Unknown Illinois: Prowling For Owls

Jun 13, 2017

It’s a perfect night to watch for nocturnal birds. Calm winds, clear sky and waxing moon just above the horizon.

I’m standing at dusk on the Lexington Blacktop, just east of Lake Bloomington. I’m with Angelo Capparella of the biology department at Illinois State University, and Given Harper, another avid bird watcher and professor at Illinois Wesleyan.

We’re on the prowl for owls.

Bird watchers often participate in official counts as a way of helping wildlife officials to keep track of the particular species residing in or passing through McLean County.  But counts of nocturnal birds, like owls, are less common.

"Most of the regular counts we do such as the spring bird count and Christmas bird county don't really capture these nocturnal birds. And we know some of these nocturnal birds are in trouble," Capparella said.

The idea for a nocturnal count actually emerged because of the plight of another bird. People who live out in the country stopped hearing a familiar summertime sound. The plaintive call of the nocturnal whippoorwill.

“Older folks probably remember hearing these birds, and they’re very hard to hear now .Their population throughout the Midwest has been collapsing and that was part of the impetus for establishing this monitoring network across the state of Illinois to track population trends," Capparella said.

"We may have to eventually list the whippoorwill as an endangered species even though it was once incredibly common and was a part of summer nights," he added.

The whipper will literally says its name.

“It’s onomatopoeia in that it actually says whippoorwill in its own little dialect,” Capparella said.

One reason the whippoorwills have gone away is habitat loss. Maple trees have taken over forest areas that once held mostly oak and hickory trees, which whippoorwills like.

Pesticides have reduced the insects they fed on. "We have been sterilizing the Midwest for years, spraying pesticides everywhere. That led to the collapse of their food supply, which is moths. It is pretty evident. Moths were so common around our street lights in the past and you hardly see that anymore," Capparella said.

Concern over the disappearing whippoorwill led state wildlife officials to study the owl population as well. 

Three types of owls currently nest across McLean County.  They the barred owl, the great horned owl and the Eastern screech owl.

Once a total of five species were common here. However, the other two,  the barn owl and the short-eared owl, are now listed as threatened and endangered.

The owls that remain seem to be doing better than the whippoorwill. That's partly because  owls eat both mammals and insects, and so they have a larger meal base. But there are some warning signs.

“Things can happen with them. When the West Nile virus came here around 2000 or 2001, the great horned owls were heavily affected. We don’t know how much or how well they might have recovered because we don’t have data," Capparella said. But the current owl count is expected to shed some light.

Capparella and Harper serve as an observation team, making a loop of 10 stops across rural McLean County listening for owl calls, and hoping to catch a glimpse of one or two. 

They play a series of recorded owl calls to prompt a response from whatever owls might be in the area. 

"We stop six minutes and listen without playing any recordings and we record all species we hear. Then we will play a screech owl call and listen for two minutes. We will also play a barn owl call and listen for two minutes," Harper explains.

They only play their recording of the barn owl, however, when they aren't near anyone's house.

"Barn owls have a really frightening, hissing scream and we just have decided we will only do that when we are some distance from homes," Harper said.

I understand what he means just as soon he plays the ear-splitting scream of the barn owl's call – the sound effect for  many a horror film or Halloween tape.

Even though barn owls have virtually disappeared from McLean County, their distinctive screech will spark a reply in other owls that might be nearby. 

"They will perceive the call as a territorial intrusion and come in and inspect, and often times they will call back," Harper said.

Capparella uses a timer in each location to see how many calls he and Harper hear in a six-minute interval. He often has to wait to start his recordings because of the incessant noise from passing cars, even on rural roads like the Lexington blacktop.

“One thing we really notice is amount of noise pollution humans create. When you're trying to focus on the natural world it is really obvious," Capparella said.

On previous evenings, they have had some close encounters with owls. 

“One night I was dong screech owl call and one landed by my feet on the road which really freaked out both of us," Capparella said.

​He places his iPod on the hood of his Subaru and broadcasts the tape of a rather loud screech owl call. 

What comes next is several minutes of intense listening.

“Two juvenile great horned owls giving begging calls in the distance," Harper whispers after a few moments.

I, on the other hand, hear nothing. Harper says he can pick up the young owls' distant raspy calls because he has been listening to owls his entire life. Sometimes, to promote a response, Harper will start cooing an owl call himself.

Owls are astonishing creatures. They have asymmetrical ears so they can locate sounds in different dimensions. They do have good eyesight, but their eyes can’t move in their sockets, which is why they move their heads around so much. They are outstanding hunters. Unfortunately, the great horned owl occasionally will feast on other owls too.

After about two hours of watching and waiting, as the wind picks up and the temperature drops, we finally actually see our first owl of the night: an adult barred owl.

It swoops by a few feet overhead so quickly, like a piece of black drapery soaring on the wind, that I don’t have time to record its call. 

It’s about 11 p.m. and three of us are tired and ready to go home. The total number of owls we’ve heard this evening: 10. They encompass all three of the species still found in the county.  

Based on just that night’s count, Capparella and Harper declare the state of at least those three kinds of owls to be in fairly good shape locally. 

"One can't really go by a single night, but this was a pretty good run. I would say tonight was one of our better runs, especially since we had all three species," Capparella said.

Be assured, though, on the next clear night of a nearly full moon, these two intrepid bird watchers will be out once again, playing their recorded owl calls and hoping for a close-up glimpse of these ghostly night prowlers.

And they keep hoping they also might hear once again the song of the elusive whippoorwill.