Réunion Kestrel
Encyclopedia
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.
Known from subfossil
bones and the writings of Dubois published in 1674, this bird was larger than its relative F. punctatus on Mauritius
, being about the size of a Common Kestrel
, or around 35 cm from head to tail, with males being noticeably smaller than females. This trait, while present in most birds of prey, is most pronounced in the larger, bird-eating species and reduces between-sex competition by niche differentiation
. It can be assumed that the bird was of the same generally brownish coloration as its closest relatives, with a lighter underside and darker spots or stipples, the tail, brown or more probably grey, being banded and tipped black. Its feet were yellow and large relative to the bird's overall size. The wingspan was 60-70 cm, its wings being more rounded than those of the Common Kestrel - just as in the Mauritius bird - for increased maneuvrability when hunting in the forest. It is probable, but not certain, that the only difference between the sexes was their size. The bird fed mainly on birds, but certainly also on insects and the local gecko
; Dubois noted that despite their small size they were able to prey on (presumably half-grown) domestic chicken
s.
which still exists), pieds jaunes ("yellow-feet") and émerillons (a term for small falcons like the Merlin
). It is not quite clear what name refers to the Réunion Kestrel. From reviewing the evidence, the bird was most probably the émerillon, with the pieds jaunes being either migrant falcons (the only species that might occur in the area, the Sooty Falcon
, Eleonora's Falcon
and the Peregrine Falcon
, are larger than F. duboisi was, if not in overall length, then at least in wingspan) or the juveniles of the marsh harrier, which are distinctly colored and also have yellow feet. The latter explanation seems more likely as the name was unequivocally applied to young marsh harriers in the late 19th century. Nonetheless, it seems remotely possible that the Réunion Falcon's sexes were not only of different size, but also differently colored. In this case, the males would be the émerillons and the females the pieds jaunes.
This seems not likely, however, as Feuilley in 1705 only mentions papangues and pieds jaunes as extant. The extinction of the Réunion Kestrel, which thus seems to have been complete around 1700, is something of a mystery, just as that of the Réunion Owl
. Introduced predators were not present in numbers at that time and even rats probably would not have presented much of a problem for the birds. Certainly, they were considered a pest as they fed on poultry, but hunting is unlikely to have been able to reduce their population much at such an early time, as evidenced by the continuous survival of the marsh harrier, which was heavily persecuted for centuries for the same reason.
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
which belongs to the falcon
Falcon
A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....
family. It inhabited the Mascarene 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...
and was part of the Western Indian Ocean radiation
Indian Ocean kestrels
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 except on forested Mauritius where kestrels hunt arboreally more like hawks...
of kestrels.
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 the writings of Dubois published in 1674, this bird was larger than its relative F. punctatus 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...
, being about the size of a 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...
, or around 35 cm from head to tail, with males being noticeably smaller than females. This trait, while present in most birds of prey, is most pronounced in the larger, bird-eating species and reduces between-sex competition by niche differentiation
Niche differentiation
The term niche differentiation , as it applies to the field of ecology, refers to the process by which natural selection drives competing species into different patterns of resource use or different niches...
. It can be assumed that the bird was of the same generally brownish coloration as its closest relatives, with a lighter underside and darker spots or stipples, the tail, brown or more probably grey, being banded and tipped black. Its feet were yellow and large relative to the bird's overall size. The wingspan was 60-70 cm, its wings being more rounded than those of the Common Kestrel - just as in the Mauritius bird - for increased maneuvrability when hunting in the forest. It is probable, but not certain, that the only difference between the sexes was their size. The bird fed mainly on birds, but certainly also on insects and the local gecko
Reunion Island day gecko
The Reunion Island day gecko is a subspecies of geckos. It is diurnal and lives in northern Réunion. It typically dwells on banana trees and feeds on insects and nectar.- Description :...
; Dubois noted that despite their small size they were able to prey on (presumably half-grown) domestic chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s.
Extinction
Dubois mentioned three kinds of birds of prey extant on Réunion in the early 1670s: in order of decreasing size, papangues (the local marsh harrierMadagascar Marsh Harrier
The Malagasy Harrier is a bird of prey belonging to the marsh harrier group of harriers. It inhabits Madagascar and the Comoro Islands in the Indian Ocean. It was formerly regarded as a subspecies of the Réunion Harrier but is increasingly treated as a separate species...
which still exists), pieds jaunes ("yellow-feet") and émerillons (a term for small falcons like the Merlin
Merlin (bird)
The Merlin is a small species of falcon from the Northern Hemisphere. A bird of prey once known colloquially as a pigeon hawk in North America, the Merlin breeds in the northern Holarctic; some migrate to subtropical and northern tropical regions in winter.-European and North American...
). It is not quite clear what name refers to the Réunion Kestrel. From reviewing the evidence, the bird was most probably the émerillon, with the pieds jaunes being either migrant falcons (the only species that might occur in the area, the 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"...
, are larger than F. duboisi was, if not in overall length, then at least in wingspan) or the juveniles of the marsh harrier, which are distinctly colored and also have yellow feet. The latter explanation seems more likely as the name was unequivocally applied to young marsh harriers in the late 19th century. Nonetheless, it seems remotely possible that the Réunion Falcon's sexes were not only of different size, but also differently colored. In this case, the males would be the émerillons and the females the pieds jaunes.
This seems not likely, however, as Feuilley in 1705 only mentions papangues and pieds jaunes as extant. The extinction of the Réunion Kestrel, which thus seems to have been complete around 1700, is something of a mystery, just as that of the Réunion Owl
Réunion Owl
The Réunion Owl was a small owl that occurred on the Mascarene island of Réunion, but became extinct before living birds could be described; it is only known from subfossil bones. It belongs to the Mascarene owls of the genus Mascarenotus, and most likely was similar to a Long-eared Owl in size...
. Introduced predators were not present in numbers at that time and even rats probably would not have presented much of a problem for the birds. Certainly, they were considered a pest as they fed on poultry, but hunting is unlikely to have been able to reduce their population much at such an early time, as evidenced by the continuous survival of the marsh harrier, which was heavily persecuted for centuries for the same reason.