Category Archives: Birds of Prey

Nesting Underground

Burrowing owl in Florida (photo from Wikimedia Commons)

12 March 2021

Ah Spring! It’s time to nest.

Pennsylvania’s bald eagles are already on eggs in their huge stick-nests. Peregrine falcons are about to lay eggs on gravel ledges. Meanwhile, in Florida and southern California burrowing owls (Athene cunicularia) are preparing to nest underground.

Burrowing owls aren’t usually seen inside the nest because it’s dark in there. No problem. There’s plenty to see at the burrow entrance. Here’s a pair in Florida.

Happy Friday!

(photo from Wikimedia Commons, tweet from Wendy @geococcyxcal in southern California, video from photoguy73)

Great Horned Owls Don’t Always Win

Screenshot of great horned owl about to attack male bald eagle, 2 March 2021, 23:38 (from Pixcams video below)

5 March 2021

If you follow the Hays bald eagle family you know the female is incubating three eggs while her mate guards her overnight. The male has good cause to stay close. A great horned owl has been harassing them!

Almost two weeks ago, on Sunday 21 Feb 2021 at 9:26pm, a great horned owl knocked the male bald eagle off the “woods perch.”

Things seemed to calm down for a week. Then on the night of Tuesday 2 March 2021 the great horned owl came back twice.

The Hays bald eagles are probably feeling murderous about that owl right now so I’m sure they’ll like this trail cam video from Washington state in which a great horned owl is attacked by three species in a row!

Great horned owls may be everyone’s enemy but they don’t always win.

(screenshot from Pixcams video; click on the caption to see the original)

Evolve Quickly!

Snail kite with island apple snail, Harns Marsh FL, 2017 (photo from Wikimedia Commons)

Native from Florida to Argentina, the snail kite (Rostrhamus sociabilis) is a gregarious bird of prey that eats only one thing: freshwater snails in the genus Pomacea. Its beak is specially shaped to do so.

Snail kite, Florida 2019 (photo from Wikimedia Commons)

The Snail Kite’s slender, deeply hooked, sharp-tipped upper mandible permits it to cut the columellar muscle of Pomacea snails and remove soft tissues from the shells. The arc of the upper mandible approximates the inner spiral of the snail’s shell.

— paraphrased from Birds of the World, Snail kite account

In the old days before humans took over Florida’s landscape, snail kites ranged over half the state, but we drained and diverted more than 50% of Florida’s wetlands, the snail kite population crashed and was listed as Endangered in 1967. Twenty years ago, from 2000-2007, their population dipped so low that scientists feared they would go extinct in the U.S. Then a curious thing happened. Their food supply changed and the kites changed so they could eat it.

Before this century the snail kite’s main food was the native Florida apple snail (Pomacea paludosa) but an invasive species, the island apple snail (Pomacea maculata), arrived in 2000 and began to spread in Florida’s lakes and water management areas.

Island apple snails eating rushes (photo from Wikimedia Commons)

The island apple snail is two to five times larger than the Florida apple snail as seen below. (The white-and-gray bars are each 5 cm.)

Size comparison of Florida apple snail (P. paludosa) to Island apple snail (P. maculata). Each scale bar is 5 cm (images from Wikimedia Commons)

When the island apple snail first arrived in Florida the snail kite population dropped but less than a decade later the population began increasing. Did the birds initially have a tool problem? Were their beaks too short to get at the snail inside the larger shell? A recent study from the University of Florida indicates this was probably the case. Since 2007…

Researchers found that the birds with bigger bills were surviving, and their offspring were inheriting the bigger bills. …

“We found that beak size had a large amount of genetic variance and that more variance happened post-invasion of the island apple snail. This indicates that genetic variations may spur rapid evolution under environmental change,” Fletcher said.

— paraphrased from UF study: Bird evolves virtually overnight to keep up with invasive prey

We think of evolution as a very slow process but for the snail kite it happened quite fast. Those with longer bills survived. Nowadays they easily eat island apple snails.

Male snail kite with island apple snail, Florida, 2016 (photo from Wikimedia Commons)

When it’s a matter of life and death, evolve quickly!

Read more at the University of Florida study: Bird evolves virtually overnight to keep up with invasive prey.

(photos from Wikimedia Commons; click on the captions to see the originals)

Raccoon Redux

Bald eagle pair scares off raccoon approaching their nest, 17 Feb 2021 (screenshot from PixCams on YouTube)

19 February 2021

On Wednesday night, 17 February just after 7pm, a raccoon scaled one of the branches that holds the Hays bald eagle nest. The mother eagle was on the nest and heard the raccoon coming so she rose up, spread her wings, and scared him away.

Seven years ago a raccoon intruder did the same thing. This one was a little braver.

The raccoon hid nearby, frozen in place, but four minutes later he moved again and the father eagle arrived to help. Two eagles!! The raccoon finally left.

