Nez Perce Tribe
Department of Fisheries and Resources Management
Aquatic Invasive & Nuisance Species Program
Avian predators in the Lower Snaker River Basin have become a major concern for the Nez Perce Department of fisheries resources management due to the losses in tribal hatchery operations. Within the last decade there have been a few species of avian predators such as the white pelican and double-crested cormorant, who have seemingly caught on to the timing of hatchery salmonid releases and have taken full advantage of these opportunities. Gulls and blue herons have been spotted snatching juvenile salmonids out of hatchery acclimation ponds and from the pools that are at the end of the pipe at fish release areas. Cormorants and pelicans have been showing up annually in increasing numbers just days before hatchery fish releases are scheduled to occur and ambush the juvenile salmonids as the migrate through the bottleneck areas of the Lower Snake and Clearwater Rivers. The Nez Perce Tribe Aquatic Invasive and Nuisance Species program is dedicated to exploring the most practical and means to addressing and minimizing avian predation on juvenile salmonids throughout the NiMiiPuu homelands.
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Avian Predators
American White Pelican
Pelecanus erythrorhynchos
Species Information
Description:
The American white pelican is a very large migratory bird weighing up to 30lbs with a wingspan that can reach up to 9 feet wide. The pelican’s feathers are white with black flight feathers on their wings. They have very big heads with long heavy pale orange bills which have a large deep pouch that is used to scoop their prey from the water. Mature pelicans will grow a “horn” on top of their bill during the breeding season.
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Impacts:
The American White Pelican has adapted to salmonid hatchery releases and juvenile salmonid outmigration with noticeable impacts in tributaries such as the Yakima, Snake, and Columbia Rivers. The impacts on salmonids throughout the Columbia River Basin are not well understood at this time but reports of pelican populations increasing throughout the basin and pelican foraging opportunities near fish hatcheries becoming more apparent in recent years has become cause for alarm.
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Native Range:
The American White Pelican is a migratory bird with the ability to fly 100 miles one way with ease allowing them to cover a very wide range. Populations west of the Rocky Mountains migrate over desserts and mountains clear to the Pacific Coast, from Northern/Central Canada south to the Gulf of Mexico. They enjoy fresh or brackish waters of marshes and lagoons but can also be found in lakes and reservoirs or along river valleys.
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American White Pelican Distribution within NiMiiPuu U&A Homelands:
American White Pelicans have been identified within the U&A homelands of the Nez Perce. The current pelican colony of concern for the Columbia River and Snake River Basins is located on Badger Island near the Tri-Cities area. Ongoing avian predator monitoring and active hazing helps inform management decisions and improves our understanding of the impacts that pelicans could be having on migrating juvenile salmonids.
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Invasion Timeline
1918
1981
1990's-2000's
2009
2017
2023
2024
2025
American white pelican becomes listed under the Migratory Bird Act and is federally protected (additional subspecies listed in 1972).
American white pelican becomes listed as State Endangered in Washington.
American white pelican populations in the Pacific Northwest dramatically increases bringing concerns to predation on juvenile salmonids throughout the Columbia River Basin.
Idaho implements management plan to address American white pelican colonies.
American white pelican are down listed to "Threatened" in Washington.
Nez Perce Tribe Aquatic Invasive & Nuisance Species program begins monitoring American white pelican in the Lewis & Clark Valley, tribe observes 300+ American white pelicans for the season.
Nez Perce Tribe Aquatic Invasive & Nuisance Species Program begins small scale avian predator hazing on the lower Clearwater River, tribe observes ~400 American white pelicans for the season.
Nez Perce Tribe Aquatic Invasive & Nuisance Species program begins avian predator hazing operations on the Clearwater River up as far as Orofino, Idaho, and up as far as the Captain Johns salmonid acclimation site on the Snake River above Asotin, Washington, tribe observes 500+ American white pelicans for the season.
Double-Crested Cormorants
Nannopterum auritum
Species Information
Description:
Cormorants are large waterbirds with black or dark brown feathers and a small patch of yellow or orange skin at the base of their dark colored hooked beak. They have a long neck and a wingspan that can reach between 44 and 48 inches wide.
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Impacts:
Cormorant populations have grown significantly since the early 1980s which has caused several issues, especially in concerns with predation on salmonids. It has been estimated that cormorants breeding upriver of the East Sand Islands on the Columbia River could be preying on up to 20% of the migrating juvenile salmonids throughout the basin. Cormorant fecal matter has also been causing infrastructure issues in areas of high density such as the Asotria-Megler Bridge which will cost millions to address.
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Native Range:
Cormorants are migratory birds with a range that extends from the Aleutian Islands in Alaska down to Mexico. They winter along the Pacific coast and can be found in lakes, reservoirs, rivers, and streams.
What to do if Encountered: Report your findings to the Nez Perce Tribes Aquatic Invasive Species Biologist Anthony Capetillo at 208-621-3553
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Double-Crested Cormorant Distribution within NiMiiPuu U&A Homelands:
Cormorants have been identified within the U&A homelands of the Nez Perce. Ongoing avian predator monitoring and active hazing helps inform us of population dynamics and improves our understanding of the impacts that cormorants could be having on migrating juvenile salmonids.
Invasion Timeline
1972
Late 1990's
2008
2015
2023
2024
2025
Cormorants are officially listed under the Migratory Bird Act giving them federal protection.
The US Army Corps of Engineers begins to monitor the rapidly growing colony of double-crested cormorants nesting on East Sand Island in the Columbia River estuary.
NOAA first identifies the management of the East Sand Island cormorant colony as a necessary action to improve juvenile steelhead survival.
US Fish & Wildlife Service issues permits allowing US Army Corps of Engineers to implement lethal take of cormorants and the destruction of nests to reduce predation on salmonids.
