Indian Ocean kestrels
Encyclopedia
Isolated on various islands around the Indian Ocean
, kestrel
populations evolved into different species, like Darwin's finches
. Behaviour remains similar to other small species of Falco (such as the Common Kestrel
, Falco tinnunculus) except on (originally) forested Mauritius
where kestrel
s hunt arboreally more like hawk
s. Due to the scarcity of mammals on oceanic islands, several species have adopted a diet containing many Phelsuma
and other gecko
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.
, F. newtoni, are recognised, one on the main island of Madagascar
and one on neighbouring Anjouan
and Aldabra
. It has adapted to human encroachment better than much of Madagascar
'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
and Praslin
. Its diet is mainly lizard
s. The species' status, as the following one's, is Vulnerable
according to the IUCN.
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
(Groombridge et al. 2002). It is found only on Mauritius
. It usually snatches arboreal prey, typically gecko
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
) 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
were released to new areas, and the population has now almost reached the carrying capacity
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
, but became extinct for reasons not entirely clear around 1700. It is only known from subfossil
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
n "gray kestrels" Falco ardosiaceus and Falco dickinsoni
The Spotted Kestrel
, F. moluccensis, is endemic to Indonesia
. The Nankeen Kestrel
, F. cenchroides, inhabits Australia
and New Guinea
. These seem to belong to a lineage much closer to the Common Kestrel
(Groombridge et al. 2002).
Other species of Falco - for example, Sooty Falcon
, Eleonora's Falcon
, and the Peregrine Falcon
- occur as occasional visitors in the region during migration
. These are generally larger and/or entirely differently colored birds.
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, kestrel
Kestrel
The name kestrel, is given to several different members of the falcon genus, Falco. Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around over open country and swoop down on prey, usually small mammals, lizards or large insects...
populations evolved into different species, like Darwin's finches
Darwin's finches
Darwin's finches are a group of 14 or 15 species of passerine birds. It is still not clear which bird family they belong to, but they are not related to the true finches. They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle...
. Behaviour remains similar to other small species of Falco (such as the Common Kestrel
Common Kestrel
The Common Kestrel 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 Britain, where no other brown falcon occurs, it is generally just called "the kestrel".This species...
, Falco tinnunculus) except on (originally) forested Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
where kestrel
Kestrel
The name kestrel, is given to several different members of the falcon genus, Falco. Kestrels are most easily distinguished by their typical hunting behaviour which is to hover at a height of around over open country and swoop down on prey, usually small mammals, lizards or large insects...
s hunt arboreally more like hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s. Due to the scarcity of mammals on oceanic islands, several species have adopted a diet containing many Phelsuma
Phelsuma
The genus Phelsuma consists of several lizards in the gecko family, commonly referred to as Day Geckos.-Description:In contrast to most other gecko species, day geckos are active mainly during the day. Other diurnal geckos are members of the genus Lygodactylus and the genus Gonatodes...
and other gecko
Gecko
Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 cm to 60 cm....
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 Madagascar KestrelMadagascar Kestrel
The Madagascar Kestrel , also known as Malagasy Spotted Kestrel, Newton's Kestrel, Madagascar Spotted Kestrel, katiti or hitsikitsika , is a small bird of prey of the genus Falco. It is named after British ornithologist Edward Newton. It occurs in two subspecies on Madagascar and at Aldabra...
, F. newtoni, are recognised, one on the main island of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
and one on neighbouring Anjouan
Anjouan
Anjouan is an autonomous island, part of the Union of Comoros. The island is located in the Indian Ocean. Its capital is Mutsamudu and its population as of 2006 is about 277,500. The total area of the island is 424 sq. kilometers Anjouan (also known as Ndzuwani or Nzwani) is an autonomous island,...
and Aldabra
Aldabra
Aldabra, the world's second largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans, has distinctive island fauna including the Aldabra Giant Tortoise, and is...
. It has adapted to human encroachment better than much of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
'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
Seychelles Kestrel
The Seychelles Kestrel 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...
, F. araea. Their ancestors diverged probably less than one million years ago (roughly around the early Ionian
Middle Pleistocene
The Middle Pleistocene, more specifically referred to as the Ionian stage, is a period of geologic time from ca. 781 to 126 thousand years ago....