This week’s episode was a raccoon redux of …

See Mary Ann Thomas’ Trib Live report, Pittsburgh Hays Bald Eagles Attack Raccoon Intruder, with video of Wednesday’s raccoon leaving.

Watch the Hays Nest Eaglecam to see what happens next.

(screenshot from PixCams on YouTube)

UPDATE, 19 Feb 2021: The female bald eagle at Hays laid her 3rd egg on 19 February 2021.

UPDATE, 22 Feb 2021: On the night of 22 Feb 2021 a great horned owl knocked the male Hays bald eagle off his roosting perch. The eagle was surprised but unharmed.

Everyone’s Enemy

Great horned owl at Frick Park, April 2019 (photo by Steve Gosser)

16 February 2021

Most birds fear great horned owls (Bubo virginianus) for they are such top predators that they will eat the young of bald eagles, peregrine falcons and red-tailed hawks.

Their nesting habits are dangerous, too. Like other owls they never build a nest but great horned owls will steal one that looks good to them. They usually pick on red-tailed hawks. It leads to a fight as shown in the video below.

In early February 2019 a red-tailed hawk was building a nest at Presidio park in San Francisco when a great horned owl decided to steal it. The details of their encounter are quoted below the video. (Abbreviations: RTH=red-tailed hawk, GHO=great horned owl)

A pair of great horned owls have been visiting this red-tail hawk nest at the Presidio for several nights. This is the first time it’s come to the nest during the day, and the first time the RTH has seen it. It didn’t take kindly to the invasion and attacked it soon after it arrived. The GHO was able to fend off the RTH the first time, but in the 2nd attempt, it falls off the nest and doesn’t come back….until the next day. The RTH returns to make sure all is secure. Confrontations done in real time and SloMo. NOTE: The owl comes back the next day & lays an egg, and another a few days later. There are a few minor skirmishes, but the RTH finally moves on & lets the GHO have the nest. One of its two eggs broke, but the remaining egg is due to hatch mid-March. UPDATE: The 2nd egg failed to hatch also. The owl eventually moved on.

description of owl vs red-tail video on Janntonne’s channel on YouTube

If the owls are persistent, the red-tailed hawks eventually give up. Great horned owls outweigh red-tails by 30% and their talons are more than twice as powerful with a talon strength of 500 lbs per square inch. On the glove you can see the difference: red-tailed hawk (left), a great horned owl (right).

Here’s a comparison of their talons: red-tailed hawk on left, great horned owl on right (photos by Kate St. John at Medina Raptor Center, Ohio, Nov 2014)

Everyone’s enemy is a formidable foe. No nest is worth dying for.

p.s. It is likely that Pittsburgh’s great horned owls have already laid eggs — much earlier than bald eagles, red-tailed hawks and peregrines According to the Breeding Bird Atlas of Pennsylvania the earliest egg dates in PA are …

  • Great horned owl = 22 January
  • Bald eagle = 6 February
  • Red-tailed hawk = 24 February
  • Peregrine falcon in Pittsburgh = 6 March (based on falconcam at Pitt)

(owl photo by Steve Gosser, talon photos by Kate St. John)

UPDATE: On the night of 22 Feb 2021 a great horned owl knocked the male Hays bald eagle off his roosting perch. The eagle was surprised but unharmed.

Hays Bald Eagles Have a Happy Valentine’s Day

First egg of 2021 at Hays bald eagle nest, 12 Feb 2021, 5:55pm (snapshot from ASWP’s Pittsburgh Eagles Facebook page)

14 February 2021

The Hays bald eagles are having a Happy Valentine’s Day with their first egg of the season just 36 hours old. The female laid her first egg on Friday 12 February 2021 at approximately 5:55pm. Their happy event was on the CBS Local news, at Trib-Live, and captured on the streaming cam on YouTube.

The female usually lays her second egg three days after the first so watch the Hays Nest Eaglecam tomorrow, 15 February, for the arrival of another egg.

Catch up on all the Hays Bald Eagle news at ASWP’s Pittsburgh Eagles Facebook page.

Happy Valentine’s Day!

(photo and video from ASWP’s Hays Eaglecam)

How Big Is This Eagle?

Steller’s sea eagle in flight, Hokkaido, Japan (photo from Wikimedia Commons)

10 February 2021

Steller’s sea eagle (Haliaeetus pelagicus), a native of coastal northeastern Asia, is in the same genus as North America’s bald eagle (Haliaeetus leucocephalus) but it’s a bigger bird.

How big is it? Watch!

Speaking of eagles, this may be the week that the Hays bald eagles lay their first egg. Watch them at ASWP’s Hays, PA Bald Eagle Nest. Join in the conversation at Pittsburgh Eagles on Facebook.

(photo from Wikimedia Commons, click on the caption to see the original; tweet embedded from @EvanKirstel)

Help Find Long-Eared Owls in PA

Long-eared owl in California (photo from Wikimedia Commons)

24 January 2021

Native to Eurasia and North America, long-eared owls (Asio otus) are shy and secretive medium-sized birds that hunt open areas and roost in woodland edges and conifer stands.