Nez Perce Tribe Aquatic Invasive & Nuisance Species program begins monitoring double-crested cormorants in the Lewis & Clark Valley.
Nez Perce Tribe Aquatic Invasive & Nuisance Species Program begins small scale avian predator hazing on the lower Clearwater River.
USGS installs additional small gage cable to deter cormorants from staging on the USGS monitoring station cable, Nez Perce Tribe Aquatic Invasive & Nuisance Species program was unable to locate any cormorants in the Lewis & Clark Valley after this installation event.
Great Blue Heron
Ardea herodias
Species Information
Description:
The great blue heron is a tall bird with a slate-blue body, a long neck with long legs, a long pointed dagger-like bill, and a wide wingspan. They have white on their cheeks, chin, and around the eyes, with a black stripe on each side of the head which extends to the slender black plumes at the back of the head. The great blue heron is known as the largest heron in North America.
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Impacts:
The great blue heron is known to be a significant predator of juvenile salmonids with consumption estimated to reach into the thousands as they primarily feed on fish. Some studies suggest that the great blue heron is one of those most influential avian species when it comes to predatory impacts on salmonid populations.
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Native Range:
The great blue herons native range spans across most of North America and can be found nearly any body of water which includes; wetlands, marshes, rivers, lakes, salt water shores, and ponds.
Great Blue Heron Distribution within NiMiiPuu U&A Homelands:
Great blue herons are well established within the U&A homelands of the NiMiiPuu and can be found in almost any tributary with rookeries on the Clearwater River near Spaulding, Idaho, along the Snake River near Heller Bar (Idaho side), and on the Wallowa River in Oregon.
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Invasion Timeline
1900
1918
2010
2025
The Lacy Act is established protections against the illegal taking of wildlife parts for trade helping to protect species like the great blue heron.
Great blue herons become listed and federally protected under the Migratory Bird Act.
The great blue heron becomes a "species of special concern" in Canada and is listed under the Species at Risk Act.
The Nez Perce Aquatic Invasive and Nuisance Species Program begins looking into great blue heron predation on salmonids.
Western Gulls and Terns
Larus occidentalis and Sternidae
Species Information
Ring-Billed & California Gulls
Gull Description:
Ring-billed gulls are medium sized birds with a wingspan of 105-117cm. they have a white head and body with pale gray backs. Their wings are gray with black, white spotted tips. Ring-billed gulls have yellow legs and bills with a black ring near the tip of their bill.
The California gull is a medium sized bird which is slightly larger than the ring-billed gull that has a white head and body with a medium gray back and yellow legs with a yellow bill that has a small black ring and a red spot on the lower mandible.
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Gull Impacts:
It is estimated that gulls could be responsible for the predation of up to 20% of out-migrating juvenile salmon and can also be found feeding from fish hatchery raceways and ponds. There is a growing concern for reports of increased gull populations targeting juvenile salmon hatchery releases causing some release operations to occur strictly at night.
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Gull Native Range:
Both species of gulls are migratory birds with ranges that span from Canada to Mexico although the California gull is only found in the western regions whereas the ring-billed gull range reaches the eastern coast. They can be found in lakes, marshes, lakes, reservoirs, rivers, and streams. Winter months are usually spent along the Pacific coast and in Mexico.
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Gull Distribution within NiMiiPuu U&A Homelands:
Both ring-billed and California Gulls have been identified within the U&A homelands of the Nez Perce and it appears that they do stay within the region throughout most of the year. Ongoing avian predator monitoring has been gathering population information to gain a better understanding of the impacts that gulls could be having on migrating juvenile salmonids.
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Caspian Terns
Caspian Tern Description:
Caspian terns are large heavy bodied seabirds with a large head, a thick straight pointed bill, and shallowly forked tail. They are pale gray with a black cap. Breeding terns will have a black cap that extends to the back of the neck with a gray belly, their bill is orange with a black tip and orange legs. Nonbreeding terns will have a white forehead with a partial black cap, black legs, and a black bill.
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Caspian Tern Impacts:
Like gulls, Caspian Terns have significant impacts on salmonids through predation. Some studies in the Columbia River Basin suggest that terns consume a substantial amount of smolts during their outmigration. ​
Caspian Tern Native Range:
Caspian Terns can be found along coastlines and inland waterways. Populations can be found in North America along the Pacific, Atlantic, and Gulf Coasts. They tend to breed in habitat near large lakes and ocean coasts.
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Caspian Tern Distribution within NiMiiPuu U&A Homelands:
Caspian Terns have not yet been reported within the U&A homelands of the NiMiiPuu.
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Invasion Timeline
1984
1985
1986
Late 1990's
1998
1999-2000
2005
2023-2024
Caspian terns are first documented besting on East Sand Island in the Columbia River Estuary.
Crescent Island is formed near Wallula, Washington from dredge-spoil which ends up supporting a successful Caspian tern colony.
A colony of Caspian terns forms on Rice Island which was man made from dredge materials dumped while creating shipping lanes.
Authorities begin oiling ring-billed gull eggs on Cabin Island in an effort to protect fish.
Rice Island's tern colony peaks at nearly 9,000 breeding pairs which were estimated to be consuming 9-15 million juvenile salmon annually migrating through the Columbia River estuary.
Caspian terns begin to be relocated from Rice Island to East Sand Island to be closer to the ocean to encourage a more marine based diet and reduce predation on salmonids.
U.S. Fish and Wildlife Service publishes the Caspian Tern Management Plan which set out to reduce salmonid predation by relocating tern colonies outside of the estuary
Nez Perce Tribe Aquatic Invasive and Nuisance Species program begins monitoring gulls and hazing gulls at tribal fish hatcheries and fish release sites.