Monday, 6 July: Sadly, one of the female fledglings was electrocuted on a power line Saturday and died. Her two siblings are still safe and accounted for this morning. Today, power structures are generally much safer for raptors, thanks to the tireless efforts of one of The Peregrine Fund’s board members, the late Morley Nelson, and Idaho Power Company, but accidents do happen. In cities, the birds’ natural predators like owls and eagles are replaced with glass windows, cars, and wires. If a bird survives the first year (more than half don’t make it), the chance of reaching adulthood improves dramatically, with mortality rates dropping to 12% or less. Knowing the many dangers they face increases our respect and admiration for these tenacious birds. 

Thursday, 2 July: Recent fledging experiences show what a dangerous time this is for the chicks. In general, a pair of Peregrine Falcons can expect only 50 percent its offspring to survive their first year in the wild. Fortunately, this nest exceeds the average, according to the Fish and Game Department. In urban settings, youngsters may smash into windows and buildings, sometimes with fatal results. They also can end up on the ground amid traffic or pedestrians. Fish and Game is asking people who see a chick on the ground or on the top floor of a parking garage to call the phone number posted on fliers around downtown. People should not approach or touch the bird and simply wait for Fish and Game to arrive. 

Monday, 29 June:  All three chicks are flying around downtown from rooftop to rooftop, closely monitored by volunteer observers. The adult birds are nearby. On Sunday, Fish and Game biologist Bruce Haak returned the male (who landed in the street Friday) to the nest box and placed a pan of water on the roof to be sure the birds have a water source during this hot weather. After returning to his car, Bruce looked up just as the third chick took her first flight about 9:45 a.m. Sunday morning.

Saturday, 27 June: Fledging has gone well so far for the female chick, the first to leave the nest. She did hit the side of Hotel 43 yesterday but got herself safely to a window ledge. A dedicated group of bird watchers has been observing her every move. The first flight was a rough one for the male, however. He fledged last night and collided with a car. He was taken to a bird rehab facility where he was well cared for overnight. The chick appears to be in good shape but Fish and Game biologist Bruce Haak will keep him for observation tonight and return him to the nest tomorrow. Observers are still waiting for the third chick to take her first flight.

Update: Friday, 26 June: One of the chicks decided to go for it this morning. The youngster took its first flight and landed safely on a building located directly across the street. Clumsy and awkward at first, fledglings must practice how to judge distance and speed and develop a sense for safe places on which to perch. This is risky business, in both wild and urban settings.

Friday, 26 June:  The chicks are likely to take their first flights this weekend. Nature has programmed them to fledge about 42-45 days after hatching. All the recent wing-flapping and ledge-exploring has given the chicks the strength and confidence they need to take that first leap into thin air. The parents don’t need to encourage fledging--the chicks will do it instinctively--but they will be close by. The adults must continue supplying food to the chicks for another month.

Wednesday, 24 June:  Anxious to answer their innate urge to fly, the juvenile Peregrine Falcons are very active now. The building on which they live affords the young birds plenty of room to move about, run, and flap their developing wings. This activity serves to both strengthen flight muscles and give them practice maneuvering their long wings. Any day now, the Peregrines will test their wings in earnest by fledging and taking that first flight.

Thursday, 18 June:  As the chicks continue to grow and prepare to fledge, they spend a lot of time preening (grooming) their feathers. As they preen, they remove protective sheaths that encase their new feathers. Once the sheath is removed, the feather expands and appears “feather-like,” rather than “straw-like.” Blood carrying nutrients through the shaft of each feather promotes rapid growth. Quality and quantity of nutrition determines how strong and well the feathers grow at this stage of a chick’s young life.  

Tuesday, 16 June:  This is a very active time for the Peregrine chicks. Feathers are growing quickly, and the instinct to prepare for flying is kicking in. Soon, the chicks will begin flapping in earnest, strengthening flying muscles, and getting a feel for what their wings can do. They are also moving much more confidently, running in and out of the nestbox and beginning to explore more of their world above Boise.

Wednesday, 10 June: Those bands the chicks got last Saturday have a special return address and number on them that, if recovered, will inform researchers about the birds’ age, sex, and hometown. The U.S. Fish and Wildlife Service maintains a database of information from bands collected in North America. Scientists use it to track such things as survival rates, migration routes, and the effects of environmental pollutants and disease. 

