Captive & Field Herpetology Volume 2 Issue 1 2018
A Description of the Successful Hatching of the Fijian Banded Iguana (Brachylophus bulabula) and Observations on Vermiculite Moisture
1Oliver K. E. Cunningham & 2Steven J. R. Allain
1Corresponding author: [email protected]
The Fijian banded iguana (Brachylophus measures in place to protect this species bulabula KEOGH, EDWARDS, FISHER, (Fisher et al., 2012). Whilst in-situ AND HARLOW, 2008) is endemic to the north conservation is typically the most effective western islands of Fiji, including Ovalau, Gau, way to protect an organism, it is evident that Kadavu, and Viti Levu; the species has also not all species can be successfully preserved in been introduced to the island of Vanuatu their natural habitats (Witzenberger & (Keogh et al., 2008). Along with the other extant members of the Brachylophus genus, B. Hochkirch, 2011). Therefore increasingly ex- bulabula populations are under threat. Now situ conservation in the form of captive Acceptedrestricted to just a few islands, numbers haveManuscript breeding is required to act as an insurance declined by 50% in the past few decades policy preserving a species until a (Fisher et al., 2012). This has contributed to its reintroduction effort becomes feasible. classification as ‘endangered’ by the IUCN and Although it may not be ideal, ex-situ its listing under appendix 1 of the Convention conservation may be the only realistic option to on International Trade in Endangered Species ensure that much of Fiji’s endemic (Fisher et al., 2012). The latter being the herpetofauna persist for the foreseeable future CITES category a species is assigned to (Narayan et al., 2009). facilitate providing it with the highest possible Some lizard species, such as the green iguana C&Flevel of protection. Wild populationsHerpetology are at (Iguana iguana) have been bred in captivity particular risk from a combination of habitat with great success for decades (Jacobson, destruction and fragmentation leading to a loss 2003). This has culminated in a huge body of in genetic diversity (Tershy et al., 2016). species specific literature in both books and Invasive species, most notably black rats peer-reviewed articles. From vitamin and (Rattus rattus) and domestic cats (Felis catus) mineral supplementation of diet to mating predate on the iguanas and their eggs (Tershy introduction methods, such information on B. et al., 2016). Furthermore feral goats (Capra bulabula is sparsely recorded. Required egg aegagrus) both destroy habitat and as incubation temperatures and humidity levels folivores/frugivores directly compete with B. being no exception. Anecdotal reports bulabula for food (Tershy et al., 2016). Despite p u b l i s h e d o n l i n e b y b o t h p r i v a t e the significant decline of B. bulabula in the herpetoculturists and zoo employees wild and the aforementioned causes being clear attempting to breed this species have stated and understood there are no conservation problems with this fundamental aspect of
Page 12 Captive & Field Herpetology Volume 2 Issue 1 2018 captive reproduction. We describe our findings of the enclosure remained at 24˚C. This with regards to this topic here. temperature gradient allowed the B. bulabula to easily thermoregulate. At night the entire In June of 2013 an unrelated, two year old pair enclosure temperature would drop to 21˚C. The of captive bred B. bulabula were imported into B. bulabula pairs’ diet was diverse including the UK from Austria. On arrival they were fruit (blueberries, apple, grapes and housed individually for a one month period of raspberries), vegetables (carrots and fresh peas) acclimatisation. The male was then introduced as well as dark leafy greens (rocket and to the female’s enclosure under close dandelion). Every feed was lightly dusted with supervision in case either iguana became a specific herbivorous lizard vitamin and aggressive. The enclosure in question was a mineral supplement. Once every two weeks six glass and wood, vertically oriented vivarium 5th instar, live locusts were offered to the B. (122cm long, 61cm deep and 183cm tall). bulabula pair as a source of protein and to Panels of cork bark where attached to the back promote natural predatory behaviours. Before and sides of the enclosures interior increasing being fed to the iguanas these prey items were surface area for activity. Cork bark tubes of ‘gut loaded’ with fresh fruit and dusted with varying lengths and diameters were positioned calcium powder. within the vivarium providing the iguanas with Acceptedbasking and refuge sites. Plastic artificial Manuscript On the 5/07/2016 three eggs were deposited in foliage in the vivarium further increased a designated egg laying site (41cm long, 35cm surface area for activity and provided both deep and 25cm tall deep plastic container filled animals with areas of cover to reduce stress. A with damp vermiculite) within the enclosure. 