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August 01, 2014

Division of Labour

Ospreys show a distinct division of labour, as we have seen here at the Hellgate nest. The male, Stan has done the majority of the hunting and the female Iris spends over 90% of the day and presumably all night brooding, guarding, sheltering and feeding the nestlings. When off the nest she is likely bathing, chasing intruders (defending the nest) and possibly foraging (rare until the young fledge). It is thought that the slow developing helpless young are a contributing factor to this division of care. For several days after hatching the young birds' internal temperature varies considerably, they therefore must be brooded by an adult until they are able to control their temperature/ thermoregulate. However they also require some protection even after they are able to thermoregulate. We have seen Iris sheltering the nestlings from both the rain and intense sun. Both Iris and Stan are helping raise the young to independence. With Stan hunting and Iris brooding they have the best chance of survival. Iris is starting to leave the nest more often now as the nestlings get older and are closer to fledging. Click ‘More…’ for further information regarding Iris’s activity.  More...

July 29, 2014

Hellgate Osprey Nestlings will not be Banded

Montana Osprey Project Leader Erick Greene explains that they do not plan to band the Hellgate Osprey nestlings as part of their study this year. This particular nest is used primarily as an educational nest for the study. Click 'More...' for further detail. More...

July 28, 2014

Nestlings Getting Big!

As we can see from this image when the nestlings first hatched they had very short down on the head and body, the down being rather sparse on the crown, nape and sides of the body behind the wings. The head and underparts were pale shades of buff with dark-brown patches on the ear-coverts (except directly below the eye). The brown marking on the head are patterned as in the adults. The juvenal feathering began to appear around 4 weeks old with the emergence of the primaries, followed by feathers of the head and upper parts. We will see the juvenal plumage fully developed over the next 2 weeks. More...

July 15, 2014

Osprey Fancy Feet

Osprey have very interesting feet and legs. The feet and unfeathered portions of legs (tarsi) are reticulate- covered with small, rough, projecting scales which become large and flat on the distal portion of the upper toes, and smaller with prickly scales or spicules on the soles of the feet for retaining grasp on slippery fish. Osprey feet are large with all toes the same length; unlike any other raptor (excluding owls) the outer toes are reversible- Zygodactyly (similar to woodpeckers, cuckoos and parrots). Raptors generally have 3 toes pointing forward and one toe back when perching. When holding fish Osprey have 2 toes forward and 2 toes back grasping the prey. The talons are long, robust, strong, evenly curved and also equal in length. Most raptors have talons with groves in, osprey do not, their talons are perfectly round. This unique foot structure facilitates retaining grasp of slippery prey. To protect the young when moving around the nest the adults will ball up their feet and shuffle around the nest so as not to injure the chicks. Click the play button for an interesting video on Osprey Evolutionary Adaptations by the Montgomeryshire Wildlife Trust DYFI Osprey Project in Wales, UK. Click 'More...' for further information from the Montana Osprey Project. More...

June 29, 2014

Montana Osprey Podcast

Montana Osprey Project team Erick Greene, Bill Munoz and Allison Mills took to the air last July. Flying over the Clark Fork River and Bitterroot Valley near Missoula, Montana in a small Cessna Airplane the crew got a great view of the landscape. Click 'More...' to check out the accompanying photos on the Montana Osprey Cams Facebook page.  More...

May 31, 2014

Stan Delivers a Fish to Iris

Around 12:15PM Stan delivers a large fish to Iris and Iris takes it away. We are approaching approximate hatch time for the Osprey eggs. If the three eggs were laid on the dates estimated they should hatch between June 10 and 16. Thanks to viewer junisissi for the video. 

June 16

Third Egg Hatches

Just after sunrise we got our first glimpse at the third osprey nestling. Stan delivered a stick to the nest and spent some time trying to position it just right. 

June 13

Second Egg Hatches

The second egg hatched just after 4:00PM. Both nestlings have been fed. Stan is doing a great job delivering large fish to the nest. 

June 11

First Egg Hatches in Hellgate

Viewers noticed signs of broken egg shell in the nest around 6PM and later in the evening it was confirmed that Iris and Stan welcomed their first nestling of the year to the World. Just after 8PM we got to see the young bird's first feed, small pieces of a large fish delivered by Stan and fed by Iris. Click "More" to see a great video clip recorded by Eaglelover1923. More...



Nest Placement

Ospreys require nest sites in open surroundings for easy approach, with a wide, sturdy base and safety from ground predators (such as raccoons). Nests are usually built on snags, treetops, or crotches between large branches and trunks; on cliffs or human-built platforms. Usually the male finds the site before the female arrives.

Nest Description

Osprey nests are built of sticks and lined with bark, sod, grasses, vines, algae, or flotsam and jetsam. The male usually fetches most of the nesting material—sometimes breaking dead sticks off nearby trees as he flies past—and the female arranges it. Nests on artificial platforms, especially in a pair’s first season, are relatively small—less than 2.5 feet in diameter and 3–6 inches deep. After generations of adding to the nest year after year, Ospreys can end up with nests 10–13 feet deep and 3–6 feet in diameter—easily big enough for a human to sit in.

Clutch Size

1-4 eggs

Incubation Period

36-42 days

Nestling Period

50-55 days

Egg Description

Cream to pinkish cinnamon; wreathed and spotted with reddish brown.

Condition at Hatching

Capable of limited motion. Covered with down and with eyes open.



