Aging laughing gull nestlings using head-bill length

We examined growth of several body components in Laughing Gull (Larus atric illa) nestlings to determine a simple method to estimate age of chicks base d on a single visit to the nest. Head-bill length provided the most precise and repeatable estimate of age of the several components we measured. The cubic equation we developed estimated age with a standard error of 1.93 day s. Use of head-bill length is a suitable technique for aging Laughing Gull nestlings when a precision of one to two days is sufficient.