Titans of Piedras Blancas

Bulls arrive for breeding season

Elephant seal bulls begin arriving around Thanksgiving for the winter breeding season. They are at their largest physical bulk, after months of feeding along the North American continental shelf. They’ll need it to get through to March without eating.

Look for long noses and big pink chest shields on massive bodies. They surf out onto the sand, their massive weight now subject to gravity instead of supported by water. Welcome to life on land!

Smaller seals are juveniles, still resting on the beach from their Fall Haul Out. They will soon leave on their own migration. They’ll feed and grow bigger, to return next spring. Seals spend most of their lives at sea.

No feeding here

Bulls stop feeding when they leave their foraging grounds and head south for the breeding beaches. They’ve been eating fish and squid, gaining as much as 28 pounds a day, since they left the Central Coast in August and September. They need enough blubber to survive 100 days or more, to the end of the breeding season. They are huge now, but will get thin over the coming months.

Every bull on the beach is a survivor in a tough system. As few as one percent of male pups born reach breeding age.

Surviving isn’t enough to guarantee breeding, though. They jockey for dominance and breeding rights. Two thirds of the bulls, the less dominant ones, don’t get to breed at all.

Why they fight

Early arrivals find enough beach to separate them. Some pick fights anyway. You may see seals fighting.

To get breeding rights, males fight for dominance and to defend their harem of females. They arrive looking for a fight and it only gets worse. Size is an advantage, but not the only factor. The alpha bull, the beachmaster, is frequently challenged by other bulls. He can lose a battle and be replaced by another tough guy.

Beachmasters are vigilant about chasing other bulls away from the harem, but it’s a constant challenge. All bulls are focused on mating, regardless of their status in the beach social hierarchy. Lower ranking bulls sneak around the harem and try to mate with females. They sometimes get away with it.

Non-breeding beaches

Less dominant bulls who lose battles may leave the beach and take refuge on other, non-breeding beaches. Look for them at San Simeon Cove, along Moonstone Beach, and other quiet, sandy places. It’s like the old joke: Where does a two-ton seal go? Anywhere he wants.

Females give birth

Females start to arrive in December, with the first pup born around the middle of the month. More females arrive in January and February, up to around 5,000 at the height of the season.

But they aren’t ready to mate until after they’ve nursed that pup for a month or so. They come into estrus, like dogs.

“Of course, these animals are dangerous,” writes elephant seal researcher Burney LeBoeuf in Elephant Seals: Pushing the Limits on Land and at Sea. “Males will run over you as if you were a piece of furniture in their way.”

Speakers Bureau

If your organization would like to learn more about the seals Friends of the Elephant Seal offers free speakers. To arrange a speaker, call the FES office, (805) 924-1628 or request a speaker through the website, https://elephantseal.org/speakers-bureau/. The Speaker’s Bureau Coordinator will respond and set up a date.

https://www.sanluisobispo.com/news/local/environment/article282000123.html 

 

New wildlife tags help Central Coast researchers understand impacts of offshore wind projects

Piedras Blancas Light Station has a new electronic wildlifetracking system, to collect data on small birds and bats, and is the site for a new acoustic bat monitoring project. The data are important for understanding how the Offshore Wind projects may affect these smaller species.

Motus

The Motus Wildlife Tracking System is an international collaborative research network that tracks birds, bats and insects with tiny transmitters. The tags transmit location data back to scientists, who then can use it for research and education. The data inform ecology and conservation of these migratory species.  Motus is a program of Birds Canada in partnership with collaborating researchers and organizations. Data collected are shared among all researchers.

“Motus allows us to track species too small to tag with traditional GPS tags,” said Laney White, U.S. Geological Survey's Western Ecological Research Center biologist.

USGS Western Ecological Research Center biologist Laney White drives a Zodiac to one of the USGS Ashy Storm Petrel study sites (photo credit: J. Felis).

The Piedras Blancas installation is funded for three years by the Bureau of Ocean Energy Management, a long-term investment. The system can be used to monitor bird and bat movements. In the future, Motus may be used to study animal movement around the turbines off the West Coast. In Central and Southern California, the USGS is in the process of building 25 stations.

The tiny battery-powered tag can weigh less than half a gram, less than the weight of a paperclip, and costs about $200. It can be glued to the bird, sutured, or attached with a harness or leg band. The batteries can be solar powered and last years.

“Until you’ve got a bird in hand, you can’t always tell which method will work,” Ms. White said.

Cassin’s Auklets, Ashy Storm-Petrels, and Western Gulls will be tagged. Western Gulls will also get GPS tags that can detect Motus tags, making them mobile receiving stations and expanding the network’s reach offshore.

USGS wildlife biologist Emma Kelsey holds a Cassin's Auklet in the Channel Islands (photo: J. Felis).

In less rigorous environments, the tags can last a bird’s lifetime. In the salty marine environment, they probably won’t last that long.

The system needs international collaboration with Canada and Mexico, because birds and bats migrate across international boundaries.

Acoustic bat monitoring

Bats hunt the insects that are their food with sonar echolocation.

“Insects are nimble,” said USGS acoustic specialist Bethany Schulze. “They are good at evading capture.”

Globally, bats play a significant ecological role, in pest control, pollination, seed dispersal and as bioindicators of environmental toxins. The bat in the coal mine, as it were.

Hoary bats, a migratory species, could be affected by the West Coast Wind Projects proposed for 20-30 miles offshore. Motus wildlife tracking and acoustic bat detectors can provide data to document how offshore bat activity is different from coastal; which species migrate offshore; whether their migration is seasonal; and ultimately, whether the wind turbines will affect them.

Piedras Blancas is the first of 10 coastal acoustic monitoring sited set up. The solar-powered acoustic bat detector is holding up well so far, Ms. Schulze said.

All 20 coastal and offshore sites are already collecting data, from 0.3 to 120 km offshore. They are on exposed areas at the edge of the ocean. They record bats calling as they fly past.

“I just deployed our last site yesterday (November 4), so now all 20 sites are collecting data!” she wrote in an email.

Target species are Hoary bats, Mexican free-tailed bats, Western Red bats, and Silver-haired bats. California bats feed mainly on insects.

 

Ms. Schulze follows the bats where they go. One Hoary bat – “they’re the big fluffy ones” – was tagged in Marin County, then tracked to north of Sacramento before it flew north to Washington state.

 

Collaborating with the U.S. Coast Guard, she’s been lowered in a basket by helicopter to deploy an acoustic bat detector on a rock in the middle of the ocean.

 

She and the rest of the Western Ecological Research Team will continue to follow the bats for several more years.