Archive for March, 2007

Nest Box Update– Egg Sitting & Territory Patrol

Friday, March 30th, 2007
Mariah and Kaver at the Nest Box

The colder weather in Rochester over the past few days has encouraged Mariah and Kaver to spend some time keeping the eggs warm. Don’t confuse this with incubation, though. Right now, they’re just keeping the eggs from freezing. Mariah and Kaver do this by sitting over the eggs to keep the cold air away. That’s what Mariah’s doing in the picture at the left (click it to see a larger image)

A falcon’s eggs are like any bird’s, with an outer shell for protection, a yolk inside the shell which acts as a source of nutrition for the developing embryo, albumen (a clear fluid that acts as the embryo’s water supply while it’s developing), and of course, the embryo itself. The intense heat of incubation is what starts the process of turning those components into an eyas (if you’ve forgotten what an eyas is, you can find out here). For now, Mariah just needs to keep the eggs from freezing.

Kaver Sitting on the Eggs

Kaver can keep the eggs warm too. In fact, Kaver seems to enjoy egg sitting duty. Sometimes he enjoys it so much that Mariah has to stand over him for quite a while before he gives her a turn!

Still, Kaver spends most of his time outside the nest box, either hunting for food or defending his territory. Over the past few days he’s driven out several intruders– Hawks, mostly– that came too close to the nest. Yesterday was a bit more exciting. He chased away another male Peregrine that wandered into the territory. Local falcon watchers reported that Kaver and the intruder took turns diving at each other until the stranger left the area. Those kind of confrontations aren’t that unusual, especially during the springtime when birds, including many species of raptors, are migrating. Rochester lies on a major migration route for birds in North America, so Kaver will have plenty of migrants to drive away in the coming weeks.

- Jess

Mariah Lays Her Second Egg

Wednesday, March 28th, 2007

At about 10:40PM (EDT) Mariah laid her second egg. Here’s a picture shortly after the event:

Mariah with two eggs

That’s a bit sooner than her average egg-laying rate of about 54 hours, coming just a bit more than 50 hours after her first, but no one at the Rochester Falconcam is complaining!

-Jess

Some Things to Know About Egg Laying

Tuesday, March 27th, 2007

I was all set to write an article about the behavioral changes we’d see as Mariah prepares to lay her eggs, but she skunked me, and laid her first egg before I was ready! That’s a lesson for us all– when watching these falcons, expect the unexpected.

Now that she’s laid her first egg, let’s talk about what we can expect from Mariah over the coming days. Since Kaver arrived on the scene in 2002 Mariah has never laid fewer than four eggs. In 2003, 2004 & 2005, Mariah laid five eggs and all fifteen of those eyases (the name for falcon chicks) survived to fledge– that is, to take their first flights. That was a record in New York State.

Last year Mariah laid 6 eggs! She suffered an injury to one of her legs right around the time they began hatching, and her reduced movement hindered her ability to care for the eggs and her new chicks. As a result, only three eyases survived, but all of them went on to be remarkable fliers.

Mariah with Eggs 2002
Mariah with eggs in 2002

How many eggs can we expect this year? It’s always hard to say, but if the past years are any indication, it should be at least four. We’ll know for sure in a few more days. Peregrines lay an egg about every two days. Mariah takes things a little slower than the average Peregrine, laying an egg every 53 hours, give or take an hour or two.

Gravid Mariah

Between eggs, her behavior is that of an expectant mom– she’s lethargic, and she’ll spend a lot of time near the nest, if not actually inside the nest box. She may also have a fluffed-up appearance, or even look unkempt, with her feathers all askew. It’s the Peregrine equivalent of a bad hair day. As the picture at the left shows, she may also look heavy, or gravid as the eggs form inside her.

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, Mariah 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

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!

-Jess

Mariah’s First Egg of 2007!

Monday, March 26th, 2007

The Rochester Falconcam is very happy to announce that Mariah laid her first egg of the 2007 season just after 8:00PM tonight! Here’s the first clear picture from the Rochester Falconcam’s infrared camera, taken at 8:23PM:
Mariah First Egg 2007
Mother and egg appear to be doing just fine! We’re all very excited to see how many eggs she’s going to lay this year. Watch for more information about Peregrine egg-laying behavior in an upcoming article.

-Jess

Falcon Identification 101 – How to tell Mariah from Kaver

Saturday, March 24th, 2007

Here’s a popular question that we get asked all the time: “How can you tell which one is Mariah, and which is Kaver?”

