Peregrine Falcon Size: How Big Are These Raptors Compared to Others?

The peregrine falcon (Falco peregrinus) is a medium-sized raptor with a body length of 34 to 58 centimeters, a wingspan of 74 to 120 centimeters, and a body weight of 330 to 1,500 grams depending on subspecies and sex. Females are consistently larger than males, a pattern known as reverse sexual size dimorphism that is common among falcons. To place these numbers in context, a peregrine falcon is roughly the size of a crow or a small goose, smaller than a red-tailed hawk but larger than a merlin or American kestrel. This article provides detailed measurements for peregrine falcons, compares them with other raptors and common birds, and explains how size affects flight performance, hunting behavior, and captive management decisions.

At a Glance: Peregrine Falcon Size Compared to Other Raptors

The table below summarizes typical measurements for adult peregrine falcons and compares them with several other raptor species. Values represent published ranges across subspecies and geographic regions.

These figures show that the peregrine falcon occupies a middle ground in the raptor size spectrum. It is larger than the small falcons such as kestrels and merlins, comparable in length to some buteos, but considerably lighter and more streamlined than eagles.

Body Length and Structural Measurements

Body length in peregrine falcons is measured from the tip of the bill to the tip of the tail feathers in a freshly dead or properly restrained bird. The range of 34 to 58 centimeters reflects substantial variation among the 19 recognized subspecies. The smallest subspecies, such as Falco peregrinus minor found in southern Africa, tend toward the lower end of the range. The largest subspecies, including Falco peregrinus anatum in North America and Falco peregrinus calidus in the Arctic, approach the upper end.

The Madagascar peregrine falcon (Falco peregrinus radama) represents a resident subspecies with a restricted distribution across Madagascar, Mayotte, and the Comoros Islands. Research on this subspecies has focused on distribution and habitat use instead of detailed morphometrics, but the subspecies is considered small compared with northern forms. The core range of the Madagascar peregrine falcon extends across the central upland plateau of Madagascar, with a patchier range across coastal and low-elevation areas. This subspecies prefers areas of high elevation and aridity, coupled with high vegetation heterogeneity and more than 95 percent herbaceous landcover, and generally avoids areas with more than 30 percent cultivated land and more than 10 percent mosaic forest. Based on inferred high-class habitat, researchers estimate this habitat area could potentially support a population size ranging between 150 and 300 pairs. Following International Union for Conservation of Nature Red List guidelines, the researchers recommend this subspecies be classed as Vulnerable due to its small population size.

Body length alone does not fully describe structural size. Wing chord, tail length, tarsus length, and bill depth are standard measurements used by ornithologists and falconers. Wing chord in adult peregrines typically ranges from 28 to 40 centimeters, with females having longer wings than males. Tail length ranges from 13 to 19 centimeters. These structural measurements are more reliable than body weight for assessing condition because weight fluctuates with feeding status and fat reserves.

Wingspan and Wing Morphology

The wingspan of a peregrine falcon ranges from 74 to 120 centimeters. This measurement is taken from wingtip to wingtip with the wings fully extended. The peregrine wing is long, pointed, and swept back at the tip, an adaptation for high-speed flight and aerial pursuit. This wing shape differs markedly from the broad, rounded wings of buteos such as the red-tailed hawk, which are adapted for soaring and hovering.

Wing loading, calculated as body weight divided by wing area, is a critical flight performance metric. Peregrine falcons have relatively high wing loading compared with soaring raptors, meaning they carry more weight per unit of wing area. This configuration favors fast, direct flight and rapid stoops over slow soaring. The peregrine's pointed wing tips reduce induced drag during high-speed dives, allowing the bird to reach speeds that make it one of the fastest animals on Earth.

The relationship between wingspan and body weight affects captive management. A falcon with inadequate wing feather condition cannot fly effectively, and falconers must monitor feather quality during molts. Birds kept in enclosures that are too small may damage their flight feathers, reducing their ability to hunt or exercise. The minimum enclosure size for a peregrine falcon should allow the bird to spread its wings fully without touching the walls, which requires a width of at least 120 centimeters for an adult with a maximum wingspan.

