Black-capped Chickadee with a deformed crossed beak
Black-capped Chickadee with a deformed crossed beakA Black-capped Chickadee with a beak that has grown long and crossed
The most commonly observed physical abnormalities among Alaskan birds are overgrown or crossed beaks.
Return to Ecosystems >> Terrestrial Ecosystems or Wildlife Disease and Environmental Health >> Beak Deformities >> Background of Beak Deformity Research
The severity of the deformities varies, ranging from a nearly indiscernible “overbite” to beaks that are more than double their normal length. The upper and lower parts of the beak are also frequently crossed or gapped. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
We conducted a captive study of Black-capped Chickadees to measure rates of beak growth in birds with AKD. We found that the beaks of affected birds grew, on average, twice as fast as those of birds with apparently normal beaks. The deformities appear to result from overgrowth of the rhamphotheca, the outer surface of the beak which is made of keratin. Like human fingernails, the rhamphotheca grows throughout a bird’s life and is constantly worn down through pecking and feeding. X-rays of affected birds indicated that neither the cranium nor the underlying bones of the beak itself were malformed. Therefore, accelerated keratin growth appears to be the primary mechanism by which deformities develop.
In a normal Black-capped Chickadee, the upper (maxilla) and lower (mandible) parts of the beak are straight and meet at the tips.
Media
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In most affected chickadees, the maxilla (the upper) is overgrown and often curves downward. Photos show elongated and decurved maxilla on Black-capped Chickadees.
Media
Sources/Usage: Public Domain. View Media Details
In some cases, the beak is crossed. Photo collage shows six Black-capped Chickadees with crossed beaks. Photos taken at various times.
Media
Sources/Usage: Public Domain. View Media Details
Black-capped Chickadees with various forms of beak deformities: a) gap between upper maxilla and lower mandible; b) overgrown part of beak becomes brittle then breaks off and leaves a blunt tip; c) extremely thickened beak; and d) laterally curved beak.
Media
Sources/Usage: Public Domain. View Media Details
Beak deformities in other species often have a similar appearance but differ slightly among groups. Deformities in woodpeckers, flickers, and nuthatches generally result from extreme overgrowth, without significant crossing or curvature.
Photos show a) Downy Woodpecker; b) Northern Flicker; and c) Red-breasted Nuthatch with beak deformities.
Media
Sources/Usage: Public Domain. View Media Details
Most affected crows, magpies, jays, and ravens have similar growth patterns as deformed chickadees. Overgrown and downward-curving upper maxillas, severely elongated lower maxillas and mandibles, and crossed beaks are the most common corvid deformities.
Photos show American Crows and a Steller's Jay with beak deformities: a) crow with elongated lower beak; b) crow with elongated and curved upper beak; c) crow with longer upper beak in Seward, Alaska, photo courtesy of Charlie Finn; and d) Steller's Jay with longer and curved upward lower beak in La Grande, Oregon, photo courtesy of Susan Daugherty.
Media
Sources/Usage: Public Domain. View Media Details
Other affected passerine species include Ruby-crowned Kinglet, American Robin, Varied Thrush, Orange-crowned Warbler, and others. Photos show a) Chestnut-sided Warbler in Newton Centre, Massachusetts, photo courtesy of John Neufeld; b) Yellow-rumped or Myrtle Warbler in Cape May, New Jersey, photo courtesy of John McNamara; c) Slate-colored Junco on Middleton Island, Alaska, photo courtesy of Rachel Richardson; and d) Boreal Chickadee in Anchorage, Alaska, photo courtesy of Rachel Richardson.
Media
Sources/Usage: Public Domain. View Media Details
Below are other science projects associated with this project.
Beak Deformities in Landbirds
Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds. This disease, called avian keratin disorder (AKD), is characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality. If...
Links Related to Beak Deformity Research
Links, videos, and news articles related to beak deformity research.
Possible Causes of Beak Deformities
Beak deformities can be caused by a variety of factors, including contaminants, nutritional deficiencies, disease, parasites, blunt trauma, or genetic abnormalities. In 2016, we identified a novel picornavirus (Poecivirus) in Black-capped Chickadees with avian keratin disorder (AKD). Our results suggest that Poecivirus is the most likely factor responsible for beak deformities in Alaskan birds...
Literature Cited for Beak Deformities
Literature Cited in the Beak Deformity web pages
Prevalence, Distribution and Timing of Beak Deformities in Birds
The rates of beak deformities documented in Black-capped Chickadees and American Crows in Alaska are the highest ever recorded within a wild bird population anywhere.
Effects of Beak Deformities on Birds
Birds with beak deformities often have difficulty foraging and preening and may not be able to keep themselves warm and well-fed during cold winter months. Although some birds with beak deformities breed successfully, they typically encounter more challenges than normal birds.
