Geography 316:  Biogeography

The Biogeography of  The Peregrine Falcon
(Falco peregrines)
 

by Mario Holloway, student in Geography 316, Fall 1999

	Kingdom:Mammalia Phylum:Chordata Class:Aves Order:Falconiforms Family:Falconidae Genus:Falco Species: Falco peregrines
(Arnold 1985)

Description of Species

The plumage of the bird is not as distinctive as would been seen in birds like mallard ducks in which the male is more brightly colored and the female is less colored. The plumage of the peregrine is reflective of the environment in the sense that the coloring serves more of a predatory purpose and not one of display of brilliant or elaborate of color, which reduces the chance of being notice. The feathers are subdued with a color scheme consisting of browns, rust, black, white, and some blues and grays. The markings of the falcon serve as in some ways as camouflage against being seen by potential prey or by potential predators.  The longevity of diurnal birds of prey such as the peregrine falcon is limited. The general belief about these birds as they exist in the wild is that they may live as long as fifteen to twenty years. Some birds have been found to live as long as twenty five years in captive breeding centers. The Peregrine Falcons nesting habitats follow a tradition involving nesting in locations that will not only provide for protection for the young but also for prey availability, location of the sun in relation to the amount of warmth for nesting in an area located in extreme cold. In some cases the role of overhanging cliffs and low to high elevation do play apart in the choice for nesting sites but primarily the amount of prey is a direct factor. Direction of the nest can also be a factor or a reason for choosing to nest at a particular site. Peregrines when choosing a site to nest  will build there own nest or will use the nest of a previous pair for nesting and raising the young. Peregrines are not the best nest builders. (Bioscience 1984). 
        Vegetation is not a critical factor in relation to the nest site in cases where some Peregrines have been found. The main concern for choosing a nest site is mainly  protection. The amount of chicks produced usually varies from two to four for any given pair. The habitat of Peregrines does change from year to year as the falcon migrates outside of its home range in search of food.  During the breeding season as the pair searches for a nesting site the pair my leave its primary range in search of an  area equipped with a source of prey that will provide for the feeding of the young. Male and female peregrines are different sizes and weights varying between male and female. The female falcons maybe up to one third larger than the male. This does not play a role in selecting a mate although; some females are larger than males. If by chance the female is larger than the male her greater size is primarily observed as protection against the male in case he decides to harm the chicks or her. The larger size does play a role in the amount and type of prey that each will hunt and bring back to the nest (Bioscience 1984). 
      Peregrine falcons prey upon a variety of other birds such as grouse, mallards and other birds. Pigeons are the primary and most favored by peregrine falcons. Small mammals are also used for food to supplement the diet. Peregrine falcons will fine food, and rear young in almost any habitat even if humans have modified this habitat. Peregrines have a period of high courtship activity that occurs before the actual mating begins. There are eight phases that a potential mating pair performs before the actual mating begins. The beginning phase involves the basic attraction of mates to each other followed by mutual roosting on a cliff. The third phase I believe is the most significant in that there are displays depicting a joining of the two through cooperative hunting excursions and courtship flights (Harris 1979). This is then followed by familiarities’ on the cliffs, courtship feeding which then is followed by the final stages of copulation and lastly nest scraping. This period of pre- nesting activity provides for the formation of pair bonding, which will serve to insure that both will aid in the rearing of the young. The breeding period of the falcon begins when the falcon is two to three years old. The number of the clutch size may vary between three and four eggs and the incubation period can range from four to seven weeks. As the time for hatching approaches, the immature chicks begin a process of breaking through the shell which is called pipping. The pipping  process is performed by the young chick with the aid of an “egg tooth” The location of the “egg tooth” is centered on the chicks bill and later falls off from the bill after the is free from the egg shell. The chicks may hatch over several days with the first one having more of an advantage over the young ones. The female generally stays on the nest with the young while the male brings food to the female during this time. The female tears apart the food for the young and then feeds the food to them. There is no real need to regurgitate the food for the young as is seen in some bird species.  As the young continue to grow, the parents or rather the female gradually leaves the nest and chicks on their own. But not for long periods of time. As the chicks become larger the they remain in the same area as the parents still being fed by the parents and still learning from the parents on how to survive and find food. This may begin in late autumn and extend to as far as mid-winter. 