Monday, 8 June: Lots of action at the nest box over the weekend! A small team led by Idaho Fish and Game Department biologist Bruce Haak went out on the ledge Saturday afternoon to put a wayward chick back in the nest box after it climbed out, then couldn’t hop over the edge of the box to get back in. Recent high winds and heavy rain influenced the decision to assist the chick, even though it was being fed and closely watched by its parents. While they were there, Fish and Game also banded the chicks. Each chick (two females and one male, we now know) sports a small aluminum U.S. Fish and Wildlife Service band on one leg. Click here to see banding photos. A chick was observed out of the box again Sunday. Bruce Haak and Jack Cafferty of The Peregrine Fund went up on the ledge Monday morning to put a rock at the edge of the box that the chicks can use to hop in and out. Clearly, the youngsters are eager to explore their surroundings.

Friday, 5 June: The darker tips of tail and wing feathers are now showing through the chick’s thick white down. Within a week, body feathers will start to emerge. The chicks are now strong enough to stand all the way up on their feet for short periods. The strength to stand up tall allows them to start feeding themselves by holding large pieces of food with their feet and tearing off small pieces. Soon the parents will be free of the beak-to-beak feeding duty.

Wednesday, 3 June: The chicks, which began emerging from their shells 18 days ago, grow rapidly, as they have little more than a month to become ready to fly. Feeding these demanding youngsters will keep both adults fully occupied for about three more weeks. Peregrine Falcon chicks typically take their first flights from the nest, or fledge, at about 41 to 45 days.

Monday, 1 June: This is the only pair of nesting Peregrine Falcons in Boise, reports the Idaho Fish and Game Department, which is responsible for monitoring the state’s falcon population. Another pair is nesting on the Amalgamated Sugar Co. silo in Nampa. Each pair needs an adequate hunting area but normally defends only the immediate area of the nest from unwanted intruders like eagles, hawks, and other falcons.

Friday, 29 May: While keeping an eye on the chicks, the adults spend a lot of time preening, or grooming. They run their beak through their feathers like a comb to keep them in tip-top shape for flight. Even the chicks do it--one was recently seen preening a sibling. This behavior is hard-wired. The birds know instinctively that feathers must be clean and groomed. A gland at the top of their tail excretes waxes, fatty acids and other elements that the birds spread through the feathers to condition them. Preening is a sign of a healthy bird.

Thursday, 28 May: Biologists will know exactly what species of birds the falcons preyed on after they leave the nest later this summer. For scientists, bones and remains are a treasure-trove, providing insights into complex ecosystems. The Peregrine Fund discovered that certain migrating shore birds take a short-cut across the Guatemalan rainforest at night after finding remains of those shore birds in a nest of forest-dwelling Orange-breasted Falcons.

Wednesday, 27 May: Peregrine Falcons are built for speed, which makes them successful hunters in flight. Very stiff feathers give them the impressive maneuverability that allows them to catch avian prey on the wing. Many birds of prey feed on a variety of mammals, birds, reptiles and insects, but the feeding habits of Peregrine Falcons are more specialized--they dine exclusively on other birds.

Monday, 25 May: A variety of reasons could explain why the fourth egg did not hatch. The mostly likely is that the egg is unfertilized, thus there was no chick inside. It is also possible that a chick died at some stage during incubation. Unhatched eggs are relatively common, which is why the falcons produce three to four eggs at a time. The adults will roll the egg aside or out of the nest.

Friday, 22 May: Even during the recent hot spell, the chicks stayed under the adults much of the time. This is called “brooding.” The chicks cannot regulate their own body temperatures at this stage so they must be kept warm by the adults, which brood the chicks for about 10 days after hatching. The chicks also keep warm by sleeping in a heap. If they are too hot, they will separate and stretch out their wings and legs to cool down.

Thursday, 21 May: It is hard to see exactly what the adults are feeding the chicks, but you can be sure that the food is some type of bird. Peregrine Falcons prey exclusively on small- and medium-sized birds, and Boise has plenty of those. When the adults catch a bird, they remove the head and wings, pluck the feathers and may partially eat it before bringing it to the nest for the chicks.

Wednesday, 20 May: Though they beg for food, the new chicks still contain some of the yolk sac they absorbed while inside the egg. This gives them the strength to survive for several days while other eggs hatch and adults begin the feeding process. The Peregrine Fund has raised 7,000 falcons in captivity since pioneering the process in the 1970s, and we have learned that feeding new chicks too much too soon creates problems. Begging is a sign of a robust young bird, but mom knows best. The adult birds know exactly how much to feed each chick.

Monday, 18 May: The tiny chick that hatched Sunday afternoon was soon joined by two siblings, which could be seen in the nest this morning. The chicks are covered with downy white feathers. We will know the fate of the fourth egg, which remains unhatched, in the next few days.

