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Peregrine Watch Update Archive - 2009
Welcome to the 2009 View from the Aerie, the update about the peregrine falcon family nesting at the Precipice. Every week while the peregrines are nesting (usually into mid-August), park staff and volunteers will keep you posted about the happenings at the cliff.
The most recent events are posted first. We hope you check back often!
July 28, 2009. The start of August marks that time of year when we prepare to say farewell to all our young peregrines around Mount Desert Island as they commence their exodus southward. Along the way, they will join many other raptor species in the sky with the hopes of traveling far away from their breeding and natal grounds to warmer climates for the winter season. The wandering falcon is synonymous with a peregrine; due to the nature of their long-distance migrations, they have been marked with this special epitaph and certainly live up to it. In late summer and early autumn, this species can travel as far south as Central or South America in a relatively short time period and will retrace their journey back to breeding grounds the following spring. There are two main factors that help them achieve this amazing feat: weather and evolutionary adaptations.
A shift in wind direction accompanies the change of season here in the Northeast. As we enter into fall, strong gusts of wind coming from the north will push our falcons toward their southern destinations along the coastline; this jagged North American boundary serves as a route for many raptors and a key landmark to keep them on course. In addition to this, as the sun rises throughout the day, temperatures increase, which cause the formation of thermals, columns of warm, rising air, that boost our peregrines’ wings upward and enable many raptor species to enjoy a free ride in the sky. Due to this, all birds of prey will migrate only during the daytime so they can use the full extent of their wings whilst exploiting these thermals.
Wing shape and size are essential during migration and are strong determinants in the type of flight a bird will employ to head southward. The classic falcon outline is a sharp, sickle-shaped wing, which was designed to employ a partial-power gliding flight; they will use powered flight to supplement gliding from thermal to thermal when that is not an option. Furthermore, birds have hollow bones, which make their skeleton very lightweight to improve the efficiency required for an energy-costly flight. Immense reservoirs of fuel, which comes in the form of fat, are needed to complete their many-thousand-mile trek. Prior to and during migration, many bird species will bulk up their fat reserves not only to ensure a triumphant flight but also to keep warm and avoid starvation.
Although many details of migration remain a mystery to us animals chained to the land, the information we have gathered throughout the years is from a combination of banding birds, tracking them with radio telemetry, and observation closely. Due to thermals forming along mountain sides, many migratory birds cross over summits along the East Coast including Cadillac Mountain, which is a prime site to watch the sky heavily spotted with raptors from late summer to early fall. The Precipice opens Tuesday, July 28, and Peregrine Watch will continue throughout this week. Please join us starting August 19 to take part in HawkWatch on top of Cadillac Mountain, and with your help we may contribute to the pool of knowledge surrounding migration.
July 21, 2009. The peregrine falcon season is starting to wind down as the young falcons’ hunting skills increase and they spend less time at the cliff. I would like to take the time to reflect on the months our young and adult falcons spent living on the Precipice and Beech Cliffs and provide exciting updates about peregrines in Maine.
In the entire state of Maine for the 2009 season, there were a total of about 24 active peregrine territories. Fifteen of those were successful with young; including Acadia, there are 37 new young peregrine falcons in the state. This is an exciting statistic because in order for peregrines to be removed from Maine’s state endangered species list, they must first produce viable young from at least 15 separate territories for five consecutive years. This year will mark the initial year, and hopefully the following four years will prove that our peregrines are securely restored in the state after their population dwindled in the mid-20th century due the pesticide DDT.
On a more local level, many park biologists and falcon enthusiasts were delightfully surprised when a new peregrine territory was discovered on an island in Frenchman Bay. Prior to this year there have only been four occupied territories on Mount Desert Island because the number of nesting falcons is limited by the availability of their natural habitat for nesting—sheer rock cliffs. This year three young fledged from this new territory, which might prove to be a perpetual site for breeding falcons to return to. In Acadia, there were two female and two male falcons born at Beech Cliffs (above Echo Lake) and one male and one female born at the Precipice. The young have developed quickly at both sites and seem to be maturing into deft birds of prey as their hunting instincts kick in. All of the young on Mount Desert Island will only be here for a couple of weeks longer and will eventually join other raptors as they travel southward to find a place to winter.
While they are still gracing the cliffs and us with their presence, please join us down at the Precipice trailhead 9 to noon daily (weather permitting) to marvel at the sight of our resident peregrine falcons. Keep in mind that the Precipice Trail and a portion of the Champlain East Face Trail are closed until August to insure the safety of the falcons and their young.
