Isolated on various islands around the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

kestrel The term kestrel (from french: crécerelle, derivative from , i.e. ratchet) is the common name given to several species of predatory birds from the falcon genus ''Falco''. Kestrels are most easily distinguished by their typical hunting behaviour ...

populations evolved into different species, like

Darwin's finches Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or t ...

. Behaviour remains similar to other small species of ''Falco'' (such as the

common kestrel The common kestrel (''Falco tinnunculus'') is a bird of prey species belonging to the kestrel group of the falcon family Falconidae. It is also known as the European kestrel, Eurasian kestrel, or Old World kestrel. In the United Kingdom, where no ...

, ''Falco tinnunculus'') except on (originally) forested

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label=Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It incl ...

where

s hunt arboreally more like

hawk Hawks are bird of prey, birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica. * The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. Th ...

s. Due to the scarcity of mammals on oceanic islands, several species have adopted a diet containing many ''

Phelsuma ''Phelsuma'' is a large genus of geckos in the family Gekkonidae. Species in the genus ''Phelsuma'' are commonly referred to as day geckos. Some day geckos are seriously endangered and some are common, but all ''Phelsuma'' species are CITES App ...

'' and other

gecko Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from . Geckos ar ...

s. The species can be distinguished by coloration, but all except the banded kestrel share rich brown wings with black spotting. Sexes are alike in color except in the spotted kestrel, where differences are minor. As usual in birds of prey, females are larger than males; considerably so in some of these species as this assists resource partitioning.

Species

Two subspecies of Malagasy kestrel, ''F. newtoni'', are recognised, one on the main island of

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and one on neighbouring

Anjouan Anjouan (; also known as Ndzuwani or Nzwani, and historically as Johanna or Hinzuan) is an autonomous high island in the Indian Ocean that forms part of the Union of the Comoros. Its chief town is Mutsamudu and, , its population is around 277,500. ...

and

Aldabra Aldabra is the world's second-largest coral atoll, lying south-east of the continent of Africa. It is part of the Aldabra Group of islands in the Indian Ocean that are part of the Outer Islands of the Seychelles, with a distance of 1,120 k ...

. It has adapted to human encroachment better than much of

's wildlife. Its diet is mainly lizards and insects. Confusingly it is sometimes referred to as the spotted kestrel, a name usually used for the Moluccan/Indonesian kestrel, while the Mauritius kestrel's scientific name literally means "spotted falcon/kestrel". Its closest relative is the

Seychelles kestrel The Seychelles kestrel (''Falco araeus'') is a small bird of prey belonging to the genus '' Falco'' in the falcon family, Falconidae. It is endemic to the Seychelles Islands where it is the only breeding bird of prey. It is known in Seychellois Cr ...

, ''F. araea''. Their ancestors diverged probably less than one million years ago (roughly around the early Ionian) It is the smallest of all kestrels, otherwise similar to the Madagascar kestrel (and originally considered the same species). Its range is reduced to Mahé, with a few pairs on

Silhouette Island Silhouette Island lies northwest of Mahé in the Seychelles. It is the third largest granitic island in the Seychelles. It has an area of 20.1 km2 and has a population of 200, mostly workers on the island. The main settlement is La Passe ...

North Island The North Island, also officially named Te Ika-a-Māui, is one of the two main islands of New Zealand, separated from the larger but much less populous South Island by the Cook Strait. The island's area is , making it the world's 14th-largest ...

and

Praslin Praslin () is the second largest island (38.5 km2) of the Inner Seychelles, lying northeast of Mahé in the Somali Sea. Praslin has a population of around 7,533 people and comprises two administrative districts: Baie Sainte Anne and Gra ...

. Its diet is mainly

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...

s. The species' status, as the following one's, is Vulnerable according to the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. The

Mauritius kestrel The Mauritius kestrel (''Falco punctatus'') is a bird of prey from the family Falconidae endemic to the forests of Mauritius, where it is restricted to the southwestern plateau's forests, cliffs, and ravines. It is the most distinct of the Indi ...

, ''F. punctatus'', is more distantly related to the preceding two, having diverged from ancestral Madagascar region kestrels some time in the

Gelasian The Gelasian is an age (geology), age in the international geologic timescale or a stage (stratigraphy), stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans ...

