Peregrine Status & Monitoring

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Peregrines in Illinois are doing great! We have achieved the goal of having a self-sustaining population of Illinois' breeding falcons at a low risk (less than 1%) of statewide extirpation. The Peregrine Falcon has preliminary approval for delisting from our state Endangered and Threatened Species Board. Final approval should happen by early 2015. The Peregrine Falcon was removed from the Federal Endangered and Threatened Species List in August of 1999.

Continued monitoring is critical for evaluating population viability and verification of the population recovery. People should feel free to email Mary Hennen with Peregrine observations or questions at any time of the year.

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". During courtship, there is not as much for webcam watchers to see, as the adults spend much of their time away from the nest. However, lucky webcam watchers may see the male, and even the female, building and perfecting the scrape. The adult will appear the lay on his belly and wiggle around while scooting gravel out from under it with its feet. Very lucky webcam watchers may witness both adults engaged in a courtship ritual in the nest. This nest display is called "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 emiting an "ee-chupping" vocalization. The female will often repeat this gesture back. As monitors, our efforts focus on confirming the return of adults to established sites and trying to locate new sites. This is the time when the public becomes very important to us as emails regarding sightings of adults in an area are often our only lead to a new site. This time of year is also when we are likely to witnesses territorial fights with new Peregrines trying to take over an established site.


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Peregrine River Pair Eggs, 2010 125
EGG LAYING (late March to early April) Females lay eggs every 24 - 48 hours. A typical clutch is three to four eggs. Incubation does not fully commence until the clutch is nearly complete. The eggs are about the size of a chicken egg and are reddish-brown in color with darker spots. At times, one or two eggs may appear paler in color - nearly cream. These eggs are just as likely to be viable. If the first clutch is lost for any reason, the female will often lay another clutch. Webcam watchers may be lucky enough to see the female walking slowly around the nest in a restelss fashion during this time, but catching the exact moment the egg is laid requires extreme patience and time. For the most part, webcam watchers are delighted to check in and find the clutch has grown by one since they last checked. Monitors use this time to watch for the adults during nest exchanges in order to try to identify them from their legbands.


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Rosie at UIC Incubating
INCUBATION (April to mid-May) The length of incubation is usually 30-32 days. Males will assist, but more so during the early stages. Webcam watchers should see an adult incubating almost any time they check in. Both adults will often use incubation as a time to nap. Nest exchanges and food deliveries are the most exciting webcam activity. Also, do not be alarmed if you check in and do not see an adult. Both adults will leave the eggs from time to time for short periods, but one or both are near by. This time period is one of the best for monitors to try to identify the adults. Females will usually stay on or directly near the eggs, which gives us the opportunity to try and read her leg bands. If we approach the nest while the male is incubating, he will usually get off the eggs and the female will fly in. Some males perch nearby, which allows us to try and read his bands. While we have a fair number of unbanded adults, we sometimes have the opportunity to confirm if it is the same bird year after year through the genetics of the offspring.


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Pilsen Peregrine Falcon Chick Hatching
HATCHING (mid-May for the Chicago area Peregrines) Hatching usually begins around Mother's Day. How appropriate! Females will brood the chicks for the first week. This is 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. This is a very active time to watch the nest for both webcam watchers and nest monitors. In the couple of weeks after hatching, webcam watchers will see the female brooding the young chicks almost constantly. Feeding time is the most fun and happens more and more often as the chicks grow. In the early stages, the adults will leave the chicks alone for short periods of time. As the chicks rapidly mature, the adults will spend most of their time outside the range of the camera, normally coming into the nest area only to feed the voracious chicks. 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 South Loop Banding 2014
BANDING (through June) Banding takes place when the chicks are around 21-24 days old. The window for banding is very small with two very good reasons. At 21-24 days old, the chicks have reached full physical growth. Banding at this time 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, you will see less and less of the young in the week before and weeks after banding. The young are very mobile during this time and will hop and climb all around the nest site, often out of range of cameras.


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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. It is the scariest time of the year for the monitors, but also the most exciting. Sadly, the young spend almost no time in the nest, so it is the most boring time for webcam devotees. 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 (September through March) 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 from the natal site significantly, however. For instance, we know that the Uptown Peregrines are very active at Montrose Harbor during the non-breeding season, but tend to stay a lot closer to the theater during breeding season. Because the adults do not use the nest at this time, all 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.


Peregrine Monitoring - Individual ID

You may see some Peregrines with bands on their legs.  These are unique to the individual and allow us document where an individual bird has gone if read.  It's important that if you see a Peregrine, try to get as much information on the bands as possible.  Which legs have a band? What color(s)? Letters and/or numbers and orientation?  In the graphic above, you see some possible color band combinations.  How do read this?  Bottom row has 4 possible color bands, all being a black over red band.  This first band I would write as b/r A/B.  The following would be b/r 98/A, third band as b/r 6/*D, and last as b/r *P/*H.

Continue to explore the exciting world of the Peregrine Falcon!