Have a Question about Peregrine Falcons?

Email your question to Jeff! His response, along with your question, may be posted here. So, check this page often as you watch the nesting activities of the peregrine falcons. 

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May 13, 2016 

From Jeff: Hello everyone! As always, thank you so much for all your great questions.
bullet        Why were 5 eggs laid, and only 2 chicks hatched? 
I wish the answer was simple and straight forward, but it is not. There could be many reasons why only 2 eggs hatched. Some are as follows.

Our female is 10 years old and within her later years of producing viable eggs. Yes, she could be over the hill. The male is 12 years old now, so he could be over the hill as well. The unhatched eggs could have developed very small fractures; too small for human eyes to see, yet more than big enough to let bacteria into the egg. Eggs, even those unfertilized, do have an immune system, but if the egg is inundated with bacteria because of a crack, it will die well before the baby can hatch. Mom and Dad peregrines almost always faithfully incubate the eggs. However, if a predatory bird comes close to the nest, both parents will harass the unwanted bird until it leaves the Peregrine territory. If this scenario were to happen on a cool day and the eggs got too chilled, they could die. I could go on with reasons some of the eggs didn’t hatch, but my point is that nature is very unpredictable. I will collect the unhatched eggs, we will grossly analyze their contents, and save the eggshells for possible future analyzing.
      What happens if a chick dies in the nest? 
I’ve not experienced finding a dead chick in any of the other 4-5 Peregrine nests I visit per year in the greater St. Louis area. Especially in the early days after chicks hatch, mom keeps the nest clean of any uneaten bird carcasses. She flies away with these parts and just drops them. I would guess mom would remove a dead chick for the same reason she would remove a prey carcass; keep the number of flies within the nest to a minimum. As far as we know, bird mothers don’t have the mental capacity to mourn the loss of a chick. Nature provides for practicality so the other chicks have a better chance at surviving.
      Do the down feathers of a chick provide the same protection from rain as a grown Peregrine’s contour feathers? 
The down definitely helps keep a young bird warm, but does not provide warmth if the down gets wet. However, mom will come to the rescue and sit on or hover over the chicks so her body and feathers keep the rain off her kids.
      Do birds fly during a rain storm, and if not, could the chicks die from starvation during a prolonged rain?
Even during prolonged rains, birds will still fly and forage for food, including Peregrines. Feathers have special, tiny spikes on them that make water droplets bead and slip off rather than get absorbed by the feathers. Also, all birds have an oil gland at the base of the tail. This gland secretes an oil which the birds spread on their feathers with their beaks and sometimes claws. This oil helps prolong the life of a feather (as feathers wear out they are dropped and replaced by the bird’s body) and helps keep the feathers waterproof.

I’ll be banding the 2 babies on Friday, May 20, when the babies are about 20 days old. The camera will be turned off for about 3 hours, but will resume once the chicks are safely back in the nest. Talk to you all next week!
May 4, 2016

From Jeff: So far, my timing has NOT been impeccable. I’ve looked at the web cam a lot since the chicks hatched Sunday night into Monday morning, May 1st and 2nd, and still have not gotten a good look at the 3 of them. I know that 2 eggs have not hatched, and at this point in the game, they will not hatch. There could be many reasons for eggs not hatching; infertile and a crack that allowed bacteria to get into the egg are 2 of the bigger reasons. The eggs will probably remain in the nest until I go to the nest on banding day, which will be May 20th. I’ll of course remove them and at least take a close look to see if I can find a crack. The parents normally don’t do anything with the unhatched eggs.

Way back when mom first started laying the eggs, she didn’t sit tight on them. Over the millennia, natural selection moved toward those Peregrines that didn’t sit on their eggs consistently until the whole clutch was laid. If the female sits tightly on the eggs as they are laid, then those first 2 laid eggs would have a 2-4 day jump on development over the last 2-3 laid. This means the chicks from those first laid eggs would be considerably bigger than the chicks from the last laid eggs, and those larger chicks would overtake the smaller chicks for food, increasing the chances the last hatched chicks wouldn’t survive to fledging.