The Osprey is the only hawk on the continent that eats almost exclusively live fish. In North America, more than 80 species of live fresh- and saltwater fish account for 99 percent of the Osprey’s diet. Captured fish usually measure about 6–13 inches in length and weigh one-third to two-thirds of a pound. The largest catch on record weighed about 2.5 pounds. On very rare occasions, Ospreys have been observed feeding on fish carcasses or on birds, snakes, voles, squirrels, muskrats, and salamanders. Ospreys probably get most of the water they need from the flesh of their prey, although there are reports of adults drinking on hot days.

Typical Voice

Ospreys have high-pitched, whistling voices. Their calls can be given as a slow succession of chirps during flight or as an alarm call—or strung together into a series that rises in intensity and then falls away, similar to the sound of a whistling kettle taken rapidly off a stove. This second type of call is most often given as an unfamiliar Osprey approaches the nest. As the perceived threat increases, the call can build in intensity to a wavering squeal.
more sounds

See full Species Info at All About Birds

About the Hellgate Canyon Ospreys

This Osprey nest is at the mouth of the spectacular Hellgate Canyon at the edge of Missoula, Montana. It’s in a very busy location, right outside the Riverside Health Care Center and next to busy parking lots, a construction site, a busy highway, and a railroad. However, it’s also an ideal location in many ways, since these Ospreys have riverfront property only about 50 feet from the Clark Fork River. Being so close to people does not bother them, and hundreds of people enjoy watching them every day.

The female Osprey at this nest is called Iris because she has very distinctive spots on her iris, especially in her left eye. These iris patterns serve as individual barcodes and allow us to identify her. She has nested at this site for many years.

Ospreys are consummate fishing birds, and this pair fishes primarily from the Clark Fork River and nearby Rattlesnake Creek. They use their 6–7 foot wingspans to soar above the water, looking for fish, then diving as deep as 3 feet for shallow-swimming prey. Adult Ospreys usually weigh 3–4 pounds, and they can carry prey up to 50 percent of their own weight. Ospreys can live up to 25 years, and they typically lay 1–4 eggs in a clutch.

Most Osprey pairs are monogamous, staying paired across seasons and beginning nesting soon after each returns from a long migration. Both sexes incubate the eggs. The female sits for the majority of the time (including throughout the night) while the male provisions her with fish. After the eggs hatch, the male continues to bring fish to the nest; the female exclusively broods the young and dissects their meals for about a month after hatching. Later on, when the chicks no longer require her protection and their appetite for fish increases, she will leave the nest and go fishing.

The nest used to be on a power pole about 200 feet west of where it is now. This was dangerous, since the Ospreys could have been electrocuted, causing fires and power blackouts. In 2007, the current nest platform was erected to provide a safer place for the Ospreys to nest. They took to it immediately. Getting the new nest platform set up, and installing and running to high resolution camera for this feed for you to enjoy has been a large effort involving many groups: Riverside Health Care Center, Karen Wagner, Kate Davis and Raptors of the Rockies, Northwestern Energy, Dave Taylor Roofing Company, and Drs. Heiko Langner and Erick Greene of the University of Montana.

2012 Breeding Details

Iris showed back up at this nest in early April 2012, and her mate of many years showed up a short time later. However, he was only around for a day or so and we never saw him again. Iris was alone for about three weeks, and spent much of her time bringing in sticks and calling from the nest. Eventually a new male showed up, much to the apparent delight of Iris. At first the new male was extremely submissive, but within a few days they appeared to be solidly paired. Eventually they fledged three chicks from the nest in 2012 (see Timeline Tab for details)

About Project Osprey

These Ospreys are an important part of a much larger project focusing on the health of aquatic systems and Osprey populations in western Montana. In collaboration with Rob Domenech (Director of the Raptor View Research Institute), Dr. Heiko Langner and Dr. Erick Greene started Project Osprey in 2007. They have been monitoring about 200 Osprey nests in western Montana.

Because of their top position in the food web, Ospreys are useful indicators of local environmental conditions. Young Ospreys eat only fish their parents catch within a few miles of the nest, so these young birds reflect the condition of the local fish population. And although many hawk species can be touchy—even dangerous—to work with, Ospreys make good subjects: they tolerate human activity well and they actually seek out human-made structures to use as nest platforms.

Osprey populations declined to near-extinction in the Lower 48 states after World War II as a consequence of exposure to DDT-based pesticides. The dwindling Osprey population helped trigger research into problems with DDT, resulting in its ban in the United States in 1972. Since then, Ospreys have returned to many large water bodies. Studies such as this one help scientists keep a watchful eye on how Ospreys—and the water bodies they depend on—are doing.

Since young Ospreys eat fish that their parents catch usually within a few miles of the nest, the young birds reflect the condition of the local water quality and fish. When the chicks are large enough to band, the researchers use a large bucket truck to get up to the nests. They take very small blood and feather samples from the chicks and put them quickly back in their nest. These samples are analyzed in Dr. Langner’s state-of-the-art environmental chemistry lab. The good news is that levels of some of the heavy metals of particular concern in western Montana (arsenic, lead, cadmium, zinc, and copper) occur at very low levels in the Osprey chicks. The bad news is that levels of mercury, a powerful neurotoxin, occurs in very high levels in Osprey chicks in some places. Project Osprey is now focusing on this serious environmental problem.

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