July 14, 2009. A body of dark gray twists quickly in the sky and talons flash; it is the juvenile female peregrine seizing small flying insects in the air. Moments later, a deafening kak kak kak ricochets off the cliff and three falcon silhouettes are seen tearing across the sky. The adult male is being pursued fervently by his children, who are expecting to be delivered some freshly caught food. Yet, today, they will be disappointed and a bit hungry because the adult male has empty talons. They continue to chase their father until all three disappear over the north ridge and fly out of sight. For the past week both our immature falcons have been seen attempting to capture insects and a few small birds; however, there has been no observed success of an avian kill.
In a few weeks, our Precipice young will join many other birds of prey in a great southern migration and will not be able to depend on their parents for food. It is vital for these young to begin to strengthen their hunting skills as they will need to provide for their own survival. Perhaps our adult male is aware of this too and, in an effort to encourage his young to develop these skills, has begun to wean them from his consistent feeding. An empty stomach might just be enough incentive to spark the predatory instincts in our juveniles—only time will tell.
By now, both juveniles have returned to the cliff face and are trailing each other in the sky, occasionally making contact when they flip over and expose their talons; the adults are not solely responsible for their education, for they learn through playing with each other as well. Another important aspect of peregrine behavior is to defend themselves and their nests against potential threats—mainly from other birds. The behavior displayed by the young can be considered training for instances where they will need to fend off other raptors from their area—bald eagles, other peregrines, and even the much less threatening turkey vultures. For large predators, peregrines utilize a mobbing technique that entails multiple falcons working together to harass one bird until the risk has been abated. This is often observed at the Precipice because peregrine falcons, in general, are known to be very territorial and will vigorously protect their nesting area from any other large bird, whether it truly poses a threat or not, up to a one-mile radius. The young peregrines appear to be developing on schedule and each day provides a new opportunity for them to learn and grow into skilled falcons.
To see this exciting transformation, please join us down at the Precipice trailhead 9 to noon daily (weather permitting). Keep in mind that the Precipice Trail and a portion of the Champlain East Face Trail are closed until mid-August to ensure the safety of the falcons and their young. There are no nesting peregrine falcons on the Valley Cove cliffs, which has allowed the park to reopen the Valley Cove Trail (formerly the northern portion of the Flying Mountain Trail).
July 7, 2009. As the Precipice young grow, their skills mature with them. They have been flying for roughly three weeks and are now fairly strong fliers, yet they are still dependent on the adults for food. However, we have observed many times that the young are performing aerial prey exchanges—talon to talon food transfers—with their parents, as well as exhibiting a piqued interest in insects and small birds; solo hunting will be soon to follow. Peregrine falcons have unparalleled predatory instincts and prey upon a broad scope of birds—from something as small as a black-capped chickadee to a much larger mallard duck. They earned the nickname of “Duck Hawk” due to their reputation of preying upon large waterfowl, which, coincidentally, also made them a highly desirable asset for the hunting world.
Falconry, the art of using falcons to pursue game for humans, originated in the Orient prior to 2000 B.C. where it was popularly performed in China, Japan, India and Persia. It later moved westward into Egypt where it is depicted in ancient hieroglyphics. Egyptians held peregrine falcons to the highest esteem; they were often mummified, a process reserved for sacred vessels, and the great deity Horus, the sun god, took a falcon form. The sport then hit many European countries in the Middle Ages. Many people of royalty and wealth took to it; in England a falcon on your wrist was a mark of nobility, and the type of falcon noted rank—a gyrfalcon for a king, a peregrine for an earl and a kestrel for a servant. Falconry stayed popular in the areas of origin, and today is even practiced in the U.S. and Canada. Typically in modern falconry, peregrines are employed with hunting dogs, which are chiefly responsible for flushing out the prey and causing them to fly, upon which the peregrines can effectively strike in the air.
This sport is often considered to be a way of life. Falconry or hawking require long hours devoted to training the bird to hunt for humans and not for itself; you may imagine it would be difficult for a peregrine to keep such predatory instincts at bay. Falconers obtain their birds in a variety of ways: hand-rearing chicks, capturing juveniles in the wild, or collecting nestlings from wild aeries. Prior to 2004, taking a peregrine from the wild for falconry was illegal. However, due to their recovery and delisting from the Endangered Species Act in 1999, this ban has been lifted in some states (but not in Maine). In areas where taking peregrines from the wild for falconry is allowed, it is done under strict limitations and requires a permit. A female falcon is considered to be more valuable than a tiercel, or male falcon, simply due to its immense power and larger size.
