Population mechanisms of a restored population of the Mauritius kestrel: The buffer effect, spatial patterns and modelling population persistence in a changing environment
		Malcolm Burgess Supervisor: Ken Norris The Mauritius kestrel (Falco punctatus) was once widely distributed throughout the Indian Ocean island of Mauritius, but following habitat loss and the intensive use of organochlorine pesticides it was reduced to just four known individuals in the wild by 1974. Following a successful species recovery programme the population now stands at 600-800 individuals and once again occupies the three main mountain chains on the island Our study population is a population of Mauritius kestrels located in the Bambous Mountains in the east of Mauritius The population in this area was extirpated by the 1960s, but reintroduced at the end of the 1980s Subsequent to its reintroduction and associated intensive management the population has grown, and has now become regulated at around 42-45 breeding pairs Since reintroduction the population has been intensively monitored. Each breeding season pairs are identified, and their breeding attempts monitored to establish clutch-size, brood-size and the number of chicks fledged. All young are marked with a unique combination of colour rings for approximately 450 individual kestrels as the population has developed Growing populations are thought to occupy the best quality habitat first where they produce many young. As suitable territory fills up they are forced to breed in poorer quality areas where less young are raised. This density-dependant mechanism reduces the net annual growth rate of the population. We are investigating whether this has happened with the Mauritius kestrel. OBJECTIVES Analyse our existing database to examine spatial patterns in fecundity and survival, and relate these to the temporal pattern of occupancy by breeding birds as the population has grown in size Undertake field studies to relate spatial patterns in fecundity and survival to habitat characteristics Examine theoretically (using our existing matrix model) how spatial patterns in habitat influence the form of density-dependence, and how this, in turn, influences long-term abundance and population persistence Use our understanding of the buffer effect within the matrix-modelling framework to examine future environmental change scenarios that include climate change and anthropogenic changes in the spatial arrangement of habitat. METHODS During the breeding season of the Mauritius kestrel we monitor all nesting attempts in the Bambous mountain sub-population, adding to the 17 years of data collected since their reintroduction. All adults are identified by their unique colour rings while clutch size, brood size, and fledgling success are determined from nest inspection. All chicks are colour ringed prior to fledging. Post fledging, juveniles from two subsets of natal territories (depending on year first occupied) are captured and fitted with radio transmitters. These are subsequently radio tracked to determine habitat use and survival. Habitat types are recorded for the entire Bambous mountain range from maps, photographs and on the ground. OUTPUTS The final model will enable impact on the Mauritius kestrel from development or environmental events to be reliably predicted, and can be adapted for many other species worldwide. Incorporated into this model will be a detailed GIS habitat map of the Bambous mountain range which can be used in other existing research in the region. The study is funded by ...