Tailed and tailless house geckos (Hemidactylus turcicus) do not differ in their specific resting metabolic rate, food consumption, and activity pattern

We hypothesized that there might be a difference between tailed and tailless geckos in oxygen and food consumption, as well as in activity patterns. Hemidactylus turcicus is a small geckonid common all over Israel, and is considered a "sit-and-wait" lizard. In nature, H. turcicus easily autotomizes its tail when in danger of predation or due to intraspecific aggressive encounters. Tail regeneration is usually completed within 45 days. Male geckos were captured on the premises of Tel Aviv University (with permission of the Nature Reserves Authority). They were kept individually at 28 °C; 12L:12D, and were fed housefly maggots every other day ad libitum. Following at least two week's adjustment to captivity, initial values of oxygen consumption rate at rest at 28 °C (SMR) were obtained for individual males. At the beginning of the study, eight geckos (experimental group) were manipulated to autotomize their tails. Another eight geckos of matching sizes and body masses (BM), with their tail intact, were selected as control. Following autotomy, SMR values were measured on pairs of control and experimental males, approximately twice a month, for five months. Food consumption rate (MFE) was recorded every other day. The average initial BM of the experimental group was 2.383 g ± 0.283 and of the control group was 2.464 g±0.598. The average tail mass of the experimental group was 0.332 g ± 0.052. The tailless lizards did not regenerate their tail during the experimental period, although the wound healed and a blastema formed. Body mass of all geckos did not change significantly during the experimental period. The SMR difference between the tailless and tailed geckos was not significant and disappeared completely in the mass-specific SMR. Mean mass-specific SMR of all the geckos was 0.151 mL[STPD] · (h · g)^-1 ± 0.064 (n = 14). It seems that the SMR was reduced in proportion to the reduction in body mass due to tail loss. Hence, the specific oxygen consumption of the tail is not different from that of the rest of the body. Nonetheless, the tailed male lizards consumed significantly more food (0.488 kJ · d^-1±0.091; n = 8) than the tailless ones (0.393 kJ · d^-1 ± 0.079; n = 8; p = 0.03), although no significant difference was found between tailed and tailless geckos when comparing mass-specific food consumption rates. The maintenance of a tail apparently requires a proportional energy supply. The activity pattern of H. turcicus (based on 24-h sessions of oxygen consumption measurements under constant conditions) seems to be diurno-nocturnal. The animals were mostly active from 14:00 to 03:00. Their activity score peaked at around 19:00. Such an activity pattern may be related to the diurnal climatic cycle in their habitat.