Vets and conservation: helping to restore the balance
Joseph Flanagan explains how vets are contributing to a unique conservation project in the Galapagos Islands.
Downloaded from veterinaryrecord.bmj.com on January 21, 2011 - Published by group.bmj.com
Joseph P. Flanagan, DVM, Director of Veterinary Services, Houston Zoo, 1513 Cambridge Street, Houston, TX 77030, USA e-mail: jflanagan@houstonzoo.org
AN ecosystem can be considered to be analogous to a living organism: each species in that ecosystem being analogous to the organs of a body, with the health of the whole dependent upon the health of each of the constituent parts.
Joseph Flanagan explains how vets are contributing to a unique conservation project in the Galapagos Islands.
Downloaded from veterinaryrecord.bmj.com on January 21, 2011 - Published by group.bmj.com
Joseph P. Flanagan, DVM, Director of Veterinary Services, Houston Zoo, 1513 Cambridge Street, Houston, TX 77030, USA e-mail: jflanagan@houstonzoo.org
AN ecosystem can be considered to be analogous to a living organism: each species in that ecosystem being analogous to the organs of a body, with the health of the whole dependent upon the health of each of the constituent parts.
Island ecosystems tend to be relatively simple, having relatively few species when compared to larger land masses or continents. Loss of one species or the introduction of others can have a rapid, dramatic impact on other species in the habitat and can cause the ecosystem itself to fail or die. While remnant populations of native species may still exist, they are at different population levels and their interspecies interactions, and impacts on the environment, might be changed.
Wildlife veterinarians can play key roles in the conservation of biodiversity and the restoration of balance in an ecosystem. One typically would think that the role played by veterinarians would be to enhance wildlife production, diagnose disease problems, treat diseased or injured animals, or provide anaesthesia or chemical restraint for translocation of animals. However, as illustrated of this issue (Knafo and others 2011), they can also contribute in other ways; the paper describes how, in a unique situation, the sterilisation of giant tortoises is contributing to the restoration of a natural state on the small island of Pinta in the Galapagos archipelago.
In December 2008, the Galapagos National Park Service asked us about the possibility of sterilising giant tortoises. Could it be done? If possible, what would be needed, and when could it happen?
Wildlife veterinarians can play key roles in the conservation of biodiversity and the restoration of balance in an ecosystem. One typically would think that the role played by veterinarians would be to enhance wildlife production, diagnose disease problems, treat diseased or injured animals, or provide anaesthesia or chemical restraint for translocation of animals. However, as illustrated of this issue (Knafo and others 2011), they can also contribute in other ways; the paper describes how, in a unique situation, the sterilisation of giant tortoises is contributing to the restoration of a natural state on the small island of Pinta in the Galapagos archipelago.
In December 2008, the Galapagos National Park Service asked us about the possibility of sterilising giant tortoises. Could it be done? If possible, what would be needed, and when could it happen?
Each of the islands in the Galapagos is a unique ecosystem. While there are many animal and plant species that are common to many of the islands, each island has a unique combination of plants and animals, unique geology, terrain, weather, and, especially, a unique degree of impact from human degradation. Humans have exploited the islands for nearly 500 years, harvesting wildlife - sometimes to extinction, and introducing domestic animals and pest species such as rodents, but also invertebrates and plants.
Restoration of the island of Pinta was nearly complete. Introduced goats had been eradicated and native vegetation, grazed to near extinction by over 40,000 feral goats, was returning with thick, herbaceous and woody growth. Other native wildlife species were still present. The only key species that was missing was the giant tortoise. Tortoises were harvested by whalers and pirates in the 18th and 19th centuries as a source of fresh meat for use during their long months at sea. Giant tortoises on Pinta were thought to be extinct for most of the last 100 years until a single animal 'Lonesome George' was found there in 1971. George was removed to the Charles Darwin Research Station in 1972 amid hopes a mate might be found, and the pair could breed, resulting in repopulation of the island with a species of tortoise found nowhere else on Earth. Despite worldwide efforts to locate tortoises with 'Pinta' genes, no mate for George has been found.
The problem on Pinta Island was that, with no herbivore, surviving vegetation was growing unchecked. There was no disturbance, no large seed disperser, and no cropping of lush growth. What should be a mosaic of grassland pampas, scrub and desert vegetation was becoming a woodland with a canopy of vegetation not conducive to the survival and well being of the other species of wildlife present on Pinta. Pinta Island needed a large herbivore, a giant tortoise. The 'native' species or a suitable alternative was not yet available. Introduction of another species as surrogate may one day occur, but a 'habitat engineer' was needed immediately to maintain biodiversity.