With the very quick glimpse I’ve gotten of the chicks, they seem healthy. Because of such cool weather over the last 5 days, mom has had to brood the chicks, which means keeping them huddled against her breast and stomach. When birds hatch, they cannot keep their body temperature at the normal 104 degrees F for very long. Some say this is a throwback to their ancestors; cold blooded reptiles. Once a bird gets to a certain size and gets that thick coat of down, then contour feathers all over its body, then they start to thermo-regulate, and mom won’t have to brood them as much.
      How big is the nest box? 
The rectangular box is 23 inches tall, 32 inches wide and 20 inches deep. There’s about 3 inches of pea gravel as nest substrate. Peregrines normally nest on cliffs, within shallow depressions on the cliffs, where they can find some gravel to scrape a nest bowl from. The Portage de Sioux Energy Center nest box is 160 feet from the ground, so there’s your “cliff” height to help keep mammalian predators from raiding the nest.
      How big are Peregrine falcons?
Male Peregrines have on average have a 30 inch wingspan (that’s wing tip to tip), with the females having a 40 inch average wingspan. Females weigh on average 2 lbs. 4 ounces and males on average 1 lb. 6 ounces. Please refer to the ASK JEFF from the week of April 20th to read about the theories on why males are smaller than females.
Finally, I had a woman write to me, and she told me she was 80 years old. She wrote only to tell me how much she enjoys watching the falcons, and also to tell me she tells all the children in her life to watch the web cam. Thank you very much to this fine lady, and I ask that all who watch please tell your friends and especially the children in your lives about the web cam. The more who are informed about wildlife, the more will want to help save it, and the habitat it needs to survive.

I’ll talk with all of you next week!
April 29, 2016

From Jeff: Well, we are all waiting with bated breath on seeing the first chick emerge from an egg. It should be any time now! I predicted between April 25 and 30, and we now have chicks at other nests hatching. We have at least 2 chicks hatched at the nest box at Ameren Missouri’s Rush Island Energy Center, and at least 1 chick as of this morning at the Washington University Medical School box; both good signs of good things to come for our Peregrines.

We had some great questions over the last week, so I’ll get right to them.

    What happens to the egg shells after the babies hatch? 
The female will sometimes eat the eggshells. In an earlier ASK JEFF I wrote about the depletion of calcium from the female’s body, and the body’s compensations for this. With the very muscular stomach that raptors have and the strong digestive enzymes, the eggshell gets processed and can more right back to growing the medullary bone, which are bone bumps that grow within the larger bone’s hollow spots. Only females have medullary bone, with the bumps waxing during the non-egg laying season and waning during the nesting season.
        Are the falcons bothered at all by the noise from the plant? 
Just like the other birds that nest on grounds (ie. Barn Swallows, pigeons, Killdeer), the Peregrines get used to all the noises, even the loud ones, that come from the various equipment that produces the electricity we all need. 

      Are the male and female colored identically?  
In essence, Peregrines of the same sub species are colored quite closely.  Within nature, it’s wise to not use absolute terms. Adaptation by plants and animals is ongoing, and some subtle changes with an organism are adapted by subsequent generations, and some aren’t. Some adaptations, for instance albinism, are sometimes quickly removed from the environment. For example, an albino moth that’s normally colored the same as the tree bark it hides on will quite quickly be spotted and eaten by, say, a Great Crested Flycatcher. I’ve not ever seen or even heard of albinistic Peregrines, or even partial albinism, but some other birds of prey are quite frequently albinistic, like the Red-tailed Hawk. A raptor that eats mostly mice really doesn’t have to be cryptically colored so the mouse has a hard time seeing it. Peregrines on the other hand would be seen from afar by the birds it preys on if the Peregrine was white, so that’s a good reason for no records of white Peregrines.

Some subtle color differences within Peregrines can be seen on the spotting of the breast feathers, and also the malar stripe, which is the dark colored stripe below the eye on a Peregrine’s cheek. Some malar stripes are thin, some medium and some don’t even look like a stripe because the whole cheek is dark. Some colors that are quite consistent are the slate gray back and top-of-the-wing feathers of the adults.


      When do the babies begin to be left unattended?
All newly hatched baby birds can’t produce enough body heat to keep them warm, which some say is a throwback to the cold blooded ancestors of birds, reptiles. So, mom has to brood the babies, or huddle over them to keep them warm. Once the babies reach the size that allows for the insulation to keep a constant body temperature, then the parents start to leave them unattended. However, the parents are never too far away. Baby Peregrines could be preyed upon by other raptors, crows, or mammals that try to climb to the nest.  You can bet mom would full-on attack any potential predator, and from the beating I took from our mom last year when I “visited” the nest to band the babies, I can honestly say any predator would be making a really bad choice to try and eat one of the babies.

      Is Mom rolling the eggs when she shuffles her body while incubating?
I don’t believe she’s moving the eggs when she shuffles around. Seems to me she’s just trying to get comfortable. I guess I can imagine having 5 lumps plastered against my chest and stomach almost 24/7 for some 30 days. I believe mom turns the eggs with her beak, but I’ll look that one up and get back to all of you next week.

A great bunch of questions this week! Talk to you all next week. 
April 27, 2016

From Jeff: Earlier this week I went to the website to see what was up with the box, of course expecting to see our female dozing as she incubated her clutch. Well, there was a Peregrine on the nest, but I could immediately tell it wasn’t our female. This Peregrine was considerably smaller. Compared to the amount of nest box floor the female takes up as she sits, the incubator at this particular time let a lot more gravel show. Of course it was the male Peregrine. To reiterate, the male this year is a 2004 hatch (same year the previous male Coal was hatched), but this new guy was hatched in captivity and released to the wild at a power plant in New Madrid County, Missouri. Check out the first ASK JEFF from early April to get more details. 

