Current Nature: Seal-y Season
Photo by Cary Hazelgrove
Our marine year-round residents are always a fun sight, whether from the water’s edge or lounging on the sand, they are a staple here on Nantucket. As pupping season gets underway, there’s a flurry of activity along the shore, and we encourage everyone to be mindful when walking or driving on the beaches.
The island is home to four seal species, two of which are more abundant - the gray seal and the harbor seal. Hooded seals and harp seals have been spotted here, but due to their dependence on pack ice for breeding, their range is restricted to areas where pack ice forms seasonally, and may be a reason why we don't see them as often.
Gray seals, distinguished by their horse-like head and large nose, give birth to their pups at varying times of the year, depending on the location. Pups east of the Atlantic are born from September to December, and pups west of the Atlantic are born in January and February. Gray seals come ashore to gather in large groups to mate, with males mating with multiple females. During this period, they display a range of vocal and non-vocal communication like hissing, flipper slapping, and growling. Females’ gestation period is approximately eleven months, and give birth to a single pup. Twins are rare! Pups rely on their mother, nursing on their high-fat milk, and are very vocal. Their cry often resembles a human baby crying.
Photo by Libby Buck
Harbor seals are recognised for their varied coat of spots and colors, V-shaped nostrils and “banana-like” resting posture. Their pupping season occurs in late spring. You may spot a harbor seal pup resting alone and think it has been abandoned. But more often than not, the mother is likely hunting and foraging and will return to her pup later. It is important to not interfere, as the mother may withdraw care if there has been human activity or the pup has been relocated.
Harp seal pups are likely what most people picture when they think of seal pups. They don their wooly, pure white coats for the first two to three weeks. This fur, known as lanugo, helps to keep them warm by absorbing sunlight and trapping heat. Later, they will molt several times as they mature, growing into the silver-white coat of adults. Harp seals are incredibly expressive. Pups call their mothers by yelling and mumbling. Courtship, which peaks during mid-March, involves males performing underwater displays, using bubbles and vocalizations to attract females. Adults have been recorded using more than nineteen different types of vocalization.
Hooded seals are the least social and most territorial of the four species found on Nantucket. Known for the unique stretchy cavity in their nose, males inflate it to resemble a red balloon. This is used to attract females during mating season and to display aggression toward rival males. They mainly reside in deep water in the Arctic Ocean and North Atlantic, although some drift to warmer regions during the year, their best survival rate is in colder climates. Born on the ice between March and April, pups nurse for just four days, the shortest lactation period of any mammal, gaining around fifteen pounds (7 kg) a day!
Seals are just some of the incredible marine animals that grace our waters, and should be given space and treated with respect when encountered. Information on marine animals and guidelines to follow can be found on the town website. The Marine Mammal Alliance on Nantucket is a non-profit organization that protects, monitors, and rescues marine mammals and can be contacted should you come across one in need of help.
Photo by Libby Buck
