult owls took the gawking of their owlets in stride.

Fortunately, this little green box is in a remote part of the park, actually in someone’s yard. One of the neighbors recently told me that “those birds” were keeping him up throughout the night. It is because he told me this that I stopped to investigate that “clonk” sound. Below, I’ve written up some tidbits of information I collected over the internet.

Territoriality. Barn Owls defend the area around their nests, but they don’t defend the area where they hunt from others of their same species — they share. In other words, more than one pair of Barn Owls may hunt on the same fields.

Contrast this with the Great Horned Owls who live in the same parks as the Barn Owls but who are very territorial: only one mated pair and their offspring live in the area. Their territoriality actually places a limit on the number of breeding pairs in any given area. Great Horned Owls who haven’t been able to establish territories are known as “floaters” — they live along boundaries of established territories.  In fact, it may be that just the male Great Horned Owls defend the territories. They are known to kill each other in territorial conflicts, and sometimes resort to cannibalism.

In the summer, the Barn Owls’ home hunting ranges are a little over a square mile; in the winter they can be many times larger. If food is extremely scarce, both of these owl species might move out of their established territories, but there is no annual migration and they maintain their territories for life.

Nesting. I found out that most Barn Owls mate for life — they are monogamous, as are Great Horned Owls — though there have been reports that some males have had several female mates at the same time. And Barn Owls tend to use the same nest site year after year. One of their courting displays is hovering in front of the female in a “moth-like fashion” — Oh, I’ve experienced this several years ago! Chicks usually start flying at 9-10 weeks and begin leaving the nest for good at about 11-12 weeks. All will probably be gone by 14 wks.

If there is nesting in July, as was the case with this find of mine, it’s usually a second clutch for the mated pair. About 10% of barn owls reproduce two times a year — and some even produce three clutches in a year! And, although the breeding season is considered from March to August — having expanded due to climate change from an original breeding season which was almost always in May — they, in fact, can produce youngsters at any time of the year.

They lay as many as 6 eggs, but more often than not, only about 4 of them hatch. The eggs are laid asynchronously, every 2-3 days and they hatch in the order in which they were laid (sounds like a business telephone answering service, doesn’t it?!). So chicks from the same clutch can actually vary up to about 21 days in their ages. The little guy in the box must have been the last in his clutch. Incubation is about 31 days. They don’t “build” nests, but find places to lay their eggs which they line with their pellets.

Poop. Pellets are actually excrement regurgitated through the mouth. Owls swallow their prey whole or tear larger prey into pieces to get it down their throats, but they don’t digest the bones and fur. The parts of the prey that actually pass through the digestive tract and out of their rumps are excreted as a softish, whitish “guano” — like that of all birds. Guano can often be found dripping down the tree trunks which they inhabit. However, in owls the larger, indigestible parts of the prey, including bones and fur, are kept in their gizzard for a couple of hours as a pellet which then travels back up into the Proventriculus (the first part of the stomach) where it remains for ten hours before being regurgitated. This stored pellet actually blocks the owl’s digestive system so that new prey cannot be swallowed until the pellet is ejected. Twice a day these are spat-up, or regurgitated out of their mouths, as “pellets”. These pellets basically look like the poop of other animals except that they are oval-shaped and not long. [see Digestion in Owls]

Hunting. All owls’ eyesight is pretty superb — they hunt at night [see “Coyote Night Vision”]. But, the ability of Barn Owls to capture prey by sound is the best of any animal that has ever been tested. Their satellite-dish shaped faces helps with this. They eat mostly small mammals such as rats, mice, voles, gophers. Also bats. They don’t eat squirrels so much because they are less active at night. They also eat some song birds. 91% of barn owls, post-mortem, are found to contain rat poison. The most long-lived Barn Owl ever recorded was 15 years old.

Poisons: Everyone, please don’t use poisons to eradicate rats, and please ask your neighbors to do the same. Rat poison is a horrible and slow death for rats, causing them to bleed from the inside out, and causing them to become disoriented and slow. This is why owls catch them. But worse, the poison actually travels up the food chain to these owls. Several years ago I sent in two dead barn owls for toxicity tests: they were found to have huge amounts of rat poisons laced throughout their bodies. We’ve also had a number of our Great Horned Owls killed by rat poisoning: One, this year, we guessed, was the mother of owlets who then never made it to adulthood.

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