Ospreys make their long-awaited return to Sonoma County

The spring equinox was just a few days away as a winter storm drenched Sonoma County this past month. And when the storm passed, the first ospreys were seen returning to our area, with perfect timing.

Like many other birds, ospreys have a long migration from their wintering grounds to their breeding grounds. Ospreys overwinter in Central and South America, and each spring they make the long journey to nest here in tall trees near rivers and lakes.

The first to arrive are the males, followed by the females in a week or so. The male announces his arrival with chirping calls from high in the sky. For some, this is the definitive sound of spring.

Ospreys generally mate for life, and they return to the same nest they used in previous years. When the female joins her mate, they will dance in the sky together, a thrilling sight.

Once reunited, the pair immediately sets to work on their nest of sticks high atop a tall tree. Winter winds and rains can wreak havoc on last year's nest. The male osprey will land with force on a dead branch of a nearby tree, snapping it off. The branch is often covered in soft lichen. He flies with the stick in his talons back to the nest and gives the stick to the female. She can be seen carefully choosing where to place each piece.

With each yearly renovation, the nest becomes bigger, the oldest ones reaching a diameter of up to six feet.

Watching a pair of ospreys through the breeding season is an exciting experience, as photographer Paul Brewer learned. He said, “I first discovered an osprey nest in 2012. The following year there was another successful nest and I vowed to follow its progress at least once a week.”

In 2013 there was just one chick in that nest.

An osprey's clutch size ranges from one to four eggs, and there is only one clutch per year. Brewer saw the newborn chick on May 14. “My hope was to photograph the dad, who does the hunting, deliver a fish to the nest and observe the baby being fed. On several occasions I was rewarded.”

Brewer watched as the father osprey delivered fish to the nest. He noticed that the head of the fish had been removed by the father. Brewer said, “I assume this was for safety, to insure the baby was not knocked out of the nest. Once the fish was delivered, the dad quickly departed. The mom tore off very small pieces of the fish and very gently placed them in her chick's mouth.”

As the young osprey grew, she began feeding herself. The mother osprey continued her murmuring call, which encourages the male to bring food to the nest. Brewer noticed the maturing chick begin making the same call.

Brewer enjoyed watching the chick grow strong. He said, “The chick started flapping and strengthening her wings. The next step was to lift a short distance off the nest, dropping directly back into the nest. Finally, the chick flew to a nearby tree. She then seemed afraid to make the return trip. Mom sat by her side and encouraged her to return.”

Fun Fact: a bird that has left the nest for the first time is called a fledgling.

Fledglings often return to their nest to rest and to be fed. Brewer continued, “The fledgling started following both parents on fishing trips, calling to be fed. The young bird finally learned she must take the plunge and hunt for herself.”

Madrone Audubon Society members created a Breeding Bird Atlas in the 1980's. They divided up Sonoma County into 195 blocks, each about five square kilometers. They surveyed from 1986 to 1991. Ospreys were found to be nesting in 29 of the blocks.

Madrone member Tiffany Erickson has recently been working on the second iteration of the Atlas. She has tips on where to see an osprey nest. She wrote, “I covered multiple blocks along the Russian River, and osprey nests are very common there. An easy spot to see an active nest at the river is at the Geyserville Bridge. Also, the fishing access in Healdsburg, off Westside Road where Foreman Road dead ends has multiple nests.”

Erickson says ospreys have been confirmed nesting at Lake Sonoma, and there is a nest at Riverfront Park in Windsor. Diane Hichwa, Past President of Madrone, advises to look for an osprey nest immediately east of the Monte Rio Fire Station.

Ospreys dive in the ocean, rivers and lakes for fish, which makes up 99 percent of their diet. They fly slowly over water, and hover when a fish is spotted. The osprey dives feet first into the water, its talons extended and its yellow eyes trained on the fish.

Ospreys have reversible outer toes that allows them to grasp fish with two toes in the front and two toes in the back.

They also have gripping pads on the bottom of their feet to help them keep ahold of slippery fish. They line up the fish head first, to ease wind resistance as they fly away with their catch.

Like bald eagles and brown pelicans, osprey numbers crashed in the 1950s to the early 1970s due to pesticides like DDT, which made their eggshells so thin that when the mother bird sat on her eggs they broke. After the DDT ban, osprey populations rebounded. Other obstacles to their continued success are shoreline development and tree removal.

Some areas of the country have put up specially constructed nest platforms to help ospreys thrive.

To watch an active osprey nest over the spring and summer months is a joy. The phrase ‘free as a bird,' doesn't apply to the hardworking parents as they nurture, feed and protect their young.

The ospreys will leave us in the autumn. The absence of their presence may take a few days to sink in. But we can take comfort in knowing that they will return next year, filling the air with their warbling cries, our heralds of spring.

Jeanne A. Jackson is the author of Mendonoma Sightings Throughout the Year. Jackson regularly posts nature photos of the Coast on her website at www.mendonomasightings.com. Paul Brewer's nature photography can be seen on his website at capturingnatureswonders.com.