Who Cooks for You?

In September, last year’s AmeriCorps members gave Ashley, Danielle, Sam, and me a tour of the School of Conservation Campus.  It was one of the few warm days that remained, and we took our time near the canoes and rowboats near the docks on the Sequoya side of campus.  We sat on red benches in the Pavilion, a small building with removable walls, open to the late summer sunshine.  Looking up at the roof of the Pavilion, we could see the remains of nests made in spring by Phoebes and Barn Swallows.  In one corner of the Pavilion, an Eastern Screech Owl perched atop a song bird’s nest.  It was so motionless in sleep that at first, I believed that the owl was a taxidermied specimen, put there on display.  In fact, it was a living owl, but it wasn’t until the bird squinted its eyes open and peeked at me that I was convinced.

The Eastern Screech Owl (Otus asio) is one of seven owls found in New Jersey.  The most common species found in the state are the Eastern Screech Owl, Great Horned Owl (Bubo virginianus), and Barred Owl (Strix varia).  Barn Owls (Tyto alba) and Northern Saw-whet Owls (Aegolius acadicus) are also found in New Jersey, and the Long-Eared Owl (Asio otus) and Short-Eared Owl (Asio flammeus) can be found overwintering here.  

Primarily nocturnal birds with excellent camouflage, owls are often better known by sound than by sight.  In Walden; or, Life in the Woods, Henry David Thoreau writes extensively about the owls that he hears nightly at Walden Pond.  Thoreau describes the Eastern Screech Owls as “Wise midnight hags!” whose “wailing” and “doleful responses” he loves to hear.  In fact, Thoreau states, “I rejoice that there are owls…It is a sound admirably suited to swamps and twilight woods which no day illustrates, suggesting a vast and undeveloped nature which men have not recognized” (82).  Known only for the sounds they make at night, owls come to represent mystery and darkness, obscurity and ghostly twilight.  From the Eastern Screech Owl’s whistled trill and the Great Horned Owl’s deep hooting to the Barred Owl’s cackling and cawing and the Barn Owl’s hissing scream, owls are recognized by their haunting calls.

Contrary to popular belief, owls cannot turn their heads all the way around.  Owls turn their heads three quarters of the way around in order to change their field of vision.  An owl doesn’t have enough room in its head for eye muscles; therefore, the owl relies on turning its head to see from different angles.  Owls also have 14 vertebrae in their necks—twice as many as in mammals—that allow them to turn their heads.  Because owls can move their heads so far and so rapidly, it often appears that they can turn their heads around completely.  This ability to have eyes in the back of their heads helps make these birds excellent hunters, able to look in almost any direction to see the animals they hunt.

These nighttime birds of prey mainly hunt rodents such as mice.  The Eastern Screech Owl will also eat insects, songbirds, and earthworms; they will even dive for fish or crayfish.  The Barred Owl also eats crayfish; it is believed that this causes the belly feathers of some Barred Owls to turn pink!  The more vicious Great Horned Owl will eat larger animals, like rabbits, squirrels, geese, and snakes.  This owl will also prey on crows, and because of this, crows regularly mob and harass owls.  The Great Horned Owl will even eat skunks!  Most owls eat a variety of small mammals, songbirds, and large insects.  The Barn Owl and Long-Eared Owl have particularly good hearing and are able to catch prey in complete darkness.  The prey of owls can be discovered by studying owl pellets, or small masses of undigested parts from the owl’s food.  Inside an owl pellet, one can find many indigestible materials, from the bones of rodents to the exoskeletons of insects to fur or feathers.  These indigestible materials collect in the owl’s stomach, and a pellet is formed.  The pellets are expelled before the night’s hunting by regurgitation; owl pellets can often be found beneath the bird’s nest or a regular roost within the owl’s hunting grounds.

Unlike most birds, owls do not build their own nests.  Some owls, like the Great Horned Owl, Long-Eared Owl, and Barred Owl will lay their eggs in the existing nest of a hawk, heron, crow, magpie, or squirrel.  The Barred Owl may also lay her eggs in a tree cavity or an old woodpecker hole, as will the Eastern Screech Owl and the Northern Saw-whet Owl.  The Short-Eared Owl will lay her eggs in a shallow, grass-lined depression, well-hidden by vegetation, and the Barn Owl will simply lay her eggs on a bare surface, such as in the corner of a barn or attic.  Depending on the species, owls will lay between two and eleven eggs; females will incubate the eggs themselves.  In some species, the males will hunt for food and protect the nests.  Most owl chicks will be ready to leave the nest after four to ten weeks, depending on the species.

This winter, New Jersey has had an unexpected visitor.  On November 8, 2011, a juvenile female Snowy Owl (Nyctea scandiaca) was spotted at Merrill Creek Reservoir in Warren County.  At the time of this writing, the owl could still be found there.  This Snowy Owl has likely taken up residency here in New Jersey, far south of its normal range, due to a strong breeding season in the northern tundra of Canada and Alaska this past summer.  Such a rise in population has sent younger birds further south to look for food this winter.  The arrival of the Snowy Owl in New Jersey has been an exciting opportunity for birdwatchers, who have flocked to Merrill Creek to view and photograph the bright white bird.  Almost as unusual as seeing the Snowy Owl in New Jersey is getting the chance to view any of the state’s seven owl species.  The lucky birdwatcher gets the chance to view these elusive, nocturnal, mysterious birds.  Their hooting, cackling, and hissing at night are indicators of their presence, even if we don’t get the chance to see these big-eyed nighttime birds.
 

References:

All About Birds. The Cornell Lab of Ornithology. 25 Jan. 2012. .

"Barred Owl." Science Museum of Minnesota. Warner Nature Center. 25 Jan. 2012.

Malok, Andre. "Snowy Owl Takes up Residence at Merrill Creek Reservoir in Warren County." NJ.com. The Star Ledger, 6 Jan. 2012. 26 Jan. 2012.    ledger/2012/01/snowy_owl_takes_up_residence_a.html

Thoreau, Henry David. Walden; or, Life in the Woods. New York: Dover Publications, 1995.

Vanner, Michael. The Encyclopedia of North American Birds. Barnes and Noble, 2003.

“What Is an Owl Pellet?” Owl Pellets. 25 Jan. 2012.