Few wildlife species are as watchable and easily observed as the Osprey. They are a big, showy raptor with a bandit mask and fierce yellow eyes. They nest in conspicuous, elevated nests along rivers, lakes, and shorelines that humans like to frequent. And having rebounded in numbers following the ban on the pesticide DDT, they are one of the most widespread birds in the world, found on all continents except Antarctica.
Ospreys do pretty well coexisting with humans, allowing us the proximity to intimately observe this bird during its nesting season. However, that coexistence poses some daunting challenges for Ospreys and humans alike.
In this diary I chronicle a few of my “adventures” working with Ospreys during my 16 years as a state wildlife biologist in east-central Idaho. Without exception, each adventure occurred due to a human impact. You are forewarned that not all of these stories had happy endings. My hope is to raise awareness of the complexities of managing Ospreys in their breeding habitats, and suggest ways in which we humans can reduce our impact on this magnificent, charismatic bird.
Fledgling osprey ready for its maiden flight, with watchful Mom (in middle) and sibling (right).
Background
Osprey nest territories in the Upper Salmon River Basin of Idaho, 2016.
In the 1950s to 1970s, Osprey numbers crashed in many parts of its U.S. range as a result of DDE-induced eggshell thinning. After the 1972 U.S. ban on DDT, Osprey populations started rebounding. Osprey reappeared in the Upper Salmon Watershed of Idaho in the early 1980s, gradually increasing to ~50 breeding pairs by 2018. The first colonizers nested in “natural” substrates – snags or treetops in the upper elevations of the Basin. Beginning in the 1990s, Ospreys started using man-made structures, namely power poles, as surrogate substrates for their large, bulky stick nests. Osprey nests built on energized structures were trouble brewing; sticks and other debris dropping into live wires and transformers caused dangerous electrical outages and pole fires. In response, local power companies and Idaho Fish & Game started installing nest platforms to lure Ospreys away from live power poles. Breeding Ospreys readily adapted to the new nest platforms and over time, 88% of all Osprey pairs in the Basin nested on man-made structures.
An Osprey pair building a nest on a freshly installed nesting platform.
Osprey vs. Canada Goose
Ospreys weren’t the only species benefiting from the platforms. Canada Geese got in on the action, thinking they’d found their kryptonite against terrestrial predators. The problem was that the geese initiated nesting a couple weeks before Ospreys arrived on their breeding grounds. You might think Osprey vs. Canada Goose is a lopsided contest, but never once did I see an Osprey chase a goose off its nest. The Osprey pair would fly round and round the nest, chirping incessantly, and occasionally diving on the goose but never making contact with those formidable hooked talons. Ospreys – the featherweight of the raptor world! Their efforts to flush the intruder thwarted, and being stubbornly territorial, Ospreys would start building their nests on the nearest tall structure; usually a live power pole, but often too a cell tower or stadium light array or in one case I recall, an irrigation wheel line.
My bucket buddy about to remove nest materials from a platform.
Being responsible for “management” of nongame wildlife in the Upper Salmon, it was my role to resolve these Osprey-goose conflicts. I started an annual program to remove all accumulated nest material on Osprey nesting platforms that had recurring conflicts with nesting geese. In fall, after Ospreys migrated south, I’d hire a local tree trimmer with a 60-ft. hydraulic bucket and make the rounds to clean off the platforms. The next spring, Canada Geese would find no nest material to establish their nest on and would move along. Returning Ospreys immediately set about rebuilding their nests, taking 2-3 days to complete. I never sensed the annual removal of their nest materials was detrimental to the Ospreys; after all, nest building is a part of their pair bonding and courtship ritual. This program was a bit expensive for my meager budget, but the alternatives – electrocuted birds, pole fires, range fires, power outages – were not acceptable.
Osprey Nest Relocations
On a few occasions, power companies had emergencies that required temporary removal or relocation of an active Osprey nest. One such occasion occurred in the upper Salmon River Canyon where Pileated Woodpecker excavations had so compromised a major transmission line pole, it was teetering on collapse. Of course, an active Osprey nest sat atop the cross arms of the structure.
Our plan was to work quickly to minimize separation stress of the parents and the 4-5 week-old nestlings. I and a lineman were lifted in a bucket about 120 feet to the nest. I collected the 2 nestlings and placed them in a pet carrier while the adults anxiously chirped around us. Back on the ground, I moved the nestlings to a large dog crate and monitored them for the next 3 hours.
Osprey chicks from the Copper Creek nest territory in temporary human custody. The family was successfully reunited after repairs to a power pole were completed.
A couple of linemen rode back up to collect the nest (~ 75 lbs.), keeping it as intact as possible. They brought it to the ground and another lineman constructed a wood platform to support the nest. The crew then replaced the old wood pole with a new steel pole and installed new cross arms. When completed, they hauled the new platform and nest up in the bucket and fastened it to the new cross arms. I took the last ride up with a lineman to place the nestlings back in their nest. We backed off the site to allow the family to reunite. Watching through binoculars, the adults were back with their chicks within 5 minutes of our departure. I monitored the nest through mid-August and both Osprey chicks successfully fledged.
Ospreys in a Bind
Baling twine is a high-tensile plastic used to secure hay bales.
