Don Lyman
The Boston Globe, February 25, 2022
A red phase eastern screech-owl. MARK FAHERTY/MASS AUDUBON
In the summer of 1996, I participated as a graduate student in a tropical biodiversity and evolution course in Costa Rica.
As we were driving to the Palo Verde Research Station near the Pacific Ocean, a tropical screech-owl collided with our bus. The driver pulled over and one of the graduate students hopped out and picked up the injured bird, so we could drop it off at a wildlife rehabilitation clinic the next day.
That night as we all hung out on the cement porch of the research station, enjoying the warm night, someone brought the little owl out to join us.
The porch light attracted a variety of insects and other arthropods, including scorpions. We were all surprised when the screech-owl grabbed a scorpion and adeptly dispatched the venomous creature by biting its stinger off and swallowing it whole. The other 20 or so graduate students and I spent the rest of the evening drinking beer, sharing stories and research ideas, and feeding scorpions to the owl. Judging by the way it was gobbling them down, that was one happy owl.
Screech-owls in Massachusetts don’t eat scorpions, but they do have quite a varied diet, which includes small mammals and birds, frogs, salamanders, and snakes, as well as insects like moths and grasshoppers, according to Wayne Petersen, director of the Massachusetts Important Bird Areas Program for Mass Audubon.
“They eat weird things, too, like earthworms,” said Petersen. “They’ll even take fish.” One way to tell what owls have been eating is by analyzing owl pellets. The non-digestible remains of what the owls have eaten, such as bones, fur, and feathers, are coalesced into a pellet and regurgitated, Petersen explained. Owl pellets are a rich source of information about their diets and can often be found on the ground beneath owl roosts.
The Eastern Screech-Owl — the species that lives in Massachusetts — is found east of the Rocky Mountains, from southern Canada to Mexico. It occurs throughout Massachusetts, but is more common in the eastern part of the state than in central and western Massachusetts, said Petersen.
A gray phase eastern screech-owl sitting in the opening of a tree cavity. DAVID LARSON/MASS AUDUBON
Eastern Screech-Owls like deciduous forests, as well as forests that contain both evergreens and deciduous trees, Petersen explained. And these little owls are surprisingly common in the suburbs.
“They’re not a wilderness bird, not a deep woods bird,” said Petersen. “They’re as apt to be in a cemetery, city park, or someone’s backyard as they are in the woods.”
Petersen added that although Eastern Screech-Owls — along with Great Horned Owls — are the most common owls in Massachusetts, most people don’t encounter them very often. This is because they’re well-camouflaged, nocturnal, and tend to hang out in tree cavities.
Eastern Screech-Owls are generally one of two colors — rusty red or more commonly gray — or occasionally an intermediate brownish color, and if they’re sitting in a hole in a tree they’re hard to see because they blend in with the bark.
People are more likely to hear screech owls than to see them, Petersen said. But their calls aren’t actually a screech.
“They sound like the whinny of a horse,” said Petersen. “They sometimes make a low monotone trilling call as well. You can often get screech-owls to call if you imitate them or play a recording of a screech-owl on your cellphone.”
The Mass Audubon website says that Eastern Screech-Owls can be heard throughout the year, but become most vocal from late winter to early spring during the beginning of their breeding season. But Petersen said August and September are when you’re most apt to hear screech-owls calling spontaneously, probably because that’s when the young are dispersing and calling.
Mass Audubon said that Eastern Screech-Owls do not build nests. They lay their eggs in natural tree cavities or in holes drilled by woodpeckers. Petersen said screech-owls also will lay their eggs in nest boxes. Screech-owl nest boxes can be built or purchased, and mounted on a tree or post in your yard.
Screech-owls usually lay four to five eggs, said Petersen. Prime egg-laying time in Massachusetts is late March through mid-April.
Mass Audubon said the incubation period averages 26 days. The young leave the nest in four to five weeks, but owl families may remain near each other through the end of the summer.
Eastern Screech-Owls grow to a length of about 8½ inches, with a wingspan of about 20 inches, according to the Sibley Birds East field guide. They are the second smallest owl in Massachusetts, after the diminutive Northern Saw-whet, said Petersen. As with most raptors, females are larger than males.
Screech-owls have pointed ear tufts on the tops of their heads, but Petersen said they aren’t really ears, but simply tufts of feathers that resemble ears. Screech-owls’ actual ear openings are located on the sides of their heads, and are asymmetrical in position and internal configuration, which helps them locate prey in the dark. Petersen explained that the difference in the positioning of their ear openings allows the owls to better determine the location of prey by pinpointing the direction the sound is coming from.
Screech-owls like to hunt along the edges of fields, said Petersen, but this makes them vulnerable to predation by larger owls such as barred and Great Horned Owls. Other causes of mortality include eating mice and rats that have been poisoned with rodenticides, and being hit by cars.
“Screech-owls get hit by cars a lot, probably because they chase moths that are attracted to street lights during the summer,” Petersen said.
The oldest recorded Eastern Screech-Owl in the wild was at least 14 years, 6 months old when it was found in Ontario in 1968, according to the Cornell Lab of Ornithology.
Petersen, who has worked with screech-owls, said they’re feisty, and will readily scratch with their talons and bite when handled.
“Screech-owls are a fun little bird, but not the friendliest owls,” said Petersen. “They can be remarkably aggressive.”
Owl Prowls:
If you would like to see or hear some owls in the wild, several local birding and conservation organizations conduct “owl prowls” this time of year. Visit these websites for more information:
The Trustees of Reservations: thetrustees.org/program/owl-prowls/
Comments