Body Weight and Reverse Sexual Size Dimorphism

Body weight in peregrine falcons ranges from 330 grams in small males to 1,500 grams in large females. This wide range reflects both sexual dimorphism and geographic variation. Females are typically 30 to 50 percent heavier than males, a difference that is more pronounced than in most other bird groups.

Reverse sexual size dimorphism, where females are larger than males, is characteristic of falcons and many other raptors. Several hypotheses attempt to explain this pattern. The most supported explanations involve division of labor during breeding, where the smaller male is more agile during courtship flights and prey capture, while the larger female is better able to defend the nest and incubate eggs. The larger female also produces larger eggs, which may improve chick survival.

Weight management is a central concern in falconry and captive breeding. A peregrine falcon in good hunting condition carries modest fat reserves. Falconers monitor weight daily using a balance scale and adjust food intake to maintain a target flying weight. A bird that is too heavy will be sluggish and may refuse to hunt. A bird that is too light becomes weak and may develop health problems. The target flying weight varies by individual and must be established through careful observation over weeks or months.

Comparison with Other Falcon Species

Within the falcon family, the peregrine is one of the larger species but not the largest. The gyrfalcon (Falco rusticolus) is the largest falcon, with a body length of 50 to 65 centimeters, a wingspan of 110 to 160 centimeters, and a body weight of 800 to 2,100 grams. The gyrfalcon breeds in Arctic regions and is prized in falconry for its size and power.

The saker falcon (Falco cherrug) is similar in size to the peregrine, with a body length of 45 to 57 centimeters and a wingspan of 100 to 130 centimeters. Saker falcons are used in traditional falconry across Central Asia and the Middle East. The lanner falcon (Falco biarmicus) is slightly smaller, with a body length of 39 to 50 centimeters and a wingspan of 95 to 115 centimeters.

Genetic research on falcon populations in the Mongolian Altai region has revealed complex relationships among these large falcons. A chromosome-level gyrfalcon reference genome was generated using the Vertebrate Genomes Project assembly pipeline. Using whole genome sequences of 49 falcons from different species and populations, including Altai falcons, researchers analyzed population structure, admixture patterns, and demographic history. They found that the Altai falcons are genomic mosaics of saker and gyrfalcon ancestries and carry distinct W and mitochondrial haplotypes that cluster with the lanner falcon. The Altai maternally inherited haplotypes diverged 422,000 years before present from the ancestor of sakers and gyrfalcons, both of which split 109,000 years before present. These findings provide insights into the question of Altai falcons as a candidate distinct species.

For practical identification, size alone cannot distinguish peregrine falcons from saker falcons or gyrfalcons in all cases. Plumage color, facial markings, and structural proportions are more reliable field marks. A peregrine falcon has a dark hood or helmet pattern on the head, a dark malar stripe, and barred underparts. Saker falcons have a paler head and less distinct facial markings. Gyrfalcons are highly variable in color, ranging from white to dark gray, and lack the bold malar stripe of the peregrine.

Comparison with Hawks and Eagles

The red-tailed hawk is a common comparison species because it shares much of the peregrine's North American range. Red-tailed hawks have a body length of 45 to 65 centimeters, a wingspan of 110 to 145 centimeters, and a body weight of 690 to 1,600 grams. While the body length ranges overlap, red-tailed hawks are bulkier and heavier than peregrines of similar length. The red-tailed hawk has broad, rounded wings and a short, wide tail, while the peregrine has long, pointed wings and a narrow tail.

Eagles are substantially larger than peregrine falcons. The golden eagle has a body length of 70 to 84 centimeters, a wingspan of 185 to 220 centimeters, and a body weight of 3,000 to 6,700 grams. The bald eagle is similar in size, with a body length of 70 to 102 centimeters, a wingspan of 180 to 230 centimeters, and a body weight of 3,000 to 6,300 grams. An eagle can weigh more than four times as much as a large peregrine falcon.

