Changes in ag lead to decline of barn owls

There was a lot of excitement, considering it was something so small. Farmers in northwest Pennsylvania recently found a little barn owl that had fallen out of the nest, obviously in distress. It had not fledged yet, so was unable to fly back up to the barn rafters. Carol Holmgren of the Tamarack Wildlife Rehab Center took it in and cared for it until it was declared fit to return to its family: three siblings and their parents.

Stacy Wolbert, Northwest Regional Wildlife Diversity Biologist for the Pennsylvania Game Commission, was one of the people responsible for taking the owlet home. “It was very exciting, and new to me,” Wolbert said.

Why new and exciting? Because nesting barn owls had not been seen in northwestern Pennsylvania since 1989. The fact that they are now speaks to the success of the Barn Owl Conservation Initiative, which the game commission began in 2005.

Threatened

Barn owls are just one step below “threatened” in Pennsylvania, and are listed as threatened in Ohio and many other states. They flourished in the first half of the 1900s when there were plenty of old, drafty barns and silos in which to nest. And they had plenty of habitat.

Barn owls prefer hay fields, wet meadows, lightly-grazed pastures and abandoned farmland, Wolbert said. That’s where they find the meadow vole — which makes up 75% of the barn owl’s diet — along with rats, shrews and other small rodents.

Changes in farmland

But scientists have seen steep declines in barn owl populations in recent decades. In Pennsylvania, it’s estimated that their population has been reduced by half since the 1980s. The main reason for their decline seems to be loss of farmland, especially those grassy fields they depend on.

That has also impacted the bobolink, Eastern meadowlark and other grassland birds, which are declining faster than any other group. Even if the farms remain, many old barns and silos were knocked down and replaced with metal structures that barn owls can’t access.

Most of all, agriculture changed. There is no longer the diversity of hay, pasture and fallow fields; most farms are now planted in corn and soybeans. Those crops are of no value to the meadow vole, therefore of no value to the barn owls that need them in order to survive, said Wildlife Diversity Biologist Dan Mummert, who has worked with the barn owl initiative since it began 15 years ago.

Conservation initiative

The purpose of the project is to “figure out where barn owls are nesting, monitor those sites year after year, and determine how many successful nests we have in the state,” said Mummert, who is stationed in Lititz. A total of 236 nest sites have been confirmed in Pennsylvania. Of those, the three that were found in the western part of the state generated the most excitement.

“The project started in 2005, but it wasn’t until 2018 that we were able to confirm barn owl nests in the western third of Pennsylvania,” Mummert said. “And it wasn’t until this year that we found a nest in the northwestern part of the state.”

The fledgelings in those 236 nests were banded, and 118 were later recovered. They had traveled an average of 21 miles, although one flew a whopping 926 miles away. Another didn’t travel at all, choosing to live in his parents’ basement, so to speak.

“Usually farmers find them,” Mummert said of the recovered birds. “Each band has a distinctive number, and a phone number to call.”

Winter struggles

It is no coincidence that most of the calls come in the winter. And the statistics surrounding those recoveries may help explain why the species has been in decline.

“About 95% of the barn owls we recover are dead,” Mummert said. “We learned that 75% of the fledgelings never make it to their first birthday.”

“They’re really inexperienced at hunting, or it’s really cold with lots of snow,” he explained. “They have a hard time finding enough food and they starve to death.”

The key to the barn owl’s hunting skills is not good eyesight, but exceptional hearing. Even in winter, under several inches of snow, they can hear meadow voles moving. They dive right through the snow and snag them.

Their hearing is helped by the flat ruff of feathers that covers the barn owl’s face — and is the cause of one of its nicknames, “monkey-faced owl.” But that flat facial disc “acts like that plastic dish that someone holds on the sidelines of the football field to amplify the sound,” Mummert said.

Nest boxes

Aside from discovering barn owl nests and banding the young birds that come from them, another goal of the barn owl initiative is placing nest boxes near existing nests, or in new areas that would provide suitable habitat for barn owls. Scientists recommend at least 100 acres of grassland habitat within a half-mile mile radius of the nest box site.

In 2013, ODNR’s Division of Wildlife began a program to place nest boxes in grassland habitat in an effort to help barn owl populations. Since then, more than 120 new nest boxes have been placed in every township that has more than 25% grassland cover.

The nest boxes are needed because, unlike other birds, barn owls don’t actually build nests. Instead, they look for a wide beam or flat area, often in a barn or near the top of a silo. The problem is that eggs can roll off, or nestlings can fall out. That makes the nest boxes much safer. And at more than three yards long, the boxes are big enough to accommodate a fairly large family of fairly large birds. Barn owls only weigh one and a quarter pounds, but their wingspan is between 3.5 and four feet. That allows them to slowly glide over farm fields, searching for prey.

Nestlings

Barn owls typically hatch five or six eggs, although in rare cases, as many as nine. Instead of laying all their eggs at once, as many other birds do, barn owls are “asynchronous,” laying an egg every other day, Mummert said. That means the eggs hatch at different times, though always in the order they were laid. Since the eggs take about a month to hatch, there could be two weeks’ difference between the oldest and youngest in a nest of six. During that month, the female barn owl is sitting most of the time.

The male goes out at night to hunt and brings food back for her. Later, he brings food for the hatchlings, too. The newborns don’t have enough feathers to regulate body temperature. The female continues to sit with them and keep them warm for another three weeks.

It takes a total of two months for the young to fledge, or be able to fly out of the nest. When they do, they go out at night with their parents, but return to the nest during the day. The parents teach them how to hunt, but continue to find food for the young and feed them.

Since each barn owl can eat between three and five rodents a day, that means the whole family could eat as many as 2,500 in a year.

“They’re absolutely one of the farmer’s best friends,” Mummert said.

Like many best friends, barn owls have a quirk that some may find annoying, maybe even frightening. Unlike those of other owls, the barn owl’s call is not a hoot, but “more like a screaming, hissing sound,” Mummert said. ” If you hear it in October, it sounds very appropriate for Halloween.”

Mummert, Wolpert and other scientists not only want folks to notify them if they find banded barn owls, but also if they find barn owl nests. If you do, call the game commission’s Regional Wildlife Diversity Biologist for your area, or visit pgc.pa.gov, click on Information Resources, Get Involved, and Landowner Programs.