)
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
Mahé, Seychelles
Mahé is the largest island of the Seychelles, lying in the north east of the nation. The population of Mahé is 80,000. It contains the capital city of Victoria and accommodates 90% of the country's total population...
, with a few pairs on Silhouette Island
Silhouette Island
Silhouette Island lies 20 km northwest of Mahé in the Seychelles. It is the third largest island in the Seychelles. It has an area of 20 km² and has a population of 135, mostly workers on the island. The main settlement is La Passe, where there is a hotel for visitors to Silhouette...
, North Island
North Island, Seychelles
North Island is a small granitic island in the Seychelles, 5 km north of Silhouette Island. Recently it has been developed as a private resort with 11 villas for guests, aimed at the eco-tourism market...
and Praslin
Praslin
Praslin is the second largest island of the Seychelles, lying 44 km north east of Mahé. Praslin has a population of around 6,500 people and comprises two administrative districts; Baie Sainte Anne and Grand' Anse . The main settlements are the Baie Ste Anne, Anse Volbert and Grand' Anse.It was...
. Its diet is mainly lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s. The species' status, as the following one's, is Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
according to the IUCN.
The Mauritius Kestrel
Mauritius Kestrel
The Mauritius Kestrel 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 Indian Ocean kestrels...
, F. punctatus, is more distantly related to the preceding two, having diverged from ancestral Madagascar region kestrels some time in the Gelasian
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 2.588 ± 0.005 Ma and 1.806 ± 0.005 Ma...
(Groombridge et al. 2002). It is found only on Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
. It usually snatches arboreal prey, typically gecko
Gecko
Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 cm to 60 cm....
s or small birds. Habitat loss and DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
poisoning pushed this species to the brink of extinction, down to possibly as few as six individuals (and an even smaller effective population size
Effective population size
In population genetics, the concept of effective population size Ne was introduced by the American geneticist Sewall Wright, who wrote two landmark papers on it...
) 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 Durrell
Gerald "Gerry" Malcolm Durrell, OBE was a naturalist, zookeeper, conservationist, author and television presenter...
were released to new areas, and the population has now almost reached the carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...
of the island; intensive conservation activity has ceased for some time, with the last captive bred birds released in 1994.
The Réunion Kestrel
Réunion Kestrel
The Réunion Kestrel 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....
, F. duboisi, is probably the latter species' closest known relative. It only inhabited the island of Réunion
Réunion
Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...
, but became extinct for reasons not entirely clear around 1700. It is only known from subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....
bones and one brief eyewitness report.
The Banded Kestrel
Banded Kestrel
The Banded Kestrel 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...
, 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
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n "gray kestrels" Falco ardosiaceus and Falco dickinsoni
The Spotted Kestrel
Spotted Kestrel
The Spotted Kestrel is also known as the Moluccan Kestrel.-Distribution and habitat:Spread throughout Australasia, Indomalaya, and most of Wallacea, the Spotted Kestrel inhabits grasslands with scattered trees, lightly wooded cultivation, and the edges of primary and tall secondary forest...
, F. moluccensis, is endemic to Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
. The Nankeen Kestrel
Nankeen Kestrel
The Australian Kestrel or Nankeen Kestrel is one of the smallest falcons, and unlike many, does not rely on speed to catch its prey. Instead, it simply perches in an exposed position, but it also has a distinctive technique of hovering over crop and grasslands...
, F. cenchroides, inhabits Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. These seem to belong to a lineage much closer to the Common Kestrel
Common Kestrel
The Common Kestrel 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 Britain, where no other brown falcon occurs, it is generally just called "the kestrel".This species...
(Groombridge et al. 2002).
Other species of Falco - for example, Sooty Falcon
Sooty Falcon
The Sooty Falcon is a medium-sized falcon breeding from northeastern Africa to the southern Persian Gulf region. It belongs to the hobby group, a rather close-knit number of similar falcons often considered a subgenus Hypotriorchis...
, Eleonora's Falcon
Eleonora's Falcon
Eleonora's Falcon 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 relative, but while they certainly belong to the same lineage, they do not seem...
, and the Peregrine Falcon
Peregrine Falcon
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-gray back, barred white underparts, and a black head and "moustache"...
- occur as occasional visitors in the region during migration
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
. These are generally larger and/or entirely differently colored birds.