Background of Beak Deformity Research
Large numbers of Black-capped Chickadees with abnormal beaks were reported in south-central Alaska in the late 1990s. More recently, similar beak deformities have appeared in other species throughout the state. At least 30 Alaskan bird species are affected and the geographic extent of the problem appears to be growing. In addition to Alaskan observations, we have received increasing numbers of...
Species Affected by Beak Deformities
At least 30 Alaskan bird species are affected by beak deformities and the geographic extent of the problem appears to be growing. In addition to Alaskan observations, we have received increasing numbers of reports from other parts of North America and Europe.
Below are multimedia items associated with this project.
Black-capped Chickadee with a deformed crossed beak
Black-capped Chickadee with a deformed crossed beak
Black-capped Chickadee with a deformed crossed beakA Black-capped Chickadee with a beak that has grown long and crossed
Red-breasted Nuthatch with an elongated deformed beak
Red-breasted Nuthatch with an elongated deformed beakA female Red-breasted Nuthatch with an elongated deformed beak. It was captured in Anchorage as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Red-breasted Nuthatch with an elongated deformed beak
Red-breasted Nuthatch with an elongated deformed beakA female Red-breasted Nuthatch with an elongated deformed beak. It was captured in Anchorage as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Boreal Chickadee with a mildly deformed beak
A Boreal Chickadee with a mildly deformed beak.
A Boreal Chickadee with a mildly deformed beak.
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight. Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds.
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight. Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds.
Black-capped Chickadee captured at an Anchorage banding station
Black-capped Chickadee captured at an Anchorage banding stationA Black-capped Chickadee with a normal beak captured at an Anchorage banding station.
Black-capped Chickadee captured at an Anchorage banding station
Black-capped Chickadee captured at an Anchorage banding stationA Black-capped Chickadee with a normal beak captured at an Anchorage banding station.
Black-capped Chickadee with a mildly deformed beak
Black-capped Chickadee with a mildly deformed beakA Black-capped Chickadee with an upper beak slightly longer than the lower beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a mildly deformed beak
Black-capped Chickadee with a mildly deformed beakA Black-capped Chickadee with an upper beak slightly longer than the lower beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a deformed beak that has grown long and curved down
Black-capped Chickadee with a deformed beak that has grown long and curved downA Black-capped Chickadee with a beak that has grown long and curved down. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a deformed beak that has grown long and curved down
Black-capped Chickadee with a deformed beak that has grown long and curved downA Black-capped Chickadee with a beak that has grown long and curved down. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a crossed beak on a branch
Black-capped Chickadee with a crossed beak on a branchBlack-capped Chickadee with a crossed beak on a branch.
Black-capped Chickadee with a crossed beak on a branch
Black-capped Chickadee with a crossed beak on a branchBlack-capped Chickadee with a crossed beak on a branch.
Normal Black-capped Chickadee
Normal Black-capped Chickadee
Normal Black-capped Chickadee
Northwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska
Northwestern Crow with deformed top beak in Auke Bay, Juneau, AlaskaNorthwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska
Northwestern Crow with deformed top beak in Auke Bay, Juneau, AlaskaNorthwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a long down-curved elongated top beak
Black-capped Chickadee with a long down-curved elongated top beakBlack-capped Chickadee with a long down-curved elongated top beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a long down-curved elongated top beak
Black-capped Chickadee with a long down-curved elongated top beakBlack-capped Chickadee with a long down-curved elongated top beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with an elongated and decurved maxilla
Black-capped Chickadee with an elongated and decurved maxillaBlack-capped Chickadee with an elongated and decurved maxilla.
Black-capped Chickadee with an elongated and decurved maxilla
Black-capped Chickadee with an elongated and decurved maxillaBlack-capped Chickadee with an elongated and decurved maxilla.
Northwestern Crow with an elongated lower beak
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with elongated upper beak
Black-capped Chickadee with elongated upper beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with elongated upper beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with upper long, curved down beak and crossed
Black-capped Chickadee with upper long, curved down beak and crossedBlack-capped Chickadee with upper long, curved down beak and crossed. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with upper long, curved down beak and crossed
Black-capped Chickadee with upper long, curved down beak and crossedBlack-capped Chickadee with upper long, curved down beak and crossed. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
The most commonly observed physical abnormalities among Alaskan birds are overgrown or crossed beaks.
