More than 90% of the sheep in that population are uniquely marked with plastic ear tags and are of known age, determined at capture by counting horn annuli (Festa-Bianchet 1986; Hogg & Forbes 1997).
More than 90% of the sheep inthat population are uniquely marked with plastic eartags and are of known age, determined at capture bycounting horn annuli (Festa-Bianchet 1986; Hogg &Forbes 1997).