The Réunion kestrel (''Falco duboisi'') is an
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 ...
bird of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...
which belongs to the
falcon
Falcons () are birds of prey in the genus ''Falco'', which includes about 40 species. Falcons are widely distributed on all continents of the world except Antarctica, though closely related raptors did occur there in the Eocene.
Adult falcons ...
family. It inhabited the
Mascarene
The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Their ...
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 ...
and was part of the
Western Indian Ocean radiation of kestrels.
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 the writings of
Dubois published in 1674, this bird was larger than its relative ''F. punctatus'' on
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 ...
, being about the size of a
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 ...
, 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
In ecology, niche differentiation (also known as niche segregation, niche separation and niche partitioning) refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive excl ...
. 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 domestic
chicken
The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...
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 harrier which still exists), ''pieds jaunes'' ("yellow-feet") and ''émerillons'' (a term for small falcons like the
merlin
Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...
). 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
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 ...
, 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
Jean Feuilley
Jean Feuilley was a pilot engineer and cartographer who was sent to Réunion by the French East India Company to investigate the possibility of agricultural and marine exploitation. He arrived in the island in 1704 and the following year returne ...
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 scops owl
The Réunion scops owl (''Otus grucheti''), also known as the Réunion owl or Réunion lizard owl, was a small owl that occurred on the Mascarene island of Réunion, but became extinct before any living birds were described; it is only known from ...
. 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.
References
* Cowles, Graham S. (1994): A new genus, three new species and two new records of extinct Holocene birds from Réunion Island, Indian Ocean. ''Geobios'' 27(1): 87–93.
{{DEFAULTSORT:Reunion Kestrel
Extinct birds of Indian Ocean islands
Falco (genus)
Bird extinctions since 1500
Birds of Réunion
Birds described in 1994