Something Wild: Tracking Osprey

Aug 5, 2016

We’re at an osprey nest in Tilton with Iain McLeod, director of Squam Lakes Natural Science Center. Our goal is recruiting another individual for Project OspreyTrack. He explains that Project OspreyTrack began in 2011, “to try to understand a little bit more about osprey migration and foraging.” 

Each year, MacLeod and his team outfit a handful of juveniles and adult males with GPS backpacks. He says since the females don’t leave the nest much between laying the eggs and fall migration they offer far fewer data points than the males. “We find out where they go for fishing [in New Hampshire] and to follow them all the way down to South America.”

The nest we find ourselves at is on a platform, built by MacLeod himself, atop a forty-foot pole just off the road. Looking around it’s probably not the location you’d pick to situate an osprey nest in; the outlet mall and route 93 are each just a stone’s throw away from where we stand. Notwithstanding, MacLeod suggests there are many features that recommend the site. 

The vast majority of osprey nests are on manmade structures like this pole in Tilton, or even cell phone towers.

“The river’s right here, Silver Lake is not far, there’s a good supply of fishing spots, [which is good because] they’re the only bird of prey to feed exclusively on fish.” It must be allowed that he knows what he’s talking about because the parents who’ve raised the chicks we’re looking to tag today have raised chicks here every year since he put the platform up. “So it’s worked for them and we’ve had an opportunity to learn about them so it’s become a great nest for science.”

 “Traditionally, osprey would have nested on a dead tree or a canopy pine,” MacLeod says. “They like to be up high, the very tallest point within any habitat.” But these days, the vast majority of osprey nests are on manmade structures like this pole in Tilton, or even cell phone towers.  The pole is conveniently located so that MacLeod’s team could easily drive a bucket truck up to it ad raise someone up to bait and set the trap. That someone is Rob Bierregaard, a Research Associate of the Academy of Natural Sciences of Drexel University. The trap we’re using is his own design, and one that he’s refined over the years. After depositing a couple of herring in the nest, he then drops a large piece of heavy-gauge chicken wire on top of them. To the chicken wire is tied dozens of nearly invisible mono-filament copper slip-knots. When the juvenile osprey comes in to grab breakfast, he ends up having his talons snared in the slip-knots. 

"It's the same general path, they’re all going through Cuba to Hispaniola before they spread out all over South America."

Once we’ve set the trap, it’s just a matter of waiting…it could be ten minutes, it could be ten hours before the trap bears fruit. We’re fortunate today, within a half-hour we hear the unmistakable calls of a juvenile osprey curious about the meal that has appeared in its nest. Moments later he is tethered to the nest. That’s Bierregaard’s cue to go up in the bucket truck again and retrieve the trapped osprey.

 His first order of business is to grab the birds legs in one hand to keep it from hopping all over the place. Then he delicately slips a hood over the osprey’s head (deftly avoiding a few lunges from the sharp beak). “Once you put the hood on its amazing how they quite right down, says MacLeod, “because they’re not getting that visual stimulation. They’re really very docile when they’ve got the hood on.” Bierregaard then goes to work cutting the slip-knots from the bird’s feet, using of all things a ail clipper to cut the mono-filament. Shortly, he comes down with a becalmed bird, the 94th osprey he’s tagged in his 16 years of doing this. In that time, he’s created quite a roadmap of where osprey travel, he calls it the osprey “Highway to the Tropics.” And it is like a highway because many of the birds follow the same path that the other osprey do. “It’s the same general path,” clarifies Bierregaard, “they’re all going through Cuba to Hispaniola before they spread out all over South America. But an individual bird doesn’t go the same way each year. They’re not following a series of landmarks from point A to point B...” 

With his years of experience, Bierregaard makes short work of banding this ten-week old chick; and though she – we think she’s a she – though she’s still learning the ropes from her parents, she’s full size and pretty much equipped for life at this point. He then fits her with the satellite tracker. “There are two straps that go over the wings, and two that go under the wings. And where they cross over, I stitch them together.”

 And with that the latest participant of Project Osprey Track is officially on the wing. EDITOR'S NOTE: This piece was recorded on 11 August, 2015. Unfortunately, we lost contact with Juliet, the bird Iain and Rob tagged that day. Project Osprey has more details about her fate here.