Well, male or female, anyhow. One frequently asked question about the
harbor seals is, how does one tell females from males?
Many species of seal show pronounced sexual dimorphism, with adult male elephant seals for example weighing up to four times as much as adult females. However... not harbor seals. Adult males average 1.6 meters (5.3 feet) long and adult females, about 1.5 m (5 feet). In actuality, there is so much overlap that length isn't going to help. Adult weights range from about 70 - 110 kg (150-250 pounds) depending on individual variation, condition, abundance of food, pregnancy, etc. so there's little help there. And no, the color variations are not related to sex.
If you really want to try telling the males from the females, here is what to look for: At left is an adult female; M indicates the mammary slits. They are even harder to make out on a seal than in this diagram. At right is a male. P indicates the penile opening and PL the penile line (again, not easily visible). The U is the umbilical scar.
