In the four years since then-youngster osprey North Fork Bob was fitted with a satellite location transmitter at the North Fork Country Club in Cutchogue, he’s spent his late winter chilling in Venezuela, taking his time moseying up the East Coast, only to find that when he gets back to Cutchogue, all the good nesting spots have already been taken.
This year is proving to be no exception.
Ospreys usually return to the East End from their winter trips to the Southern Hemisphere around St. Patrick’s Day, but as of March 20, Bob still hadn’t begun his three-week long trip north, says ornithologist Rob Bierregaard of the University of North Carolina at Charlotte, who has been tracking osprey migrations for 14 years.
“Maybe he’s on the internet or someone texted him and said ‘it’s too cold on Long Island. Stay there a little while,'” he said in a telephone interview this week. “We’re hoping he can get a nest and a mate this year.”
North Fork Bob was likely two or three years old when he was tagged in Cutchogue, and he’s spent the past three summers hanging around Downs Creek without finding a mate. Three summers ago, in August, after the nesting season was over, Bob lay claim to an abandoned nest in Downs Creek for the rest of the season, but he didn’t have a mate, and by the time he returned the next spring, the nesting pole was already claimed by another couple.
Mr. Bierregaard said Bob’s problems are symptomatic of an issue that faces areas whose osprey population has dramatically grown.
“A few years ago, it was a buyer’s market, but as the population got bigger and bigger, it became a seller’s market,” said Mr. Bierregaard, who added that other researches on Long Island have shown that, in areas with a small osprey population, the birds begin mating at around three years of age.
“But in a population where it’s dense, with not a lot of available nest sites, the average age of first reproduction went up to 5.7 years,” he said.
By now, Bob could be six or seven years old. The average osprey lives between 10 and 12 years, though the world record-holding bird is a 26-year-old female in Scotland who is estimated to have raised about 50 young. So time hasn’t yet run out for him.
“We’re hoping he’s hoping the male that keeps chasing him away from that nest doesn’t make it back from migration,” said Mr. Bierregaard. “Males have to claim territories before the whippersnappers take their poles. Males usually get back first, but it’s pretty close.”
Though ospreys are monogamous when they get to their nesting grounds, they don’t migrate with their mates, and they have no idea whether their mate from the previous year will return. Often, if a male osprey doesn’t meet up with his mate early on in the season, he’ll set up house with a younger female, said Mr. Bierregaard.
“If the older female shows up, she will chase away the young one,” he said. “They rarely will fight it out.”
At this point in North Fork Bob’s life, he’s been wearing a radio transmitter for longer than any bird on Mr. Bierregaard’s tracking list. At the time he was tagged, the tracking team was only using satellite radios, but they’re now also using cell tower transmitters, which allow for continuous transmitting of the birds’ positions, while the satellite radios only transmit once every three days.
Mr. Bierregaard is planning to wind down the tracking program over the next few years, recapturing birds and removing their transmitters, while he sifts through the mountain of data he’s collected.
“It’s enough to keep me out of osprey poles for a while,” he said.
He plans now to focus more effort on education, including the promotion of the brand new World Osprey Week, March 24 through 28, a worldwide school program to help students learn about osprey migration and share data with other schools around the world. He’s hoping some schools on the East End will get involved, particularly because North Fork Bob has become one of his most popular birds.
In the meantime, he said, it’s not a bad idea for naturalists to continue putting up osprey poles to encourage the burgeoning population to nest.
“It never hurts. I don’t think you can have too many osprey poles,” he said. “But they’re weird. You can put up a pole and think it’s a perfect location, but ospreys can end up nesting in a dangerous place like a transmission tower down the road. But giving them as many opportunities as possible is certainly a good idea.”
Rob Bierregaard’s migration update newsletter is available online here.