Survival of a Translocated Population of the Maud Island Frog (Leiopelma Pakeka) and Morphometric Comparisons with the Source Population

Abstract

A trial translocation was undertaken on the native endangered Maud Island frog (Leiopelma pakeka) nearly 20 years ago. One hundred frogs were moved 0.5km in two separate translocations, one year apart. Both the translocated and source populations have been monitored annually since. An intensive one-off survey was carried out in 2002 to determine current population and survival estimates. Morphological comparisons between the translocated and source populations were also made to establish if any variation existed. Body condition indices were compared between the two populations. Head width of Leiopelma pakeka was also tested for allometric growth against snout-vent and tibiofibula lengths. Fifty-eight captures of 42 frogs were obtained over 20 nights, 70% of these were founder members. Ten were of frogs that had not been previously captured, indicating recruitment into the population. A population estimate of 116 (± 35) was obtained by using the Schwarz and Arnason model of Jolly-Seber. Cormack-Jolly-Seber was used to gain a daily survival rate of 0.92. Disturbance and low recapture rate could account for this relatively low rate. Weather conditions experienced over the study period were relatively stable; therefore correlations with frog emergence from retreat sites were not possible. Frogs were found to have moved up to 26m to alternative habitat sites outside of the permanent grid, these included both founder members and frogs recruited into the population. The Boat Bay frogs were significantly heavier and larger for head width than the source population. Snout-vent and tibiofibula lengths of Boat Bay frogs were larger than only one of the two grids sampled from the source population. Boat Bay frogs also had a significantly higher average body condition index. Allometric growth in head width was negative against both snout-vent and tibiofibula lengths. These results together can be considered as a partial evaluation of translocation success. The translocated population is persisting in Boat Bay, recruitment is evident and the frogs are in better condition than those from the source population.