Lawrence Peregrines: eggs week #2!

April 19, 2017 in In the Nest Box

LP4.19.2017As the incubation process continues, many have asked for more specifics about how it all works?

Heat makes the eggs start developing. When the eggs reach about 98.6°F, or 37°C the egg begins changing into an eyas. Conveniently enough, a Peregrine’s natural body temperature is about 103°F, or 39.5°C, so to heat up the eggs all they need to do is to get some of that body heat onto the eggs. Now, a Peregrine’s feathers make very good insulation. That’s how they can stand to stay out in cold temperatures without freezing to death. But while those feathers keep the cold air away from the falcon’s skin, they also keep their body heat from getting out. So to incubate the eggs, the Peregrine carefully settles down, shifting from side to side to get the eggs beneath their feathers. Falcons have brood patches, areas on their breasts with a lot of blood vessels close to the surface of their skin. The blood vessels concentrate their body heat, making it easier to transfer the heat to the eggs. Both adults have brood patches, though his are smaller than hers, which makes sense since he’s a smaller bird.

LP.4.19.2017.2-001Peregrines incubate their eggs for 29 to 33 days. In the early days of brooding it’s important to keep the eggs as close to their ideal incubating temperature as possible. Too hot or too cool and the eggs won’t develop properly. Later in the incubation process, proper temperature isn’t quite as important. In fact, after a couple of weeks the falcons will be able to leave the eggs uncovered for longer periods of time. Sometimes leaving the eggs uncovered frequently, or for long periods can mean that the eggs hatch a few days later than normal. For the Lawrence Peregrines, their nest box is in a place where it’s not likely to be disturbed, so they most often incubate steadily until the eggs hatch.

Lawrence peregrines: 4 eggs!

April 10, 2017 in In the Nest Box

LP.4.10.2017The female Peregrine in Lawrence has finally laid all four eggs, a bit later than usual for this location.  Here’s how the process works. Once fertilization occurs the egg begins moving down her oviduct. It’s sort of on an assembly line where the egg gets built, layer by layer. First comes several coatings of yolk. The egg moves a little farther down the ovidicut where it gets covered with albumen (the clear fluid that we’d call egg white) and various membranes. Then it continues on its way until shortly before she’s ready to lay the egg, it gets its final layer, the shell. The whole process takes a little more than a day.

The actual act of laying the eggs can take as little as a few minutes or as long as an hour or more. When she’s ready to lay her egg, the female will sit in the scrape. She may look like she’s sleeping, or at least taking a nap, but if you watch carefully, you’ll notice that she starts to move around as the egg is laid. She typically keeps the egg covered after it’s laid for 10 to 20 minutes before moving off the nest and letting us have a good look.

Peregrine eggs are speckled, and vary in color from light pink to darker brown or purple. Older falcons may produce lighter colored eggs. Each one is about the size of a small chicken egg.

One bit of behavior that many people find unusual is that she won’t begin incubating the eggs, or brooding, right away. Believe it or not, that’s perfectly normal for Peregrines. She’ll begin brooding when the next to last egg is laid, so when she starts, we can be pretty sure we know how many eggs she’ll lay– just add one to the current number. Before then, she’ll mostly leave the eggs uncovered. Don’t worry though– Peregrine eggs can survive just fine unless the temperature drops below freezing. If that happens, she’ll sit on the eggs just to keep them warm enough to stay viable. We’ll talk more about brooding and incubation soon. In the meantime, keep watching!

In this photo on Monday morning after the last eggs were laid over the weekend, the female is taking a break and resting on the outer edge of the nest box!

Lawrence Peregines: feeding time at nestbox!

May 23, 2016 in In the Nest Box

CF2C0985-001The Lawrence Peregrine fledglings continue to grow and get bigger. The female in this photos is tearing apart prey and feeding it to the chicks.  The nestbox is getting crowded and the meals are more frequent.  The chicks are spending more time near the front of the nestbox!  The are now using their legs fully and no longer sitting on tarsi.  Banding time is very close at hand.

Lawrence Peregrine: male on watch!

March 23, 2016 in On the Clock Tower

CF2C4269-001The Lawrence Peregrines now have a single egg that has been laid.  The first egg was laid late Monday night.  It is expected that 3 more eggs will be laid in the next handful of days!  The male is on watch on a ledge very next the nestbox!

Peregrine chicks banded!

May 27, 2014 in In the Nest Box

Three peregrine falcon chicks roosting above the New Balance factory were pronounced healthy Tuesday and fitted with federal and state tracking bands to help Mass Wildlife biologists and local volunteers keep tabs on them.

Mass Wildllife staffers and other volunteers gently lifted the fluffy chicks out of their nesting box and used pliers to fasten metal bands around their legs.

The chicks were completely checked for health issues and to make sure they were growing and developing without major issues.  They observed that flight feathers are starting to emerge.

When fully fledged, the peregrine chicks will be fierce hunters that can dive at speeds of 200 mph or more to snatch other birds in mid-flight.

The chicks’ parents are among some 30+ peregrine falcon pairs that live in Massachusetts, favoring bridges and tall buildings where they can easily spot their prey.  Based on feathers found in the nest, the falcons have recently preyed  on Bluejays and Pigeons.

The mother falcon, sleek and gray with a banded gray and white belly, squawked furiously as Mass Wildlife staffers and volunteers opened the back access hatch of the nesting the box. All the humans wore appropriate gear for protection from her talons. The babies squawked at a higher pitch, then bleated as the falcon banders gently reached in to secure each chick for banding.

There were three chicks along with one unhatched egg. Overall, all were healthy. It is very normal for one chick to be a little less developed from others due to lower food allocation issues from stronger siblings At just over three weeks old, these chicks were mature enough to band, because their legs won’t grow any more, but too young to fly away.


Peregrine chicks very active!

May 22, 2014 in In the Nest Box

At three weeks, flight feathers and body contour feathers are poking through the down. Very active, the young birds are moving around the nest box and exploring the area around all the corners. They have a marked interest in anything that moves.

Chicks feed and grow: getting stronger!

May 12, 2014 in In the Nest Box

The 3 chicks continue to grow and gain strength!

Peregrine chicks continue feeding

May 8, 2014 in In the Nest Box

The feeding activity continues each day and the chicks devour all items brought to nest box….many Blue Jays on the menu!

Peregrine chicks continue to feed and grow!

May 5, 2014 in In the Nest Box

The chicks continue to grow and are are able to have a few moments where female is in nest and nearby but not brooding all the time!  4th egg remains unhatched.



Parents involved in food exchange!

Peregrine chicks: now there are 3!

May 4, 2014 in In the Nest Box

Newly hatched chicks weigh about 1.5 ounces and are virtually blind.  Covered with only a light coat of fluffy white down, newborn chicks require constant brooding by the female in order to stay warm.  Feeding usually commences on day two when the small chick bobs its head looking for food.  The female provides small pieces of food for the chicks!