The size difference between falcons and eagles has practical implications for captive management and conservation. Captive birds of prey often exceed their wild counterparts' lifespan, as seen in bald eagles at about 20 years wild versus about 40 years captive, golden eagles at about 32 years wild versus about 46 years captive, and Andean condors at about 50 years wild versus about 79 years captive. This highlights the impact of controlled environments on longevity. However, recent evidence suggests a rising incidence of neoplastic processes in these species. While previous studies have indicated a higher than expected prevalence of neoplasia in raptors, comprehensive research on this topic remains scarce. Squamous cell carcinoma, a frequently reported neoplasm in pet birds, has been documented in birds of prey. Retrospective studies have identified squamous cell carcinoma cases in peregrine falcons, primarily affecting the flank or thigh, with locally invasive behavior and rare distant metastasis. Complete surgical excision is the preferred treatment, yet its feasibility is often constrained by tumor invasiveness and anatomical limitations. Electrochemotherapy has emerged as a promising alternative, utilizing electroporation to enhance intracellular drug uptake while minimizing systemic toxicity. Bleomycin and cisplatin have been successfully used in avian intralesional chemotherapy. A case report describes the use of electrochemotherapy with bleomycin in a peregrine falcon diagnosed with squamous cell carcinoma, contributing to the growing body of evidence supporting its clinical utility in avian medicine.

Comparison with Common Non-Raptor Birds

For general readers, comparing the peregrine falcon with familiar birds helps visualize its size. An American crow (Corvus brachyrhynchos) has a body length of 40 to 53 centimeters and a wingspan of 85 to 100 centimeters, making it very close in overall dimensions to a peregrine falcon. However, the crow weighs only 300 to 600 grams, considerably less than a large female peregrine.

A rock pigeon (Columba livia) has a body length of 29 to 37 centimeters and a wingspan of 62 to 72 centimeters. The peregrine falcon is noticeably larger than a pigeon, which is its primary prey in urban environments. A mallard (Anas platyrhynchos) has a body length of 50 to 65 centimeters and a wingspan of 81 to 98 centimeters. A large female peregrine approaches the size of a small mallard, though the falcon is more lightly built.

A Canada goose (Branta canadensis) is much larger, with a body length of 75 to 110 centimeters and a wingspan of 127 to 185 centimeters. Peregrine falcons do not typically prey on geese of this size, though they may attack smaller waterfowl. The comparison with crows and pigeons is more useful for field identification because these species share urban and suburban habitats with peregrine falcons.

Size Variation Across Subspecies and Geography

The peregrine falcon has one of the widest distributions of any bird species, breeding on every continent except Antarctica. This broad range has produced substantial geographic variation in size. Bergmann's rule, which states that populations in colder climates tend to be larger than those in warmer climates, applies to peregrine falcons. Arctic and subarctic subspecies such as Falco peregrinus tundrius and Falco peregrinus calidus are larger than tropical subspecies such as Falco peregrinus minor and Falco peregrinus radama.

The Madagascar peregrine falcon research provides a useful example of how distribution and habitat affect population assessment. The study used point process regression models and ordination to identify environmental range limits and propose a population size estimate based on inferred habitat. From the models, the core range of the Madagascar peregrine falcon extends across the central upland plateau of Madagascar with a patchier range across coastal and low-elevation areas. The estimated population of 150 to 300 pairs is small enough to warrant a Vulnerable classification under IUCN Red List guidelines.

For researchers and wildlife managers, understanding subspecies size variation is important for several reasons. Captive breeding programs should maintain genetic diversity by pairing birds from appropriate geographic origins. Reintroduction programs must use birds from subspecies that are adapted to the local climate and prey base. Field identification guides should include subspecies-specific measurements where available.

How Size Affects Flight Performance and Hunting

The peregrine falcon's size and wing morphology are directly related to its hunting strategy. Peregrines are aerial hunters that capture prey in flight, typically by stooping from above at high speed. The pointed wings and streamlined body reduce drag, allowing the bird to accelerate during the dive. The high wing loading provides the power needed for rapid flight and maneuverability during pursuit.