The Galapagos National Park Service has maintained a herd of giant tortoises, which was produced in the early years of its tortoise captive propagation programme. These animals had no known ancestry when hatched, but are now recognised as hybrids between species of tortoises found on the different islands in Galapagos. These animals have no 'home island' where they could be released. If sterilised, however, they could be used to help restore the habitat on Pinta, while the search for the most appropriate pure species of tortoise continues. The hybrid tortoises ranged in size from 20 to 100 kg and there were both male and female tortoises in the group.
Veterinarians sterilise a giant tortoise ahead of its release on to Pinta Island in the Galapagos archipelago and discomfort to the animal. Castration or vasectomy would have required an intracoelomic procedure utilising general anaesthesia and a much greater risk of complications. In addition, the procedure developed and performed can be done in the future by local veterinarians without elaborate equipment or advanced surgical skills.
Planning and logistics had to account for performing up to 50 surgeries in one week. A veterinary team, endoscopic surgical equipment, supplies, and medications all had to be brought in. A surgical 'suite' had
Elective sterilisation in chelonians is not routinely performed. Surgery of the chelonian reproductive tract is normally performed when there is a health problem such as retained ova in females, or prolapsed phallus in males. In these cases, surgery is generally performed to salvage the life of the patient. There are a number of procedures that can be done to render tortoises reproductively sterile. Males can be castrated, vasectomised, or their phallus can be amputated (the phallus is used for copulation, but does not play a role in the elimination of urinary waste). Females can be ovariectomised or hysterectomised. The goal was that both sexes would be rendered infertile, so there would be no chance of genetic contamination if a pure species from another island is one day introduced to the island.
Ultimately, the decision to perform endoscope-assisted ovariectomy was made because it could be performed through the limited access of the prefemoral fossa. A small incision and minimal tissue handling would result in rapid healing and minimal discomfort to the animal (Knafo and others 2011). Males were sterilised by amputation of the phallus (Rivera and others 2011). The procedure could be done utilising intrathecal anaesthesia, resulting in minimal risk
to be established, and housing identified for postoperative monitoring and recovery. Contingencies for managing emergencies or adverse response to anaesthesia, and aftercare of the patients were necessary. Most importantly, the team had to be able to adapt their skills to solve unique problems and achieve their goals. Surgeries were performed during November 2009.
Restoration of the island of Pinta was nearly complete. Introduced goats had been eradicated and native vegetation, grazed to near extinction by over 40,000 feral goats, was returning with thick, herbaceous and woody growth. Other native wildlife species were still present. The only key species that was missing was the giant tortoise. Tortoises were harvested by whalers and pirates in the 18th and 19th centuries as a source of fresh meat for use during their long months at sea. Giant tortoises on Pinta were thought to be extinct for most of the last 100 years until a single animal 'Lonesome George' was found there in 1971. George was removed to the Charles Darwin Research Station in 1972 amid hopes a mate might be found, and the pair could breed, resulting in repopulation of the island with a species of tortoise found nowhere else on Earth. Despite worldwide efforts to locate tortoises with 'Pinta' genes, no mate for George has been found.
The problem on Pinta Island was that, with no herbivore, surviving vegetation was growing unchecked. There was no disturbance, no large seed disperser, and no cropping of lush growth. What should be a mosaic of grassland pampas, scrub and desert vegetation was becoming a woodland with a canopy of vegetation not conducive to the survival and well being of the other species of wildlife present on Pinta. Pinta Island needed a large herbivore, a giant tortoise. The 'native' species or a suitable alternative was not yet available. Introduction of another species as surrogate may one day occur, but a 'habitat engineer' was needed immediately to maintain biodiversity.
The Galapagos National Park Service has maintained a herd of giant tortoises, which was produced in the early years of its tortoise captive propagation programme. These animals had no known ancestry when hatched, but are now recognised as hybrids between species of tortoises found on the different islands in Galapagos. These animals have no 'home island' where they could be released. If sterilised, however, they could be used to help restore the habitat on Pinta, while the search for the most appropriate pure species of tortoise continues. The hybrid tortoises ranged in size from 20 to 100 kg and there were both male and female tortoises in the group.
