Richard Dale
The May speaker was Richard Dale, the esteemed Secretary of SBSG, who was talking about two breeding seasons he spent on Mauritius working with the Mauritius Kestrel conservation project.
Mauritius is an island in the Indian Ocean, about 850 Km to the east of Madagascar. It is about 55 Km from north to south, and 45 Km west to east, and is mostly covered in sugar plantations but with some remote and inaccessible forests, mountains and gorges. The human population numbers about 1.2 million, which are mainly concentrated in the plains on the western side of the island. There are several smaller offshore islands, the largest of which is Rodriguez.
Because of its isolation, the truly indigenous flora and fauna of Mauritius have followed their own evolutionary paths, and many species are unique to the island. The most (in)famous of these is the Dodo which became extinct in the seventeenth century and, in fact, out of a total of 18 endemic bird species, 9 have become extinct, whilst most of the others are far from secure. In other words, only 9 bird species are endemic to the island, and the rest have come relatively recently from elsewhere; some, such as Red-breasted Bulbul and Common Mynah are quite abundant. The chief conservation body is the Mauritian Wildlife Foundation, and this runs a number of projects, including some that specialise in conservation of a particular species.
The Mauritius Kestrel is the only raptor species on the island. It is similar in appearance to the European Kestrel, but with slightly shorter and more rounded wings and longer legs; the male is only very slightly smaller than the female. Clutch size is 2-5, with 3-4 being the norm; it is relatively common for one or two eggs not to hatch. The species inhabits two regions on the island, one on the east coast and one on the west coast. The east coast ones normally use nest boxes provided for them, or cliff ledges, and the west coast ones, which inhabit the forested gorges where there are no nest-boxes, use cliff ledges or tree cavities. They mostly eat arboreal geckos and small birds.
Historically, the Durrell Wildlife Conservation Trust (based in Jersey) has been much involved with conservation projects on Mauritius. The Kestrel seemed to be a lost cause in 1974 when the population dropped to just four individuals, all living in the Black River Gorges area in the south-west of the island; consequently, Dr. Carl Jones was sent to collect these four, and bring them back to Jersey for a captive breeding programme. However, instead of doing this, he set about trying to conserve the species in situ and, by 1979, he had established the Mauritius Kestrel Project to try to achieve this. The procedure involved collecting eggs (leaving the birds to re-lay), artificially incubating the eggs, raising the chicks in captivity, and then releasing them back into the wild.
By the end of the 1980s the population was strong enough to start re-introducing birds to the Bambous Mountain area on the east coast of the island, and these birds are monitored intensively by a team including research students from Reading University. Some 95% of the birds are colour ringed, and this enables the researchers to build up a database of virtually all individuals and their complete ancestry. In 2006 there was a vacancy for a researcher, and Richard was invited to join the project. Unfortunately, delays with visa etc. meant he was a little late in getting there, and had a very steep learning curve involving not only ringing techniques, but also motorbikes and abseiling. Most of the birds now use the nest boxes provided, but some nest on inaccessible cliff ledges requiring climbing up and abseiling down. Chicks are ringed at 14-20 days, and isometric data taken. There is the occasional deformity, such as an extra hind claw, but the inbreeding does not appear to have caused undue problems. It is thought this is because the population was only at its very low point for a relatively short time, so the four individuals had a reasonable genetic spread between them.
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In addition to the Kestrel project, similar work has been carried out on the Pink Pigeon and Echo Parakeet by their respective teams, and both populations are growing. The Pink Pigeon population is sufficiently stable to think of releasing some birds to the offshore islands, but first the rats will have to be eradicated. Attention is now turning to the Tomb Bat, and to passerines such as the Olive White-eye. There are less than 100 of the latter, and the project team is engaged upon a similar programme to that used with the Kestrel: collection of eggs, artificial incubation and rearing in aviaries, acclimatisation and release, with supplementary feeding.
An additional experience in 2006 was a spell at a field station on Round Island, about 20 Km off the north-east coast of Mauritius. Round Island was designated as a nature reserve in 1957, and is administered jointly by the National Parks and Conservation Services and the Mauritian Wildlife Foundation. Here, the original hardwood forests were destroyed by non-native goats and rabbits ? introduced to provide food for shipwrecked sailors ? and this has led to soil being washed away to expose the volcanic rock underneath. The goats were eradicated by 1978, and the rabbits by 1986, so now there is a massive programme of re-vegetation, with seedlings being grown under controlled conditions, and then transplanted. The associated watering requirement is very labour intensive. There have never been any rats on the island, and the thousands of seabirds (including tropic birds, shearwaters and petrels) provide nutrients for a flourishing reptile population.
In 2007, Richard was able to arrive in Mauritius in good time, and recruited a team to carry out a full survey of the Kestrels - not just the Bambous Mountain ones ? the first for ten years. Unfortunately the team of four was subsequently reduced to two following a football-related toe injury to one member, and rather more serious injuries following a motorbike crash to another. To carry out the survey in the wilder parts of the Black River Gorges National Park, they had to hack their way through the forests where no tracks existed, and machete was the only way. The Kestrels here were all cliff nesters, as there were no nest boxes, and again it was a case of climbing and abseiling. There are huge problems in these forests, with native tree species being overcome by exotics such as Chinese Guava and Privet, and the native species would all become extinct without a huge conservation effort. The survey showed there to be about 600 Kestrels altogether, which was down on the estimated 800 of ten years ago. There are an estimated 40 territories in the gorges.
Mauritius does not support a huge number of bird species, and Richard's list for the two years comprised 62 species; Richard had some impressive photographs (and, of course, drawings) of most of them.
Richard was thanked for a most enjoyable first-hand account of bird conservation at such a very "sharp end" ? and it is not often that we get a talk covering the entire avifauna of an area! It was also a very pleasant change to hear some good news of species expansion. Also of note, of course, were Richard's excellent photographs and drawings. And we learned something of the migration habits of avian researchers (as promised by Helen Hipperson in her inimitable introduction).
Wendy Thomson |
