Isolated on various islands around the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

kestrel The term kestrel (from , 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 which is to hover ...

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 being a classic example of adaptive radiation and for their remarkable diversity in beak form and function. They ...

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

common kestrel The common kestrel (''Falco tinnunculus''), also known as the European kestrel, Eurasian kestrel or Old World kestrel, is a species of bird of prey, predatory bird belonging to the kestrel group of the falcon family (biology), family Falconidae. ...

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

Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...

where

s hunt arboreally more like

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

s. Due to the scarcity of mammals on oceanic islands, several species have adopted a diet containing many '' Phelsuma'' 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. They range from . Geckos are unique among lizards ...

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, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

and one on neighbouring

Anjouan Anjouan () is an autonomous volcanic island in the Comoro Islands in the southwestern Indian Ocean, part of the Comoros, Union of the Comoros. It is known in Comorian languages, Shikomori as Ndzuani, Ndzuwani or Nzwani, and, until the early twentie ...

and

Aldabra Aldabra, the world's second-largest coral atoll (the largest is Kiritimati), is located 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 (Seychelles), Outer Islands ...

. 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, ''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,

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

and

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

. Its diet is mainly

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

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

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

. The Mauritius kestrel, ''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 in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary Period/System and Pleistocene Epoch/Series. It spans the time between 2.58 Ma (million y ...

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

. It usually snatches arboreal prey, typically

s or small birds. Habitat loss and DDT 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 the size of an idealised population that would experience the same rate of genetic drift as the real population. Idealised populations are those following simple one- locus models that comply with ass ...

) 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 Order of the British Empire, OBE (7 January 1925 – 30 January 1995) was a British naturalist, writer, zookeeper, conservation movement, conservationist, and television presenter. He was born in Jamshedpur in British Ind ...

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

carrying capacity The carrying capacity of an ecosystem 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 the ...

of the island; intensive conservation activity has ceased for some time, with the last captive bred birds released in 1994. The Réunion kestrel, ''F. duboisi'', is probably the latter species' closest known relative. It only inhabited the island of

Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...

, but became

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce 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 ...

bones and one brief eyewitness report. The banded kestrel, ''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. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

n "gray kestrels" '' Falco ardosiaceus'' and '' Falco dickinsoni''. The spotted kestrel, ''F. moluccensis'', is endemic to

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. The Nankeen kestrel, ''F. cenchroides'', inhabits

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

. 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, and the

peregrine falcon The peregrine falcon (''Falco peregrinus''), also known simply as the peregrine, is a Cosmopolitan distribution, cosmopolitan bird of prey (raptor) in the family (biology), family Falconidae renowned for its speed. A large, Corvus (genus), cro ...

– 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
Bird common names Falco (genus)