Prey selection is influenced by the falcon's size. A typical peregrine falcon takes birds ranging in size from small songbirds to medium-sized waterfowl. The most common prey includes pigeons, doves, shorebirds, and ducks. The size of the female falcon allows her to take larger prey than the male, which may reduce competition between the sexes during the breeding season.

In urban environments, peregrine falcons have adapted to hunt feral pigeons and other city birds. The structural environment of buildings and bridges provides nesting sites and hunting perches that mimic the cliff ledges used by wild peregrines. The success of urban peregrine populations demonstrates the species' behavioral flexibility, though the size of available prey in urban areas may limit the maximum size of prey that can be captured.

Measuring and Recording Peregrine Falcon Size

Wildlife biologists, falconers, and veterinarians use standardized measurement protocols to record peregrine falcon size. These measurements are essential for assessing individual condition, tracking growth in nestlings, and comparing populations.

Body weight should be measured using a digital scale accurate to 1 gram. Weigh the bird in the morning before feeding for consistent results. Handle the bird using appropriate restraint techniques to minimize stress and prevent injury. Record the date, time, and any relevant notes about the bird's condition.

Wing chord is measured with the wing folded against the body. Place a ruler against the bend of the wing and measure to the tip of the longest primary feather. This measurement is less variable than wingspan and is preferred for scientific records.

Wingspan requires the bird to extend both wings fully. This measurement is more difficult to obtain accurately and is less commonly used in scientific studies. When wingspan is needed, use a flexible tape measure and have an assistant hold the bird while you measure from wingtip to wingtip.

Tail length is measured from the base of the tail feathers to the tip of the longest rectrix. Tarsus length is measured from the back of the intertarsal joint to the base of the middle toe. Bill depth is measured at the base of the bill. These structural measurements are useful for sex determination and subspecies identification.

For nestlings, growth rates provide important information about health and development. Weigh chicks daily or every other day during the first three weeks after hatching. A healthy peregrine chick gains weight rapidly, reaching approximately adult weight by three to four weeks of age. Weight loss or slow growth may indicate inadequate feeding, disease, or parasite infestation.

Common Failure Patterns in Size Assessment

Several common errors occur when assessing peregrine falcon size. These mistakes can lead to incorrect sex determination, inaccurate subspecies identification, or poor management decisions.

Measuring a bird with damaged or missing feathers produces unreliable results. A peregrine in active molt may have gaps in the wing or tail feathers that reduce measured wingspan or wing chord. Wait until feather growth is complete before taking final measurements. For birds in active molt, record the measurement and note the molt stage.

Confusing body weight with structural size is another common error. A well-fed peregrine may weigh more than a lean bird of the same structural size. Conversely, a bird that has not eaten for several days may weigh less than expected. Use structural measurements such as wing chord and tarsus length to assess size, and use body weight to assess condition.

Comparing measurements across subspecies without accounting for geographic variation can produce misleading conclusions. A small female from a tropical subspecies may weigh less than a large male from an Arctic subspecies. Always consider the subspecies and geographic origin when interpreting size data.

Misidentifying the sex of a peregrine falcon based on size alone is possible because the size ranges of males and females overlap. The largest males may approach the size of the smallest females. Use multiple measurements and behavioral observations to confirm sex. In adult birds, the female is typically 30 to 50 percent heavier than the male of the same pair.

Welfare and Safety Considerations for Handling and Measuring

Handling peregrine falcons for measurement requires proper training and equipment. Peregrines have sharp talons and a hooked beak that can cause serious injury. Use appropriate gloves and restraint techniques. Never handle a peregrine without proper training or supervision.

Minimize handling time to reduce stress. A stressed falcon may refuse to eat, lose weight, or develop health problems. Have all equipment ready before removing the bird from its enclosure. Work in a quiet, dimly lit area to reduce visual stimulation.

For captive birds, establish a regular weighing routine that the bird learns to tolerate. Many falconers train their birds to step onto a scale perch, allowing weight measurement without physical restraint. This approach reduces stress and provides more consistent data.

Wild peregrine falcons should only be handled by licensed and experienced professionals. Capturing and handling wild birds requires permits and should be done for legitimate research or management purposes. Never attempt to capture or handle a wild peregrine falcon without proper authorization.

