Temporal changes in the quality of hot-iron brands on elephant seal (Mirounga leonina L.) pups

Abstract

Hot-iron brands were used to mark permanently 14 000 six-week-old southern elephant seal (Mirounga leonina L.) pups at Macquarie Island between 1993 and 2000. We assessed temporal changes in the quality of 4932 brands applied in 1998 and 1999 to determine the duration of the brand wound, and the relationships between brand healing, brand readability and the amount of skin and hair damage peripheral to the brand characters. Most (98%) brand wounds were healed within one year. Brand-mark healing, peripheral skin damage and brand readability were significantly (P < 0.05) correlated. The proportion of healed and readable brands increased in the population during the first annual moult, and thereafter these proportions remained high (>95%) for the marked population. The mean number of brand characters with peripheral skin damage decreased significantly over the same period. The seal’s annual hair and skin moult is the process that contributed most to the healing of brand wounds. We also assessed our branding technique to determine whether any of the features we measured contributed to a poor-quality brand. Excessive pressure used during brand-iron application is the most probable cause of unsightly peripheral skin damage, but this damage is short lived.