Range map of long-eared owl (from Wikimedia Commons)

In Pennsylvania they are present year-round and listed as Threatened, but are so elusive that it’s hard to keep track of them. The Game Commission plans to study Pennsylvania’s long-eared owls but needs preliminary data. They are asking birders for help.

The Pennsylvania Game Commission is interested in learning more about long-eared owls in Pennsylvania, who are threatened and extremely vulnerable to disturbance [so] we’re asking birders to share their long-eared owl observations with us.

To protect the location of the birds, we are asking birders NOT to post their observations on eBird or other platforms at this time(*) but instead to send all observations–past or present–to Game Commission Wildlife Biologist, Patti Barber, at with “LEOW Observations” in the subject line. Include date, location, number of owls and evidence of owls in the area (seen, heard, pellets, feathers, heard etc).

Pictures are welcome, however, please maintain enough distance so as to not disturb the birds. Long-eared owls often abandon roosts when disturbed. Please do not walk on private property without owner’s consent. Thank you, in advance, for your help.

— partially paraphrased: Pennsylvania Game Commission, 19 January 2021 via Instagram

So how do you find a long-eared owl? Find is the hardest part. Long-eared owls are more strictly nocturnal than other owls so you’ll have to find them at the roost where they are masters at hiding in plain sight. Here are a few examples.

Roosting in dense deciduous woods in Minnesota:

Long-eared owl comouflaged in Minnesota (photo from Wikimedia Commons)

Roosting in a conifer stand in Illinois, 2011. This owl looks like a fat branch with ear tufts.

Long-eared owl resembles a branch, Carlyle Lake, IL, 2011 (photo by Andy Reago & Chrissy McClarren via Wikimedia Commons)

Owl eyeing the photographer but still hidden.

Long-eared owl looks at the photographer, Illinois, 2011 (photo by Andy Reago & Chrissy McClarren)

I’ve only seen a long-eared owl three times in my life with each sighting 10 years apart. My last was in Beaver County in 2015 so I’m not due to see another one until 2025. I wonder if my quest will be successful.

(photos and map from Wikimedia Commons; click on the captions to see the originals)

(*) eBird reports: The Game Commission is working with eBird to develop a process to allow these observations to be entered while also protecting these sensitive locations.

Falconry Moves Portland’s Winter Crows

screenshot from OPB video: Urban Falconry in Portland Oregon

7 January 2021

Huge flocks of crows roost in Portland, Oregon in the winter just as they do Pittsburgh. By 2017 the city realized that the crows’ huge sanitation problem could not be solved with cleanup crews and pyrotechnics so they turned to a team of falconers.

This 9-minute video from Oregon Public Broadcasting, published in November 2018, shows how trained Harris hawks — which normally operate during the day — move the crows at night. Awesome!

(screenshot from OPB video; click on the caption to see the original)

Red-tailed Hawks Look Different In the West

Dark morph red-tailed hawk, San Mateo County, CA (photo by Robin Agarwal, via Flickr Creative Commons license)

4 January 2021

One of the surprises when traveling in North America is that our most common hawk in Pittsburgh, the red-tailed hawk (Buteo jamaicensis), looks very different out west.

In western Pennsylvania, red-tailed hawks are best identified by the belly band of stripes below their breasts and dark patagial marks on their underwings. Some have dark markings, some are pale. Adults are redder than immatures.

Red-tailed hawks in western PA: Adult (by Steve Gosser) and immature (by Donna Foyle)
Red-tailed hawk at the Allegheny Front, PA, 2016 (photo by Steve Gosser)
Adult red-tailed hawk at the Allegheny Front, PA, 2016 (photo by Steve Gosser)
Red-tailed hawk, Lawrence County, PA, 2013 (photo by Cris Hamilton)

Though most western red-tailed hawks are similar to their eastern cousins they are generally darker, as shown below in Washington state. There’s also a dark morph that’s completely chocolate brown as in the photo at top from San Mateo County, California.

Adult red-tailed hawk in Kirkland WA, Immature red-tail in Stanwood, WA (photos by Mick Thompson via Flickr Creative Commons license)

Here are more examples.

Arizona: Underwings on this adult are darker and redder than back east.

Adult red-tailed hawk, Maricopa County, AZ (photo by Steve Valasek)

Utah: Dark underneath on an immature red-tail.

California: While many red-tails in California are merely darker, the dark morph is over the top.

Dark morph red-tailed hawk, San Diego County, CA (photo by Andy Reago & Chrissy McClarren)
Adult dark morph red-tailed hawk, San Diego County, CA (photo by Andy Reago & Chrissy McClarren)

Some day when we can travel again I’m looking forward to seeing a dark morph red-tailed hawk.

(photos by Robin Agarwal, Steve Gosser, Donna Foyle, Cris Hamilton, Mick Thompson, Steve Valasek, Andy Reago & Chrissy McClarren; click on the captions to see the originals posted in Flickr with Creative Commons license)