Another highlight from the boat trip to Bodega Canyon and Cordell Bank yesterday was a group of Common Dolphins (Delphinus sp.). Although I'm familiar with this species from the Atlantic Ocean, this is the first time I've seen this dolphin on a trip off Bodega Head.
In contrast to Pacific White-sided Dolphins, Common Dolphins have a more pronounced beak and a darker dorsal fin (see above) and a striking hourglass-like pattern on their sides. The front portion of this hourglass is colored with a beautiful golden hue:
I'm tempted to call these Short-beaked Common Dolphins (Delphinus delphis), but I'm not 100% certain about the identification. If you have more experience separating Short-beaked from Long-beaked Common Dolphins, please weigh in!
Don Roberson does a great job at describing some of the differences on his web page about Monterey Bay dolphins and porpoises. A Short-beaked Common Dolphin has (1) a shorter beak, (2) a brighter front panel (of the hourglass), especially between the pectoral fin and the eye, (3) a dark eyeline between the beak and the eye contrasting with the bright white front panel, and (4) a dark line extending from the pectoral fin to the vent.
Short-beaked Common Dolphins are also known for spending time in deeper, offshore waters, whereas Long-beaked Common Dolphins are more often in shallow, coastal waters.
Here are more views of some of those characteristics: the dark dorsal fin, the golden color along the side, the bright area behind the eye, and the short beaks:
While the dolphins were bowriding, we noticed a smaller animal among them — a young calf! This young dolphin was grayer than the adults. In the pictures below, look for the calf swimming above the adults and note the much grayer coloration overall.