In the next few days the peregrine eggs at the University of Pittsburgh are going to hatch, so now’s a good time to explore…
How does a baby bird get out of the egg? It’s a strenuous one to two day process in very tight quarters.
When a chick is ready to hatch, he pulls himself into the tucking position with his beak sticking out between his body and right wing. This gives him the leverage he needs to whack at the shell.
The chick then breaks through the membrane at the large end of the egg that isolates the air sac and he breathes for the first time.
Next he starts to bump the shell with the curved ridge of his beak where he has a calcified egg tooth that’s sharp enough to crack the shell.
His strenuous hammering is aided by the hatching muscle on the back of his neck.
While still in the egg he communicates with his parents and siblings by peeping and pecking sounds. The parents know which eggs are alive because they’re speaking. The siblings know their brothers and sisters are ready to emerge. In precocial species, which must all hatch at once, the chicks listen to each others’ tapping to coordinate the hatch. Elder chicks tap slowly, younger ones tap rapidly so that all of them reach the finish line in a 20-30 minute window.
Finally the chick cracks his shell all the way around. He pushes with his feet and the egg splits open. His mother moves the shell away and he lies quietly, waiting for his down to dry.
After hatching the chick’s specialized tools aren’t needed anymore. The egg tooth falls off (in songbirds it’s absorbed) and the hatching muscle shrinks into just another neck muscle.
Watch the National Aviary falconcam for hatching at Dorothy and E2’s nest. The streaming cam is blurry but it is broadcasting sound so you’ll be able to hear the chicks peeping inside their shells. That will be our first sign that hatching is underway.
(Credits: photo of a chicken emerging from its egg from Wikimedia Commons. Click on the image to see the original. Today’s Tenth Page is inspired by page 460 of Ornithology by Frank B. Gill.)
Whoa it is warm today! Over 80 degrees in the sun!
Dorothy was panting at the nest so when E2 showed up for nest exchange Dorothy jumped at the chance. Here he’s the one standing in the background as Dorothy leaves in a hurry.
Watch for their eggs to hatch around Earth Day (Monday 4/22) give-or-take a day or two. I plan on zooming the snapshot camera during the hatch so we can see the babies better. This year it’s the only webcam we have. Will you miss the wide view?
(photo from the National Aviary falconcam at the University of Pittsburgh)
This week the trees in Pittsburgh are putting on the green.
The flank of Mt. Washington is my favorite place to see it. All winter the hillside is a flat brown color without the look of individual trees but now each leafing tree shows up as a pale green crown. Some are white with flowers.
This appearance is ephemeral. Soon the leaves will be large and shady and the hillside will look uniformly green. So now while the trees are changing so fast here’s a close look at what they’ve been up to.
Above, in Schenley Park an Ohio buckeye leafs out. Below at a later stage the flower buds emerge. (*see the Comments for discussion on this tree)
I blog about birds Outside My Window. Glen Apseloff went a step further and photographed the birds outside his window.
Several years ago Apseloff set himself the challenge of photographing birds in his backyard in Powell, Ohio with an added twist — all the photos had to be taken through the window glass and none could use a flash.
Accompanying more than 120 photos are descriptions of the birds’ plumage, their behavior, the foods he’s seen them prefer, and his experience watching them. Occasionally he gives tips on photography. For instance, “Around my house dark-eyed juncoes usually feed on dropped finch food rather than directly from feeders. Males tend to be darker than females; females have more brown or a paler black in their plumage. Males can be challenging to photograph in the snow and in bright sunlight because of the contrast between white and black.”
Glen’s book is like an outing to his backyard. The birds are familiar and intriguing, often so close we can see their eyelashes. As on all outings I like to pick a “Best Bird.” My favorite: The pileated woodpecker on page 96.
There are beautiful birds outside Glen Apseloff’s window.
When Charlie posted these photos on his Flickr account he alluded to Edgar Allen Poe’s Raven and wrote, “In spite of Carole opening the door and the trash pickup, [the robin] kept returning until Carole covered the kickplate with the door mat.”
At the Pitt peregrine nest, E2 is sometimes so eager to incubate the eggs that he won’t get up when Dorothy arrives to relieve him.
If E2 stays put and Dorothy’s not in a hurry she’ll wait as much as 15 minutes. Last year she fell asleep while she was waiting!
To get him moving she “talks” and walks around him. If he’s really stubborn she pokes him with her beak.
@PittPeregrines created videos of this parental bargaining using the webcam snapshots: Stubborn E2, above, and Nest Exchanges, below. E2 doesn’t dare to poke Dorothy but he’s persistent about taking his turn.
In a week or so Dorothy will take command and hardly allow E2 any time on the eggs. That’s because she’s in charge of hatching, expected around Earth Day. Visit the Pittsburgh Falconuts Facebook page to vote on the day you think the eggs will hatch.
Every spring I’m stumped by this small flower that blooms in lawns, fallow gardens and waste places. With four petals and alternate “divided” leaves I could tell it’s in the Mustard family. When I keyed it out in Newcomb’s Wildflower Guide I arrived at Pennsylvania bittercress (Cardamine pensylvanica*).
But that’s not what it is. It grows too well in poor soil to be a plant known for preferring wet habitats, swamps and stream banks. I began to suspect it’s an alien.
Based on that hunch I sent photos to friends. Mark Bowers answered that this is hairy bittercress (Cardamine hirsuta), native to Europe and Asia.
Like Pennsylvania bittercress, its young leaves can be used in salads and are said to taste like radishes.
Click here for a video describing what to look for if you’d like to eat it. Notice the dog at the end.
(photo by Kate St. John)
* Not a typo, the person who classified Cardamine pensylvanica omitted the second ‘n’ in our state’s name.
During incubation there’s not a whole lot of activity at a bird’s nest except for this: Mom (or Dad) periodically stands up, stares at the eggs and draws each one toward her with her beak. She’s not just rearranging the eggs, she’s turning them.
Other than a few notable exceptions, all birds turn their eggs because it’s required for the embryos’ survival. For instance:
The temperature in the middle of a clutch is warmer than the edge. Birds move the outer eggs to the middle to keep them evenly heated.
In the early days of incubation, it’s important that the embryo floats inside the egg while the membranes that support its life are growing and developing. Turning optimizes membrane growth.
Eventually the chorion and allantoic membranes will be pressed to each other and to the shell. If these membranes adhere too soon the chick will not be able to move into the hatching position later and get out of the egg. Turning prevents premature adhesion.
The albumen (the egg white) is the embryo’s fluid cushion and water supply. Turning the egg optimizes the fluid dynamics of the albumen so the chick can absorb it properly.
Egg turning is so important that it’s a wonder some species don’t do it. One notable exception are the megapodes who lay their eggs in compost heaps and let the heat of the decomposing vegetation incubate them. No turning there!
I’d rather watch a peregrines’ nest where things are happening, if only a bit of egg turning.