Friday, 15 May: As incubation ends, the chicks are beginning to stir and feel the urge to get out of their eggs. Chicks are equipped with a notched “tooth” on top of their beaks called a pip or egg tooth, which they use to open a small hole in the egg. Then they turn, cracking the shell around the circumference. Once pipping has begun, the chicks vocalize from inside the egg, and the parents respond as they keep an eye on the process. From pip to hatching can take 24-72 hours.  

Tuesday, 12 May: The four eggs in this nest are strong enough to withstand the weight of the adults incubating them. That wasn’t always true in the 1960s, when scientists discovered that DDT caused physiological problems with females, resulting in thin-shelled eggs that often broke during incubation. DDT was banned in 1972. While strong, the eggs also are fragile enough that chicks can peck their way out when the eggs begin to hatch.

Friday, 8 May: It is difficult to distinguish male and female Peregrine Falcons because their appearance is basically the same. The best way to tell these two apart is to compare size. Females are larger and heavier than males by as much as a third. This “reverse sexual dimorphism” is common among birds of prey.

Wednesday, 6 May: It’s not easy raising offspring--some eggs don’t hatch, some chicks die. Last year, Idaho Fish and Game monitored 23 occupied falcon territories in Idaho. Nineteen of those sites produced 41 chicks that successfully hatched and fledged. A fledging rate of 1.5 young per site is considered good.

Monday, 4 May: This nest is one of 42 recent and historical nesting locations in Idaho. Peregrine Falcons were essentially gone from Idaho about 40 years ago when the pesticide DDT was decimating raptors. From 1982 to 1995, The Peregrine Fund and our state and federal partners released 188 captive-produced falcons at 15 Idaho locations. Idaho Fish and Game did other releases through the years. Now, Peregrine Falcons are found around the state.

Wednesday, 29 April: The falcons are now into the second week of the incubation period, which can last up to five weeks. At 10 days old, the embryo inside the egg is about 1 centimeter (less than a half-inch) long. The egg loses weight as the yolk is consumed and the air cell grows larger. By hatching time, the egg will have lost up to 18 percent of its original weight.

Monday, 27 April: Food exchanges are part of a successful nesting attempt. Sometimes the male flies to the ledge outside the next box and leaves all or part of a prey item for the female to eat. Other food transfers occur on a nearby building. Even aerial exchanges may take place, with the female actually flying out to meet the male. If he were not a good provider, she would spend too much time off the eggs hunting on her own, which could cause the nest to fail. 

Friday, 24 April: Chilly nights and breezy days make it necessary for the eggs to be well-insulated. The incubating birds don’t move much, although they stand up occasionally to re-position themselves over the eggs more completely. As incubation progresses, the birds rotate the eggs to be sure they are warmed evenly and thoroughly. They also are rotated to prevent the embryo from sticking to the egg’s inner membrane. If it sticks, the chick may not hatch properly. 

Wednesday, 22 April: The incubation period, which lasts 32 to 35 days, is a quiet time for the adults. Their job now is to keep their warm bodies in contact with all four eggs to allow the embryos to grow. As the embryo develops, blood vessels begin to form while the developing chick utilizes the yolk as a food source. Oxygen goes in and CO2 goes out through the porous shell. 

Monday, 20 April: The female generally sits on the eggs at night. The male helps during the day. When he’s not on egg duty, the male keeps busy providing food for both of them. He stores food in a nearby cache so the female doesn’t have to go far to eat. He also keeps a close eye on the nest to defend it against intruders if necessary. 

Friday, 17 April: A fourth egg is observed in the nest this morning--a great start to a gorgeous spring day.  

Tuesday, 14 April: A third egg arrives right on schedule. The male and female take turns sitting on the eggs.  

Sunday, 12 April: The falcon pair produced their own Easter egg, which arrived about 3 p.m. The male flew into the nest immediately, keeping his head bowed low while she stood over this second egg. Both gave it a good look, then he flew off and she laid down for a well-deserved rest. She occasionally leaves the eggs alone for short periods while she goes out to eat.  

Friday, 10 April: The first egg arrives this morning! The female stood over her small brown egg for a short time as she and her mate carefully inspected it. She will likely produce three or four eggs, laying one every other day. The egg arrived after an active courtship season. In March, the birds did everything Peregrine Falcons do when it is time to start a family. They built a depression called a “scrape” in the gravel where the eggs were deposited, all the while “bowing” and making “chupping” noises to each other. The male faithfully brought the female food to court her and to make egg laying a little easier. He will continue to do this throughout the incubation process.