Category Archives: Birds of Prey

Cooper’s Hawk Nesting Questions

Adult Cooper’s hawk (photo from Wikimedia Commons)

21 April 2022

On 12 April my friend Charity and I saw a Cooper’s hawk building a nest. Yesterday we saw an adult in the nest, incubating. We wondered about the process: When did nest building end? When did incubation begin? Does the male share incubation duties? How long before the eggs hatch?

The answers are fascinating because Cooper’s hawks don’t follow the expected rules. In the quotes from Birds of the World, below, did you know? …

  • Cooper’s hawks are a “common backyard breeding bird in cities of all sizes.”
  • Male Cooper’s hawks do most of the nest building. The female stops by occasionally to check on his progress and helps a bit, especially at the end.
  • Nest-mates have multiple genetic fathers. “Cooper’s Hawks exhibit high rates of extra-pair paternity involving both territorial and especially non-territorial floaters.”
  • Only the female has a brood patch. She does most of the incubation. The male takes over for short periods while she eats.
  • The female broods the chicks for two weeks, about twice as long as peregrines do.
  • Both parents tend the young.
Cooper’s hawk building a nest (photo by BrockmeyerPhoto)

Further details from Birds of the World help answer our questions about the nest:

  • Nest building takes 2 weeks.
  • Eggs are usually laid in the morning at 2 day intervals (occasionally 3 days) for a total of 3-5 eggs.
  • Incubation begins after the 3rd egg and lasts 34 days. The first 3 eggs hatch on the same day; the 4th and 5th eggs laid usually hatch 1 day later, occasionally up to 3 days later.
  • The young leave the nest at about 30 days (males) to 34 days (females), although able to clamber short distance in nest tree 4–5 days earlier.

The earliest schedule would be: Nest completion on 12 April, female laid 3 eggs 12-16 April, incubation began 16 April, hatching on 20 May, young leave the nest 19-23 June.

The latest schedule would be: Female began incubation 19 April, hatching on 23 May, young leave the nest 22-26 June.

I plan to stop by occasionally to see what’s up. The excitement will start in late May.

Meanwhile, see photos of a Cooper’s hawk family nesting in a backyard in this vintage article from 2017.

(top photo from Wikimedia Commons, nest-building photo by BrockmeyerPhoto)

Whooo’s There?

Great horned owl (photo by Alan Wolf via Flickr, CC license)

15 April 2022

At the end of March in Great Falls, Montana …

Meanwhile in southwestern Pennsylvania, great horned owls (Bubo virginianus) laid eggs in January/February and hatched young around the time of this video. Keep an eye out for activity above. As the owlets grow up their nests will become more obvious, even during the day.

For a view of Great Falls and other Montana towns see Montana Webcams here.

(photo by Alan Wolf via Flickr, CC license)

USS Irvin Eaglets Hatching Soon

5 April 2022

Early yesterday morning the mother bald eagle at the USS Irvin nest in West Mifflin turned her eggs and revealed a pip. You can see the pip in the video below.

Watch the USS Irvin Works Eaglecam for the first egg to hatch today.

video from PixCams on YouTube

This nest is only 5 miles away, as the crow flies, from the Hays bald eagles. For more information on this site see: New Eagle Cam at USS Irvin Works in the Mon Valley.

(screenshot and video from USS Irvin Works eaglecam via PixCams on YouTube)

The Clean Up Crew Is Back

Turkey vulture in flight (photo from Wikimedia Commons)

31 March 2022

Have you noticed them lately?

Turkey vultures (Cathartes aura) are migrating over Pittsburgh during the warmest parts of the day. They returned to Hinckley, Ohio on 15 March. Now they’re here.

Since my first sighting of a lone turkey vulture on 10 March I now see groups of at least four every day, especially near their roosts.

Turkey vultures at the roost (photo from Wikimedia Commons)

Very soon we are going to appreciate that the Clean Up Crew has returned to eat the dead things that rot in warm weather.

Unlike us, vultures can always eat what they want. Find out why in this vintage article.

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

The Chase!

