This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.
Mauritius Kestrel Falco punctatus is restricted to Mauritius. It is currently listed as Vulnerable under criterion D1+2 because it has a very small population, susceptible to a variety of threats.
This species has undergone a spectacular recovery from just four wild birds (including one breeding pair in 1974 (Safford and Jones 1997, Anon. 2005). By the end of the 1994 breeding season there were an estimated 222-286 birds in the population, following a successful recovery programme launched in 1973 (Nicoll et al. 2004). At the end of the 1999-2000 season, the population was estimated at the time to number 145-200 breeding pairs and a total population of 500-800 individuals (C. Jones in litt. 2000), divided into three subpopulations on mountain chains in the north, east and south-west of Mauritius (Jones and Swinnerton 1997). In 2007-2008 the population was estimated at 500-600 individuals by Dale (2008); 800-1,000 individuals were estimated in 2005 (Anon. 2005, Mauritian Wildlife Foundation in litt. 2006) but it is now thought unlikely that the population ever approached 1,000 (V. Tatayah in litt. 2012), and may have only peaked at 350-500 individuals at the end of the 1990s (C. Jones in litt. 2012). By 2011-2012 the population was estimated to number c400 individuals on the east and west coast, with the small subpopulation in the Moka Range in the north of the island apparently extinct (possibly due to low habitat quality, predators and safe nesting sites), and declines observed in the south-western population, particularly in suboptimal habitat on the periphery of the range, since 2007-2008 (V. Tatayah in litt. 2012). The eastern population is described as stable and appears to be limited by nesting sites to around 40 pairs, although the population remains dependent on conservation measures (Groombridge et al. 2001) and there is no record of dispersal to other locations despite intensive monitoring through colour ringing (Ewing et al. 2008, Senapathi et al. 2011). Nevertheless, attempts are being made to revert the decline on the west coast with the provision of nest boxes in this area and maintaining those on the east of the island (V. Tatayah in litt. 2012).
Confirmation that the global population is undergoing a continuing decline will warrant the uplisting of this species to a higher category of threat. The Extent of Occurrence (EOO) is estimated to be 160 km2; it is now found in 2 locations (since the northern range is now extinct) and with sufficient evidence of a continuing decline in this species’s number of mature individuals and area, extent and/or quality of habitat, it would qualify as Endangered under criterion B1ab(iii,v) of the IUCN Red List. The number of mature individuals in the largest subpopulation is estimated to be 150 individuals (V. Tatayah in litt. 2012). As the population is estimated to be <2,500 mature individuals, if all subpopulations are confirmed to be ≤250 mature individuals and the global population is declining, this species could also qualify as Endangered under criterion C2a(i).
Subpopulations are defined by the IUCN as geographically or otherwise distinct groups in the population between which there is little demographic or genetic exchange (typically one successful migrant individual or gamete per year or less). The term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat. (IUCN 2001). For example, where the most serious plausible threat is habitat loss, a location is an area where a single development project can eliminate or severely reduce the population. Where the most serious plausible threat is volcanic eruption, hurricane, tsunami, frequent flood or fire, locations may be defined by the previous or predicted extent of lava flows, storm paths, inundation, fire paths, etc.
Further information is requested on this global population size and trends of this species and any additional comments on the proposed uplisting are welcome.
Anon. (2005) 30 years working with the Mauritius Kestrel. MWF Newsletter: 4.
Dale, R. (2008) In Search of Mauritius Kestrels. The Peregrine Fund Newsletter 39: 10-11.
Ewing, S. R., Nager, R. G., Nicoll, M. A. C., Aumjaud, A., Jones, C. G. and Keller, L. F. (2008) Inbreeding and loss of genetic variation in a reintroduced population of Mauritius Kestrel. Conservation Biology 22(2): 395-404.
Groombridge, J. J., Bruford, M. W., Jones, C. G. and Nichols, R. A. (2001) Evaluating the severity of the population bottleneck in the Mauritius kestrel Falco punctatus from ringing records using MCMC estimation. Journal of Animal Ecology 70: 401-409.
Jones, C. G. and Swinnerton, K. J. (1997) A summary of the conservation status and research for the Mauritius Kestrel Falco punctatus, Pink Pigeon Columba mayeri and Echo Parakeet Psittacula eques. Dodo: Journal of the Jersey Wildlife Preservation Trust 33: 72-75.
Nicoll, M.A.C., Jones, C.G. and Norris, K. (2004) Comparison of survival rates of captive-reared and wild-bred Mauritius kestrels (Falco punctatus) in a re-introduced population. Biological Conservation 118(4): 539-548.
Safford, R. J. and Jones, C. G. (1997) Did organochloride pesticide use cause declines in Mauritian forest birds? Biodiversity and Conservation 6(10): 1445-1451.
Senapathi, D., Nicoll, M. A. C., Teplitsky, C., Jones, C. G. and Norris, K. (2011) Climate change and the risks associated with delayed breeding in a tropical wild bird population . Proceedings of the Royal Society B Published online before print March 23, 2011.