Editor’s note: This article has been updated to correct the name of the department that manages the osprey camera.
With two of three osprey eggs at the Boulder County Fairgrounds having cracked, officials hope that the remaining egg will hatch by the end of its incubation period Thursday.
The nest, which is monitored by a camera from Boulder County Parks and Open Space, has been in its current location since 2012, and hatched successful chicks every year until 2019.
But the cracked eggs this year follows a string of unsuccessful hatching years at the site. Jasmine Finks, the chat moderator for the nest camera, said that the poor results of the last few years are likely an anomaly.
“This nest has been one of the most successful nests in the area,” Finks said. “I think it’s just random chance, these unsuccessful last three years.”
Both chicks died after hatching in 2020, which officials attributed to disease. Last year, one egg cracked and the others did not hatch at all, potentially due to snowstorms that soaked the eggs.
This year’s cracked eggs may have had thinner shells for a number of reasons, Finks said. Their mom is older, which has been proven to produce thinner shells in some species. Finks also hypothesized that insecticides banned in the United States but not in Mexico and South America, where ospreys migrate for the winter, could have made the eggs weaker and more prone to cracks. Finally, Finks said that the eggs may have been fertilized incorrectly, which would have produced weak shells.
Finks noted that it was unlikely that either of the parents, who have hollow bones and weigh around six pounds, could have broken the shells.
“Osprey eggs are really strong,” she said. “So I’m thinking that is has to be some external something.”
The third egg at the camera-monitored fairgrounds nest is in day 38 of its 36 to 42 day hatching period. If it does not successfully hatch by Thursday, its chances of survival will decrease, with no potential for hatching after Saturday.
Finks expressed uncertainty about the third egg’s chances given the fate of the other two eggs.
“It hasn’t cracked yet, but I don’t know about the chances,” she said. “This is kind of new to us. Most of the mom’s eggs usually hatch, and these last couple of years they just haven’t.”
Meanwhile another osprey nest, near the Boulder Reservoir, was relocated this week to protect the chances of future eggs. After the original nests were taken over by geese, the osprey moved to a nearby pole dangerously close to electrical wires.
Moving quickly to avoid the osprey laying eggs in this dangerous nest, the city partnered with Xcel Energy to build a new platform and relocate the nest. Jonathan Thornton, the communication program manager for Boulder Parks and Recreation, called the successful move an “amazing collaboration between organizations.”
“The bottom line is we want to make sure we don’t interfere and we want to take care of the osprey,” he said.
Within hours of the nest’s building, the ospreys had successfully moved in. City officials don’t know if eggs have been laid in the new nest yet, but they are optimistic for the health of the ospreys.
“The osprey need to have some sort of platform and a space that they can call their own,” Thornton said. “As the nest was being built, the osprey were close by watching. They didn’t mind that kind of human interference and they just went right over to it.”