        Why are male Peregrines so much smaller than female Peregrines?
It’s not just Peregrines, but birds of prey in general. There are theories on the size differences, but no one really knows for sure. One theory on why the female is bigger is she has to produce and then incubate the eggs, so a bigger body is better to draw the extra nutrients from and more surface area to more easily incubate the eggs. Another theory is the female is the higher ranking nest protector because she spends so much time there, so a bigger body makes her more formidable to any potential nest raider.
The only theory I know on why the male is smaller is to help make him more maneuverable, and therefore better at catching prey, so he can more easily provide for the incubating female, then for the young chicks. Out of all the theories I agree with this one the least because the female quite easily provides for herself when she’s not nesting, and also helps the chicks by bringing food to the nest once the chicks don’t have to be brooded.

      How long can the eggs go without being incubated?
Sometimes the female must leave the nest, especially when another bird of prey comes into the nesting territory, and especially if it comes close to the nest, which is the zenith of the territory. This kind of a threat almost always makes the female want to defend the territory and her eggs, so she will leave to help the male chase the other raptor away. The cooler the day, the less length of time the female can afford to not be incubating. Too much of a chill could cause the egg or young chick within the egg to die. When the temperature is warmer, the female can afford to be away from the eggs longer. I don’t have any data on specific temperatures compared to specific times away from incubating. 

      How long is the incubation period for Peregrines and when our eggs will start to hatch?
Peregrine incubation time is about 30 days. I say “about” because cooler weather may lengthen the incubation period, and warmer weather may decrease it. Our eggs should start hatching between April 25th and 30th.

Thank you all, and keep those questions coming!

April 18, 2016

From Jeff: Well, I have some good news and not so good news. I’m the type that always wants the not so good news first, so here we go. One of the area peregrine nests from last year that I mentioned in the last ASK JEFF is not in existence this year. It’s the nest that was on the St. Louis University Hospital. Last year was the first year they were there, and I banded 2 babies. There could be literally a million reasons the pair is not there this year. I have a very reliable source that keeps me informed of them, and to this point he has not seen them. With all the other area pairs sitting on eggs now, it’s safe to assume this pair should have started their nesting cycle. You never know, maybe they will be back next year.

Now for the good news, we have a new pair of peregrines nesting at Ameren’s Rush Island Energy Center! I got the good news on Tuesday, April 12. With the assistance of a couple of staff members, in late summer 2014 I put up a nest box on the structure that’s used to unload coal from barges (Rush Island Energy Center is on the Mississippi River downstream of St. Louis). No falcons used it last year, but they are there now. I’ll probably be banding the babies in late May or early June.


      What is the range of the peregrine falcon?
Peregrines are found worldwide on every continent except Antarctica. There are at least 17 recognized sub-species on earth, with 3 of those sub-species found in the U.S.. A sub-species has big enough differences in size, color, habitat preferences, prey preferences, etc. to make the designation. Any sub-species can still mate with any other sub-species and produce offspring. Anywhere cliffs meet water is a good place to find peregrines, since they like to nest on the cliffs and hunt from them, too. Cities are the new “cliffs,” and the skyscrapers provide the birds with the same things as cliffs; places to nest on and hunt from.

      When will the eggs hatch?
We should see our first glimpses of the little ones between April 25th and 30th. A Peregrine’s incubation is about 30 days, but could vary by a few days depending on the individual and subtle climate phenomenon.
        Someone also asked about camera angles.Our camera hangs from below its support pole, and in fact this morning around 8 there was a perfect shadow of the camera right on the female. The camera can pan in and out, and can move a little to the left and right. Last year the 4 babies left the box several days before they could fly, and even after they made their first flights, still came back and liked to hang out behind the box on metal beams and walkways. The camera can move far enough left that we got to watch the youngsters for about 10 days after they left the box. The camera is worked by a Portage de Sioux Energy Center employee. This person is as busy as the rest of us with a full time job, but they still manage to get us some great footage and still shots. A hearty “Thanks” goes out from me to the camera person!

I’ll talk to all of you next week!  Keep those questions coming.
April 6, 2016

From Jeff: I left for Boston last Wednesday, having to drive all the birds there for the Stone Zoo bird show, which World Bird Sanctuary produces and presents with our own 4-member staff. The drive is a grueling one. It must be done straight through so the birds are in their travel crates as little time as possible. To say the least, I was one tired puppy upon arriving home last Saturday. I took a long afternoon nap.

I’ll stop complaining now because my long, 3-day trip to and from Boston is nothing compared to what our mother peregrine must go through to raise the next generation of peregrines. I’ll not even consider that every day for any wild creature is a life and death struggle, avoiding predators, territorial attacks from their own kind and acquiring enough food for survival, with your own abilities and body parts.


