When you see a bird eating white berries from a hairy vine you might not realize it’s eating poison ivy. Birds are blissfully immune to the urushiol in poison ivy sap that gives us humans a nasty rash.
By late October poison ivy (Toxicodendron radicans) doesn’t look like the plant we’ve been avoiding all summer. The leaves are red or missing, the vine is exposed, and bunches of white berries hang from the branches. It’s easy for migrating yellow-rumped warblers (Setophaga coronata) to find the food they’re so fond of.
In eastern North America our chimney swifts (Chaetura pelagica) land every evening to roost in chimneys. In Eurasia and Africa the common swift (Apus apus) stays airborne for 10 months of the year!
No one knew this until Lund University in Sweden attached geolocator tracking devices to common swifts in 2015. When the swifts returned from their winter range in Africa the Swedes recaptured the tagged birds and found that most had not landed since they left!
Since common swifts spend so much time in the air and can live for 20 years an individual swift may fly 3 million miles in his lifetime. Wow.
(image from Wikimedia Commons; click on the caption to see the original)
Now that the breeding season is over birds have gathered for migration and the winter.
Early this week 50 common grackles leapfrogged over the trees and forest floor as they searched for food and bathed in Panther Hollow Run. (This photo gives you an idea of their abundance.)
Cedar waxwing numbers peaked in Schenley Park in early October when they devoured most of the porcelain berries. They’ll spend the winter further south, for instance in Memphis, Tennessee where this photo was taken.
Pine siskins were everywhere a couple of days ago. Are they still visiting your feeders? Where will they head next?
Starlings numbers are building in Pittsburgh as northern visitors arrive. Soon there will be thousands.
Crow numbers are building too. Last weekend I counted 2,400 but more arrived last night. Eventually the flock will look like this video from 2011. Where will they roost? Stay tuned.
Watch for spectacular flocks this fall. Let me know what you see.
(photos from Wikimedia Commons and Mr. T in DC, video by Sharon Leadbitter. Click the captions to see the originals)
The most numerous wild bird on earth, estimated at 1.5 billion individuals, is the red-billed quelea (Quelea quelea) of sub-Saharan Africa. This very social weaver finch migrates and nests in flocks that number in millions.
When the flocks get going they resemble swarms of locusts.
Red-billed queleas eat mostly grain and seeds. As they feed on the ground the flock leapfrogs from back to front like a rolling cloud.
In Africa they are so well known as flocks that it’s hard to think of them as individuals. Two males are pictured above. Here’s a female.
This species is a major pest of cereal crops, and huge efforts have been expended by national and international agencies on lethal control and attempts to reduce population numbers by use of explosives, petrol bombs and aerial spraying of [organophosphate] avicides; in South Africa up to 21 million reported killed in a single month, with annual kill estimates of up to 180 million.
Control operations, however, probably do no more than replace naturally occurring mortality, and there is a significant adverse impact on other species, which are poisoned directly or die after eating dead queleas.
During their first year of life young peregrines wander, looking for places where prey is abundant. A full grown peregrine needs to catch just one good-sized bird or a couple of small ones (blackbird size) each day to satisfy its hunger. Locations where thousands of birds gather on migration is prime hunting ground. That’s why young peregrines gravitate to the shore.
Shorebirds gather in the thousands at the water’s edge on migration. To protect themselves against peregrines they fly up in a very tight ball so the peregrine can’t pick out a single bird. If any shorebird breaks out of the ball the peregrine will catch it.
Watch the dramatic action of a lone peregrine hunting among thousands of shorebirds in videos below by Mark Wyna and Rob Palmer.
With thousands of potential prey items, the peregrine needs to catch just one.
p.s. If you think the shorebirds’ evasive flight uses up a lot of energy you’d be right. Peregrine pressure on shorebirds keeps them fit. Read more in this vintage blog: Peregrines as a Fitness Program.
(photo of Zoetic with prey by Chad+Chris Saladin. Zoetic is the first female fledgling from the Cleveland Metroparks Zoo site)
There weren’t many warblers at Frick Park yesterday but we saw nearly every woodpecker that occurs in Pennsylvania except for the red-headed woodpecker (Melanerpes erythrocephalus), a very rare bird in Frick(*). Soon we were dreaming about red-headeds, reminiscing about the times we’ve seen them, and remarking on their attitude.
Red-headed woodpeckers sometimes exhibit clownish behavior but more often I’ve seen them fighting. They’re rated as the most pugnacious woodpecker in North America and live up to it by challenging every cavity-nesting bird. They go hard after starlings, northern flickers and red-bellied woodpeckers. They will even challenge pileated woodpeckers four times their size.
Last year Lauri Shaffer was lucky to witness a red-headed woodpecker attacking a pileated.
It didn’t take long for the much larger woodpecker to leave the tree. Enough is enough!
