Mauritius Kestrel

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Image:MauritiusKestrel.JPG

Common Name: Mauritius Kestrel
Scientific Name: Falco punctatus

Size: 7.8-10.2 inches (20-26 cm); Wingspan: 15.7 inches (40 cm)

Habitat: Africa; it is endemic to the Mauritius Island.

Its primary habitat was native, evergreen, subtropical forests, but captive-bred birds have shown greater tolerance for degraded and open areas. They are no longer considered obligate forest dwellers but also exploit grassland. Avoidance of agricultural areas may be partly due to a lack of isolated mature trees to use as vantage points.

Status: Endangered. Global population: 400+/- individuals. Deforestation by early colonists initiated declines, with less than 3% of original forest now remaining. More recent declines appear related to organochloride pesticide-use in the 1950s and 1960s in agriculture and to control malaria-carrying mosquitoes. Black rats, crab-eating macaques, small Indian mongooses and feral cats are all introduced predators of eggs, young or adults. Introduced plants, including traveler’s palm, Chinese guava, Ligustrum robustum and the creeper have invaded much of the species’ habitat, particularly in the north of the island. This may reduce the kestrel's hunting efficiency. Birds in suboptimal habitat in the west have been lost when natural nest sites are absent. In addition, the species suffered an extreme loss of genetic variation and high rates of inbreeding, due to the population bottleneck, which are considered sufficient to affect the long-term viability of the population. Climate change may be affecting the species through the increase in wet days at the start of the breeding season, which has led to the laying date becoming later.

Diet: Indigenous lizards (primarily geckos), insects, small birds and mice.

It hunts by means of short, swift flights through forests.

Nesting: Females are noticeably larger than males. Small, chestnut-and-white falcon. Rich warm brown to chestnut upperparts, with black crescentic markings on wings and mantle. It has gleaming white underparts with bold, black heart-shaped blotchings. In flight, wings relatively rounded and long, thin tail. Females and juveniles have light blue eyelids and grayish-yellow talons.

It traditionally nests in volcanic rock-cavities, and probably tree-holes, within forest territories, but now even breeds in a few suburban areas.

Two or three eggs are laid; they are white with brown markings and are incubated for 28–31 days. The young birds fledge after 35–42 days and then remain with their parents for another 14 weeks.

Cool Facts: The Mauritius Kestrel has undergone a spectacular recovery from just four wild birds (including one breeding pair in 1974 to an estimated 222-286 birds by the end of 1994, thanks to a recovery program launched in 1973. At the end of the 1999-2000 seasons, the population was estimated at the time to number 145-200 breeding pairs in a total population of 500-800 individuals, divided into three sub-populations on mountain chains in the north, east and south-west of Mauritius.

In 2005 the population was estimated at 800-1,000 individuals, but by 2008, dropped to an estimated at 500-600. By 2011-2012, the population was estimated to number c.300-400 individuals, with the small sub-population in the Moka Range in the north of the island apparently extinct. Declines have also been observed in the south-western population, particularly in suboptimal habitat on the periphery of its range, since 2007-2008 with c.40-50 pairs and a pre-breeding season population of c.120-150 birds estimated to be there now. The eastern population has grown and stabilized at c.45-50 pairs and a total of 130-150 birds in the pre-breeding season. The population data from the 1970s to 2010 are being re-analyzed to clarify what the peak population size was and what rate of decline has occurred. There is no record of dispersal to other locations despite intensive monitoring through banding.

Inbreeding does not appear to affect this Kestrel and the reason why lies in its history. It colonized its island home to evolve into a distinct species probably during the Gelasian (Late Pliocene). Mauritius is a volcanic island, and although the colonization of the island by kestrels cannot be dated with high precision, it was almost certainly some time before volcanic activity died down. The Mauritius kestrel population seems to have survived a prolonged period of volcanic activity, which must have kept the population small and fluctuating as habitat, food, and kestrels were destroyed by volcanic eruptions time and again. As near-panmictic conditions were sustained for many generations, alleles that might cause inbreeding depression were steadily removed by means of natural selection. The phenomenon that effective population sizes as low as 4-5 can be tolerated without pronounced inbreeding depression is also known from other small-island birds, such as Petroica traversi or the Laysan duck.


This 3D model is found in Songbird Remix Birds of Prey Volume I: Kestrels, Hobbies and Falcons

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