The answer is easy– they look different. Just like no two people look exactly alike, no two Peregrines do either. At first glance (or even second and third glance) it might not be easy to see the differences, but we’re here to help with that, so read on!

First, let’s compare Mariah and Kaver side by side:
Mariah and Kaver Comparison

In this picture, Mariah is on the left, and Kaver is on the right. The very first thing you’ll notice is the difference in size between the two Peregrines. Mariah is a much larger bird than Kaver. In fact, in most birds of prey including falcons, hawks, eagles and owls, the female is larger than the male. When one sex is larger than the other, scientists call it sexual dimorphism. Many animals exhibit sexual dimorphism inlcuding humans, but for us it is the males who are generally larger. In raptors, the female is larger. This difference in size even influences what we call male and female falcons. Only the female Peregrine is called a falcon. The male peregrine is called a tiercel. Tiercel comes from the latin word tertius, which means “one-third”, because the male is typically 1/3 smaller than the female.

When Mariah and Kaver are side by side it’s easy to tell who’s who by their size. When they’re alone, it’s a little harder, but not too much. If you can see them on the Falconcam’s high resolution Main Camera, you’ll notice some differences in their features that can help.

After her size, the next thing to notice about Mariah is the white stripe that runs between her eyes, just above the yellow part of her bill. That part is called the cere, and among other things, its where her nostrils are. Most times if you’re looking at Mariah’s face you’ll be able to see the white feathers above her cere. Kaver doesn’t have a stripe above his cere, so that’s a pretty easy way to tell them apart.

Next is the shape of the head. The top of Mariah’s head is a bit flatter than Kaver’s. One of the distinctive features of falcons is their head coloring. Peregrines have a dark “hood” and malar stripes. The malar stripes are the dark patches on their cheeks that resemble sideburns. The combination of dark hood and malar stripes makes it look like the Peregrine is wearing a helmet. Mariah’s malar stripes are longer than Kaver’s.

It’s hard to tell in our picture above, but Kaver’s helmet is darker than Mariah’s. In brighter light Kaver’s helmet looks almost black, while Mariah’s almost always appears slate gray, with white highlights.

Mariah in Flight

If you come to Rochester to watch the falcons, you’ll rarely get close enough to see their faces. Good binoculars or a spotting scope can help, but even if you don’t have those, all hope is not lost. That’s because Mariah and Kaver often look different in flight, and that difference can be used to tell them apart. Mariah, in particular, often flies with the first couple of feathers on her right wing (called “primary” flight feathers) split from the others. The picture above is a good example. Her wings often have a broad, rounded shape, especially when she’s soaring. And since she’s a larger bird, sometimes her size alone is enough to identify her.

Kaver in Flight

In contrast, Kaver’s wings often have a more pointed shape. His smaller size also gives him a sleeker look. When he flaps his wings, his wingbeats are more frequent than Mariah’s, and not as powerful. Believe it or not, it’s pretty easy to pick up on these differences after watching them for a while.

So there you go– Size, facial markings, coloration, wing shape and flight differences are the clues you need to tell Mariah from Kaver. Keep watching the Rochester Falconcam and you’ll be an identification expert in no time.

-Jess

Courtship, Mating, & Nest Preparation

Tuesday, March 20th, 2007

Late winter and early spring brings the return of the falcons to the nesting territory they have occupied since Mariah settled in Rochester over a decade ago. Where were they over the winter? Only they can know for sure, and the falcons aren’t talking.

Peregrines are creatures of habit. Like tony jet-setters with expensive apartments and high-rise condos scattered through midtown Manhattan, wild Peregrines typically select two or three nest sites within a given territory, and move among them from year to year. Mariah bucks this trend, as do many of her urban-dwelling cousins. It turns out that the nest boxes set up by their human benefactors on the tops of buildings, smokestacks and other lofty structures are so ideally placed that there’s little need to wander around– a bit of a contradiction for a bird whose name means “wanderer”.

Mariah and Kaver have been tearing up the skies over downtown Rochester, but surprisingly they spend a considerable amount of time not flying, in the rather boring, but no doubt important task of perching near the nest site. It’s their way of staking claim to the territory, and letting others know that there’s no room at the inn. They’ve even been seen escorting other Peregrines out of the area since their return in late February. So Step 1, Reclaiming the Territory, is complete.