Red-headeds will even attack each other, as witnessed by Chris Saladin when an immature attacked an adult. On Throw Back Thursday check out her photos of the battle between two red-headeds, the woodpeckers with attitude: The Most Pugnacious Woodpecker.
(*) p.s. Red-headed woodpeckers are Rare Birds indeed. eBird describes them this way:
The Second Atlas of Breeding Birds in Pennsylvania reports an alarming decline throughout the state with a 46 percent decrease in the number of blocks that recorded the species between the first and second atlas periods. In that short amount of time, the Red-headed Woodpecker withdrew significantly from its former breeding range and was no longer found in 13 of Pennsylvania’s northern counties.
Birding is great on the morning after high migration because the birds travel at night. They start their journey after sunset and land before sunrise, flying over us when it’s too dark to see them.
On good weather nights they’re so anxious to leave that they burst into the sky after sunset, a phenomenon that’s visible on time lapse weather radar. The slideshow below shows this effect on the evening of 15 September 2020 when the birds took off only 20 mins after sunset.
Pittsburgh radar, 15 Sep 2020, 6:59pm
Pittsburgh radar, 15 Sep 2020, 7:09pm
Pittsburgh radar, 15 Sep 2020, 7:28pm
Pittsburgh radar, 15 Sep 2020, 7:38pm
Pittsburgh radar, 15 Sep 2020, 7:47pm
Pittsburgh radar, 15 Sep 2020, 7:57pm
Pittsburgh radar, 15 Sep 2020, 8:07pm
Pittsburgh radar, 15 Sep 2020, 8:16pm
Pittsburgh radar, 15 Sep 2020, 8:26pm
Note that the image is circular because the radar’s reach is circular and it is fainter on the edges because radar fades as it gets far from the source.
Who was flying that night? In addition to warblers, which will be waning soon, we now see thrushes, tanagers, and rose-breasted grosbeaks (Pheucticus ludovicianus). The grosbeaks may resemble females, but don’t be fooled. If they have a touch of orange or red color on their breast they are immature males as shown at top. Here’s another immature male.
This weekend is a great time to go birding in Pittsburgh. Let’s get outdoors!
In September chimney swifts (Chaetura pelagica) migrate through western Pennsylvania on their way to South America. Unlike songbirds, swifts migrate during the day but we often don’t see them because they travel so high. Birds of the World says they’ve been recorded above the clouds on the warm leading edge of a cold front, 7000 feet up!
At night swifts sleep in chimneys, choosing the most convenient place. The roost may hold more than 1000 birds per night though the individuals change as some leave for the south and others arrive from the north.
Since moving to Oakland in early August I now live within sight of the Cathedral Mansions chimney, one of the largest migratory roosts in the Pittsburgh area. When the weather’s fine I step out to watch them circle the chimney and dive into the roost. Last Sunday I invited Michelle Kienholz to join me. Her videos show some of what we witnessed.
We started watching while the sun was up but the swifts didn’t come close to the chimney until a few minutes after sunset. By that time it was obvious they were making very large circles around the chimney, flying out of our peripheral vision.
As the sky got darker the swifts circled closer and closer, faster and faster. To enter the chimney they stalled upright, then dove in. There were so many swifts they had to wait in line or circle out and try again.
We tried to count as they dove in but they were quick.
It was almost too dark to see when the last swift disappeared 20 minutes later.
On Labor Day let’s honor working birds. This year … domestic geese.
A couple of domestic geese are often kept with chickens to guard them from predators. Geese are always alert and will naturally honk and shout when they see danger. The chickens run for cover while the large and aggressive geese may attack the threat. Some geese are so aggressive that they’ve injured people. (By the way, Canada geese will attack if you approach their young.)
When you see geese with chickens you can be sure those geese are at work.
p.s. When seen in Pennsylvania, geese like those pictured above are barnyard escapees. Here are some tips on their background: Chinese geese have long necks and knobs on their heads (top photo) and were domesticated from swan geese (Anser cygnoides). Domestic geese in white or gray with faces like snow geese (the attacking goose above) are descended from greylag geese (Anser anser).
Did you know that, when threatened, this Eurasian woodpecker uses the same distraction display as a South American flycatcher? Though the birds aren’t related their similar behavior looks like convergent evolution.
Convergent evolution is when similar traits evolve in unrelated species because they’ve had to adapt to similar environments.
A classic example is the body shape of sharks and porpoises. Both have long streamlined bodies, dorsal fins and flippers because both must swim fast to catch underwater prey.
But sharks are fish and porpoises are mammals. They aren’t related.
The eastern meadowlark of North America (a member of the blackbird family Icterid) and the yellow-throated longclaw of Africa (a member of the wagtail/pipit family Motacillidae) live in similar habitats on separate continents. Though strikingly similar they are not related.
So what do you think? Is the neck-turning behavior of the Eurasian wryneck (Jynx torquilla) …