Category Archives: Birds of Prey

Eagle Productivity Drops For a Good Reason

Juvenile bald eagle at Hays, H8, 23 June 2018 (photo by Dana Nesiti)
Juvenile bald eagle at Hays, H8, 23 June 2018 (photo by Dana Nesiti)

Bald eagles have made an amazing comeback since the days of DDT.  From less than 900 birds nationwide in the early 1960s to more than 20,000 in the U.S. in 2007, their population more than doubled in Pennsylvania in the last 10 years.

At some point the number of nesting bald eagles will reach Pennsylvania’s carrying capacity.  What happens then?  How do bald eagles respond to match available food and nest sites?   We can look to Virginia for the answer.

Since 1964 the Center for Conservation Biology in Williamsburg has monitored and mapped bald eagle nests in the James River watershed.  Every year they do a flyover of the entire area to count both nests and chicks. Their eagle population grew from none in 1976 to a record 289 nests in 2018.  Meanwhile the number of chicks per nest — called “productivity” — rose sharply in the early years of recovery and now is dropping.  CCB announced this trend in two articles:

To see how this works, I have made a slideshow of two graphs from the Center for Conservation Biology’s article.  The bar chart is the count of nesting pairs, 0 to 289.  The line chart, the arc, is the average number of chicks per nest, 0 to 1.6.

As you can see, the number of nesting pairs continues to increase while the number of chicks per nest moves down.

CCB reports that in 2018 the number of chicks reached 1.09 and adds, “The two opposing trends appear to continue the population’s path to stability.”

“Productivity decline” sounds bad but it’s actually good news.  Breeding eagles respond naturally to accommodate lots of adults in the habitat.

So what does this mean for Pennsylvania’s bald eagles?

If the James River experience applies here, we’ll still see an increasing number of bald eagle nests that will eventually average one eaglet per nest.  We know bald eagles can produce more if they need to.  The good news is, they don’t need to.

 

p.s. See how rapidly the James River nest count grew!   Click here for CCB’s maps of the James River bald eagle population, 1990-2017.

(photo of juvenile bald eagle H8 at the Hays nest site by Dana Nesiti. Slideshow of two graphs from the Center for Conservation Biology article Eagle Productivity Continues to Slide.)

Merlin Attack! Raven or Crow?

Merlin attacks a big black corvid at Renews, NL (photo by Trina Anderson)
Merlin attacks a raven at Renews, NL, 10 July 2018 (photo by Trina Anderson)

Last week in Newfoundland our birding tour witnessed an amazing bird interaction when a merlin attacked a big black corvid in the air.  It happened so fast that we had to think hard about the birds’ identities.

Yes the attacker was a merlin —  a small, streaky dark, very fast falcon that made this sound as it attacked. (Xeno-canto XC332445: alarm calls of merlin pair recorded by Pritam Baruah in Churchill, MB, August 2016)

But was the big black bird a crow or a raven?

Fellow traveler Trina Anderson captured the action with her camera. Before we saw her photos we could only identify the corvid by size and behavior.  We decided “raven” based on the relative size of the two birds and the behavior of the raven.

  • Merlins are 2/3 the size of a crow but less than half the size of a raven.  Overhead the merlin was tiny compared to the bird it attacked, so it had to be a raven. Trina’s photos show the size difference.
  • The black bird barely flapped during the interaction and it flipped upside down in flight (see the last photo). Crows flap hard when they’re under attack and they don’t fly upside down.
  • During the fight it was hard to see the diagnostic field mark — the tail — but Trina’s next photo shows the corvid has a wedge-shaped tail. That means “raven.”
Merlin attacks a corvid, Renews, NL, 10 July 2018 (photo by Trina Anderson)
Merlin attacks raven, Renews, NL, 10 July 2018 (photo by Trina Anderson)
Merlin attack! Raven flips upside down, Renews, NL, 10 July 2010 (photo by Trina Anderson)
Merlin attacks! Raven flips upside down, Renews, NL, 10 July 2010 (photo by Trina Anderson)

It’s hard to tell ravens from crows unless you have some practice.  Get tips on how to tell them apart in this 3 minute video from The Raven Diaries: Ravens vs Crows, they’re different!

 

(photos by Trina Anderson. See more of photos of our Newfoundland trip in her Flickr album.)

What Is He Doing?

Canadian blowing up a fish (photo by Chris Colaianni)
Captain Ray with a fish (photo by Chris Colaianni)

On Throw Back Thursday:

Eight years ago Chris Colaianni went on a fishing trip in the Canadian Rockies and came back with this amazing story.

Their guide, Captain Ray, used a fish to attract a bird. But why does he have the fish in his mouth?  Click here to find out in this vintage article: WHAT Is He Doing?