Time for Step 2: Courtship

Peregrines mate for life. There are exceptions to that rule, but we won’t concern ourselves with that for now. Since Kaver’s arrival in 2002 (he replaced Cabot-Sirocco, who failed to return that year) he’s been Mariah’s constant companion. Scientists and other smart people who study Peregrine behavior think that this fidelity has as much to do with the birds’ affinity for a particular territory as it does with their affininty for each other. So every year, we find the Peregrines re-establishing their bond through a complex set of ritualistic courtship behaviors. The male makes bold aerobatic flights that might include loops, tight turns, and swooping dives.

Kaver Brings Food to Mariah

Like a teen with a flashy sports car, he’s trying to impress her with his speed and agility. If she likes what she sees, the male starts coming around with gifts– not flashy jewels, but something even more precious to a female falcon– food. By bringing food, Kaver demonstrates his hunting prowess, assuring Mariah that he’ll be a good provider for her family.

Courtship - Bowing

If she accepts the food, the falcons will meet in the nest box for another ritual. This time, the birds face each other and take turns bowing– a very polite way of courting. This is their talk time, too. While they’re bowing Peregrines vocalize with a series of gentle sounds called “ee-chupping”.

On to Step 3: Mating

Kaver Approaches Mariah to Mate

Kaver and Mariah Mating

Kaver Flies Away After Mating with Mariah

As with humans, mating isn’t just a way to procreate. Peregrines’ mating activity also establishes and reinforces the relationship, what experts call the “pair bond”. Mating activity for Peregrines may take place many times each day. In fact, watchers in Rochester have seen Mariah and Kaver mating as often as every half hour!

Mariah initiates the mating by landing on a convenient perch and lifting her tail. Kaver, circling nearby will fly to her and land gently on her back to mate before flying off a few seconds later. In falcon relationships, the female is always the dominant partner (come to think of it, that sounds like most human relationships too!). She decides where the nest will be, when to mate, and when to lay her eggs.

Some birds have external sex organs similar to mammals, but most, including Peregrines, have something called a cloaca. Both males and females have a cloaca near the end of their tails. The cloaca is a common opening through which the birds expel waste and it is also used as the conduit for reproduction. During the act of copulation the birds touch their cloacas together, at which point the sperm is transferred from Kaver to Mariah. Mariah stores the sperm in her cloaca until she’s ready to fertilize her egg.

Unlike humans, Peregrine females can choose when to fertilize their eggs. That’s a great advantage in the wild. It means Mariah can store Kaver’s sperm and only begin the egg production process when she’s found a safe nest site.

Step 4: Nest Preparation

Kaver Excavates the Scrape

The final step is to prepare the nest. In the wild, a Peregrine’s nest is little more than a depression that’s been scraped out of the dirt and gravel on a cliffside or rocky outcrop. Not surprisingly, scientists call this kind of nest a “scrape”. The name lacks imagination, but there’s no denying its accuracy.

In nest boxes like the one on the Kodak tower, Mariah and Kaver’s human hosts have provided a bed of pea gravel several inches deep. To build the scrape in the nest box, one of the falcons (Kaver, usually) pushes stones out of the depression with its feet. On the camera it sometimes looks as if Kaver is ice skating while he’s excavating the scrape. Other times he gets right down on his belly and pushes with both feet. Then he looks more like a body surfer.

The courting, mating and nest-building behavior continues up until the time Mariah is ready to lay her eggs. I’ll cover that in my next post.

-Jess

Welcome to Imprints!

Friday, March 16th, 2007

Imprints is the official journal of the Rochester Falconcam. Check in every couple of days to read the latest news about the falcons’ activity in the nest box or around town. You’ll also find information about Peregrines’ behavior and life-cycle, to make it easier to understand how they relate to each other and their environment.

Imprints is here to help you understand and appreciate the fascinating world of the Peregrine falcon, so be an active reader! Use the Comments link at the end of any journal entry if you have a question or comment about the falcons. We’re happy to entertain queries about the Rochester Falconcam website too, but one thing we can’t help with is technical support. After all, we’re bird people, not computer nerds (OK, maybe a few of us are members of the taped spectacles and pocket protector set– but we’re much too busy watching the falcons to offer advice with web browsers, Internet connections and other problems) so please keep the questions focused on our favorite subject, the Peregrine falcons.

We hope you’ll find Imprints to be both informative and fun. There’s quite a bit of information about Peregrines in the Falcon Information pages on the website to get you started. If it seems overwhelming or impossibly complex, don’t worry; Imprints will help to put it all into context by relating it to what you see in the images provided by the Rochester Falconcam’s five cameras. And if there’s something you don’t understand even after we’ve dazzled you with our brilliance, feel free to ask!

-Jess