Species Survival Plan Veterinary Advisor Report for 2007–2008: Virgin Islands Boa (Epicrates monensis granti) and Mona Boa (Epicrates monensis monensis)
The Mona boa (Epicrates monensis monensis) is a species of Caribbean boa listed as threatened, and is found only on one small island, Isla Mona, also off the coast of Puerto Rico. There has been a captive breeding plan in place for this subspecies since 1990, but the Species Survival Plan (SSP) focus for the population has been management in the wild.6 The Toledo Zoo holds a captive assurance population of 16 Mona boas (8.8 animals).
The Virgin Islands boa (Epicrates monensis granti) is an endangered subspecies of the Mona boa, endemic to a constellation of small islands off the coasts of Puerto Rico and the U.S. and British Virgin Islands. There has been a captive breeding and reintroduction program in place for this subspecies since 1985.4,5 Two successful reintroductions have been carried out—one to the U.S. Virgin Islands and one to a satellite Island of Puerto Rico. Ten-year evaluations of these reintroductions have recently been completed. There are currently 42 Virgin Islands boas in captivity (14 male, 26 female, two undetermined) housed at seven different institutions. The Toledo Zoo holds 32 of the 42 captive specimens.
Review of medical records of both subspecies from January 2007 through April 2008 revealed two cases of bullous spectaculopathy/subspectacular abscessation, and one case of cloacitis.1-3 Etiologies were undetermined. Stomatitis was associated with one of the two cases of spectaculopathy. One of the cases of subspectacular abscessation was ultimately euthanatized after extensive treatment, and necrotizing histiocytic dacryoadenitis was found on histopathologic examination. One other VI boa death was reported during this period. The histopathologic diagnosis for this animal was generalized septicemia of undetermined etiology.
Current health recommendations for these species include annual physical exam and biannual fecal examinations for parasites. Preshipment/quarantine testing should include physical exam, fecal exam for parasites (ideally three negative fecals during the quarantine period), fecal culture, blood work, including CBC and chemistries (minimally calcium, phosphorus, uric acid, AST levels), whole body radiographs, and paramyxovirus testing (hemagglutination inhibition [HI], paired samples) if there has been exposure potential. The recommended quarantine period is minimally 90 days. Testing and quarantine protocols of animals designated for release programs are being reviewed. Blood collection has proven to be somewhat challenging for this species in the authors experience due to the snake’s small size. Blood has been successfully collected using standard tail vein and cardiac puncture techniques. There has been one reported death in this species resulting from complications after cardiac puncture for routine blood collection. Caution should be used when attempting this technique and general anesthesia (isoflurane) should be considered to aid in the collection process.
A retrospective review of medical records for the captive population of Mona/VI boas is underway to identify any disease trends. Health care recommendations may be adjusted once the review is completed. There are no reported infectious disease issues present in the captive population at the time of this writing.
Active research projects include a long-term population study of the Mona boa on Isla Mona by the Toledo Zoo, and periodic evaluations of the status of the reintroduced populations in Puerto Rico and the U.S. Virgin Islands. A joint study of the University of Nevada at Las Vegas, the Departamento Recursos Naturales y Ambientales de Puerto Rico, and the Toledo Zoo is examining the phylogenetic relationships among the disjunct populations of Virgin Islands boas using gene sequencing.
Information from the field reveals that despite recommendations from both the Virgin Islands Division of Wildlife and the Departamento de Recursos Naturales de Puerto Rico, it appears that the U.S. Fish and Wildlife Service will attempt to downlist the Virgin Islands boa to “Threatened” from “Endangered” (Pierce, pers. comm.).
Other field reports indicate that the attempt to eradicate rats from Congo Cay, USVI (prime boa habitat and a potential reintroduction site) by the U.S. Department of Agriculture was unsuccessful. Rat eradication on another cay in the USVI is being considered. A rapid evaluation of the wild boas at Río Grande, Puerto Rico in November 06 showed continued deterioration of habitat as development continues to surround the locality (unpublished observation).
1. Cullen, C.L., Grahn, B.H., and Wheler, C. 2000. Diagnostic ophthalmology. Can. Vet. J. 41(4): 327–328.
2. Lawton, M.P.C. 1998. Diseases of the spectacle. Proc. Assoc. Reptilian Amphibian Vet. 0:119.
3. Lawton, M.P.C. 2006. In: Douglas R. Mader (ed). Reptile Medicine and Surgery, 2nd Ed. Elsevier. pp 327–332.
4. Tolson, P.J. 1989. Breeding the Virgin Islands boa at the Toledo Zoological Gardens. Intl. Zoo Yrbk. 28:163–167.
5. Tolson, P.J. 2005. Reintroduction Evaluation and Habitat Assessments of the Virgin Islands Boa, Epicrates monensis granti, to the U.S. Virgin Islands. U.S. Fish and Wildlife Service. Pp 1–13.
6. Tolson, P.J., García, M.A. and C.L. Ellsworth. 2007. Habitat use by the Mona boa, Epicrates monensis monensis on Isla Mona, West Indies. In: R.W. Henderson and R. Powell (eds). Biology of the Boas and Pythons. Eagle Mountain Publishing, LC, Eagle Mountain, UT. Pp. 117–126.
7. Tolson, P.J. and García, M.A. 1997. Mona/Virgin Islands Boa. Endangered Species Update, AZA Species Survival Plan Profile. 14(1&2):9–10.