Genetics reveal Katiti’s past
The Seychelles kestrel, Katiti in Creole, crashed to approximately eight individuals since the 1940s before the population recovered, apparently unassisted, a recent genetics study has revealed. This crash, it is thought, approached the severity of the genetic bottleneck of the Mauritius kestrel whose numbers reduced to only four known individuals in the wild in the early 1970s. Intriguing however, is that the Seychelles kestrel seems to have recovered undetected and without intensive intervention.
The Seychelles kestrel, Katiti in Creole, crashed to approximately eight individuals since the 1940s before the population recovered, apparently unassisted, a recent genetics study has revealed. This crash, it is thought, approached the severity of the genetic bottleneck of the Mauritius kestrel whose numbers reduced to only four known individuals in the wild in the early 1970s. Intriguing however, is that the Seychelles kestrel seems to have recovered undetected and without intensive intervention.
A clear understanding of the recent population history of a species is important because it helps managers to anticipate problems associated with a dip in population. Island endemic bird populations generally have lower levels of genetic diversity than species with a continental distribution. This increases inbreeding and its associated risks of extinction. Inbreeding causes problems such as lowered reproductive fitness and vulnerability to disease. Preservation of genetic diversity is thus the basis of many conservation efforts because diversity is vital for evolutionary adaptation, and adaptation is key to the long-term survival of any species. Therefore, interventions on behalf of endangered birds on islands usually involve boosting population sizes in order to vary the genetic material. This has been true for species action for most of Seychelles endemics including the Seychelles Magpie robin (Pi Santez) and Seychelles warbler (Timerl Dezil).
In the past, conservation efforts relied on historical accounts and some anecdotal data. Historical records have variously described the Seychelles kestrel as “tolerably common” in the 1860s, “frequently seen in all islands” in the 1930s, both “well distributed” and “rare” in the 1950s, “Critically Endangered and close to extinction” by 1966, with “probably less than 30 birds” confined to Mahe in 1969. Surveys in 1973 located 49 pairs and estimated a population of 150- 300 birds and by 1981, there was an estimated carrying capacity of 370 pairs. In 1985, the Katiti was described as being “far more numerous than previously thought”. Surveys in 2000-2001 suggest that the population remained stable in the previous 25 years.
The Seychelles kestrel recovery from a severe population bottleneck relatively unaided by intensive conservation efforts is extremely rare. Many seemingly comparable ‘unmanaged’ species recoveries can often be explained by indirect intervention, such as broad-scale ecosystem management. But the study bears a note of caution. “Given the current pressure on global conservation resources, this recovery may appear encouraging. However, outcomes such as this are likely to be the exception rather than the rule for other endangered island endemics,” the authors say.
Source: Regar 3-5-10