10cm deep layer of coarse orchid bark was Two were white in coloration with a slight pink used as the enclosure substrate to help maintain hue. The third was a fraction of their size, miss ambient humidity. Two 160W mercury vapour shaped, dehydrated and yellow. The two eggs lights bulbs in reflectors provided heat and that appeared fertile were quickly removed and UVB. This combined light and heat source was prepared for incubation. To do this a C&Fcontrolled by a timer switch Herpetology set to give the Tupperware container (25cm long, 20cm wide iguanas twelve hours of daylight all year and 15cm deep) with six ventilation holes round. This ensured one aspect of abiotic punctured in its lid was filled with vermiculite environmental consistency. The lights were to a depth of 10cm. The vermiculite had been positioned on top of mesh covered sections cut soaked in lukewarm water before excess into the vivarium roof preventing the occupants moisture was removed by compressing it coming into direct contact with them and getting burnt. Two digital thermometers were between two hands. The eggs were then half used to monitor ambient temperature both at buried in this incubation medium and the the hottest and coolest areas within the Tupperware containers lid secured. This was enclosure. To do this the temperature sensor of t h e n p l a c e d i n a ‘ Z o o M e d one thermometer was placed at the basking site Reptibator’ (www.zoomed.com) reptile egg directly below the lights and the other near the incubator with the built in thermostat set to enclosure floor. During daylight hours the 27˚C. A digital thermometer probe was inserted basking site temperature would fluctuate into the egg incubation container to monitor between 38˚C and 41˚C whilst the coolest area the ambient temperature. Its digital readout Page 13 Captive & Field Herpetology Volume 2 Issue 1 2018 positioned outside of the incubator was 2017) are fully established and growing checked at least once a day until the eggs quickly. hatched. The incubation temperature remained As previously stated the extent to which the at 27˚C whilst the vermiculite slowly dried. drying out of the vermiculite incubation Within two months this incubation medium medium is required or simply tolerated for was dry to the touch. However, contrary to successful B. bulabula egg development is expectations the eggs showed no signs of uncertain. It is hypothesised that as the dehydration, the usual evidence of which being vermiculite dried ambient humidity concavities of the shell. The decision was made surrounding the incubating eggs dropped. not to rehydrate the vermiculite. From this However humidity measurements were not point on the eggs were monitored several times taken to prove this hypothesis. When the a day for expected signs of dehydration. authors are next presented with eggs from this However despite this considerable drop in pair of B. bulabula the egg incubation protocol vermiculite moisture content lasting until the outlined here will be repeated. However along very end of the incubation period the eggs with monitoring temperature routine remained healthy. What is not clear is whether measurements of ambient humidity within the B. bulabula eggs are resilient to the egg incubation container will be taken with a Accepteddehydration of incubation medium or require Manuscript it digital hygrometer. for successful development. It is hoped that the previously stated Five days before hatching a considerable observations will be applied by all those concavity was observed in one of the eggs. individuals and institutions attempting to breed Initially thought to be a sign of dehydration this endangered species and so increase the this concavity disappeared in minutes without captive population. There could also be broader any increase in incubation medium moisture ex-situ conservation applications as the content or ambient humidity. It is hypothesised observations outlined here may be applicable C&Fthat this was the nearly fully Herpetology developed iguana t o b r e e d i n g o t h e r m e m b e r s o f t h e moving inside its egg. In retrospect such an Brachylophus genus. This can only be proved observation could be used as an indication that if information collected by those involved in hatching is imminent. Beginning at the husbandry and captive propagation of the approximately 8am on the 12/01/2017 both taxonomic relatives of B. bulabula (B. iguanas (one male and one female) hatched fasciatus and B. vitiensis) are recorded and within an hour of each other. Minutes after then shared. emerging from their eggs, both hatchlings exhibited considerable aggressive behaviour (chasing and biting each other). Consequently Reference List: the means to separate hatchling B. bulabula in Fisher, R., Grant, T. and Harlow, P. (2012) the same incubation container immediately Brachylophus bulabula. IUCN Red List of after hatching must be prepared for in advance. Threatened Species. Version 2013.2. The two iguanas were then set up in individual enclosures and now ten months on (December,
Page 14 Captive & Field Herpetology Volume 2 Issue 1 2018 Jacobson, E.R. (2003) Biology, husbandry, and medicine of the Green iguana. Krieger Publishing Company.
Keogh, J.S., Edwards, D.L., Fisher, R.N. and Harlow, P.S. (2008) Molecular and morphological analysis of the critically endangered Fijian iguanas reveals cryptic diversity and a complex biogeographic history. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 363 (1508), 3413-3426.
Narayan, E., Christi, K. and Morley, C., (2009) Captive propagation of the endangered native Fijian frog Platymantis vitiana: Implications for ex-situ conservation and management. Pacific Conservation Biology, 15 (1), 47-55. AcceptedTershy, B., Newton, K.M., Spatz, D.R.,Manuscript Swinnerton, K., Iverson, J.B., Fisher, R.N., Harlow, P., Holmes, N.D. and Croll, D.A. (2016) The biogeography of threatened insular iguanas and opportunities for invasive vertebrate management. Herpetological Conservation and Biology, 11, 222-236.
Witzenberger, K.A. and Hochkirch, A. (2011) C&FEx situ conservation genetics: Herpetology a review of molecular studies on the genetic consequences of captive breeding programmes for endangered animal species. Biodiversity and Conservation, 20 (9), 1843-1861.
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