We’re not the only ones who celebrate love this month. February is raptor courtship time.
Last year on Valentine’s Day the Decorah Eagles nestcam captured the bald eagles, “Mom and Dad”, vocalizing and mating.
This year the eagles have built a second nest that’s closer to the fish hatchery and not on camera! At this point it’s unclear which nest the eagles will use, but they’ll certainly disappoint their 60,500 followers if they choose the off camera site.
Pittsburgh’s “falconuts” experienced that disappointment a year ago when Dori and Louie chose a new nest site Downtown. Unfortunately it looks like the peregrines aren’t coming home to the Gulf Tower so we’re going to have another year of off-camera love birds.
How do you survey a population of owls who are afraid to make noise? Dogs to the rescue!
In 1990 northern spotted owls were listed as Threatened under the Endangered Species Act. Since then their population has been surveyed year after year, but despite changes in logging practices northern spotted owls continue to decline 3.7% per year.
Part of the problem could be that some owls have fallen silent and are impossible to count. The typical survey method is to play an owl recording and listen for the owl to respond. But barred owls have infiltrated the old growth forest, displaced northern spotted owls, and sometimes killed them. Some northern spotted owls would rather not respond when the tapes are played. They don’t want to give themselves away.
So how do you count these owls?
Researchers at the University of Washington trained two dogs, Max and Shrek, to identify owl pellets by species! Amazingly, the dogs can smell the difference in regurgitated mouse bones from a barred owl versus a northern spotted owl.
The team takes the dogs out for a spin in the forest. They don’t use recordings at all. The dogs sniff for pellets below owl roosts and are so good at identifying the species that they have a 30% better success rate at finding northern spotted owls than the recordings do.
Here’s Max triumphant. See the northern spotted owl in the tree above him?
How do owls turn their heads this far without killing themselves?
Trauma experts know that when humans turn their heads too far or too fast the arteries to the head are stretched or torn, cutting off the blood supply or producing blood clots that can kill.
Why doesn’t this happen to owls? A team at Johns Hopkins decided to find out.
Led by medical illustrator Fabian de Kok-Mercado, they used imaging technology on barred, snowy and great horned owls who had died of natural causes. The researchers found four adaptations that make the owls’ wide range of movement possible:
As in humans, the major arteries that feed the brain go through bony holes in the vertebrae but in owls these holes are 10 times larger than the arteries, allowing them to move within the hole without pinching.
The owls’ vertebral artery enters the neck higher up than in other birds — in the 12th vertebrae rather than the 14th. This provides more slack.
When an owl turns its head the arteries at the base of the head balloon to take in more blood. In humans the arteries get smaller and smaller.
Owls also have small vessel connections between the carotid and vertebral arteries so if one path is blocked the other still works.
A simple turn of the head that’s so hazardous to us is all in a day’s work for an owl.
Peregrine fans, does this photo remind you of someone?
This scene is from Baringo Cliffs, Kenya where a lanner falcon attacked a Verreaux’s eagle and forced it to flip upside down to defend itself.
Lanners are about the size of peregrines and they hate eagles just as much as our peregrines do.
The photographer, Steve Garvie, describes it this way:
“A pair of Lanner Falcons were nesting at one end of the cliffs and this massive female Verreaux’s Eagle drifted into their airspace. The female Lanner took to the air and quickly gained height then she flapped twice twisted onto her side then plunged in a deep stoop striking the circling eagle on the back of the head. The female eagle got a sore one and as the Lanner approached again she flipped upside down and clearly indicated there would be no second chance!”
Half a world away on June 6, 2012, Pitt’s famous peregrine Dorothy saw a bald eagle approach her “cliff” at the Cathedral of Learning. She too flapped a couple of times and then attacked. The bald eagle flipped upside down but it didn’t matter. Dorothy won.
Eagles, whether Verreaux’s or Bald, can’t fly upside down for long. Though Garvie doesn’t say it, I’m sure the lanner drove the eagle away just as Dorothy did at Pitt.
As winter approaches our local wildlife looks for safe, dry places to take shelter from the cold. Eastern screech-owls use hollow trees, dense foliage and holes in upright structures.
Last year Bill Powers of PixController set up an eastern screech-owl roosting study with five owl boxes in a dry wetland in Westmoreland County. Each box is equipped with a small infrared video camera and small microphone wired back to a server that detects motion and streams video.
The program begins in familiar territory, a farm in Wisconsin where two young snowies hunt the winter fields. Meanwhile their parents are back home in perpetual darkness. The show’s excellent footage of the arctic night gives a real taste of life in the dark.
In spring the camera crew searches for nesting owls, eventually finding a pair alone. Their solitude might not be a good sign. Will there be enough to eat? Will their young survive to adulthood?
Peregrine nestcam fans will love watching close-ups of Mother Owl with her cute babies. The saga of Father Owl’s hunt for food will sound familiar, but the dangers of polar bears and the plague of mosquitoes will not.
And there isn’t enough food. Eventually the parents have to move their entire family to the coast even though the babies can’t fly yet. The young have to walk and swim(!) to get there.
The family’s endurance is amazing. The snowy owls are almost magical.
Don’t miss Magic of the Snowy Owl on Wednesday October 24 at 8:00pm on WQED. Check local PBS listings if you’re outside WQED’s viewing area.
(photos of snowy owls in the arctic from PBS NATURE)
p.s. If you like to identify birds by ear, you’ll enjoy the soundtrack of the arctic summer.
Last evening as I left work I heard a scrabbling on the edge of this huge satellite dish behind WQED. It sounded like claws scratching metal — almost as unpleasant as fingernails on a chalkboard. The noise attracted the attention of everyone nearby.
The sound was made by a red-tailed hawk who had landed on the dish to hunt rabbits in the weeds below. Not a good move! He slid down to the seam and stood lopsided, one foot higher than the other, gripping the edge.
Since he didn’t care that I was watching I took his picture with my cellphone. (He’s in the exact center of the photo.)
Fortunately it doesn’t matter if he hurts this dish as we haven’t used it for years. Trees have grown up around it and mossy dirt stains the inside. Like many defunct structures it’s too expensive to take down, so it’s slowly surrounded by urban wildlife.