Habitat

Peregrine Falcon are found in areas such as the tundra, the savanna, and large metropolitan areas. Peregrine Falcons are also found in open conifer forests rock outcrops and cliffs and can also be found in Greenland of all places.The Peregrine Falcon has a worldwide range in which it winters through California and the West Indies to Tierra  del Fuego. This worldwide range is more extensive than that of any bird. The peregrine falcon is found to exist in a wide range of areas around the globe from the Arctic to the Equator. The peregrine can be found on all six continents.
 

(Arnold 1985) young peregrine

Natural History

Falconiformes is an order made up of five families, eighty one genera and three hundred and eleven species. Among some of the members of these species are the raptors which consist of  falcons, caracaras, hawks, eagles, Old World vultures, kites, Osprey, Secretary birds, and New World vultures. Most members of the Order of Falconiformes are diurnal, raptorial birds with short, strong bills that have a fleshy cere accompanied by forate nostrils and a bony tubercle in the nostril (Gill 1990.) Falcons are places in the Class: Aves subclass: Neornithes, Order: Falconiformes, Family: Falconidae, and the Genus:Falco and Species:peregrine. Members of the order Falconiforms also have very sharp curved talons or claws with generally short legs.  The word falcon comes from the Latin term “falx (“sickle”) in English which was used to describe the sicklelike talons and beak found on this class of falcons.  The word peregrine also draws its roots from a Latin source which means wonderer or pilgrim. The wings vary in shape from broad and rounded in eagles and in hawks to long and narrow or pointed such as in falcons. Falcons are found in a variety of habitats and location and are not restricted to just living in a natural environment away from humans. The evolution of birds from reptiles over time along with diet created diversity in the Class of Aves that encompassed land roaming birds to predatory birds. Predatory birds such as raptors have many species that are related to them and that share many similar characteristics. The family of falconiforms is the branch of predatory birds, which the Peregrine Falcon is placed in. Within this circle of birds there are characteristics that are seen in all birds of prey such as the curved bill and the talons which are equipped with sharp thin claws as is seen in reptiles and dinosaurs (Gill 1990). The Peregrine Falcons home range seems to have no limits in relation to the conditions of the habitat or where it will nest. The falcons distribution is worldwide and seems to be only hindered by man as the falcon is highly sensitive to chemicals introduced to it habitat such as DDT which will affect the composition of the egg shell. The Peregrine Falcon exists from the Arctic to the Equator with the exception being that falcons would not be found really in wooded plains. The distribution of the Peregrine may have changed over time 
 

(Arnold 1985)

 
Egg shells affected by DDT. Thinning eggs shells was one of the main affects of  DDT
exposure which lead to the reduced surival-ship of juvenile peregrines.

Evolution

(Gill 1990) (Archaeopteryx lithographica) .The fossilized remains  that show feathers and wing evolution.

The first proof of the evolution of birds came  with the discovery of the fossilized remains of Archaeopteryx lithographica(Gill 1990). This fossil provided much about the history,evolution,bird development, and also how the evolution of feathers and flight develop. Natural selection did play a role in the development of the present  day bird species. But, the development of wings as seen in the fossilized remains began as out stretched skin like what is seen on bats. The Class Aves which is the classification used to describe and place birds, is in part based upon the remains of the fossilized fore runner (Archaeopteryx lithographica) of present  birds species which was discovered in the late nineteenth century in eastern Europe(Gill 1990). Until this discovery there was little evidence that supported the theory that birds may have arose from some common ancestor related to the present day reptiles or even that they  showed any relationship to the very much extinct dinosaur. The most critical aspect of this fossilized evidence which lent support to the theory of birds evolving from reptiles was not only the amount of shared similarities but the additional discovery  of one small feather that was found with the fossilized  remains of Archaeopteryx. This  discovery finally proved and provided evidence that birds did develop from a dinosaur species and those birds at one time did not just have flaps of skins covering an elongated arm,which propelled them into the air.  The other findings which was equally important came from the morphological study that would later show that bird species had greater brain capacity,a cranial structure that mirrored that of reptiles and the eye structure was similar in some ways to that of reptiles(Gill 1990). In addition to this fact that the main characteristics that are shared by both birds as well as reptiles is egg laying (oviparous) and the possession of scales on the body by both organisms.

