Hello all! Our female, being 13 years old this year, has done it again. She’s managed to lay 5 eggs, just like last year. Thirteen years old is quite old for a Peregrine, and the male is 15 this year. Just like humans in their later years, bodily systems don’t work as efficiently as when we were younger. There’s more of a chance some of the eggs won’t hatch, but of course we will hope for the best.

If my calculations are correct, our female laid her last egg on March 26th. She laid her first egg on 18 March, and Peregrines usually lay an egg every 2 days until the clutch, or full number of eggs laid, is finished. The incubation period for a Peregrine egg is about 30 days, so the chicks should start hatching on 26 April.

You may notice I used words like “usually” and “about” to describe egg laying and incubation period. As much as we know about birds, there are still variables that could make small changes in number of days between eggs laid and egg development during incubation. If our female had 3 days between, say, egg 3 and 4, then the hatching date could be off by a day or 2. If mom had to leave the eggs to, say, defend the nest from another bird of prey, egg development could have slowed, which may change the hatch date. Most birds usually (there, I used it again) won’t start constant incubation until the full clutch is laid. This delay in incubation makes it so all the eggs hatch in about 24 hours. In the Peregrine world, mom and dad will feed those chicks that push, squabble and get closest to mom/dad as they present the food. Birds grow so quickly that if there were 2 days between the ages of each chick, the first 2 or 3 hatched would be bigger, stronger and would probably get most of the food, and the 2 smallest would more likely perish. Having all the chicks hatch within 24 hours makes it so they are roughly the same size, and each will have a great shot at getting their fair share of the food and surviving to fledging (flying from the nest).

So far I’ve had no questions to answer. Let’s get to it, folks! Put a challenging question out there for me to tackle. I look forward to any and all questions you may have.

Jeff Meshach, Deputy Director

As with every year we’ve had the privilege of watching the Ameren Missouri’s Portage de Sioux Energy Center Peregrine pair (we’re into our 8th year in a row), we are now into the incubation period by about 14 days. I’ll admit there’s not too much to see as the female provides the warmth that allows the eggs to develop into chicks. I’ll use the example of raking leaves. Yes, not the most stimulating of jobs, but when you are done, take a step back and look at your yard, you almost always say, “Wow, that looks nice!” I know we will all be elated when in 2 and a half weeks or so our female gets up from her scrape and shows us her beautiful chicks.

Earlier this week I was watching in the 3 o’clock hour and got to see some hilarious footage (the footage I speak of is on the web site). When I turned on the feed, I could tell the male was on the nest. A couple of times a day the female takes a break, and the male flies in and assumes incubation duties for sometimes as long as an hour. I could tell the bird I was looking at was the male because he’s considerably smaller than her, and just doesn’t take up that much space in the nest box.

For those that don’t already know, there are 5 eggs. When the female incubates, she has no problem covering all 5 with her bigger body, and seems to be comfortable enough to even doze off as she sits. Not so with the male. With the smaller body, I had to laugh out loud as he got up, changed angle, settled back down, then got up again, changed angle, settled down, then got up…you get the picture. He had to use his wings to help keep the eggs underneath him. Several times he also gently used his beak to push an egg back under his breast. It was so obvious he was not comfortable with all the “lumps.” After 10 minutes of this, I saw that he was looking up at something, and even slowly turned his head to follow the progress of the invisible-to-me entity. Of course it was the female, probably soaring on a thermal, enjoying the last minutes of her break. The male gently got off the eggs, stretched his sleek wings above his body, hopped to the perching in front of the box, then jumped into the blue. About 1 minute later, mom landed on the same perching, stepped into the box, balled up her feet and settled on the eggs.
There’s a theory that a female raptor’s body is larger than the males so she can more easily keep the eggs, and then young chicks warm. From what I observed, I’m in 100% agreement with this theory.

There were a few questions this time! Thanks to those of you who took me up on the challenge from the last ASK JEFF. First question is how high off the ground is the nest box? It’s 167 feet from the ground. I do not have to climb all that way. Most of that distance is covered by an elevator ride. The last 30 feet are ladders.
Second question is what happens to a chick or chicks that die as youngsters? Are they consumed by the parents or other chicks? With Peregrines it would be quite rare for a dead chick to be eaten by its nest mates or a parent. The parents are great food providers and would have had to fall on hard, prey catching times for this to happen. One of the theories on why any mated pair of birds settles on a territory is food abundance.

Last question is would I intervene and remove a weak chick to correct the health issue and then get it back to the nest? I would not, with the main reason being the disturbance I would have to create to climb to the nest to remove the chick, then have to climb to it again to put the chick back in. Climbing to the nest creates stress on especially the parents, so I make sure I go to the nest only once to place the bands on the chicks and draw a small sample of blood to make sure there are no human made toxins within. The scientific knowledge we gain from placing bands on the chicks and knowing what is and isn’t in their blood is the only instance worth placing stress on the parents. When I climb I make sure all my actions, and the actions of those around me are efficient, so the chicks are removed from the nest as little time as possible.
Great questions, folks! Keep them coming. Talk to you next week.