(Groombridge ''et al.'' 2002). It is found only on

. It usually snatches arboreal prey, typically

s or small birds. Habitat loss and

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

poisoning pushed this species to the brink of extinction, down to possibly as few as six individuals (and an even smaller

effective population size The effective population size (''N'e'') is a number that, in some simplified scenarios, corresponds to the number of breeding individuals in the population. More generally, ''N'e'' is the number of individuals that an idealised population wo ...

) in the mid 1970s. The conservation effort was initially unsuccessful but results improved when new approaches were tried by Carl Jones in 1979. Chicks hatched at a sanctuary run by

Gerald Durrell Gerald Malcolm Durrell, (7 January 1925 – 30 January 1995) was a British naturalist, writer, zookeeper, conservationist, and television presenter. He founded the Durrell Wildlife Conservation Trust and the Jersey Zoo on the Channel Island ...

were released to new areas, and the population has now almost reached the

carrying capacity The carrying capacity of an environment is the maximum population size of a biological species that can be sustained by that specific environment, given the food, habitat, water, and other resources available. The carrying capacity is defined as t ...

of the island; intensive conservation activity has ceased for some time, with the last captive bred birds released in 1994. The

Réunion kestrel The Réunion kestrel (''Falco duboisi'') is an extinct bird of prey which belongs to the falcon family. It inhabited the Mascarene island of Réunion and was part of the Western Indian Ocean radiation of kestrels. Known from subfossil bones ...

, ''F. duboisi'', is probably the latter species' closest known relative. It only inhabited the island of

Réunion Réunion (; french: La Réunion, ; previously ''Île Bourbon''; rcf, label= Reunionese Creole, La Rényon) is an island in the Indian Ocean that is an overseas department and region of France. It is located approximately east of the island ...

, but became

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

for reasons not entirely clear around 1700. It is only known from

subfossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

bones and one brief eyewitness report. The

banded kestrel The banded kestrel (''Falco zoniventris'') is a bird of prey belonging to the falcon family Falconidae. It is endemic to Madagascar and is also known as the Madagascar banded kestrel, barred kestrel or Madagascar barred kestrel. Its closest r ...

, ''F. zoniventris'', is also restricted to Madagascar and is less common than ''F. newtoni''. It is found in more arid habitats. It appears to be closer to the mainland

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

n "gray kestrels" '' Falco ardosiaceus'' and '' Falco dickinsoni''. The

spotted kestrel The spotted kestrel (''Falco moluccensis'') is also known as the Moluccan kestrel. Distribution and habitat Spread through Wallacea and Java, the spotted kestrel inhabits grasslands with scattered trees, lightly wooded cultivation, and the edge ...

, ''F. moluccensis'', is endemic to

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. The

Nankeen kestrel The nankeen kestrel (''Falco cenchroides''), also known as the Australian kestrel, is a raptor native to Australia and New Guinea. It is one of the smallest falcons, and unlike many, does not rely on speed to catch its prey. Instead, it simply pe ...

, ''F. cenchroides'', inhabits

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

. These seem to belong to a lineage much closer to the

(Groombridge ''et al.'' 2002). Other species of ''Falco'' - for example,

sooty falcon The sooty falcon (''Falco concolor'') is a medium-sized falcon breeding from northeastern Africa to the southern Persian Gulf region. The word sooty means to be covered in soot (ash), and is used to describe the color of the Sooty Falcon. Hence, ...

Eleonora's falcon Eleonora's falcon (''Falco eleonorae'') is a medium-sized falcon. It belongs to the hobby group, a rather close-knit number of similar falcons often considered a subgenus ''Hypotriorchis''. The sooty falcon is sometimes considered its closest re ...

, and the

peregrine falcon The peregrine falcon (''Falco peregrinus''), also known as the peregrine, and historically as the duck hawk in North America, is a Cosmopolitan distribution, cosmopolitan bird of prey (Bird of prey, raptor) in the family (biology), family Falco ...

- occur as occasional visitors in the region during

migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...

. These are generally larger and/or entirely differently colored birds.

References

* Groombridge, Jim J.; Jones, Carl G.; Bayes, Michelle K.; van Zyl, Anthony J.; Carrillo, José; Nichols, Richard A. & Bruford, Michael W. (2002): A molecular phylogeny of African kestrels with reference to divergence across the Indian Ocean. ''Molecular Phylogenetics and Evolution'' 25(2): 267–277. {{doi, 10.1016/S1055-7903(02)00254-3 (HTML abstract)

Footnotes

External links

Birds of Mauritius
Falco (genus)