Captive & Field Herpetology Volume 2 Issue 1
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 conservation is typically the most effective bulabula KEOGH, EDWARDS, FISHER, way to protect an organism, it is evident that AND HARLOW, 2008) is endemic to the north not all species can be successfully preserved in western islands of Fiji, including Ovalau, Gau, their natural habitats (Witzenberger & Kadavu, and Viti Levu; the species has also Hochkirch, 2011). Therefore increasingly ex- been introduced to the island of Vanuatu situ conservation in the form of captive (Keogh et al., 2008). Along with the other breeding is required to act as an insurance extant members of the Brachylophus genus, B. policy preserving a species until a bulabula populations are under threat. Now reintroduction effort becomes feasible. restricted to just a few islands, numbers have Although it may not be ideal, ex-situ declined by 50% in the past few decades conservation may be the only realistic option to (Fisher et al., 2012). This has contributed to its ensure that much of Fiji’s endemic classification as ‘endangered’ by the IUCN and herpetofauna persist for the foreseeable future its listing under appendix 1 of the Convention (Narayan et al., 2009). on International Trade in Endangered Species (Fisher et al., 2012). The latter being the Some lizard species, such as the green iguana CITES category a species is assigned to (Iguana iguana) have been bred in captivity facilitate providing it with the highest possible with great success for decades (Jacobson, level of protection. Wild populations are at 2003). This has culminated in a huge body of particular risk from a combination of habitat species specific literature in both books and destruction and fragmentation leading to a loss peer-reviewed articles. From vitamin and in genetic diversity (Tershy et al., 2016). mineral supplementation of diet to mating introduction methods, such information on B. Invasive species, most notably black rats bulabula is sparsely recorded. Required egg (Rattus rattus) and domestic cats (Felis catus) incubation temperatures and humidity levels predate on the iguanas and their eggs (Tershy being no exception. Anecdotal reports et al., 2016). Furthermore feral goats (Capra 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 aegagrus) both destroy habitat and as herpetoculturists and zoo employees folivores/frugivores directly compete with B. attempting to breed this species have stated bulabula for food (Tershy et al., 2016). Despite problems with this fundamental aspect of the significant decline of B. bulabula in the captive reproduction. We describe our findings wild and the aforementioned causes being clear with regards to this topic here. and understood there are no conservation measures in place to protect this species In June of 2013 an unrelated, two year old pair (Fisher et al., 2012). Whilst in-situ of captive bred B. bulabula were imported into
Accepted Manuscript Page 12 of 42 Captive & Field Herpetology Volume 2 Issue 1 the UK from Austria. On arrival they were B. bulabula pairs’ diet was diverse including housed individually for a one month period of fruit (blueberries, apple, grapes and acclimatisation. The male was then introduced raspberries), vegetables (carrots and fresh peas) to the female’s enclosure under close as well as dark leafy greens (rocket and supervision in case either iguana became dandelion). Every feed was lightly dusted with aggressive. The enclosure in question was a a specific herbivorous lizard vitamin and glass and wood, vertically oriented vivarium mineral supplement. Once every two weeks six (122cm long, 61cm deep and 183cm tall). 5th instar, live locusts were offered to the B. Panels of cork bark where attached to the back bulabula pair as a source of protein and to and sides of the enclosures interior increasing promote natural predatory behaviours. Before surface area for activity. Cork bark tubes of being fed to the iguanas these prey items were varying lengths and diameters were positioned ‘gut loaded’ with fresh fruit and dusted with within the vivarium providing the iguanas with calcium powder. basking and refuge sites. Plastic artificial 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 used as the enclosure substrate to help maintain Two were white in coloration with a slight pink ambient humidity. Two 160W mercury vapour hue. The third was a fraction of their size, miss lights bulbs in reflectors provided heat and shaped, dehydrated and yellow. The two eggs UVB. This combined light and heat source was that appeared fertile were quickly removed and controlled by a timer switch set to give the prepared for incubation. To do this a iguanas twelve hours of daylight all year Tupperware container (25cm long, 20cm wide round. This ensured one aspect of abiotic and 15cm deep) with six ventilation holes environmental consistency. The lights were punctured in its lid was filled with vermiculite positioned on top of mesh covered sections cut to a depth of 10cm. The vermiculite had been into the vivarium roof preventing the occupants soaked in lukewarm water before excess coming into direct contact with them and moisture was removed by compressing it 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 of the enclosure remained at 24˚C. This positioned outside of the incubator was temperature gradient allowed the B. bulabula checked at least once a day until the eggs to easily thermoregulate. At night the entire hatched. The incubation temperature remained enclosure temperature would drop to 21˚C. The at 27˚C whilst the vermiculite slowly dried.
