Tropical islands always have lots of seabirds but are often missing entire families of land birds. Sometimes a family is represented by just one endemic species. In Hawaii this is true of both crows (Corvidae) and hawks (Accipitridae). There is one endemic crow, the Hawaiian crow, and only one endemic hawk.
The Hawaiian hawk or i’o (Buteo solitarius) is in the same genus as our red-tailed hawk (Buteo jamaicensis) but he evolved to eat birds, such as rails and ducks, because there weren’t any small mammals on the islands. When humans brought rodents, lizards and game birds to Hawaii many of the hawk’s original prey disappeared so he switched to hunting introduced species.
The Hawaian hawk comes in light morph and dark morph plumage. Dark morphs are dark chocolate brown. Pictured here are light morph individuals — an adult above, a juvenile below. You can tell the males and females apart not by plumage but by size. Females are 50% heavier than males, the most sexually dimorphic of all buteos.
As with red-tailed hawks, juvenile i’os are easier to get close to.
The i’o is a loud bird whose Hawaiian name imitates his voice: “I’o.” “Eee Ohhh.” He often calls while soaring. Click here to hear.
The Hawaiian hawk used to inhabit four islands but is now found only on the Big Island of Hawai’i. The population declined for many years but is making a comeback. That’s good news for Hawai’i. This hawk is important to Hawaiian culture and a symbol of Hawaiian royalty.
(photo of adult (striped) hawk by Bettina Arrigoni on Flickr, Creative Commons license; photo of juvenile (pale) hawk from Wikimedia Commons. click on the captions to see the originals)
Tour Day 5: Travel from Kauai to the Big Island of Hawai’i, Kealakekua and Pu’u Anahulu
February is a great month for watching raptors in Pittsburgh. Peregrine falcons are courting and bald eagles are already nesting. This week was especially full of raptor news. Here are just four of our many pairs.
First things first: Peregrine falcons!
Peregrines love good weather — don’t we all — so they were particularly active on Tuesday February 20, a single sunny day in the midst of snow, sleet, rain and fog.
Tarentum Bridge Peregrines:
At Tarentum, Steve Gosser found the resident female peregrine perched on a lamppost. Though she isn’t banded she’s easy to recognize because her breast is very dotted. This is quite different from her mate who has an almost clear white breast and is banded Black/Green 48/BR (Westinghouse Bridge, 2014).
Above, she looks regal on the lamppost. Below, Steve whistled to attract her attention and she gave him the “Who’s whistling at me!?” look. Many of you saw this photo when I shared Steve’s post on Facebook. It’s the perfect Peregrine Attitude shot.
Neville Island Bridge Peregrines:
There was a lot of Peregrine Attitude at the Neville Island I-79 Bridge when Karen Lang and I stopped by on Tuesday.
We found the female in a tree, preening in the sun but it wasn’t long before the male flew in and mated with her. (Yes, my digiscoped photo is awful. )
Afterward it looked like the peregrines weren’t paying attention but the female was alert for trouble. She flew over our heads in pursuit of a raven, then perched on the topmost arch and the pair mated again. This is serious Peregrine Attitude, as in: “We own the place! There are two of us here!”
Minutes later the female pumped upriver to chase away an immature female peregrine. After the ladies flew out of sight, the male circled up and away as well.
I was able to see through my scope that the male is banded Black/Green, possibly the same male as in prior years: “Beau” Black/Green 05/S (Pitt, 2010). However I couldn’t see any bands on the female, no dark spot like the Black/Red bands on Magnum, the resident female of prior years. This female deserves another look. I wonder if Magnum is gone.
Cathedral of Learning Peregrines:
Courtship is underway for Hope and Terzo at the Cathedral of Learning. Yesterday, February 21, she called for him to bow with her at the nest. We can’t hear her but people inside the Cathedral of Learning probably did. She is one loud bird.
The pair bowed for less than half a minute and then they were gone.
Keep up with the Hays bald eagles at the Audubon Society of Western Pennsylvania’s Hays Bald Eaglecam.
(credits: Tarentum peregrine photos by Steve Gosser. Neville Island peregrine by Kate St. John. Cathedral of Learning peregrines from the National Aviary snapshot camera at Univ of Pittsburgh. Bald eagle photos from ASWP’s Hays bald eagle camera.)
Love is in the air at the Harmar bald eagle nest. Gina Gilmore saw lots of activity last weekend.
Sometimes the female calls for her mate (above). He flies in to see her and they mate (on 8 Feb).
… and mate again (on 10 Feb).
They’re getting ready to nest, though their first egg is at least a week away, maybe more.
The Harmar pair historically lays 10-18 days later than the Hays bald eagles whose first egg arrived this week on 12 Feb 2019 at 6:45pm. In 2015-2018, Harmar’s first egg was between February 20 and March 9.
