As we made our way seaward on the main pier at Avila Beach, California, we heard what at first sounded like a men's chorus practicing. When we got closer to the source of the noise, we realized that it was not singing but barking. We looked over the railing to a boat-launch platform below and saw an enormous male California sea lion (Zalophus californianus) hauled out on the platform and vocalizing repeatedly and loudly.
I went through a gate, where a sign warned that "seals and sea lions bite" and down the steps to the lower platform, but I kept my distance from the sea lion. It was then that I noticed that he was not alone. About 8 feet behind him was a pink pile of eight or ten napping sea lionesses. The male was just letting everyone know that this was *his* spot and that these were *his* females.
It was not breeding season (this was in March; sea lions breed during July), but the male wasn't taking any chances. He sat with his neck extended and his snout in the air, and I was not tempted to get any closer to take a picture with my phone camera.
Sea lion males have to be large and well fed. During the breeding season, each male tries to control a rookery (call it a harem) of females. If the male wanders too far from the rookery, as he must in order to hunt and feed, another male may usurp his place. Thus the males must feed well and fatten up enough in advance to go two or more weeks living on their blubber. All of this activity tends to occur on remote islands and other places not frequented by humans.
After the birth of the young, the females are ready to breed again in about three weeks. The lucky male is on hand, but doesn't get to choose his mate. Rather, one or another of the females will periodically separate herself from the milling pile and come to offer herself to the male. In time, he will manage to impregnate some or even all of the females.
Sea lions are one of the Pinnipeds ("fin-" or "flipper-footed" animals). The Pinnipeds were once considered a single taxonomic family of marine mammals, but now are divided into three distinct families of the Caniform ("dog-shaped") carnivores: the Otariidae (fur seals and sea lions), the Phocidae (true seals), and the Odobenidae (walruses).
The Otariids can be distinguished from the Phocids by two easily observable traits. Fur seals and sea lions have visible, external ears. (Otariidae means "eared" animals.) The Orariids can also turn their rear flippers forward and under their bodies to help them move on land. The Phocids, or true seals, do not have external ears, and their rear flippers are useless on land; the true seals move along on land by squirming, sliding, and bouncing.
Other less obvious differences between the two seal families include the nature of the animal's fur. As adults, Phocids may have little or no fur, with no significant undercoat; blubber provides insulation for these seals. The Otariids, as their common name "fur seals" implies, all have fur. In the sea lions, the hairs are relatively coarse, while in the fur seals a dense underfur is also present. All Pinnipeds molt once a year.
I finished taking pictures and climbed back up the stairs to the upper platform. As we walked away, we heard the men's chorus tuning up again, practicing no doubt for the big event in July.