Youngsters arriving

As summer draws to a close, the young seals start arriving on the beach for their fall haul-out. The young of the year, last January's pups, return at this time, too. Several very small seals are already on the beach. They may be this year's pups, already successful at their first migration.

 They co-exist comfortably with the adults and subadults on the beach. They may tussle with each other, but they don't pick on the kids.

Adults made their presence known from the water. This one kept raising his head out of the water and bellowing, as if challenging other males to come get him.

These two adult males are completing their molt, while the third above them already shows his 2013 skin.

Pelicans

A flock of pelicans dropped down out of the sky, gracefully landing on the water. They weren't actively feeding, diving from the air into the water, but there must have been something there to attract them.

 They flapped around as if they were bathing, cleaning their feathers.

 Some appeared to have fish in their bills.

 And poking the water for fish.

 Their wingspan is powerful. You can almost hear the whirl of their wings.

More boys on the beach

 Adult males enjoy the beach in August. They don't have much to do except let their skin peel off and rest.

 This impressive male has a well-developed chest shield, indicating he's mature. They can live to 14 years but 12 is the prime breeding year.

 New skin needs not additional treatment. Just peel off the old layer and the new is ready to wear. This experienced old guy has scars to show his years. Initially, I thought he had something on his head, but it's just light-colored old skin.

Lying around in a pile makes a good day at Piedras Blancas.

Boys on the beach

Females are gone now, leaving the each to the males. There's plenty of tussling going on, in the water and on land. These three fought each other all morning today.

 This old guy caught my eye. He has a lot of miles on that scarred old hide, but he showed plenty of energy to those youngsters.

 No doubt he'll look much better when he has finished molting.

 Two Harbor Seal pups swam on to the beach. This one swam back toward the rocks where the other Harbor Seals were reting.

The other stayed on the beach for a few minutes, but soon realized he was in the wrong place. He headed back into the waves.

Sonar blasts strand whales

The Guardian reports on loud sonar's effects on whales. No doubt, elephant seals are also affected. This was the argument against PG&E's seismic tests last year. Thanks for the scientific data to support the reasonable assumption that animals that depend on sound will be harmed by explosive blasts.

Whales flee from the loud military sonar used by navies to hunt submarines, new research has proven for the first time. The studies provide a missing link in the puzzle that has connected naval exercises around the world to unusual mass strandings of whales and dolphins.

Beaked whales, the most common casualty of the strandings, were shown to be highly sensitive to sonar. But the research also revealed unexpectedly that blue whales, the largest animals on Earth and whose population has plummeted by 95% in the last century, also abandoned feeding and swam rapidly away from sonar noise.

The strong response observed in the beaked whales occurred at noise levels well below those allowed for US navy exercises. "This result has to be taken into consideration by regulators and those planning naval exercises," said Stacy DeRuiter, at the University of St Andrews in Scotland, who led one of the teams.

"For whales and dolphins, listening is as important as seeing is for humans – they communicate, locate food, and navigate using sound," said Sarah Dolman, at charity Whale and Dolphin Conservation. "Noise pollution threatens vulnerable populations, driving them away from areas important to their survival, and at worst injuring or even causing the deaths of some whales and dolphins." Dolman said there were no accepted international standards regarding noise pollution and there was an urgent need to re-evaluate the environmental impacts of military activities.

The US Navy part-funded the new studies but said the findings only showed behavioural responses to sonar, not actual harm. Nonetheless, Kenneth Hess, a US Navy spokesman, said permit conditions for naval exercises were reviewed annually and added: "We will evaluate the effectiveness of our marine mammal protective measures in light of new research findings."

Unusual mass strandings, where multiple species of whale and dolphin beach at several locations at once, have soared since the introduction of military sonar in the 1950s and can be fatal. The strandings occur every year and major recent events saw up to 15 animals beached in the Canary Islands, the Bahamas and Greece. In May, the naval activity was found to be the most probable cause of the deaths of at least 26 short-beaked common dolphins in Falmouth Bay, Cornwall in June 2008.
Beaked whales are the most common species affected by unusual mass strandings, perhaps because their shy nature makes them more easily scared by noises that they may interpret as killer whale sounds. Researchers used suction cups to attach digital devices to Cuvier's beaked whales off the coast of Southern California to measure the noise they were exposed to and their response.

When a simulated military sonar signal was sounded at 200dB and between 3km and 10km away, the whales initially stopped feeding and swimming. They then swam rapidly away from the noise and some performed unusually deep and long dives. "The missing piece of the puzzle was how whales changed their behaviour and how that led to mass strandings," said DeRuiter. She added that they also stopped feeding for 6-7 hours, which is unusual. "If they miss out on food, they will be less healthy," she said, noting that where populations have been measured, numbers of Cuvier's beaked whales are declining.

A second study, also off Southern California, estimated that a blue whale spooked by the sonar missed out on over a tonne of krill, about a day's worth of food. "Blue whales rely on large aggregations of dense krill to sustain their extreme body size, so they continuously dive and feed throughout the day when high-density prey patches are present," said Jeremy Goldbogen, at Cascadia Research, a non-profit US research organisation in Olympia, Washington. "Because of this, we suggest that sonar-induced disruption of feeding could have significant and previously undocumented impacts on individual baleen whale fitness and the health of their populations."

A spokesman for the UK's Royal Navy said: "The Royal Navy already limits its use of sonar around whales. We are committed to taking all reasonable and practical measures to protect the environment and mitigate effects on marine mammals. This new research will be taken into account in the regular review of MoD active sonar mitigation procedures."

• This article was amended on 3 July 2013 to clarify the claims made by the US Navy, which part-funded the new studies.

Green Tie

Green Tie is an elephant seal who had two plastic entanglements around his neck, leaving him with a pair of distinct scars. Veterinarians from the Marine Mammal Center disentangled him the first time in 2011 and checked on him in 2012, when his scarred skin appeared to be another entanglement. It turned out to be a skin irritation, but not another plastic strap.

He showed up on the beach again in February 2013, when he accommodated me by taking this pose for a photo.

On June 24, this seal slept on the beach. Is he Green Tie? If he cooperates, I'll get a better picture and be able to tell for sure. Green Tie has an orange tag, placed on him in 2011 when he was first disentangled by the Marine Mammal Center. The tags are difficult to see, being only an inch and a half long and placed on the back flippers. when the flippers are folded up, the tag is usually concealed.

Distinctive scars are another way of identifying individual seals.

Moving on

The juveniles and adult females are leaving the beach, It's less crowded than it was only a few weeks ago.

 There are still hundreds of seals on the beach, but not a solid mass as it was at the height of the molting season.

Adult males are starting to arrive. Youngsters continue to practice sparring in the surf and resting in the shallows.