What happens to the female falcon's body when laying eggs and during incubation?

To save weight, a peregrine’s primary sex organs, ovaries and testes, become active for only about a month. Mating occurs during about 2 weeks of that month, and occurs many times a day.  After the tiny egg within the female’s body detaches from the bunch-of-grapes looking ovary, it becomes fertilized and starts its path down the reproductive tract. This is where the yolk sack is developed, the egg shell is laid down, with the pigmented layer being the final step before passing out of the female’s body and into her scrape (the depression she makes in the nest gravel).

All this takes a toll on the female’s body.  A few hours before she lays an egg, she becomes sickly looking, with feathers fluffed up, eyes closed, and sometimes even yells. Yes, as all human females can vouch for, the next generation passing from the body is painful. She’s helped through the egg laying and incubation process by the male. He waits on her wing and foot, bringing her meals and taking up to an hour per day to incubate while mom eats, does some preening and generally takes a break. Still, the female incubates the other 23 hours of the day and her body must provide the extra calcium needed to lay down the very important egg shell. Many of a bird’s larger bones are hollow to save weight. Within the female’s hollow bones grows small bumps of calcium called medullary bone. They grow during the non-breeding season, and then are used to provide the calcium for the egg shell.

Other things the female is more vulnerable to during incubation are, a) predators such as Great Horned Owls and raccoons that could climb to the nest, and b) ectoparasites such as mites and lice. So, although most of what you see on the web cam right now seems to be the female taking a break from life’s struggles, she has gone and will continue to go through a lot until her kids leave the nest.
      How many eggs are there now?
Our female has 5 eggs, with one of them light in color. I talked about this in the last Ask Jeff, and in short, the pigmented layer wasn’t laid down quite right with this first-of-the-clutch egg, but it has as much a chance to hatch as the other 4.
      Do the Falcons have names?
Last year the Falcon Cam Team decided not to name the male and female.  With all the perils the pair must face, including being chased away from the territory by a rival male or female, we felt it best to not name birds that may be gone next year. FYI, Coal, the male that we watched for the last 4 years, has been replaced. The new male was released to the wild through the process known as hacking in 2004, at a power plant in north central Missouri.

How many other pairs of Peregrines are there in the St. Louis area? 

There are 8 pairs as far as I know: Clayton, Washington University’s Medical School, St. Louis University Medical Center, the AT&T building in downtown St. Louis, Ameren’s Labadie Energy Center, the Jefferson Barracks bridge, the Chain of Rocks bridge and of course Ameren’s Portage de Sioux Energy Center.  I can’t get to the bridge pairs, but was able to reach the other 6 sets of babies last year, banding 21 babies in all.  FYI, the AT&T building has had a pair nesting on it since 1991.


March 24, 2016 

From Jeff:
WELCOME, WELCOME, WELCOME!!!!!!!!! I'm so happy that I can again share with all of you some insight on the Portage de Sioux Energy Center Peregrine Falcon pair, and of course their eggs and hopefully babies, which should start hatching in late April. As always, ask any questions you have. I'll try to get to all of them.


First of all, we have a new male peregrine this year. His colored band is black over green, D over 53 (D being in the black field and 53 in the green field). Unlike Coal, the male from the 4 previous years that was hatched in the wild at Ameren's Labadie Energy Center, this male was hatched in captivity and then released to the wild through a process known as hacking. He was released to the wild in June of 2004 at the New Madrid Power Plant, in New Madrid County, Missouri.

Coal was the same age as this new male. We will probably never know what happened to Coal. His whereabouts are unknown, but he also may be the "new" male at another nest site. Since SouixZee, the female of our pair from 2012-2014, was replaced last year by a female of the same age, both Coal and SiouxZee could still be producing babies somewhere else on the continent. By the way, we probably have the same female as last year. I say "probably" because the green field of her black over green band has faded so much, we can't tell what number/letter is there. However, the black field has a sideways D, which is what the female from last year had.

As of today we have 3 eggs. You will notice one of the eggs has a faded appearance. That egg was the first egg laid, and it was laid Thursday, March 17th. I have consulted as to the faded look of the egg with one of the world's leading bird of prey vets, and he explained the following. As an egg develops in the female's body, the last layer of shell laid down before the egg is laid is the pigmented, or egg color layer. For reasons unknown, the pigmented layer of this first egg was not laid down properly. However, the vet says the egg has all the potential to hatch, just like the normal colored eggs.

The female won't start sitting tight on her clutch (group of eggs) until the last egg is laid, so about a month from that time we will see the chicks. Last year our female had 4 eggs, and all of them hatched. We of course shall hope all her eggs hatch this year, and we again get to watch her and the male go about raising their kids.

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