The preferred nesting site, called an aerie, throughout the range is on a cliff ledge with an overhang for weather protection. The average overhang will cover about 80 percent of the nesting ledge. Occupied cliffs vary in height from 50 to 110 feet (15.5 to 34.1 meters) with nest heights ranging from 12 to 90 feet (3.7 to 27.9 meters) above the base. There appears to be no preference for extremely high cliffs. Unoccupied stick nests of the Common Raven or Golden Eagle are readily used. Westerly or southerly exposures are preferred in some areas, but elsewhere, no directional preferences are apparent. Nest sites are most often not accessible to mammalian predators or humans without climbing gear. In wooded areas, stick nests built in trees by other raptors such as the Rough-legged Hawk are used. The nest may also be a slight scrape on a ledge with no nesting structure at all. The Gyrfalcon has occupied old stick nests on man-made structures such as gold dredges, pile drivers, and even a sluice box. Often, piles of debris such as old bones litter the nest site and the area is usually heavily-stained with droppings.
Clutch size varies geographically from two to seven, but frequently three to four eggs. The clutch size appears to be linked to the current food supply. The eggs are broadly oval and average 2.4 inches (6.1 centimeters) long and 1.8 inches wide (4.6 centimeters). The ground color is creamy white with various degrees of fine cinnamon-reddish spotting often overlain with brownish blotching. Rarely, eggs are all whitish but may also look brownish overall. The shell is granular and not glossy. A replacement clutch will be laid if lost early in the season.
The interval between laying averages 56 hours with the incubation period averaging 35 days. Incubation usually starts when the third egg is laid such that hatching is partially asynchronous in case of a large clutch size. The total time from the start of laying until the last egg is hatched in a four egg clutch averages 43 days. Some authors report incubation starting with the first egg laid. Clutch replacement in the event of loss early in the nesting period has been reported within 14 days. Incubation is mainly by the female, but the male may sit on the eggs for as much as one-third of the daylight hours. As the incubation period progresses, the male may sit for longer periods of time. Brooding of the young is done by the female but the male may show some interest for the first few days after hatching. Throughout the entire incubation and first ten days of the nestling period, the female is entirely dependent upon the male for food. Ordinarily, he does not feed the brood, but rather he brings food to the female who rips it into pieces for the nestlings. At about ten days after hatching, the down of the young is sufficiently-well developed for them to thermo-regulate on their own. The female begins to hunt and bring food along with the male.
During the nestling period, the young start actively competing for food at 15 days although they are not aggressive. At 30 days, they are able to feed on carcasses independently. Fledging takes place at 46 to 49 days and complete independence is gained after a further 30 or more days. The young are fed by the parents for the four to five weeks after fledging with the time from egg laying to complete independence of the young being at least 110 days.
#What kind of bird uses this type of nest?;question\Q09\Q09.wav
P3ImageView
nestcoll\trecol1.bmp
nestcoll\trecol1b.bmp
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#What kind of bird uses this type of nest?;question\Q09\Q09.wav
P3ImageView
nestcoll\trecol2.bmp
nestcoll\trecol2b.bmp
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#What kind of bird uses this type of nest?;question\Q09\Q09.wav
P3ImageView
nestcoll\clicol1.bmp
nestcoll\clicol1b.bmp
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#What kind of bird uses this type of nest?;question\Q09\Q09.wav
P3ImageView
nestcoll\clicol2.bmp
nestcoll\clicol2b.bmp
ùôÇÇîÇÇ Cliffs and ledges
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#What kind of bird uses this type of nest?;question\Q09\Q09.wav
P3ImageView
nestcoll\mancol1.bmp
nestcoll\mancol1b.bmp
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#What kind of bird uses this type of nest?;question\Q09\Q09.wav