You can see this power for yourself down at the Precipice trailhead 9 to noon daily (weather permitting). Keep in mind that the Precipice Trail and a portion of the Champlain East Face Trail are closed until mid-August to ensure the safety of the falcons and their young. Park staff recently confirmed that there are no nesting peregrine falcons on the Valley Cove Cliffs, which has allowed the park to reopen the Valley Cove Trail (formerly the northern portion of the Flying Mountain Trail).
June 30, 2009. The results are in…The nonviable peregrine egg collected from the 2008 Precipice scrape tested extremely high in four out of the five main contaminant categories: PCBs, organo-pesticides (e.g., DDT), PFCs (e.g., in stain-resistant products), and PBDEs. The first three groups of slow-degrading toxins have been persistent in our environment for many decades, and this evidence supports the fact that we have not seen the last of them. The final group, PBDEs, is a relatively new class of pollutants that are used in products to prevent fire by releasing bromine atoms that squelch oxygen in the air.
There are various forms of PBDEs; the most stable and common is deca-BDE, which can be found in everyday items like electronics, rugs, furniture—even the clothes on your back. In 2004, U.S. manufacturers ceased production of more potent forms, penta-BDE and octa-BDE, due to known health and environmental hazards but included the “safer” deca-BDE in their products. It turns out that the standard perception of deca-BDE as a stable and thus harmless compound of PBDE for humans and the environment was incorrect. As it is released into the earth through production, landfills, or runoff and settles in the soil, microbes will break it down and convert it into the aforementioned harmful forms. It builds up throughout the food chain and is deposited in the fatty tissue of organisms—like DDT did in the mid-1900s. The main effects related to these flame retardants encompass neurobehavioral problems such as impaired learning, memory, and attentiveness as well as some physiologic effects like hyperthyroidism and liver toxicity. What does this mean for our peregrines?
Our falcons sit on top of the food chain, which means that they acquire high concentrations of PBDE and are therefore more vulnerable to its detrimental effects. As birds that rely heavily on employing fast speeds and well-executed aerial maneuvers to strike prey out of the air, they would not fare well with disorders like A.D.D. (attention deficit disorder). This difficulty in catching food may lead to starvation and reproductive failure. Also, attentiveness to young is another issue that is threatened by PBDE: incubation, rearing, feeding, and teaching their young require a large amount of energy, time, and effort that is a feat even for a healthy peregrine falcon.
In 2007, Maine legislation banned deca-BDE and will phase it out of use in all consumer products by 2010. Many European nations have taken similar actions. For now, it seems only time will tell if PBDEs have any effect on species populations, which is a major concern—in particular for the recently recovered peregrine falcons. Nevertheless, our Precipice parents are doing a great job caring for their young and sculpting their flying and hunting abilities as they approach the time that they will disperse from the area to begin life in a new place.
Please join us down at the Precipice trailhead 9 a.m. to noon daily (weather permitting) to catch a glimpse of our resident peregrine falcons. Keep in mind that the Precipice Trail, including a portion of the Champlain East Face Trail, is closed until mid-August to insure the safety of the falcons and their young. Park staff recently confirmed that there are no nesting peregrine falcons at Valley Cove, which has allowed the park to reopen the Valley Cove Trail (formerly the northern portion of the Flying Mountain Trail).
June 23, 2009. The two young at the Precipice have now fledged and are exploring their new-found ability by chasing the adults as best as possible and mimicking their swift movements. As I watch the Precipice falcon family, so vibrant and ever present on the rock face, it is hard to imagine that two decades ago there was absolutely no sign of peregrines soaring around the high cliffs on Mount Desert Island: the eastern subspecies (Falcus peregrinus anatum) had been extinct since the late 1950s. These magnificent birds, known for their especially large feet, met their demise due through the vast spraying of an infamous pesticide, DDT.
Although highly efficient at killing insects and controlling the spread of disease, this contaminant infiltrated many ecosystems and accumulated throughout all trophic levels. Peregrine falcons are considered a keystone species because they are a top predator and indicate overall health of the environment. This means that due to a process called biomagnification, the amplification of a certain substance (i.e., contaminant) as it moves up a food chain, falcons were found to contain the highest concentrations of DDT and suffered most evidently from it. DDT prevented the deposit of calcium that is responsible for healthy egg production; instead of laying hard-shelled eggs, peregrines laid very thin and fragile ones that were vulnerable to shattering. Every time a female tried to incubate her clutch, her weight would smash the damaged eggs; this continued until the eastern U.S. literally ran out of peregrines.