Veterinarians sterilise a giant tortoise ahead of its release on to Pinta Island in the Galapagos archipelago and discomfort to the animal. Castration or vasectomy would have required an intracoelomic procedure utilising general anaesthesia and a much greater risk of complications. In addition, the procedure developed and performed can be done in the future by local veterinarians without elaborate equipment or advanced surgical skills.
Planning and logistics had to account for performing up to 50 surgeries in one week. A veterinary team, endoscopic surgical equipment, supplies, and medications all had to be brought in. A surgical 'suite' had
Elective sterilisation in chelonians is not routinely performed. Surgery of the chelonian reproductive tract is normally performed when there is a health problem such as retained ova in females, or prolapsed phallus in males. In these cases, surgery is generally performed to salvage the life of the patient. There are a number of procedures that can be done to render tortoises reproductively sterile. Males can be castrated, vasectomised, or their phallus can be amputated (the phallus is used for copulation, but does not play a role in the elimination of urinary waste). Females can be ovariectomised or hysterectomised. The goal was that both sexes would be rendered infertile, so there would be no chance of genetic contamination if a pure species from another island is one day introduced to the island.
Ultimately, the decision to perform endoscope-assisted ovariectomy was made because it could be performed through the limited access of the prefemoral fossa. A small incision and minimal tissue handling would result in rapid healing and minimal discomfort to the animal (Knafo and others 2011). Males were sterilised by amputation of the phallus (Rivera and others 2011). The procedure could be done utilising intrathecal anaesthesia, resulting in minimal risk
to be established, and housing identified for postoperative monitoring and recovery. Contingencies for managing emergencies or adverse response to anaesthesia, and aftercare of the patients were necessary. Most importantly, the team had to be able to adapt their skills to solve unique problems and achieve their goals. Surgeries were performed during November 2009.
After recovery, the tortoises were monitored for complications. General health was determined through individual physical examination, haematology and serum chemistry assays, and faecal examinations. Their intestinal tracts had to be free of seeds from any vegetation they consumed before transport to Pinta, so they had to be fed a seed-free herbaceous diet for two months before release. Finally, to prevent the introduction of parasites or other disease-causing agents, the animals had to be screened and prophylactically treated for enteric nematodes before being transported to their release site. Thirty-nine tortoises travelled by boat to Pinta Island in May 2010 to play their part in restoring the balance of nature in this remote part of the world.
Veterinarians skilled in reptile medicine and surgery were critical to the success of this project. The release site was selected based on knowledge of historical habitat used by tortoises on the island. Post-release monitoring of the tortoises is being performed to assess their impact on the environment and to monitor their interactions with other species on the island.
References
KNAFO, S. E., DIVERS, S. J., RIVERA, S., CAyOT, L. J., TAPIA-AGUILERA, W. & FLANAGAN, J. (2011) Sterilisation of hybrid Galapagos tortoises (Geochelone nigra) for island restoration. Part 1: endoscopic oophorectomy of females under ketamine-medetomidine anaesthesia. Veterinary Record doi: 10.1136/vr.c6520
RIVERA, S., DIVERS, S. J., KNAFO, S. E., MARTINEZ, P., CAyOT, L. J., TAPIA-AGUILERA, W. & FLANAGAN, J. (2011) Sterilisation of hybrid Galapagos tortoises (Geochelone nigra) for island restoration. Part 2: phallectomy of males under intrathecal anaesthe- sia with lidocaine. Veterinary Record doi: 10.1136/vr.c6361
References
KNAFO, S. E., DIVERS, S. J., RIVERA, S., CAyOT, L. J., TAPIA-AGUILERA, W. & FLANAGAN, J. (2011) Sterilisation of hybrid Galapagos tortoises (Geochelone nigra) for island restoration. Part 1: endoscopic oophorectomy of females under ketamine-medetomidine anaesthesia. Veterinary Record doi: 10.1136/vr.c6520
RIVERA, S., DIVERS, S. J., KNAFO, S. E., MARTINEZ, P., CAyOT, L. J., TAPIA-AGUILERA, W. & FLANAGAN, J. (2011) Sterilisation of hybrid Galapagos tortoises (Geochelone nigra) for island restoration. Part 2: phallectomy of males under intrathecal anaesthe- sia with lidocaine. Veterinary Record doi: 10.1136/vr.c6361
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