Return to Ecosystems >> Terrestrial Ecosystems or Wildlife Disease and Environmental Health >> Beak Deformities >> Background of Beak Deformity Research
The severity of the deformities varies, ranging from a nearly indiscernible “overbite” to beaks that are more than double their normal length. The upper and lower parts of the beak are also frequently crossed or gapped. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
We conducted a captive study of Black-capped Chickadees to measure rates of beak growth in birds with AKD. We found that the beaks of affected birds grew, on average, twice as fast as those of birds with apparently normal beaks. The deformities appear to result from overgrowth of the rhamphotheca, the outer surface of the beak which is made of keratin. Like human fingernails, the rhamphotheca grows throughout a bird’s life and is constantly worn down through pecking and feeding. X-rays of affected birds indicated that neither the cranium nor the underlying bones of the beak itself were malformed. Therefore, accelerated keratin growth appears to be the primary mechanism by which deformities develop.
In a normal Black-capped Chickadee, the upper (maxilla) and lower (mandible) parts of the beak are straight and meet at the tips.
Media
Sources/Usage: Public Domain. View Media Details
In most affected chickadees, the maxilla (the upper) is overgrown and often curves downward. Photos show elongated and decurved maxilla on Black-capped Chickadees.
Media
Sources/Usage: Public Domain. View Media Details
In some cases, the beak is crossed. Photo collage shows six Black-capped Chickadees with crossed beaks. Photos taken at various times.
Media
Sources/Usage: Public Domain. View Media Details
Black-capped Chickadees with various forms of beak deformities: a) gap between upper maxilla and lower mandible; b) overgrown part of beak becomes brittle then breaks off and leaves a blunt tip; c) extremely thickened beak; and d) laterally curved beak.
Media
Sources/Usage: Public Domain. View Media Details
Beak deformities in other species often have a similar appearance but differ slightly among groups. Deformities in woodpeckers, flickers, and nuthatches generally result from extreme overgrowth, without significant crossing or curvature.
Photos show a) Downy Woodpecker; b) Northern Flicker; and c) Red-breasted Nuthatch with beak deformities.
Media
Sources/Usage: Public Domain. View Media Details
Most affected crows, magpies, jays, and ravens have similar growth patterns as deformed chickadees. Overgrown and downward-curving upper maxillas, severely elongated lower maxillas and mandibles, and crossed beaks are the most common corvid deformities.
Photos show American Crows and a Steller's Jay with beak deformities: a) crow with elongated lower beak; b) crow with elongated and curved upper beak; c) crow with longer upper beak in Seward, Alaska, photo courtesy of Charlie Finn; and d) Steller's Jay with longer and curved upward lower beak in La Grande, Oregon, photo courtesy of Susan Daugherty.
Media
Sources/Usage: Public Domain. View Media Details
Other affected passerine species include Ruby-crowned Kinglet, American Robin, Varied Thrush, Orange-crowned Warbler, and others. Photos show a) Chestnut-sided Warbler in Newton Centre, Massachusetts, photo courtesy of John Neufeld; b) Yellow-rumped or Myrtle Warbler in Cape May, New Jersey, photo courtesy of John McNamara; c) Slate-colored Junco on Middleton Island, Alaska, photo courtesy of Rachel Richardson; and d) Boreal Chickadee in Anchorage, Alaska, photo courtesy of Rachel Richardson.
Media
Sources/Usage: Public Domain. View Media Details
Below are other science projects associated with this project.
Beak Deformities in Landbirds
Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds. This disease, called avian keratin disorder (AKD), is characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality. If...
Links Related to Beak Deformity Research
Links, videos, and news articles related to beak deformity research.
Possible Causes of Beak Deformities
Beak deformities can be caused by a variety of factors, including contaminants, nutritional deficiencies, disease, parasites, blunt trauma, or genetic abnormalities. In 2016, we identified a novel picornavirus (Poecivirus) in Black-capped Chickadees with avian keratin disorder (AKD). Our results suggest that Poecivirus is the most likely factor responsible for beak deformities in Alaskan birds...
Literature Cited for Beak Deformities
Literature Cited in the Beak Deformity web pages
Prevalence, Distribution and Timing of Beak Deformities in Birds
The rates of beak deformities documented in Black-capped Chickadees and American Crows in Alaska are the highest ever recorded within a wild bird population anywhere.
Effects of Beak Deformities on Birds
Birds with beak deformities often have difficulty foraging and preening and may not be able to keep themselves warm and well-fed during cold winter months. Although some birds with beak deformities breed successfully, they typically encounter more challenges than normal birds.
Background of Beak Deformity Research
Large numbers of Black-capped Chickadees with abnormal beaks were reported in south-central Alaska in the late 1990s. More recently, similar beak deformities have appeared in other species throughout the state. At least 30 Alaskan bird species are affected and the geographic extent of the problem appears to be growing. In addition to Alaskan observations, we have received increasing numbers of...