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Within two months this incubation medium successful B. bulabula egg development is was dry to the touch. However, contrary to uncertain. It is hypothesised that as the expectations the eggs showed no signs of vermiculite dried ambient humidity dehydration, the usual evidence of which being surrounding the incubating eggs dropped. concavities of the shell. The decision was made However humidity measurements were not not to rehydrate the vermiculite. From this taken to prove this hypothesis. When the point on the eggs were monitored several times authors are next presented with eggs from this a day for expected signs of dehydration. pair of B. bulabula the egg incubation protocol However despite this considerable drop in outlined here will be repeated. However along with monitoring temperature routine vermiculite moisture content lasting until the measurements of ambient humidity within the very end of the incubation period the eggs egg incubation container will be taken with a remained healthy. What is not clear is whether digital hygrometer. B. bulabula eggs are resilient to the dehydration of incubation medium or require it It is hoped that the previously stated for successful development. observations will be applied by all those Five days before hatching a considerable individuals and institutions attempting to breed concavity was observed in one of the eggs. this endangered species and so increase the Initially thought to be a sign of dehydration captive population. There could also be broader this concavity disappeared in minutes without ex-situ conservation applications as the any increase in incubation medium moisture observations outlined here may be applicable content or ambient humidity. It is hypothesised 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 that this was the nearly fully developed iguana Brachylophus genus. This can only be proved moving inside its egg. In retrospect such an if information collected by those involved in observation could be used as an indication that the husbandry and captive propagation of the hatching is imminent. Beginning at taxonomic relatives of B. bulabula (B. approximately 8am on the 12/01/2017 both fasciatus and B. vitiensis) are recorded and iguanas (one male and one female) hatched then shared. within an hour of each other. Minutes after emerging from their eggs, both hatchlings exhibited considerable aggressive behaviour Reference List: (chasing and biting each other). Consequently Fisher, R., Grant, T. and Harlow, P. (2012) the means to separate hatchling B. bulabula in Brachylophus bulabula. IUCN Red List of the same incubation container immediately Threatened Species. Version 2013.2. after hatching must be prepared for in advance. The two iguanas were then set up in individual Jacobson, E.R. (2003) Biology, husbandry, and enclosures and now ten months on (December, medicine of the Green iguana. Krieger 2017) are fully established and growing Publishing Company. quickly. Keogh, J.S., Edwards, D.L., Fisher, R.N. and As previously stated the extent to which the Harlow, P.S. (2008) Molecular and drying out of the vermiculite incubation morphological analysis of the critically medium is required or simply tolerated for endangered Fijian iguanas reveals cryptic
Accepted Manuscript Page 14 of 42 Captive & Field Herpetology Volume 2 Issue 1 diversity and a complex biogeographic history. Harlow, P., Holmes, N.D. and Croll, D.A. Philosophical Transactions of the Royal (2016) The biogeography of threatened insular Society of London B: Biological Sciences, 363 iguanas and opportunities for invasive (1508), 3413-3426. vertebrate management. Herpetological Conservation and Biology, 11, 222-236. Narayan, E., Christi, K. and Morley, C., (2009) Captive propagation of the endangered native Witzenberger, K.A. and Hochkirch, A. (2011) Fijian frog Platymantis vitiana: Implications Ex situ conservation genetics: a review of for ex-situ conservation and management. molecular studies on the genetic consequences Pacific Conservation Biology, 15 (1), 47-55. of captive breeding programmes for endangered animal species. Biodiversity and Tershy, B., Newton, K.M., Spatz, D.R., Conservation, 20 (9), 1843-1861. Swinnerton, K., Iverson, J.B., Fisher, R.N.,
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