Fig. 2. The effect of heat exposure on CWE, T_s and T_b of heat-acclimated (HAc; filled bars and symbols) and non-acclimated (NAc; open bars and symbols) pigeons. The birds were exposed to different ambient temperatures (30-60°C T_a) for 90 min prior to each measurement. (A) Cutaneous water evaporation (CWE) increased continuously with increased T_a in both NAc (N=8) and HAc (N=12) pigeons. However, this trend was much stronger in the HAc birds, reaching a CWE mean value of 10.6 mg cm^-2h^-1 at 50°C T_a and a maximum mean value of 18.9 mg cm^-2h^-1 at 60°C T_a, compared with 3.3 mg cm^-2h^-1 at 50°C T_a in NAc pigeons. (B) The different effect of T_a on T_s (triangles) and T_b (circles) in the NAc (N=7) and HAc (N=8) birds. While T_s and T_b at 30-55°C T_a in the NAc birds was 2.0 and 1.4°C, respectively (P<0.005), the corresponding values in the HAc birds were 0.5 and 0.6°C, respectively (not significant). Values are the means ± S.E.M. Dunnett's analysis was used to determine the significance of difference from control (values at T_a 30°C); ^*P<0.05, ^**P<0.005.