Bald eagle in pursuit (photo from Wikimedia Commons)

29 March 2022

Les Leighton had his camera set up at Canada’s Vancouver harbor when a drama played out in front of him. A gull zipped by with both a bald eagle and peregrine falcon pursuing it in flight. What was it about that gull that attracted two predators at the same time?

Watch the chase and notice the difference between the eagle’s and peregrine’s hunting techniques. Why did both of them give up?

The gull had a good day after all.

(video by Les Leighton “wetvideocamera” in Vancouver, BC, Canada)

Hays Eagles: Hatching & Action at Duck Hollow

Female at Hays bald eagle nest, 21 March 2022, 06:58a (snapshot from the Hays bald eaglecam)

21 March 2022

Lots of news this morning!

At the Hays bald eagle nest the first pip was confirmed yesterday morning at 8:36am. You can see the pip in the video below. Watch the Hays bald eaglecam for the first egg to hatch today.

Six of us braved the drizzle yesterday morning at Duck Hollow and were rewarded with an exciting visit from one of the Hays bald eagles. Connie Gallagher captured part of the action in photos.

Five of 6 participants at the Duck Hollow outing, 20 March 2022 (photo by Kate St. John)

It all began with two herring gulls on the mud spit, manipulating a large fish.

Two herring gulls with a big fish, 20 March 2022, 8:45am (photo by Connie Gallagher)

The gulls hadn’t made much progress opening the fish when they saw the male Hays bald eagle flying upriver toward Duck Hollow. All the waterbirds could tell the eagle wanted that fish. The ducks stayed put, the gulls quickly stashed the fish and flew up calling and complaining.

Hays bald eagle wanted that fish (photo by Connie Gallagher)

The eagle made three dropped-talon passes at the fish but it was too hard to grab in flight. Meanwhile the gulls divebombed him and chased him every time. That fish was stashed so tightly that the eagle would have to land to get it. But the gulls were relentlessly annoying.

Finally the eagle left and the gulls resumed their meal, watched by a crow.

Herring gulls resume their meal, 20 March 2022, 10am (photo by Connie Gallagher)

In all we saw 29 species including an odd mixed-up mallard who might be an “intersex hen.” Photos are on our checklist here.

So glad we went birding in the rain!

p.s. At the Cathedral of Learning peregrine nest, Morela laid her second egg this morning, 21 March, around 3am. You can see both eggs by the light of the moon. Watch the peregrines at the National Aviary falconcam at Univ of Pittsburgh

Morela with two eggs, Cathedral of Learning peregrine nest, 21 March, 4am (snapshot from the National Aviary falconcam at Univ of Pittsburgh)

(photos by Kate St. John, Connie Gallagher and snapshot from the National Aviary falconcam at Univ of Pittsburgh)

Hays Bald Eagles: Pip Watch

Female bald eagle on nest at Hays, Pittsburgh, 17 Mar 2022, 17:54 (snapshot from Hays Bald Eaglecam)

18 March 2022

It’s “Pip Watch Week” at the Hays bald eagle nest. Hatching of the first egg is expected any day now.

Bald eagle eggs hatch, on average, after 35 days of incubation. At the Hays nest this pair has hatched 15 eggs over the past nine years, averaging just over 36 days per egg. Their first egg of the season, laid on 11 Feb 2022, is due to hatch soon. 35 days is today (18 March), 36 days is tomorrow (19 March).

Our hint that it’s close to hatch time will be a hole in the shell — a pip — hammered by the chick who’s preparing to hatch. After pipping the egg it takes an eaglet as much as a day to break out of his shell. Read the step-by-step hatching process here.

It won’t be long now. Watch for hatching at the Hays bald eaglecam. By the time you read this article the first eaglet may be here!

p.s. Five miles away, the USS Irvin bald eagles have two eggs. The first was laid on 27 Feb so Pip Watch will start there at the beginning of April. Click on this link to watch the USS Irvin bald eaglecam. Approximate first hatch date there is 2/27/2022 + 35 days = 4/4/2022.

