Wednesday, December 20, 2006

Bulls on the Beach

Elephant seal males that are sexually mature are called bulls. At the beginning of each breeding season, bulls arrive at the Farallones and establish their dominance hierarchy through displays of their mass and nose size, bellowing, and occasional fights. The highest-ranked bull is called the alpha, and he defends the largest harem (group of females). The rankings are fluid, and challenges occur daily. The payoff for the males comes at the end of the breeding season, when the cows they have been defending for a month wean their pups and become sexually receptive. The bull mates with each cow just before she returns to sea, leaving her pup on the beach as a weanling. Let's take a look at the main contenders for alpha bull status on the Farallones this year.

Nero became the alpha bull early last season by deposing JD, the previous alpha bull. Nero is the bull of Sand Flat, the largest harem on the Farallones with 97 cows last year. He's not the most massive male around, but his nose is enormous. Harem-organized species usually have a sexually-selected body part that acts as a signalling device to other members of that species to transmit information about sexual maturity and dominance. For elephant seals, the proboscis (nose) says it all. When Nero inflates his nose and bellows, the other males quickly move away.

Don Francisco is a veteran male who held a small harem last year on the Marine Terrace. He successfully defended this group from the constant incursions by satellite males. Last year he stayed away from Nero and contented himself with his 16 cows. We'll see if this year Don is still happy on the Terrace, or if he will challenge Nero.

Puffy is a newcomer to the Farallones, he was first seen this year, already an adult, and has established himself on Mirounga Beach. There are usually about 35 cows in this harem, but it is not a great location for the pups, over half die each year due to crowding and high swells washing out the small beach. Not a great investment in future gene survival, but about the same payoff as the Marine Terrace. Puffy is pretty large, he may make a move on the Sand Flat harem, but his nose just isn't up to Nero's caliber.

Bedlam Boy is a big satellite male who orbits the periphery of Sand Flat. Nero can't control the entire harem at all times, so satellite bulls like Bedlam Boy keep lesser males cleared away from certain portions of the harem's edge, never engaging the alpha directly, always ready for an opportune moment to mate with a cow while Nero is preoccupied on the other side of the beach. Bedlam may challenge Nero later, but thus far he has retreated every time Nero trumpets.

Brendan is still too young to claim a harem of his own, but he has been hanging around, sparring and harassing bulls for the last few years. He's earning his fighting chops and learning the terrain for future years when he will have the mass and the nose to defend a harem.

Still missing from last year's class of males are Altamont, Eeyore and Charlie H. Perhaps they are still foraging to get that bit of mass that will put them over the top.


Anonymous said...

I am so glad that JD made it, I have been worrying about the guy all year after his bruising by that nosey upstart Nero.

Great reporting, by the way, please keep it up! I`m always eager to hear the news from Los Farrollones.

-No. 1 Fan

Anonymous said...

Hey guys ! So glad to see the e-seal journal up and running again. I wish i could be there and see it all for myself. Great news on Nero and the other returnees. But where's JD, or Dingle, the wuzz ? I hope Bedlam Boy lives up to his name this year and spreads some mayhem. Can't wait for the first cute pup pictures.

- Old Europe

Anonymous said...

Hurray for SEFIs bulls! Keep up the good reporting - ever the soap opera, I'd hate to miss an installment of the bull wars :)

Los Farallones said...

Always a pleasure to hear from our readership! We'll post the latest cow and pup news right away.