 

(photo by Chris Colaianni)

Happy 4th With The Harmar Eagles

Juvenile bald eagle near the Harmar Twp nest, 1 July 2018 (photo by Annette Devinney)
Juvenile bald eagle near the Harmar Twp nest, 1 July 2018 (photo by Annette Devinney)

In Pittsburgh we’re lucky to have three bald eagle nests in Allegheny County:  Hays on the Monongahela River, Harmar on the Allegheny River, and Crescent Township on the Ohio River.

Last weekend the two youngsters at the Harmar nest made their first flight.  Annette and Gerry Devinney were on hand to record their progress on 1 July 2018.  Here are some of Annette’s photos and Gerry’s video.

Below, the two young eagles fly near each other.  They’re looking good.

Juvenile bald eagles in flight near their Harmar Twp nest, 1 July 2018 (photo by Annette Devinney)
Juvenile bald eagles in flight near their Harmar Twp nest, 1 July 2018 (photo by Annette Devinney)

Woo hoo! They’re playing in the sky.

Two juvenile bald eagles play in the sky, Harmar Twp, PA, 1 July 2018 (photo by Annette Devinney)
Two juvenile bald eagles play in the sky, Harmar Twp, PA, 1 July 2018 (photo by Annette Devinney)

Gerry captured their soaring and antics in this video.

Happy Fourth of July!

 

(photos by Annette Devinney, video from Gerry Devinney on Vimeo)

 

Thank You For Eating Them

Hays bald eagle female returns with a rat to feed her fledgling, H8, 23 June 2018 (photo by Dana Nesiti)
Hays bald eagle female returns with a rat to feed her fledgling, H8, 23 June 2018 (photo by Dana Nesiti)

We often complain when birds of prey eat “our” songbirds, rabbits, chipmunks and squirrels but there’s one prey item that no one quarrels about.

Last weekend Dana Nesiti posted a photo series at Eagles of Hays PA:  The mother bald eagle brought food for her fledgling, H8, who quickly crowded her and grabbed for it. The prey was nearly lost in the scuffle.  (click here for the photo album)

What did she bring him for dinner?  A rat!

Thank goodness birds of prey are eating rats. I’ve seen red-tailed hawks eat them, too.

On Throw Back Thursday, read about a red-tail that’s Performing a Public Service.

 

p.s. If you see a hawk eating a rat, it’s not a peregrine falcon.  Peregrines catch their prey in flight. Rats don’t fly.  😮

(photos by Dana Nesiti)

Air Traffic Control

Dorothy stoops on an immature bald eagle, 6 June 2012 (photo by Peter Bell)
Dorothy stoops on an immature bald eagle, 6 June 2012 (photo by Peter Bell)

The airspace over Greenfield was busy with bird traffic on Sunday. One of those birds was in control.

Around noon Anne Marie Bosnyak, Linda Schmidt and I were chatting at a table outside the Staghorn Cafe when Anne Marie pointed out four distant turkey vultures. She’d left her binoculars in the car so she wasn’t sure about the fourth one. With my binoculars I identified it — a peregrine falcon.  At that distance I couldn’t tell if it was immature or adult.

Most birds avoid flying near peregrines because of their swift pursuit of avian prey and fierce territoriality.  The vultures were no exception.  They circled together and moved westward, away from the peregrine heading south.

The peregrine rose in the heated air, then noticed a pair of dark birds rapidly heading west and turned to follow them.

Ravens.  As if to acknowledge the peregrine’s presence one of them tumbled three times in the sky but they didn’t slow down.  The ravens left without incident.

The peregrine circled lazily in the heat and then something really interesting flew below him — an adult bald eagle heading toward the Monongahela River.

As I watched, the peregrine dove several times at the bald eagle and drove it lower and away.  Even through binoculars I could see the eagle flinch as it tried to evade the peregrine.  They disappeared over the horizon toward Hays.

In Pennsylvania peregrine falcons control the airspace whenever they want to.  Bald eagles don’t stand a chance, as shown in Peter Bell’s photo above.

Here’s what happened during a similar incident in 2012: Peregrine Versus Bald Eagle … Guess Who Won.

 

(photo by Peter Bell)

Watch Nesting Ospreys

Feeding the chicks at the Hellgate osprey nest, 5 June 2018 (photo from Cornell Lab Hellgate Osprey cam)
Feeding the chicks at the Hellgate osprey nest, 5 June 2018 (photo from Cornell Lab Hellgate Osprey cam)

If you miss seeing nesting peregrines on camera here’s a raptor family to watch online.  As of last night (June 5), there were two chicks and one egg still to go at an osprey nest in Montana.

The nest is in Hellgate Canyon next to the Clark Fork River in Missoula, Montana.  It looks like a very public place but the birds are right next to the river.  The Hellgate valley is so narrow here that the river, the railroad, some businesses, and Interstate 90 are all close by.  We see and hear I-90 traffic in the background. (Click here for a map of the site.)