(snapshot from the Hays bald eaglecam via PixCams)

Focus in the Midst of Distractions

Immature red-tailed hawk focused on prey (photo by Chuck Tague)

10 March 2022

Despite distractions we humans can focus on just one thing if we want to. Birds of prey can do it, too, as seen in this video of a red-tailed hawk in Tompkins Square Park, New York. The hawk doesn’t care about squirrels or people or the ambulance but when he sees a rat …!

This ability to focus is called selective attention and was proven eight years ago in chickens. See this vintage article, Selective Attention in Chickens, with an amazing video to test your own selective attention.

Bonus test: After you see the video in the chicken article, try another test. (This test + answer lasts 3 minutes. The remaining 2 minutes show family & friends reactions.)

(photo from Wikimedia Commons; click on the caption to see the original. Videos embedded from YouTube)

Soaring Is A Signal

Red-tailed hawk soaring, 2013 (photo by Cris Hamilton)

3 March 2022

In March red-tailed hawks conspicuously soar over western Pennsylvania. They take to the skies alone or in pairs to soar and dive and dangle talons. Sometimes they even scream.

What is all this soaring about? It’s a multi-purpose signal.

Pair of red-tailed hawks soaring (photo by Melissa McMasters via Wikimedia Commons)

Soaring is part of hunting and migration of course, but in the spring it’s a way to claim territory, advertise availability to potential mates, and cement the pair bond.

What better way to tell other red-tailed hawks that a territory is already taken than by soaring above it? Adults do this alone and in pairs. Unwelcome red-tails are escorted away. “This is mine!”

A lone red-tail also soars to advertise for a mate saying, “This is mine and I need a mate to share it.” (I have no idea how they signal the difference between ‘stay away’ and ‘come here.’)

Before the female lays eggs pairs of red-tailed hawks soar to cement their pair bond.

Prenesting displays typically consist of both birds soaring in wide circles at high altitudes and the male performing maneuvers similar to the Sky-dance [in which the] bird dives steeply from high altitude, checks descent and shoots immediately upward at similarly steep angle.

After several series of dives and ascents, the male slowly approaches the female from above, extends his legs and touches or grasps her momentarily. Frequently, both birds dangle their legs during aerial maneuvers. The birds may grasp one another’s beak or interlock talons and spiral toward the ground. Piercing screams and quiet, raspy calls often accompany courtship flight displays.

Birds of the World: Courtship displays of the Red-tailed Hawk
A pair of red-tailed hawks dangles talons in a courtship display in Santa Barbara (photo from Wikimedia Commons)

In the video below you’ll see a pair soaring, dropping talons, and persuading a third bird to leave.

For red-tailed hawks soaring is a signal.

(photos by Cris Hamilton and from Wikimedia Commons; click on the captions to see the originals)

Cutest Bird of the Year

Burrowing owl, Imperial County, CA (photo from Wikimedia Commons)

20 February 2022, San Diego Bird Festival, Big Day across the county

In more than a decade of choosing an annual ABA Bird of the Year, this year’s choice, the burrowing owl (Athene cunicularia), has the most personality. It’s hard to look at one posing near it’s burrow without seeing its defiant and endearing stance.

The owls, of course, take themselves seriously, choosing a mate, finding an appropriate prairie dog, ground squirrel or man-made burrow to nest in, and raising a family.

Burrowing owls at man-made nest near Salton Sea (photo from Wikimedia Commons)

The owls have had recent success in Imperial County, California where many of these photos were taken. Unfortunately by 2019 their population in nearby San Diego County was down to 75 pairs due to habitat loss and destruction of the ground squirrels whose holes the birds rely on.

In 2020 researchers began to turn that around by releasing eight young owls at Rancho Jamul Ecological Reserve. In the winter of 2020-2021, 24 pairs were reintroduced to man-made burrows at Ramona Grasslands Preserve. This winter they plan to reintroduce several more. The hope is that the young birds raised at Ramona will return to their birthplace to nest.

Ramona grasslands, San Diego County (photo from Wikimedia Commons)

Read more about burrowing owls in San Diego County at San Diego Burrowing Owls get new homes.

If you want to see great photos every day of the cutest Bird of the Year, follow Wendy @geococcyxcal on Twitter.

They are so photogenic!

UPDATE 21 Feb 2022: Did not see a burrowing owl on this trip.

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