G. Bryant

Improved procedure for implanting radiotransmitters in the coelomic cavity of snakes

OBJECTIVE To investigate the expulsion of radiotransmitters in snakes and modify the surgical technique for coelomic implantation to prevent its occurrence. DESIGN To enable monitoring of snakes for an ecological study, radiotransmitters were implanted in 23 south-west carpet pythons (Morelia spilota imbricata) using the standard surgical technique. In a further 23 pythons we used a refinement of the technique, which anchored the tracking device, using non-dissolvable sutures, to the snakes rib-cage. We also investigated the potential mechanisms for expelling the radiotransmitters in one snake that underwent an exploratory coeliotomy. RESULTS Of the initial group of snakes, 12 (52%) expelled the radiotransmitter between 4 days and 3 years post implantation. In the later group, which underwent the refined technique of implantation, none of the radiotransmitters was expelled and no adverse responses were observed. CONCLUSION An appropriately sized radiotransmitter anchored to the rib-cage of the snake will prevent expulsion of the device and appears to be well tolerated. Non-attachment of the tracking device enables it to migrate along the length of the body, particularly during feeding and reproduction. Caudal positioning of the transmitters antenna provides a possible pathogenesis for expulsion into the cloaca.

FACTORS AFFECTING HEMATOLOGY AND PLASMA BIOCHEMISTRY IN THE SOUTHWEST CARPET PYTHON (MORELIA SPILOTA IMBRICATA)

Despite increased worldwide popularity of keeping reptiles as pets, we know little about hematologic and biochemical parameters of most reptile species, or how these measures may be influenced by intrinsic and extrinsic factors. Blood samples from 43 wild-caught pythons (Morelia spilota imbricata) were collected at various stages of a 3-yr ecological study in Western Australia. Reference intervals are reported for 35 individuals sampled at the commencement of the study. As pythons were radiotracked for varying lengths of time (radiotransmitters were surgically implanted), repeated sampling was undertaken from some individuals. However, because of our ad hoc sampling design we cannot be definitive about temporal factors that were most important or that exclusively influenced blood parameters. There was no significant effect of sex or the presence of a hemogregarine parasite on blood parameters. Erythrocyte measures were highest for pythons captured in the jarrah forest and at the stage of radiotransmitter implantation, which was also linked with shorter time in captivity. Basophil count, the only leukocyte influenced by the factors tested, was highest when the python was anesthetized, as was globulin concentration. Albumin and the albumin:globulin ratio were more concentrated in summer (as was phosphorous) and at the initial stage of radiotransmitter placement (as was calcium). No intrinsic or extrinsic factors influenced creatinine kinase, aspartate aminotransferase, uric acid, or total protein. This study demonstrates that factors including season, location, surgical radiotransmitter placement, and anesthetic state can influence blood parameters of M. s. imbricata. For accurate diagnosis, veterinarians should be aware that the current reference intervals used to identify the health status of individuals for this species are outdated and the interpretation and an understanding of the influence of intrinsic and extrinsic factors are limited.

Tantalising tongues: male carpet pythons use chemoreception to differentiate among females

For animals sparsely distributed across a landscape, finding and identifying a receptive female during a short breeding period can be a challenge for males. Many snakes appear to rely on the production of sex-specific pheromones to synchronise the timing of reproductive behaviour. The rare Australian south-west carpet python (Morelia spilota imbricata) displays non-aggressive mating aggregations of up to six males around a receptive female, suggesting that males are responding to some chemical signal that enables multiple males simultaneously to identify and locate the female. We investigated chemoreceptive response (tongue-flicking) of 10 male pythons under laboratory conditions to 12 (randomly ordered) treatments each presented for three minutes. Cutaneous chemicals (dissolved in hexane solvent) were collected on cotton buds from the skin of six female pythons and male responses to these were compared with six control treatments. Male pythons produced a greater number of tongue flicks during the first minute of each trial, with fewer in minutes 2 and 3. Male chemoreceptive response in the third minute varied significantly between treatments and was only maintained for trials presenting cutaneous chemicals collected from the three relatively largest female pythons. This experiment suggests that male carpet pythons can use chemoreception to obtain information about their social environment, identifying pheromone cues from large, potentially fecund females. This ability would be adaptive for male mate-selection behaviour and is likely to also reduce costs of searching behaviour.