Louis and Iris are devoted parents whose lives are sometimes complicated by terrible weather and threats from challengers.  And yet they persist.  In this video clip Louis brings Iris a fish to eat while she was incubating last week.  Click here for a 36 minute video of the first chick’s first feeding.

The chicks are tiny.  There’s plenty to see.  Tune in here to watch their progress at the Hellgate Osprey nest.

 

p.s. If you watch before 7:15a Pittsburgh time, you’ll see that the sun hasn’t risen yet in Montana!

(photo from tweet of Cornell Lab’s Hellgate Osprey nestcam)

Red-Tailed Hawks Getting Ready To Fly

Young red-tailed hawk nearly airborne, 3 June 2018 (photo by Gregory Diskin)
Young red-tailed hawk nearly airborne, 3 June 2018 (photo by Gregory Diskin)

The Pitt peregrines have flown. The young red-tailed hawks in Schenley Park are getting ready to go. Here are photos of their recent activity by Gregory Diskin.

The youngsters are fully feathered now, ledge walking and wing exercising.  On June 3, one of them flapped so hard he was nearly airborne.

Young red-tailed hawk exercising his wings, 3 June 2018 (photo by Gregory Diskin)
Young red-tailed hawk exercising his wings, 3 June 2018 (photo by Gregory Diskin)

When they aren’t busy exercising, they gaze at their parents who often perch in a large sycamore tree across the way.

Young red-tailed hawks in Schenley Park, almost ready to fly, 2 June 2018 (photo by Gregory Diskin)
Young red-tailed hawks in Schenley Park, almost ready to fly, 2 June 2018 (photo by Gregory Diskin)

And they watch intensely as their parents fly.  “So that’s how it’s done.”

Red-tailed hawk takes off from the nest as a chick watches, 30 May 2018 (photo by Gregory Diskin)
Red-tailed hawk takes off from the nest as a chick watches, 30 May 2018 (photo by Gregory Diskin)

For more photos of the hawk family’s progress, click here to see Gregory Diskin’s album.

 

(photos by Gregory Diskin)

Red-tailed Hawks At Home

Red-tailed hawk family in a nest in Schenley Park, 14 May 2018 (photo by Gregory M. Diskin)
Red-tailed hawk family in Schenley Park, 14 May 2018 (photo by Gregory M. Diskin)

This spring (2018) I’ve seen two red-tailed hawk nests in Schenley Park and there’s probably a third. Gregory Diskin is documenting one of them with his camera.

Above, the mother hawk watches her two chicks on May 14.  Below, the chicks gaze out from their bridge nest on May 17.

Two red-tailed hawk chicks look out from their bridge nest, 17 May 2018 (photo by Gregory M. Diskin)
Two red-tailed hawk chicks look out from their bridge nest, 17 May 2018 (photo by Gregory M. Diskin)

On May 18 a chick tests his wings.

Red-tailed hawk chicks in a nest in Schenley Park, 18 May 2018 (photo by Gregory M. Diskin)
Red-tailed hawk chick tests his wings in Schenley Park, 18 May 2018 (photo by Gregory M. Diskin)

On May 21 a chick displays his new, reddish chest feathers.

Red-tailed hawk chick, Schenley Park, 21 May 2018 (photo by Gregory M. Diskin)
Red-tailed hawk chick, Schenley Park, 21 May 2018 (photo by Gregory M. Diskin)

(Click on any photo to see more of Gregory Diskin’s album.)

These two will fly in the next few weeks.  They’re much further along than the tree nest overlooking the Parkway where the mother is still incubating or brooding.  She’s hard to see now among the leaves.

If you watch red-tailed hawks in your area you might find a nest. When you see one carrying prey in its talons, it’s taking food to the chicks.  Follow the bird and you’ll find the red-tailed hawks at home.

 

(photos by Gregory M. Diskin)

 

Happy Friday

We’re taking a break from peregrine drama with the cutest owls on the planet.

This video of young burrowing owls was sent as a Thank You from Cornell Lab of Ornithology to its contributors in 2016.

Enjoy!  And happy Friday!

 

(video from Cornell Lab of Ornithology)

p.s. In case you’re not familiar with Cornell Lab … they’re a unit of Cornell University that works to advance the study, appreciation, and conservation of birds.  We, and the birds, have all benefited from their work.

You’ve probably used at least one of their online tools or participated in their programs:  All About Birds website, eBird, the Merlin ID app, online bird ID classes (new class this month on Warbler ID!), nestcams & feeder cams, Great Backyard Bird Count, Project Feeder Watch,  … to name a few.

Read more about Cornell Lab of Ornithology’s workJoin them here.