                   During the Jurassic period the European continent was tropical with lagoons and warms seas that covered part of the continent. These coastal lagoon my have attracted flying reptiles of various sizes and  weights called pterodactyls much in the small way that  present lagoons and estuaries attract birds of today. Archaeopteryx may have been a crow sized  bipedal reptile with a snout and small reptilian teeth that was able to glide over reduced distances but may not have been a true flyer as is seen today in birds(Gill 1990). The ability of flights was reduced due to the lack of the development  of these specialized muscles, which would be used, for elevation, flight was more likely controlled and produced by the flapping of out stretched wings. Archaeopteryx, even with the ability to glide, was most likely  unable to launch itself  into the air from the ground due to the lack of these principal  muscle groups(Gill 1990). The ability to fly is not just  a case of having feathers and strength. The muscles involved are very important in the act of sustaining  the organism in the air and for take off from the ground. The lack of development  of these muscles lends support  for the belief  that true birds did not develop the power of flight until later. The superacoracoides, which aids in the rapid recovery stroke, is one of the many defining characteristics of true birds. Hollow  bones and feathers are added features, which serve to promote flight. But the development and possession of this muscle  is needed for maintaining flight.

                 The most current theory about how the evolution of birds evolving is based upon the closest living relative to birds. Some other theories postulate  that birds may have also evolved from a group of thecodonts or from small theropod dinosaurs. An additional theory, which is much more current in connection with the the codonts theory, National Geographic provides more evidence that birds are therapods,and hypothesizes that birds may have evolved from sea turtle's. This theory which  is based upon the morphology between birds and turtles, and the fact that turtles are among some of the oldest living species still in existence to date on Earth. Birds and reptiles have long been  held to share commonalties that make the theory of bird evolution of birds with that of reptiles realistic. Archaeopteryx provided evidence  that links the evolution of birds with that of reptiles. Birds are bipedal vertebrates that are distinguished from the other vertebrate on earth due to one of many singular characteristics, the ability to grow feathers. Feather are modifications of shin that are filamentous, soft in texture, and flexible and lightweight, which aid in maintaining temperature(Gill 1990). Along with feathers the formation of hollow bones and  specified muscles groups endemic to bird species, create the defining characteristic for bird, the power of flight.
 

(Arnold 1985)

Distribution

The Peregrine Falcon has a world wide distribution and is found on every continent except for Antarctica. The falcon can be found nesting on or in any habitat were there is a food stable food source and safety to raise the young.
 

Map of Distribution:

Bibliography

Arnold, Caroline. 1985. Saving the Peregrine Falcon. Minneapolis MN Carolrhoda Books, Inc.

Burnham,William A., Mattox, William G.;(1979,1984) Biology of the peregrine and Gyrfalcon in Greenland Meddelelser om Gronland Bioscience(Geosicence,Man &Society) Gronland.  Bioscience 1 1979
 
Dobkin, David S.,Ehrlich, Paul R., Wheye, Darryl; (1988) The Briders handbook: The Natural History of    North American Birds.   Published by Simon/Fireside Books 

Gill,Frank B.;(1990,1995)  Ornithology 2nd edition  by W.H. Freeman and Company

Harris, James T.;(1979) The Peregrine Falcon in Greenland; Observing an Endangered Species Univeristy   of Missouri Press Columbia. 

Newton,Ian;  (1979) Population Ecology of Raptors. USA.  Buteo Books.  

Ratcliffe, Derek;(1980) The Peregrine Falcon. USA. Buteo Books.  

Sherrod, Steve K.;(1983) Behavior of Fledgling Peregrine The Peregrine Fund, Inc. Ithaca ,NY

Document from a website:
A Bursch Gardens/Sea World Educational Resource 1996 Busch Entertainment Yahooligans!-Science and Birds_of_Prey Oddities:Animals:Birds of Prey  Title[online]. Available: http://www.yahooligans.com/science_and_oddities/animals/birds_of_prey  or go to snap.com keyword "falcon classifcation"
 
Cade,T.J., Enderson,J.H., Linthicum,J  1996. Guide to Management of Peregrine Falcons at the Eyrie. The Peregrine Fund. Santa Cruz Predatory Bird Research Group 1998-1999  Title[online]. Available: http://www.2.ucsc.edu/~scpbrg or goto www.snap.com  keyword "peregrine falcon"
 
 

send comments to bholzman@sfsu.edu
 

Geog 316 homepage Back to Geography home page    Back to SFSU homepage