Twin Cities area osprey nests are a catchall for castoffs

Most bird species choose to nest in seclusion. A hidden nest is a safe nest.

And then we have the osprey.

Last year there were 136 osprey nests in the metro area, not so many, but that doesn't mean they were — or are — hard to see.

Ospreys once chose natural nesting sites, like trees or cliffs. Today, the birds are much more likely to choose obvious man-made structures. We've changed the landscape.

In 2018, 75 osprey pairs here used custom nesting platforms. Twenty-three nests were on cell or radio towers, 18 on ball-field lights, 15 on power poles or transmission towers, and three at other locations humans provided. (FYI: Nesting platforms are most easily found in Three Rivers parks.)

Two nests were built in a dead tree late in the breeding season, with no eggs laid.

Osprey nests are built by both members of the pair. Males bring sticks, females make building decisions. As the nest nears completion, material brought to the nest begins to vary.

Vanessa Greene, founder of Twin Cities Metro Osprey Watch (osprey.mn@att.net), has seen arrows, a lanyard with keys, gloves, hats, baling twine, colored ribbons, a pet leash, and landscaping material in nests while banding chicks.

There is a funny video of a male osprey bringing a hat to his San Francisco nest. He rather clumsily tries to find a suitable place for it, all the time disturbing the incubating female. She finally has had enough, taking the hat in her bill and flying away. The male bird's posture says "What the …." (sfbayospreys.org)

There is much more about ospreys and their nests in "Birds of Prey, Part 1," one in the 21-volume set "Life Histories of North American Birds" by Arthur Cleveland Bent (available via Amazon, the Hennepin County Library and birdsbybent.com).

Bent, 1866-1954, was an ornithologist who used observer reports and anecdotes to compile life histories in nonscientific language. The books are informative and very readable.

Last year eggs were laid in 125 of the 136 local nests. Two hundred and five chicks were known to have survived to fledging age, the point at which they leave the nest.

In addition, there was the usual uncounted population of immature birds. Osprey begin to breed at just under 5 years of age. Some of those birds were hatched and raised here, returning to their natal neighborhood.

Almost 2,300 chicks are known to have survived to fledging age since monitoring began in 1984. Some of these birds become local replacements. Others seek new territories.

We know all of this because of Greene. She worked for the predecessor to the Three Rivers district for 15 years as point person on osprey reintroduction and management.

When the park district discontinued that effort, Greene continued, sometimes funding work with her savings. (She has a Facebook site and a GoFundMe page.)

"This seems like a critical time for us to pay attention to the natural world," she wrote in an e-mail.

She believes strongly in the value of long-term study and accumulation of data. She shares what she learns via Facebook and a blog (ospreywatch.blogspot.com).

Greene says she would like two things as she continues her work: volunteers to help monitor nests, and money to help cover expenses.

Ospreys were seen in the Twin Cities at least as early as April 10, Greene said. They're building or repairing nests, adding sticks and who knows what else.

Read Jim Williams' birding blog at startribune.com/wingnut.