Two different types of artificial marking and/or tagging exist and are used in
scientific studies - short term marking and long term marking. Short term markings last
for a limited duration, from just a few weeks or months to upwards of a year depending
on how the animal is marked. Such markings include paint, dye, glued tags, or
clipping/shaving of fur/hair which are used to identify individuals by colors or
combinations of numbers or letters (Walker et al. 2012). Peterson and Bartholomew
(1967) found that by using scissors to clip identification patterns into the hair of
California sea lion pups, they could create patterns that would last up to 3 months but
would likely disappear once hair was regrown. Molting or periodic shedding of a coat or
outer covering which is replaced by new growth affects the duration of short term
markings (Fitz and Wieger 1991, Vincent et al. 1999). The frequency of the molts
determines the duration of a positive identification of an individual.