Jeff Meshach, Deputy Director

Hello Everyone! There were no questions asked last week, and with our female patiently incubating her clutch of 5 eggs, I skipped last week’s Ask Jeff. However, that doesn’t mean I didn’t have an interesting Peregrine Falcon experience over last week.

I got a call from a photographer in the Hannibal, Missouri area, and he told me he was watching a Peregrine that consistently perched in a group of cottonwood trees just upstream from the bridge that takes interstate 72 and U.S. route 36 across the Mississippi River. He sent me pictures, and sure enough he got some great images of an adult Peregrine.

The bird’s consistent position peaked my interest. First, I know Peregrines like to nest on bridges crossing large bodies of water. Bridges provide good hunting perches for this bird eating predator. As birds try to fly across the Mississippi, Peregrines streak to them to try to catch them before they can get to cover one side or the other. Second, what caught my interest most is bridges provide safe nesting places for the falcons. I asked the photographer if he ever saw this bird flying up and under the bridge, and he said he’d seen this behavior several times. I speculated the photographer was taking pictures of the male of a pair, and the female had her nest on the underside of the bridge.

My speculation was turned to truth when a Missouri Department of Transportation (MODOT) bridge engineer saw the 4 eggs on a steel beam when he was performing an inspection of the bridge on the same day the photographer sent me the pictures. MODOT was going to hang a “snooper” scaffold under the bridge over the next 2 days to continue their inspection, but once they found out the Missouri state endangered Peregrines were nesting there, they postponed their inspection until after 1 August (a special thanks goes out to MODOT for this postponement). The nesting cycle would be all over by that time of the summer, and they could do their inspection under safer conditions. Yep, the birds would be done with their nesting, and just as importantly, the workers would be safe from attacks by the female as she defended her nest (once the chicks leave the nest the female mostly loses her need to defend the nest). If there’s anyone that knows how viciously a female Peregrine defends her nest, it’s certainly me! Over the last 4 years at Portage de Sioux Energy Center the female has struck with her feet my helmet at least 30 times per nest visit, as she tried to shoe me away from her precious chicks.

So, all parts of the above story are quite fascinating to me, but the one bit of information that spun my mind into a series of questions was the part where the bridge engineer said the 4 eggs are on a steel beam, with no nesting material around them. There are no falcons in the world that bring nesting material to their nest. No sticks, grasses, wood bark; nothing. At Portage de Sioux we provide a nest box with pea gravel on its floor, which simulates a cliff nesting situation. Before humans came on the scene Peregrines would search for a place on a cliff that provided a level, mostly dry surface with some gravel or soil within which they’d dig with their feet a depression, or scrape, so their eggs stayed in one place. The depression also allows the pair to more efficiently incubate all the eggs at once.

So, how does a female Peregrine incubate her eggs when they are sitting on a hard, flat surface? How does she not break them with her weight? How does she get all the eggs (as many as 5) under her at the same time? In my experience I’ve witnessed Peregrines in the “hard, flat surface” scenario be perfectly successful, and ones that were not.
All birds have feathers on their bellies, as they have over most other parts of their bodies. During a nesting season, females of some species actually pluck their belly feathers so their warmer skin is against their eggs and young chicks. This mostly featherless patch is called the brood patch. In my experience observing Peregrines, the females don’t pluck their belly feathers. This could be so they can keep their eggs and young chicks warmer with no nesting material to help insulate the eggs/chicks. If you are lucky enough to watch especially the female just before she settles her belly on the eggs, she fluffs up those belly feathers, thus enveloping most of the surface of each egg with those insulating feathers. The heat from her body (birds have a 104 degree average temperature, where humans are 98.6 degrees) warms the eggs and the feathers insulate.

Still, a female Peregrine on a flat, hard surface must have to prop her body up somewhat so her full weight isn’t on the eggs. A bird egg is very strong, but with all her weight on the upper side of the egg pushing the underside of the egg against the hard surface, you’d think cracks would form. Also, you would think she’d be much less comfortable for the 30 or so days of incubation. Her weight is probably supported with her whole foot. A bird foot includes the toes, the joint where all the toes meet and the bone that goes from that joint all the way up to the next joint, which is in essence the ankle joint. In my experience I’ve seen 2 females on flat surfaces incubate only one egg at a time, while the other eggs rolled around on the surface. When she’d leave for her brake, the male might incubate a different egg then the female was incubating, and when she returned she might incubate a different egg than she incubated before she left. You can probably guess that each of these nests failed. I’ve also observed 2 different Peregrine females successfully incubate all 4 of their eggs on a flat, hard surface, with all eggs hatching. The difference between the successful and unsuccessful females; hard to say. These are the questions that keep it interesting for me. You can bet I’ll again report on the Peregrine nest under the bridge at Hannibal, Missouri. In the meantime, our female should have chicks sometime over the nest 7 days. Keep your eyes pealed!

Jeff Meshach, Deputy Director