Hay cropping tied to beef-cattle production is the cornerstone industry on private ranchlands in the Upper Salmon Basin. Wherever you have agriculture, hayfields, and livestock – which is a lot of the West – you also have baling twine, a polypropylene plastic rope used to bind hay bales. For reasons not entirely understood, Ospreys have a fatal attraction to the twine, using the pliable material to line their nests. Ospreys can easily get their sharp talons, feet, legs, and wings entangled in the unforgiving twine. Every year there was at least one Osprey entanglement incident I had to respond to.
Fledgling Osprey entangled and suspended from its nest in baling twine. This bird survived this ordeal.
Another fledgling ensnared by the god awful stuff. I brought this bird in for observation, concerned it was severely dehydrated (it was). The remaining twine was removed for the adults’ safety.
Miraculously the fledgling’s feet and talons weren’t lacerated or strangled by the twine.
After a few days of rehab, the fledgling was released back to its nest platform and was flying within the week. I paid a visit to the neighboring cattle rancher and got his permission to organize a baling twine ‘clean-up day’ on his property with a group of volunteers. From then on, the rancher maintained clean fields and this nest stayed relatively free of twine.
I’m thankful a passerby reported this entangled Osprey so it could be rescued post-haste. After removing the twine, the poor traumatized bird flew off to the river like a bat outta hell.
Female Osprey with feet and talons bound with twine; fishing would be impossible with this impediment.
One memorable incident of twine entanglement turned into a day-long rodeo trying to capture an adult female Osprey with twine-bound feet and talons. Raptor Ecologist Rob Domenech and his amazing crew from the Raptor View Research Institute in Missoula, MT drove 3 hours to Salmon, ID to help me with the capture. The entangled female was part of a mated pair of Ospreys nesting on an artificial platform. I observed her in incubation posture earlier that week, so was pretty sure she had eggs in the nest.
Rob and his crew fashioned a “bal-chatri” trap, one of the most effective traps for capturing raptors. Roughly translated to “noosed umbrella,” a bal-chatri is a metal mesh cage with monofilament nooses tied to the top, sides, or both, typically with a lure animal placed inside. The plan was to place the bal-chatri atop the nest using eggs as a lure.
A bal-chatri trap is fashioned from hardware cloth shaped into a cone with dozens of monofilament nooses tied to it.
My faithful bucket operator arrived and lifted us to the nest platform where 3 beautiful, brown-mottled eggs were gathered for safe-keeping and swapped out for indestructible “dummy” eggs. Over these, the bal-chatri trap was placed and secured. Back down on the ground and backed off a ways, we waited...and waited.
Gorgeous brown-mottled Osprey eggs were collected from the nest for safekeeping. The nest also had an errant, non-viable Canada Goose egg, here showing the size contrast between eggs of the 2 species. Osprey eggs were kept warm in an insulated lunch box.
The female came in to the nest and was snagged for a moment, but managed to pull free. She did this again. And again.
Almost got her...
Defying the bal-chatri snares for a second time
Then the adult male landed on the trap and was promptly captured. Damn! We quickly moved to retrieve him from the trap. Once in hand, we took the opportunity to band him.
The male comes in for a landing.
The male was in hand long enough to place leg bands and draw blood for heavy metal analysis. I had the spritz bottle handy to keep the Osprey and Rob cooled down on this very warm June day.
After a long, hot 3 hours, the female was finally captured in the bal-chatri. She was retrieved, hooded to reduce stress, cut free of baling twine, and examined for injuries. Finding none, she was given intravenous fluids, banded, and released to her and our great relief. She and her mate went on to raise and fledge 3 young that year. Based on resightings of their leg bands, the pair returned to successfully nest in 2015-2018, the year I retired.
Finally, the female is captured!
Removing the baling twine from her legs and feet. Surprisingly, no injuries were sustained.
Free and clear of twine, banded, and blood sample taken. Our girl is ready for release.
After this ‘adventure’ – I was outright PISSED at people for carelessly discarding baling twine and monofilament fishing line – lethal materials to Osprey and other wildlife. But being pissed and reactive wasn’t cutting it. I brainstormed with a local nonprofit, Salmon Valley Stewardship, and with a bit of grant money we developed community recycling programs for baling twine and fishing line to get the insidious stuff cleaned from our waterways. The baling twine recycling program operated for a few years with documented reductions of baling twine in Osprey nests. But in 2018, China announced it would no longer buy most plastic waste from the U.S. and the market for plastic waste – including baling twine – dried up overnight. Our program evolved into an education-awareness initiative, advocating for people to pick up and store baling twine safely out of reach of Ospreys and other wildlife.
A poster raising awareness of the lethal hazards of baling twine to wildlife.
Reel In & Recycle bin at Jimmy Smith Lake
Our fishing line recycling program was modeled on the Reel In and Recycle program developed by BoatUS Foundation, popular in the Gulf Coast and Eastern Seaboard. We installed monofilament recycling bins at 15 boat and fishing access sites along the Salmon River. Fishing line is periodically collected, then packaged and mailed to Berkley Conservation Institute where the monofilament is manufactured into underwater, artificial habitat structures for fish called “Fish-Habs.”
In retrospect, I am grateful and humble to have known the Ospreys of the Upper Salmon as though they were my extended family. And like family, they were often a big pain in my ass, but I would do anything to ensure their welfare and I loved them – still love them – unconditionally.
*****
The floor is now open for your latest bird observations and other avian news!