This year there’s no camera on the new Harmar nest so we’ll have to watch the female’s behavior to know when her first egg arrives.
In the meantime love is in the air. Happy Valentine’s Day!
Bald eagle nesting season has come to western Pennsylvania. Our favorite pair at Hays Woods finished their new nest in early winter and are spending lots of time together. The Hays eaglecam is up and running. Everyone’s ready for eggs.
Yesterday Dan Dasynich spent time on the Three Rivers Heritage Trail taking photos of the eagles. He captured this one just after they had a mating session. Then the male flew off downriver.
Because the Hays pair has been on camera for five years we have details of their nesting history. From 2014 through 2018 the female laid her first egg between February 10 and February 19.
Her earliest date was in an unusual year. In 2017 she laid her first egg on February 10 but the nest tree blew down on February 12 so the pair built another nest very quickly. She laid her first egg in the replacement nest on 20 Feb 2017.
If history is any guide, the first egg is one to two weeks away. Meanwhile the Hays eagles are putting finishing touches on the nest, the male is bringing food for his lady, and they mate many times.
Hatched at the National Aviary on 12 January 2019, this Eurasian eagle owl chick is growing up fast. In the photo above he’s six days old.
His parents are education birds at the National Aviary and he(*) will be, too. To prepare him for this role he’s being hand-raised with lots of love and attention and began close encounters with a few Aviary visitors at the tender age of 17 days.
By the time he’s four weeks old he’ll look like this owlet — one of his siblings from 2013.
When he grows up he’ll look like his parents. By then he’ll be a very big bird.
Eurasian eagle owls (Bubo bubo) are virtually the world’s largest owl. Native to Europe and Asia, they can weigh up to 10 pounds with a wingspan more than six feet long. That’s 1.5 times larger than North America’s great horned owl. You can tell the difference between the two species — even in photographs — when they open their eyes. Adult Eurasian eagle owls have orange eyes. Great horned owls have yellow eyes.
Watch the owlet grow up at the National Aviary‘s Avian Care Center window or schedule a close encounter to meet him in person. Participants can touch the chick’s downy feathers, take photos, and interact with him under the supervision of National Aviary animal care experts. The number of encounters is limited and available for only a few weeks. Click here to sign up for an owlet encounter.
Why does this red-tailed hawk throw up a long gray lump? Is he sick? Not at all. He’s casting a pellet.
Birds’ digestive systems are very different from ours, beginning with their beaks. Since birds don’t have teeth they swallow most of their food whole. The rest of their digestive system is geared to deal with this.
Birds have little saliva and few taste buds compared with mammals, which chew and physically process food as the first step and then subject it to chemical processing as the second step. Birds reverse this sequence. They start chemical digestion in the proventriculus [then the food] undergoes physical processing in the gizzard.
Ornithology, 3rd Edition by Frank B. Gill, page 164
We chew with our teeth and spit out the bones. Birds chew with their gizzards which then collect the bones, fur, and other indigestible bits into a lump. The bird spits out the lump when it’s a convenient size.
Owls, eagles, hawks and falcons cast pellets but so do many other birds “including grebes, herons, cormorants, gulls, terns, kingfishers, crows, jays, dippers, shrikes, swallows, and most shorebirds.” (quote from Wikipedia)
Scientists examine pellets to find out what the bird ate. One of the long-eared owl pellets below was dissected to reveal the rodent bones inside.
For whatever reason, it’s rare to see a bird casting a pellet so consider yourself lucky if you witness it, as Chad+Chris Saladin did in the photos above.
A NOTE ABOUT HANDLING OWL PELLETS from Wikipedia: Some rodent viruses and bacteria can survive the owls’ digestive system so wear gloves and sterilize the pellets in a microwave oven before handling. A 2005 study found outbreaks of salmonellosis at elementary schools associated with dissection of owl pellets: Smith KE, Anderson F, Medus C, Leano F, Adams J, 2005. Vector-Borne and Zoonotic Diseases,5, 133–136.
(red-tailed hawk photos by Chad+Chris Saladin; pellet photo from Wikimedia Commons; click on the captions to see the originals)
Pigeons (Columba livia) and the raptors who hunt them have evolved together for millions of years. The raptors’ successful hunts leave only the fastest, most maneuverable pigeons. Speedy, elusive pigeons mean only the most skillful raptors can survive. Most of us never get to see this interaction so this dramatic video from Romania is a real treat.
The pigeons stay in a tight flock because raptors can’t pick out a victim in a moving ball of birds. The raptors try to separate one bird from the group by slicing through the flock. If it works, the raptor pursues the lone bird.