Health Monitoring and Size-Related Conditions

Body weight changes are among the most sensitive indicators of health in peregrine falcons. A sudden weight loss of more than 10 percent over a few days warrants investigation. Common causes include inadequate food intake, digestive disorders, parasite infestation, or infectious disease.

Peregrine falcons in captivity can develop obesity if overfed or under-exercised. An obese falcon has reduced flight performance and may develop cardiovascular or joint problems. Monitor body condition by palpating the pectoral muscles and assessing the amount of fat over the keel bone. Adjust food intake to maintain a lean but not emaciated condition.

Research on peregrine falcon health has identified several environmental contaminants that may affect populations. A study on per- and polyfluoroalkyl substances (PFAS) and heavy metals in peregrine falcon eggs in West England found that long-chain perfluoroalkyl acids were predominantly detected in peregrine eggs. Perfluorooctane sulfonyl acid (PFOS), perfluorohexanesulfonic acid (PFHxS), and perfluorooctanoic acid (PFOA) residues significantly differed among counties. PFOS and PFHxS residues were significantly higher in eggs from Devon, the study area around urban settlements, than in Cornwall. PFOA residues were significantly higher in Lancashire, an inland study area, than in Devon. Several perfluoroalkyl carboxylic acid residues showed significant and negative correlations with delta carbon-13 in eggs, suggesting that the sources of these PFAS might come from terrestrial habitats. No significant relationship was observed between eggshell index and PFAS residues. Given the variation in PFAS exposure among areas, it remains challenging to determine the impact of PFAS on the Cornwall peregrine population.

Infectious diseases also affect peregrine falcons. A study on circoviruses in wild birds in Hungary identified pigeon circovirus in a peregrine falcon. Circoviruses infect a wide range of avian hosts, including domestic, ornamental, and wild birds. The immunosuppressive effect of these viruses could make the host more susceptible to other pathogens. The results draw attention to the widespread distribution of these viruses among wild birds which, by hiding in the host and reducing defensibility, could pose a threat to both poultry farming and efforts to wild bird conservation.

Avian influenza surveillance is another important consideration for those who work with peregrine falcons. Migratory wild birds play a critical role in highly pathogenic avian influenza virus spread and evolution. An effective surveillance strategy to study avian influenza dispersal in wild birds and identify critical interfaces between wild birds and poultry on the landscape for potential interspecies transmission and virus evolution is essential. Peregrine falcons that prey on wild birds may be exposed to avian influenza viruses, and falconers and wildlife rehabilitators should follow biosecurity protocols to prevent disease transmission.

Professional Escalation Criteria

Certain observations related to peregrine falcon size or condition require professional consultation. Contact a licensed wildlife veterinarian, experienced falconer, or wildlife agency if you observe any of the following:

A captive peregrine falcon loses more than 15 percent of its body weight over a one-week period despite adequate food intake. This may indicate an underlying health problem that requires veterinary diagnosis.

A peregrine falcon shows visible swelling, lameness, or reluctance to bear weight on a leg or foot. Bumblefoot, a bacterial infection of the foot, is a common problem in captive raptors and requires prompt treatment.

A wild peregrine falcon appears unable to fly or is found on the ground and cannot be encouraged to fly away. This may indicate injury, illness, or poisoning. Contact a licensed wildlife rehabilitator.

A peregrine falcon has damaged or missing flight feathers that prevent normal flight. Feather damage may require veterinary assessment and possible imping, a procedure to repair broken feathers.

A captive peregrine falcon refuses to eat for more than 24 hours. Loss of appetite can indicate stress, illness, or management problems that require investigation.

A peregrine falcon shows signs of respiratory distress, including open-mouth breathing, tail bobbing, or wheezing. Respiratory disease can progress rapidly in birds and requires immediate veterinary attention.

Frequently Asked Questions

How big is a peregrine falcon compared to a crow?

