Common Dolphin, photo courtsey of NOAA
ADULT FEMALE FACTS
ADULT MALE FACTS
Common dolphins (including short- and long-beaked) can be identified by their complex, colorful pattern of dark gray, light gray and yellow on their sides. The short-beaked common dolphin has a smaller body size with a more rounded melon head, and has a larger dorsal fin and flippers in comparison to the long-beaked common dolphin.
HOW TO SPOT
Common dolphins are often found swimming in large groups. Look for the elaborate color patterns filled with dark grey, light grey and yellow. Also, look for a “V” shape on the sides below the dorsal fin, forming an hourglass pattern.
WHEN AND WHERE TO SEE
While rarely seen in the Pacific Northwest, common dolphins can be seen off of California on the U.S. west coast—from near shore to about 300 miles offshore.
The common dolphin generally prefers warmer, tropical temperatures. Long-beaked common dolphins are found more in coastal waters while short-beaked common dolphins are primarily found in the ocean and offshore. The long-beaked common dolphin can be frequently seen in the eastern tropical Pacific. Both long-beaked and short-beaked common dolphins occur in the Southern California Bight. From summer through autumn though, large groups of common dolphins can be seen near Georges Bank (extending from Cape Cod, Massachusetts, to Nova Scotia, Canada), Newfoundland, and the Scotian Shelf.
Common Dolphins Swimming, courtsey of NOAA
Common dolphins can extend in length from 7.5 to 8.5 feet and weigh up to 297 lb. The short-beaked common dolphin tends to weigh more than a long-beaked common dolphin and has a larger dorsal fin and flippers.
SOCIAL STRUCTURE AND BEHAVIOR
Short-beaked dolphins are usually seen in large social groups averaging hundreds of individuals and are occasionally seen in larger herds—known as mega-pods—consisting of thousands of animals (up to at least 10,000). These large schools are thought to consist of sub-groups of 20 to 30 individuals that are possibly related or separated by age and/or sex.
Common dolphins can be found in large groups of hundreds or even thousands. They are energetic, fast and active—particularly at the surface where they are often seen riding boat waves and leaping out of the water. The common dolphin feeds on squid and small schooling fish. In some parts of the world, short-beaked common dolphins usually rest during the day and feed at night. A group of dolphins may work together to herd schools of prey (including anchovies, pilchards and sardines).
Common dolphins are protected under the Marine Mammal Protection Act and are not endangered or threatened in the United States.
CURRENT AND HISTORICAL THREATS
Common dolphins can become entangled or captured in commercial fishing gear. Other dangers include hunting (for food and oil) in the Russia, Japan, Caribbean, Peru, West Africa and other offshore islands. Long-beaked common dolphins are also in danger of domoic acid poisoning which is a neuro-toxin produced by algae that can build up over time.