Well, the world certainly took notice and action. In 1970, peregrine falcons were placed on the Endangered Species Act, and two years later DDT was banned in the United States. A decade later many reintroduction programs were implemented nationwide to restore this important bird on the East and West Coasts. Genes from various peregrine subspecies were used to create our falcons, which were raised in artificial nests, known as hack boxes, on cliff sides known to be historic peregrine breeding sites. In Acadia National Park, between 1984 and 1986, 22 peregrine eyases were released from Jordan Cliffs. This recovery scheme proved successful when one returned to the park. In 1991, thirty-five years after the last known peregrine pair was seen on Mount Desert Island, a male falcon returned to the Precipice Cliffs and attracted a mate. Every year since, there has been a pair nesting on these cliffs and, including the other three territories, 99 young have fledged in the park!
Thriving populations of peregrines in the West and most of the East led to their removal from the Endangered Species Act in 1999, yet they are still considered endangered in the state of Maine. It is important to understand that although DDT was banned in the U.S. many years ago, it takes a very long time to degrade; its prevalence in our environment means it continues to be a serious threat for peregrines. In 2007, a non-viable egg was collected from the Precipice scrape and tested for five categories of contaminants: mercury, PCBs, PBDEs, PFCs, and organ-pesticides. The results of this examination were extremely unexpected and opened many eyes, but you will have to stay tuned to find out more…
Please join us down at the Precipice trailhead 9 a.m. to noon daily (weather permitting) to catch a glimpse of our resident peregrine falcons. Keep in mind that the Precipice Trail, including a portion of the Champlain East Face Trail and the Valley Cove Trail (formerly the northern portion of the Flying Mountain Trail) are closed until mid-August to ensure the safety of the falcons and their young.
June 16, 2009. The maiden flight of a young peregrine is like the first solo drive after getting a driver’s license—a momentous occasion. Both our young falcons at the Precipice are on the cusp of achieving this and can be seen exploring their wings’ capabilities through vigorous flapping on the rock ledge. This behavior often precedes initial flight and is a strong indication of the chicks’ preparations and intentions to leave the nest.
The silhouette of an adult peregrine falcon as it soars and cuts through the sky is elegantly seamless and appears to be executed with great ease. The breadth of their aerial abilities is unparalleled to any other living creature on earth because as their wings are drawn inward close to the body. A skilled falcon can dive at speeds near 150–200 mph, typically deployed during a hunt or chase. It may take years for a young falcon to fully grasp and refine the art of flying and hunting before they can rival the aerial aptitude of an adult. In fact, it is very common to see a juvenile peregrine blunder in the air and misjudge a landing or crash into a tree. When our peregrines do take wing it will most likely be the male to make the premiere flight. This is due to the reverse sexual dimorphism that many raptors exhibit; females are larger than males, which generally means development takes longer for females to reach the full-grown stage. A typical first flight will happen early in the morning when they are most active and energetic, especially if it is a gusty day, and will not be a great distance from the nest.
The Precipice parents have been seen spending less and less time in the nest, which is largely due to the persistence of their young soliciting for food. At this point, the fully grown young are still entirely dependent on their parents as food providers and will act aggressively towards them when an adult makes a prey drop at the scrape. It has been suggested that in an attempt to elicit the young to fly, the parents will withhold food to try to tempt them from the nest with hunger. It is hard to know whether our Precipice pair are utilizing this strategy because they are not under 24-hour surveillance; prey drops to the nest may go unnoted. Even so, the Precipice young should take wing any day now and begin exploring the cliff and surrounding areas.
Please join us down at the Precipice trailhead 9 to noon daily (weather permitting) to catch a glimpse of our resident peregrine falcons. Keep in mind that the Precipice Trail, a portion of the Champlain East Face Trail, and the Valley Cove Trail (formerly the northern portion of the Flying Mountain Trail) are closed until early to mid-August to insure the safety of the falcons and their young.
June 10, 2009. This past week there was a great accomplishment in Acadia: the chicks at the Precipice and at Beech Cliffs were banded by the park biologist. On June 1, a team of trained climbers and researchers hiked the Precipice Trail while a group of excited visitors and volunteers watched in glee from the viewing area in the parking lot below.
Shortly after the troupe departed and headed up the closed trail, the female falcon began calling at their unwelcome presence. As they climbed closer, the male joined the female in defending their nest by continually swooping over the team. The banding process can be dangerous to both humans and peregrine falcons, so to insure protection hard helmets and harnesses are worn and the process is finished as quickly as possible to limit the stress on the adult and young birds. Researchers confirmed two chicks, one male and one female, roughly 23 days old, who vocalized while researchers were still at the aerie. The window to band the chicks is very narrow and must be completed between 21 and 25 days. At this point their legs are fully grown so the band will not interfere with their development and are young enough to not try to escape off the edge when a human approaches.
