Peregrine Seasonal Activities

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Zoom and GG at the Uptown Theater by Kanae
COURTSHIP (late Jan through March) As the season begins, the adult Peregrines are once again seen together at the natal territory and are fully engaged in courtship activities. During courtship, aerial behaviors include hunting as a pair, food transfers, and flight displays. The pair will also tend to be more defensive of the area. On the nest ledge, the male will busy himself getting the nest ready. Peregrines do not build nests out of twigs like many birds, but rather dig a shallow depression or cup in the existing substrate called a "scrape". The adult will appear to lay on his belly and wiggle around while scooting gravel out from under it with its feet. Courtship also involves behaviors such as "bowing". Bowing generally consists of the male standing over the scrape and leaning forward, head down and tail held high while looking his mate straight in the eye and emitting an "ee-chupping" vocalization. The female will often repeat this gesture back.


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Peregrine River Pair Eggs, 2010 125
EGG LAYING (late March to early April) Females lay a single egg every 24 to 48 hours. A typical clutch is three to four eggs. Incubation does not fully commence until the clutch is nearly complete. The eggs are roughly the size of a chicken egg and are reddish-brown in color with darker spots. Egg color can vary slightly between individuals as well as within a single clutch. At times, an egg may appear paler in color - nearly cream. These eggs are just as likely to be viable. Webcam watchers may be lucky enough to see the female walking slowly around the nest in a restless fashion during this time, but catching the exact moment the egg is laid requires extreme patience and time. If the first clutch is lost for any reason, the female will often lay another clutch.


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Rosie at UIC Incubating
INCUBATION (April to mid-May) The length of incubation is typically 30-32 days. Males will assist, but more so during the early stages. Both adults may leave the eggs from time to time for short periods, but they don't go far. The adult Peregrines may react differently from each other when something (such as a person) approaches the nest. Females will usually stay on or directly near the eggs while the male will get off the eggs to allow the female will to fly in. Webcam watchers should see an adult incubating almost any time they check in. Do not be alarmed if you check in and do not see an adult, remember they may take breaks for short periods of time. As a monitor, incubation is a great time to try and identify the adults through reading leg bands. A good time to do this is during a nest exchange when the adults switch off who is incubating the eggs.


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Pilsen Peregrine Falcon Chick Hatching
HATCHING (mid-May for the Chicago area Peregrines) Because incubation is delayed, most eggs hatch within 1-2 days. For the Chicago area, hatching usually begins around Mother's Day. This is also the time period where the adults are most defensive of the natal site. Males will spend most of their time hunting in order to feed the female and chicks. In the couple of weeks after hatching, webcam watchers will an increase in activity. For the first 7-10 days females will brood the chicks, which means tucking them under her wings for warmth or shading. Feeding is frequent as the chicks can only handle small amounts of food at a time. As the chicks rapidly mature, they no longer fit under the female are large enough to thermo-regulate on their own. After two weeks, the chicks are more mobile and by the third week, they will often move out of camera range.


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Peregrine South Loop Banding 2014
BANDING (through June) Banding takes place when the chicks are around 21-24 days old. At this stage the chicks have reached full physical growth. This age insures that we can place bands on the legs and not worry that the bird will outgrow it. Secondarily, the chicks still lack flight feathers. This means we can retrieve the chicks from the nest without the risk of premature fledging. Chicks receive two bands that bracelet their lower legs; one on the right and one on the left. These bands are unique to the individual. They allow scientists to study longevity and dispersal of individuals. It should be noted that not all nests are accessible, so some birds go unbanded. As for webcam watchers, if the nest is suddenly empty, think how old the chicks are. Perhaps the chicks are out being banded which means they should return shortly.


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Peregrine Seasonal Nestlings
NESTLINGS(Mid June to July) For the three weeks following banding, the chicks become fully feathered out and are extremely mobile. Webcam watchers rarely see the adults as they normally come into the nest area only to feed the voracious chicks. Also, the older the nestlings, the more likely they will be out of sight as they wander out of camera range. Monitors use this time of high adult activity in and out of the nest to confirm any adult identifications left unrecorded. Monitors also survey the area below the nest ledge and retrieve prey remains. Once identified, these remains provide invaluable data regarding what a local pair is eating.


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Peregrine MCC Fledging 2008 125
FLEDGING (mid-June to July) A Peregrine's first flight (called "fledging") is generally a glide down from the nest site to a level in line with or below the nest site. Occasionally, a fledgling will make it all the way to the ground. We call this "grounding". In the city, if a fledgling grounds on the street, it needs to be retrieved quickly due to the high levels of activity on most city streets. We pick the fledgling up, make sure it is not injured and if not, return it to the nest. Usually the second attempt at flight goes fine. The Chicago Peregrine Program is indebted to the many individuals who keep track of each site and watch to make sure the young Peregrines are safe. Please check out the 'In Case of Emergency' portion of the website if you have found an injured fledgling.


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David at Wacker Peregrine Nest
MIGRATION / WINTERING: Through reported sightings of banded Peregrines, we have been able to determine that most of adults stay in the area for the winter. Territories do expand significantly from the natal site range. For instance, in the past our Uptown Peregrines were very active at Montrose Harbor during the non-breeding season, but tended to stay a lot closer to the theater during breeding season. Because the adults do not use the nest at this time, most webcams are turned off. However, monitors still have something left to do. Though we try for the most part to allow the Peregrines to breed without human assistance, some of our Peregrines use human-constructed nest boxes. We use the off-season to make repairs to boxes, replace old boxes and re-gravel nests for the next season. We also use this time to collect prey remains from inside the nesting site.

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