Effects of sampling date, gender, and tick burden on peripheral blood cells of captive and wild tuatara (Sphenodon punctatus)

Abstract

The aims of this study were: (1) to examine changes in immune parameters in tuatara (Sphenodon punctatus) sampled three times between winter and spring and (2) to examine the possible effects of gender and tick burden on peripheral blood cells. The three blood samples were taken from each of two male and two female captive tuatara at 4‐ to 6‐week intervals from July through October 2003. A single blood sample was also obtained from each of 39 wild tuatara captured on Stephens Island in October of the same year. For each blood sample of captive and wild tuatara, total leukocyte and erythrocyte counts were made with the aid of a haemacytometer and differential leukocyte counts were made from Giemsa stained blood smears. Among captive tuatara, counts of total leukocytes (WBC), heterophils, and lymphocytes varied between samples but with an insignificant increase from winter into spring. Wild tuatara had lower numbers of erythrocytes (RBC) compared with captive tuatara, accompanied by a larger number of erythrocyte precursors, more so in wild females than males. In wild tuatara, an increase in total leukocytes (WBC) was associated with tick burden.