Species Affected by Beak Deformities
At least 30 Alaskan bird species are affected by beak deformities and the geographic extent of the problem appears to be growing. In addition to Alaskan observations, we have received increasing numbers of reports from other parts of North America and Europe.
Below are multimedia items associated with this project.
Black-capped Chickadee with a deformed crossed beak
Black-capped Chickadee with a deformed crossed beakA Black-capped Chickadee with a beak that has grown long and crossed
Black-capped Chickadee with a deformed crossed beak
Black-capped Chickadee with a deformed crossed beakA Black-capped Chickadee with a beak that has grown long and crossed
Red-breasted Nuthatch with an elongated deformed beak
Red-breasted Nuthatch with an elongated deformed beakA female Red-breasted Nuthatch with an elongated deformed beak. It was captured in Anchorage as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Red-breasted Nuthatch with an elongated deformed beak
Red-breasted Nuthatch with an elongated deformed beakA female Red-breasted Nuthatch with an elongated deformed beak. It was captured in Anchorage as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Boreal Chickadee with a mildly deformed beak
A Boreal Chickadee with a mildly deformed beak.
A Boreal Chickadee with a mildly deformed beak.
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight. Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds.
Black-capped Chickadee with lower elongated and upper curved beak
Black-capped Chickadee with lower elongated and upper curved beakA Black-capped Chickadee with a severely deformed beak where the upper beak is elongated and curved down while the lower beak is elongated and straight. Over the past 26 years, Alaskans have witnessed a startling increase of beak deformities among Black-capped Chickadees and other species of resident birds.
Black-capped Chickadee captured at an Anchorage banding station
Black-capped Chickadee captured at an Anchorage banding stationA Black-capped Chickadee with a normal beak captured at an Anchorage banding station.
Black-capped Chickadee captured at an Anchorage banding station
Black-capped Chickadee captured at an Anchorage banding stationA Black-capped Chickadee with a normal beak captured at an Anchorage banding station.
Black-capped Chickadee with a mildly deformed beak
Black-capped Chickadee with a mildly deformed beakA Black-capped Chickadee with an upper beak slightly longer than the lower beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a mildly deformed beak
Black-capped Chickadee with a mildly deformed beakA Black-capped Chickadee with an upper beak slightly longer than the lower beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a deformed beak that has grown long and curved down
Black-capped Chickadee with a deformed beak that has grown long and curved downA Black-capped Chickadee with a beak that has grown long and curved down. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a deformed beak that has grown long and curved down
Black-capped Chickadee with a deformed beak that has grown long and curved downA Black-capped Chickadee with a beak that has grown long and curved down. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a crossed beak on a branch
Black-capped Chickadee with a crossed beak on a branchBlack-capped Chickadee with a crossed beak on a branch.
Black-capped Chickadee with a crossed beak on a branch
Black-capped Chickadee with a crossed beak on a branchBlack-capped Chickadee with a crossed beak on a branch.
Normal Black-capped Chickadee
Normal Black-capped Chickadee
Normal Black-capped Chickadee
Northwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska
Northwestern Crow with deformed top beak in Auke Bay, Juneau, AlaskaNorthwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska
Northwestern Crow with deformed top beak in Auke Bay, Juneau, AlaskaNorthwestern Crow with deformed top beak in Auke Bay, Juneau, Alaska. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a long down-curved elongated top beak
Black-capped Chickadee with a long down-curved elongated top beakBlack-capped Chickadee with a long down-curved elongated top beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with a long down-curved elongated top beak
Black-capped Chickadee with a long down-curved elongated top beakBlack-capped Chickadee with a long down-curved elongated top beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with an elongated and decurved maxilla
Black-capped Chickadee with an elongated and decurved maxillaBlack-capped Chickadee with an elongated and decurved maxilla.
Black-capped Chickadee with an elongated and decurved maxilla
Black-capped Chickadee with an elongated and decurved maxillaBlack-capped Chickadee with an elongated and decurved maxilla.
Northwestern Crow with an elongated lower beak
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Northwestern Crow with an elongated lower beak. It was captured as part of the beak deformity research project. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with elongated upper beak
Black-capped Chickadee with elongated upper beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with elongated upper beak. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with upper long, curved down beak and crossed
Black-capped Chickadee with upper long, curved down beak and crossedBlack-capped Chickadee with upper long, curved down beak and crossed. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.
Black-capped Chickadee with upper long, curved down beak and crossed
Black-capped Chickadee with upper long, curved down beak and crossedBlack-capped Chickadee with upper long, curved down beak and crossed. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues. Affected birds have difficulty feeding and preening and may suffer high rates of mortality.