page_title: Peregrine falcon
section_title: Reproduction
hierarchical_section_title: Peregrine falcon / Ecology and behaviour / Reproduction
caption_attribution_description: Deutsch: Wanderfalke Falco peregrinus , Ei, Coll. Museum Wiesbaden English: Peregrine falcon Falco peregrinus , egg, Coll. Museum Wiesbaden
context_page_description: The peregrine falcon, also known as the peregrine, and historically as the duck hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-grey back, barred white underparts, and a black head. The peregrine is renowned for its speed, reaching over 320 km/h during its characteristic hunting stoop, making it the fastest bird in the world, as well as the fastest member of the animal kingdom. According to a National Geographic TV program, the highest measured speed of a peregrine falcon is 389 km/h. As is typical for bird-eating raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males. According to one study, it has the fastest visual processing speed of any animal tested so far, and can register discrete changes up to 129 Hz or cycles per second. Analogically, film is a series of still images projected onto a screen. Those still images need to be changing at roughly 24 frames per second before humans see them as fluid and no longer as individual, discrete pictures.
context_section_description: The peregrine falcon is sexually mature at one to three years of age, but in larger populations they breed after two to three years of age. A pair mates for life and returns to the same nesting spot annually. The courtship flight includes a mix of aerial acrobatics, precise spirals, and steep dives. The male passes prey it has caught to the female in mid-air. To make this possible, the female actually flies upside-down to receive the food from the male's talons.
  During the breeding season, the peregrine falcon is territorial; nesting pairs are usually more than 1 km (0.62 mi) apart, and often much farther, even in areas with large numbers of pairs. The distance between nests ensures sufficient food supply for pairs and their chicks. Within a breeding territory, a pair may have several nesting ledges; the number used by a pair can vary from one or two up to seven in a 16-year period.
  The peregrine falcon nests in a scrape, normally on cliff edges. The female chooses a nest site, where she scrapes a shallow hollow in the loose soil, sand, gravel, or dead vegetation in which to lay eggs. No nest materials are added. Cliff nests are generally located under an overhang, on ledges with vegetation. South-facing sites are favoured. In some regions, as in parts of Australia and on the west coast of northern North America, large tree hollows are used for nesting. Before the demise of most European peregrines, a large population of peregrines in central and western Europe used the disused nests of other large birds. In remote, undisturbed areas such as the Arctic, steep slopes and even low rocks and mounds may be used as nest sites. In many parts of its range, peregrines now also nest regularly on tall buildings or bridges; these human-made structures used for breeding closely resemble the natural cliff ledges that the peregrine prefers for its nesting locations.
  The pair defends the chosen nest site against other peregrines, and often against ravens, herons, and gulls, and if ground-nesting, also such mammals as foxes, wolverines, felids, bears, wolves, and mountain lions. Both nests and (less frequently) adults are predated by larger-bodied raptorial birds like eagles, large owls, or gyrfalcons. The most serious predators of peregrine nests in North America and Europe are the great horned owl and the Eurasian eagle owl. When reintroductions have been attempted for peregrines, the most serious impediments were these two species of owls routinely picking off nestlings, fledglings and adults by night. Peregrines defending their nests have managed to kill raptors as large as golden eagles and bald eagles (both of which they normally avoid as potential predators) that have come too close to the nest by ambushing them in a full stoop. In one instance, when a snowy owl killed a newly fledged peregrine, the larger owl was in turn killed by a stooping peregrine parent.
  The date of egg-laying varies according to locality, but is generally from February to March in the Northern Hemisphere, and from July to August in the Southern Hemisphere, although the Australian subspecies macropus may breed as late as November, and equatorial populations may nest anytime between June and December. If the eggs are lost early in the nesting season, the female usually lays another clutch, although this is extremely rare in the Arctic due to the short summer season. Generally three to four eggs, but sometimes as few as one or as many as five, are laid in the scrape. The eggs are white to buff with red or brown markings. They are incubated for 29 to 33 days, mainly by the female, with the male also helping with the incubation of the eggs during the day, but only the female incubating them at night. The average number of young found in nests is 2.5, and the average number that fledge is about 1.5, due to the occasional production of infertile eggs and various natural losses of nestlings.
  After hatching, the chicks (called "eyases") are covered with creamy-white down and have disproportionately large feet. The male (called the "tiercel") and the female (simply 
caption: Egg, Museum Wiesbaden
exif: {"Image Make": "NIKON CORPORATION", "Image Model": "NIKON D90", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "GIMP 2.8.10", "Image DateTime": "2015:01:19 14:56:18", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "222", "GPS GPSVersionID": "[2, 2, 0, 0]", "Image GPSInfo": "10078", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "300", "Thumbnail YResolution": "300", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "10202", "Thumbnail JPEGInterchangeFormatLength": "9633", "Thumbnail YCbCrPositioning": "Co-sited", "EXIF ExposureTime": "2", "EXIF FNumber": "16", "EXIF ExposureProgram": "Aperture Priority", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2012:05:30 14:58:42", "EXIF DateTimeDigitized": "2012:05:30 14:58:42", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "5", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "85", "EXIF SubSecTime": "00", "EXIF SubSecTimeOriginal": "00", "EXIF SubSecTimeDigitized": "00", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "0", "EXIF ExifImageLength": "0", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "10048", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CVAPattern": "[0, 2, 0, 2, 1, 2, 0, 1]", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Manual", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "127", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}