The chicks were affixed with two different bands that provide researchers with vital information: a silver U.S. Fish and Wildlife Service band and a black-over-green band that denotes a chick born in the Northeast. The banding process allows biologists to asses the scrape site wherein they will determine number, age, and sex of the chicks. Furthermore, they can collect egg fragments to test for contaminants as well as prey and pellet remains to gather information of their typical diet. Bands also provide long-term information that allows a view into the average lifespan of a falcon in the wild, distances traveled during migration, and areas that they settle in to breed. The word peregrine means wanderer, and chicks banded in Acadia National Park are certainly true to their name; Acadia falcons have been found breeding in New Hampshire, Vermont, and even New York City. If you see a banded bird and can read the bands, write down the information and report it to the U.S. Fish and Wildlife Service.
All in all the banding at Precipice and Beech Cliffs, which has 4 young, went very smoothly and both humans and birds alike resumed to their normal life relatively unscathed. Please join us down at the Precipice trailhead 9 to noon daily (weather permitting) to witness the majestic flight and presence of our peregrine falcons. The chicks should have their first flight in the next 10 days.
June 3, 2009. Hello and welcome to the 2009 edition of View from the Aerie! My name is Jenna Dodge, the new raptor intern for this season, and I will be providing the weekly updates of our resident peregrine falcons. Since graduating from St. Lawrence University in northern New York a year ago, I have been on the move pursuing opportunities in the wildlife biology realm and am quite ecstatic to have landed in Acadia National Park for the summer and fall terms.
There are four known falcon-nesting sites within the park boundaries: Jordan Cliffs, Valley Cove, Beech Cliffs, and the Precipice. Currently, there are confirmed successful breeding pairs at two of the sites, the Precipice and Beech Cliffs. Jordan Cliffs and Valley Cove are still being watched closely to determine their status.
The Precipice has been a favorite site for peregrines to establish aeries, or nest sites, since 1991 due to its sheer, high cliffs that provide the falcon home with protection and offer an excellent vantage point to spot potential prey in the nearby marsh, pond, and ocean habitats. The nest of a peregrine falcon is atypical from most birds that utilize sticks and other materials to build a nest. Instead, the falcon nest is called a scrape, wherein the female falcon will use her large feet to scrape away at soil, gravel or sand upon the rock ledge to make a depression in which she will lay her eggs or clutch. Many factors, such as weather, play a vital role in the success of a nesting attempt; we learned in 2007 that winter storms are debilitating to falcon nests, when all four sites on the island failed after two large nor’easters struck the coast late in the season. Furthermore, human disturbance, contaminants like DDT and other pollutants, predation (chiefly from great horned owls), and other factors affect the outcome of the eggs/chicks and adult falcons.
This year the Precipice pair has 2 eyases, or chicks, (one male and one female) that are roughly 26 days old. At this point in their development, the chicks require a lot of attention from mom and dad mostly in the form of food. Falcons hunt primarily other birds such as blue jays, robins, red-winged blackbirds, pigeons, etc. Peregrine falcons usually need to eat about five ounces of meat a day, which is approximately the size of a pigeon. Typically at the Precipice, the female will stay near the cliff and will vocalize to the male that she and chicks need food. This may stimulate a prey exchange between the adults or a visit to the nearby food cache where they often store food in the rock face. The male falcon is the chief hunter and will predominately hunt constantly to support the chicks and the female. His smaller size allows for more adept aerial maneuvers that aid in catching prey. While the female guards the nest from possible intrusions, her larger size allows for a stronger defense against bald eagles, osprey, and humans. The bond between the adult falcons is a true partnership, and the success of the young greatly depends on the efficacy of this bond. This year is sure to be full of excitement and great bird watching at the Precipice as the young, guided by their sagacious parents, grow and eventually fledge or learn to fly. This will then be closely followed by their departure from the parents and park in which they will travel, both near and far, to begin life in a new home!
Eyes to the sky: Just a few key field characteristics of peregrine falcons (Falco peregrinus)! They are crow-sized raptors with large feet and sickle-shaped wings that allow for great speed and maneuverability; peregrines are the fastest creatures on earth and can dive at about 100–200 mph. The adults have a striking dark hood and sideburns that accentuate the horizontal black barring on their white breasts. Like most birds of prey, they exhibit reverse sexual dimorphism, wherein the female is about one-third larger than the male, which permits numerable advantages such as occupying different prey niches.
Did You Know?
Since 1999, propane-powered Island Explorer buses have carried more than two million passengers in Acadia National Park, eliminating more than 685,000 automobile trips and preventing 6,444 tons of greenhouse gases. The fare-free buses are supported by your entrance fees. More...