A peregrine falcon is similar in length to an American crow, with both species ranging from about 34 to 58 centimeters in body length. However, the peregrine falcon is more heavily built and weighs more, with females reaching up to 1,500 grams compared with a crow's maximum of about 600 grams. The falcon has longer, pointed wings and a narrower tail than the crow.

What is the wingspan of a peregrine falcon?

The wingspan of a peregrine falcon ranges from 74 to 120 centimeters. Females have larger wingspans than males. The wings are long and pointed, adapted for high-speed flight and aerial hunting. This wing shape differs from the broad, rounded wings of soaring hawks and eagles.

How much does a peregrine falcon weigh?

A peregrine falcon weighs between 330 and 1,500 grams. Females are typically 30 to 50 percent heavier than males. Weight varies by subspecies, with Arctic and subarctic subspecies being larger than tropical subspecies. Body weight also fluctuates with feeding status and fat reserves.

Are female peregrine falcons larger than males?

Yes, female peregrine falcons are larger than males. This pattern, called reverse sexual size dimorphism, is common among falcons and other raptors. Females are typically 30 to 50 percent heavier than males and have longer wings and larger body measurements. The size difference is thought to relate to division of labor during breeding.

How does a peregrine falcon compare in size to a red-tailed hawk?

A peregrine falcon and a red-tailed hawk have overlapping body length ranges, with the peregrine at 34 to 58 centimeters and the red-tailed hawk at 45 to 65 centimeters. However, the red-tailed hawk is bulkier and heavier, weighing 690 to 1,600 grams compared with the peregrine's 330 to 1,500 grams. The red-tailed hawk has broad, rounded wings while the peregrine has long, pointed wings.

What is the largest falcon species?

The gyrfalcon is the largest falcon species, with a body length of 50 to 65 centimeters, a wingspan of 110 to 160 centimeters, and a body weight of 800 to 2,100 grams. The gyrfalcon breeds in Arctic regions. The saker falcon and the peregrine falcon are the next largest falcon species.

How can I tell the difference between a peregrine falcon and a gyrfalcon?

Size alone cannot always distinguish a peregrine falcon from a gyrfalcon because the size ranges overlap. Plumage color and facial markings are more reliable. A peregrine falcon has a dark hood or helmet pattern on the head, a dark malar stripe, and barred underparts. Gyrfalcons are highly variable in color, ranging from white to dark gray, and lack the bold malar stripe of the peregrine.

Why do peregrine falcon sizes vary so much across their range?

Peregrine falcons have one of the widest distributions of any bird species, breeding on every continent except Antarctica. Geographic variation in size follows Bergmann's rule, with populations in colder climates being larger than those in warmer climates. Arctic and subarctic subspecies are larger than tropical subspecies. This variation reflects adaptation to local environmental conditions and prey availability.

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References and Further Reading

• NCBI Literature Resources. National Center for Biotechnology Information.
• PubMed. National Library of Medicine.
• Per- and polyfluoroalkyl substances (PFAS) and heavy metals in the egg of peregrine falcon (Falco peregrinus) populations in West England, United Kingdom.. 2026.
• Chromosome-level reference genome assembly of the gyrfalcon (Falco rusticolus) and population genomics offer insights into the falcon population in Mongolia.. 2025.
• Electrochemotherapy Intralesional Treatment in a Captive Peregrine Falcon (&lt,i&gt,Falco peregrinus&lt,/i&gt,) with Dermal Squamous Cell Carcinoma.. 2025.
• Descriptive histological analysis of the upper, lower, and third eyelids and the conjunctiva-associated lymphoid tissue in birds of prey.. 2025.
• Assessing the spatial risk of wild birds in avian influenza transmission using global risk score.. 2025.
• Occurrence of diverse circoviruses in wild birds in Hungary.. 2026.
• Distribution and habitat use of the Madagascar Peregrine Falcon: first estimates for area of habitat and population size. bioRxiv, 2021.
• Peregrine falcon predation algorithm: a better solution to multiple engineering problems and lithium-ion battery model parameter identification problem. Cluster Computing, 2025.
• BUFFing FALCON without Increasing the Signature Size. IACR Cryptology ePrint Archive, 2024.

This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.