Tuesday evening (October 23) Michelle Kienholz sent me the photo below of a huge flock of crows flying over Schenley Park toward CMU at 6pm. See those specks above the horizon? Hundreds of them!
Yes, it's late October and the crows are back in Pittsburgh for the winter. This is just the beginning of the flock. More will follow.
In the next few weeks the crows will move their roost several times until they settle on a favorite safe place. Meanwhile, you'll see them at dawn and dusk flying down the Allegheny River valley and through Oakland.
Last weekend at Cape Cod I saw a swirling flock of tree swallows at their staging area.
Staging: Designating a stopping-place or assembly-point en route to a destination -- from The New Shorter Oxford English Dictionary.
Tree swallows (Tachycineta bicolor) breed as far north as the tundra/tree line in Canada and Alaska and spend the winter from Florida to Central America. Their departure from western Pennsylvania is barely noticeable but on the East Coast they gather in salt marshes in huge flocks of a hundred thousand birds. Their interim stops on migration are called staging areas.
In the evening tree swallows funnel down to the marsh in a tornado of birds. At dawn they burst up from the roost, as shown in the Central Florida video above.
Last Saturday I saw thousands of tree swallows flying in tight formation at West Dennis Beach. Though sunset was two hours away they flew low across the salt marsh, hovered and touched down on bushes, swirled up and around and away.
At the height of their swirling I took some photos but couldn't capture their magic. However, this picture shows why they flew so fast and so close. There's a falcon in the upper right corner with a swallow in its talons. Perhaps it's a merlin. I would never have noticed without this photo.
This month chimney swifts (Chaetura pelagica) are migrating to South America, leaving before the weather's too cold for the flying insects they eat on the wing.
At dusk the flocks swirl around large chimneys then dive in to roost. This video from New Glasgow, Nova Scotia shows them streaming into an old schoolhouse chimney. Wow!
Don't worry when you see smoke coming out of the chimney at the end of the video. An observer explains: "There are actually two flues in the chimney. The chimney swifts use the larger flue, while the smoke is vented from the smaller flue, so the birds are safe. In fact, they probably benefit from the bit of heat that comes from the smaller flue."
Stake out a chimney in town to enjoy the air show or monitor a wooden chimney swift tower near you.
Where are the birds? What did they do during the storm?
Fortunately birds have strategies for coping with bad weather including:
Shelter in Place
Like us, birds hide out of the wind and rain and wait for the storm to end. They use man-made structures, thickets, and deep valleys where the wind is less intense. Their strategies are described here in Shelter From The Storm.
Birds can sense when a storm is coming and often evacuate before it strikes. A study of golden-winged warblers found that they left Tennessee a day ahead of a tornado: Warblers Fled Tornado One Day Ahead. Land birds in Florida can move northwest as Irma approaches but the birds on Caribbean islands had nowhere to go.
Fly In the Eye of the Storm
Sea birds have a third option. As they fly in search of a calm spot, they end up in the eye of the hurricane where they travel with the storm until the winds die down. This NASA image shows that the eye of Irma on Sept 5 was larger than both Anguilla and St. Martin so it was probably a relatively safe place. However, the hurricane won't lose power until it's over land so the sea birds may be exhausted when they finally stop far inland.
People and birds in the path of Hurricane Irma are all getting ready. I think of my friends and family in Florida.
(photo credits: Hurricane Irma satellite animation from NOAA, photo of pigeons sheltering from Wikimedia Commons, photo of tornado from Wikimedia Commons, Eye of Hurricane Irma from NASA Sport. Click on the images to see the originals.)
Why do birds look fat in winter and thin in the summer? Have they lost weight?
No. They're trying to stay cool.
Underneath their smooth outer feathers birds wear down coats all year long. The down keeps them especially warm when they fluff it out to hold more heat next to the skin. This fluffing makes them look fat on cold winter days.
When it's hot, they can't take off their down coats so they force hot air out of the down by compressing their outer feathers. This makes them look thin.
The cardinal on the left, above, is not the thinnest one I've ever seen. Cris Hamilton took his picture in May when the temperature was pleasant. He'll look considerably thinner this month.
It's just another way that birds cope with heat.
p.s. We think of down as white but on a northern cardinal it's black. Click here to see a northern cardinal's body feather, called a semi-plume, black at the root and red at the tip.
In this video from India, see the house crows (Corvus splendens) use their slotted wings to stay aloft in the strong wind. Someone off camera is tossing bread in the air. The crows hover and flap to catch it.
Slotted wings save energy as the crow flies.
It looks like fun.
p.s. Test your skills at identifying birds in flight. Find a pigeon (or three) that parachutes in to join the flock. How can you tell it's a pigeon? Pigeons have pointed wings.
How will birds and animals react to the solar eclipse on Monday, August 21? Will they act differently during the total eclipse (from Oregon to South Carolina) compared to the partial eclipse here in Pittsburgh? You can help Science answer these questions.
We have anecdotes about animal behavior during solar eclipses but not a lot of scientific data.
People have noticed that birds stop singing, farm animals return to the barn, and night critters wake up. Are they reacting to totality as if it's a miniature night? Or is it something else?
But this time will be different. On Monday August 21, thousands -- or even millions of us -- will collect data on animal behavior before, during, and after the eclipse thanks to the Life Responds: Solar Eclipse 2017 project and the iNaturalist app. The project will analyze our data and repeat the experiment during the next eclipse.
When you get to your observation site, choose the birds and animals you'll observe.
Post at least 3 observations of the birds/animals in iNaturalist at the times below. Add anything interesting you notice in the Notes.
30 minutes before maximum darkness.
During maximum darkness or totality
30 minutes after maximum darkness.
Make additional observations if you wish.
The cool thing about this project is that you don't have to be in the path of totality to provide useful data.
Do the birds stop singing at dark and restart when it's light? (This is a trick question! Few of them sing in August.) Do the chimney swifts dive into chimneys to roost? Do the squirrels go to bed? Do the deer come out? What about your pet? And if you're a beekeeper, how are your honeybees?
I've downloaded the app and I'm ready. I sure hope it isn't cloudy on Monday, August 21!
(photo from Wikimedia Commons; click on the image to see the original)
p.s. Observing Machines: If you're in a city in the path of totality, the street lights will come on. Will they come on in Pittsburgh?