Okay, here's a fun story. Yesterday (21 March 2024) I was working at my desk, which at the moment has a view of the ocean, and something white offshore caught my eye. I thought it might have been a whale spout at first, but I saw it again and could see it was more of a splash, so I grabbed my binoculars for a better view. I could now see extensive splashing and backs of cetaceans that didn't look like whales, but they were ~3/4 mile offshore, so a bit distant. They were moving quickly to the south, but I had a spotting scope nearby, so I ran down the hall with it and set up just outside the door in hopes of identifying them.
Now I could see a very large group of dolphins, probably over 100 individuals! I could see large distinct dorsal fins, some full-body breaches, some tail slapping — a very energetic group. It was still far enough away that I wasn't sure about the species, but because it's rare to see so many dolphins close to shore off Bodega Head, I started shouting down the hallway for others to come see.
We had nice views of the dolphins, but I still wasn't sure about the species. I could tell they weren't Bottlenose Dolphins (Tursiops truncatus) — they didn't have long beaks and the group size was too large. I'd never seen Pacific White-sided Dolphins (Lagenorhynchus obliquidens) so close to shore, and usually they have some paler color on their dorsal fins and these dorsal fins looked dark to me. Long-beaked Common Dolphins (Delphinus capensis) or Short-beaked Common Dolphins (Delphinus delphis) might have been possible, but they're not common in this area, and I couldn't see enough details to be sure.
At one point I had wondered about Risso's Dolphins (Grampus griseus) because some of the dorsal fins looked quite tall (tall enough that Orca even crossed my mind). But I was thrown off because some of the smaller individuals leaping out of the water looked very pale below, especially in contrast with the darker backs. I haven't seen Risso's Dolphins that often, but I think of them as being more uniform gray. However, my lack of experience with the variation in this species likely biased my expectations.
I could see at least one boat out where the dolphins were, and was hopeful someone might have gotten a photo, so I sent out a few inquiries. I didn't hear back...until this afternoon! Bill Keener from The Marine Mammal Center let me know that they had a team on a research cruise out by Tomales Point around the same time. They photographed a group of 100-200 Risso's Dolphins near Bird Rock. The Marine Mammal Center kindly shared a couple of their photos, so here you go!
Photo credit for both photos: N. Cristales/The Marine Mammal Center under NOAA permit # 26532. [You can click on the images for larger versions.]
