Understanding microhabitat requirements for species vulnerable to anthropogenic threats can provide important information to conservation managers. This may be particularly true for ectotherms, where behaviour and physiology (e.g. digestion, responsiveness and activity patterns) are strongly influenced by thermal conditions of microhabitat retreat sites. Retreat sites selected by south-west carpet pythons (Morelia spilota imbricata) were identified through radiotracking 46 pythons over 3 years. Tree hollows appear to be a very important resource for pythons: 61% (22 of 36 individuals tracked over winter) used tree hollows as retreat sites (56% of all observations in winter), and remained in hollows for an average of 124 ± 49 (range 34 to 210) days. If pythons did not use tree hollows over winter, they found refuge in one of four alternative microhabitats: low vegetation cover (26% of winter observations), ground cover (10%), on tree branches (6%) or in hollow logs on the ground (2%). We tested whether tree hollows provide a thermally distinct environment compared with alternative microhabitats, but found no difference in minimum, average, maximum or range of temperatures recorded between microhabitats. When within tree hollows over winter, pythons had colder daily average and maximum body temperatures (cf. pythons that used other microhabitats), but this did not give them an energy saving (in terms of body condition scores). Pythons ate very little over winter and we predict that animals sequestered within tree hollows do not access prey at this time. Tree hollows provide a critical refuge over winter when python body temperature is low, and their responsiveness is limited, rendering individuals vulnerable to predation by terrestrial predators (e.g. introduced red fox). Destruction of hollows through fire, land clearing, competition with other fauna species and the significant age required for hollows to form in trees all contribute to the decline in availability of this important microhabitat.

ABSTRACT: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.

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ambush feeding to actively foraging on slower prey would account for the differences in prey taken by these animals. The concept of altered foraging behaviour warrants further investigation in this species.

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 snake's 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 transmitter's antenna provides a possible pathogenesis for expulsion into the cloaca.