Rainforest Thread #78 -- Is April cruel?

Thus far, the U.S. Coast Guard boats monitoring the whales as they swim down river only have had to deal with recreational boats and windsurfers. But as the whales get closer to the bay, they will encounter large oceangoing vessels that could harm them.

"We will try to keep a safe zone around them," said Greg Hurner, a senior adviser with the California Department of Fish and Game. Boats also were being positioned to block entrances to a number of tributaries and sloughs, where the whales are at risk of getting stuck in shallow mudflats.

Both whales have gashes likely suffered from a run-in with a boat's keel that have also worsened during their river stay. But veterinarians believe antibiotics injected into the whales Saturday could slow the damage, and scientist were ready to administer a second dose.

The calf also appears to be more active, which is an encouraging sign, they said.

SAN FRANCISCO (Reuters) - Two humpback whales that swam from the Pacific Ocean far up into central California's inland waterways are approximately 20 miles from open ocean, a U.S. Coast Guard spokesman said on Tuesday.

The whales, presumed to be a mother and calf, have been in the Sacramento-San Joaquin Delta for the past two weeks. At one point, they swam as far north as the state capital of Sacramento after entering inland waters through San Francisco Bay.

After efforts to coax them out of the delta failed, the whales began swimming toward the bay on Sunday and by Tuesday afternoon were about 20 miles from the bay's landmark Golden Gate Bridge, where the bay and Pacific Ocean meet, U.S. Coast Guard Petty Officer Jonathan Cilley said.

Humpback whales Delta and Dawn are wayward no longer. They are swimming seaward with a purpose, speeding past Angel Island at 4:50 p.m. today and aiming for the Golden Gate.

That fabled portal marks the finish line of their remarkable, two-week saga.

Bernadette Fees, spokeswoman for California State Fish and Game, described the euphoria flooding the whale rescue team as the humpbacks sliced through San Pablo Bay.

Before reaching the Pacific, the whales have one more bridge to navigate: the Golden Gate.

But the Carquinez Bridge and the Richmond-San Rafael Bridge seemed to pose no obstacle to the pair. After some hesitation, they swam beneath its spans while a freight train rumbled by, blowing its horn. There was also a plane overhead and vehicular traffic on the bridge -- plus a gallery of onlookers.

Earlier this morning, there were euphoric shouts from spectators as the calf breeched from the water in a silvery spray - behavior typical of healthy whale young.

Researchers think the antibiotics administered over the weekend are taking effect -- their skin condition is improving with some of the lesions sloughing off.

This 20-day saga has been a virtual treasure trove for researchers seeking to understand whale psychology and physical health. They have been taking still photos, video, and studying the whales' every move from tail lobbing to breeching -including their sometimes seemingly erratic behavior.