The translocation of the Round Island keel-scaled boa
The Round Island keel-scaled boa, Casarea dussumieri, is the only surviving species in the snake family Bolyeriidae. Once present on mainland Mauritius and many of the surrounding islets, this endemic snake had become restricted to Round Island by the mid-1800s. Round Island is a closed nature reserve found some 22km off the coast of Mauritius and harbours the richest reptile community in Mauritius with 7 species of endemic reptiles still present and thriving there. The translocation of the keel-scaled boa to the neighbouring islet, Gunner’s Quoin, is the continuation of a series of reptile translocations, which have been ongoing since 2006, through a joint collaborative project involving the Durrell Wildlife Conservation Trust (UK), and the Mauritian Wildlife Foundation and the National Parks and Conservation Service of Mauritius. The main goal of the Mauritian Reptile Recovery Programme is to restore and secure the remaining reptile communities of Mauritius.
The translocation of the boa to Gunner’s Quoin is built upon 35 years of Durrell’s involvement in Mauritius and represents a monumental conservation achievement for the region. In 1977 when Gerald Durrell first visited Round Island there were fewer than 100 boas remaining. The snake’s habitat was being destroyed by introduced rabbits and goats. The removal of these herbivores by the mid-1980s has led to the regeneration of the island’s vegetation and recovery of the reptile community that now supports more than 1000 boas, which are the apex predators on the island. In the 1990s mammalian predators, such as rats were removed from the other key islands of Mauritius. Rats that invaded the other islands, like Gunner’s Quoin, in the mid-1800s caused the loss of the larger reptiles like the Gunther’s gecko, Telfair’s skink and boas, but the smaller endemic reptiles (Bojer’s skink, Bouton’s skink, ornate day gecko and lesser night-gecko) managed to persist at low numbers. In the 1990s, rats and other introduced mammals (Indian lesser-naped hare and rabbits) were removed from Gunner’s Quoin, which allowed the recovery of the small sized reptile fauna and opened up the island for reintroductions. In 2007 the reptile team reintroduced the boa’s key prey item, the Telfair’s skink, from Round Island. From 250 founding individuals the Telfair’s skink population is now greater than 3000 and a steadily growing. With the reintroduced skink population doing so well the time had finally come to restore another missing link to the Gunner’s Quoin’s ecosystem by re-introducing its former top predator, the boa!
The translocation project was meticulously planned and coordinated with a significant number of working hours going into preparatory work and logistic planning. The translocation trip spanned from the 11th to the 31st of October. The reptile team was divided into two. One team was based on Round Island for the night searches, captures and processing of the boas and the other one was based on Gunner’s Quoin for the release and subsequent monitoring of the released boas. The teams were composed of staff from the three organisations working on the Mauritian Reptile Recovery Programme, as well as staff from the Mauritius Forestry Service, involving a total of 30 individuals. Transport to and from the islands was supplied by the Police Helicopter Squadron and the National Coast Guard.
For the first night of boa searches on Round Island, the team broke the record of the maximum number of boas caught in one night with 19 boas found out of which 15 were selected for the translocation. Three days later, Dr Nik Cole, the programme Team Leader arrived on Gunner’s Quoin with a total of 30 boas. The same day, at around 3pm, we started placing the boas in their special release boxes, which were located along paths at regular intervals throughout the selected site. The purpose of these subterranean release boxes was to allow the boa to acclimatise to the location prior to their release at night fall when all the boxes were opened. The air was filled with excitement as we spent the afternoon putting the boas in their respective boxes. We all sat for dinner that evening feeling thrilled, looking forward to the full release later on. After dinner we had a quick re-briefing and broke up into 4 teams. Each team was assigned a specific number of boxes. As each box was opened the behaviour and movement of the boa was monitored with the aid of night vision equipment and red torch light in order to minimise disturbance.
The first release started at 8 p.m. I remember sitting approximately 2 metres away from the first opened box, still, my eyes glued to the opening awaiting eagerly for any movement. It was a very special moment as I witnessed the first boa emerging from its box and starting to explore its new habitat. Each boa reacted differently to the release. Some came out boldly and disappeared quickly in the thick vegetation, some were more wary, slowly sensing out their new environment, while others preferred to stay into their box and did not come out straight away. At around midnight, we all gathered back at the camp and toasted to the return of the keel-scaled boa to Gunner’s Quoin after 150 years of absence!
Subsequently we had three other nights of releases, with a total of 30 male and 30 female boas released on the island. The team based on Gunner’s Quoin searched for the released boas every night following release. We found the first boa roaming in the wild three days after the initial release. It was a beautiful female crossing one of the paths in the area where we were doing the searches. This was another climax of the trip and subsequently several more boas were found during the following night searches.
We returned to mainland Mauritius after three weeks of hard work looking forward to a shower and a good night’s sleep, but overly happy and satisfied because the whole trip went incredibly well. I feel very privileged to have been part of this translocation project and fantastic team. We now hope that the released boas will quickly adapt to their new home and eagerly await for the sighting of the first baby boa in the coming years!
Martine recently joined the Mauritius Reptile Recovery Programme as Reptile Coordinator for the Mauritian Wildlife Foundation. Martine brings much experience and expertise to the Reptile Programme having worked for the MWF since 2004 as a warden of Round Island and project coordinator for MWF's Flora Team. In 2010 Martine was a participant of Durrell's ESR course and has recently completed her MPhil in Conservation at the University of Cambridge.
Posted 22 November 2012