A Black-capped Chickadee with a beak that has grown long and crossed
Literature Cited in the Beak Deformity web pages
Return to Ecosystems >> Terrestrial Ecosystems or Wildlife Disease and Environmental Health >> Beak Deformities
Sources/Usage: Public Domain. View Media Details
- Beak Deformity and Banded Bird Observation Report
- Beak Deformity Home
- Background
- Species Affected
- Physical Description
- Prevalence, Distribution and Timing
- Effects on Birds
- Possible Causes
- Photo Gallery - see the Multimedia tab
- Publications - see the Publications tab
- Links
- Literature Cited
Altman, R. B. 1986. Noninfectious diseases. Pp. 379–385 in Fowler, M. E., ed. Zoo and wild animal medicine, second edition. W. B. Saunders Co., Philadelphia.
Altman, R. B., S. L. Clubb, G. M. Dorrestein, and K. Quesenberry. 1997. Avian medicine and surgery. W. B. Saunders Co., Philadelphia.
Bailey, R., L. A. Barrie, C. J. Halsall, P. Fellin, and D. C. G. Muir. 2000. Atmospheric organochlorine pesticides in the western Canadian Arctic: evidence of transpacific transport. J. Geophys. Res. 105:11805–11811.
Blais, J. M., D. W. Schindler, D. C. G. Muir, L. E. Kimpe, D. B. Donald, and B. Rosenberg. 1998. Accumulation of persistent organochlorine compounds in mountains of western Canada. Nature 395:585–588.
Chaplin, S. B. 1974. Daily energetics of the Black-capped Chickadee, Parus atricapillus, in winter. J. Comp. Physiol. B. 89:321–330.
Chaplin, S. B. 1976. The physiology of hypothermia in the Black-capped Chickadee Parus atricapillus. J. Comp. Physiol. B. 112:335–344.
Craves, J. A. 1994. Passerines with deformed bills. N. Am. Bird Bander 19:14-18.
Custer, T. W., J. W. Bickham, T. B. Lyne, T. Lewis, L. A. Ruedas, C. M. Custer, and M. J. Melancon. 1994. Flow cytometry for monitoring contaminant exposure in Black-crowned Night Herons. Arch. Environ. Contam. Toxicol. 27:176-179.
Easton, M. 1999. A report to the United States Fish and Wildlife Service on an investigation of DNA damage in Black-capped Chickadees. Unpublished report. International EcoGen, Inc., North Vancouver, BC.
Gilbertson, M., T. Kubiak, J. Ludwig, and G. Fox. 1991. Great Lakes embryo mortality, edema, and deformities syndrome (GLEMEDS) in colonial fish-eating birds: similarities to chick-edema disease. J. Toxicol. Environ. Health 33:455–520.
Harrison, G. J., and L. R. Harrison. 1986. Nutritional diseases. Pp. 397–407 in Harrison, G. J., and L. R. Harrison, eds. Clinical avian medicine and surgery. W. B. Saunders Co., Philadelphia.
Hitchcock, C. L., and D. F. Sherry. 1990. Long-term memory for cache sites in the Black-capped Chickadee. Anim. Behav. 40:701–712.
Hoffman, D. J., H. M. Ohlendorf, and T. W. Aldrich. 1988. Selenium teratogenesis in natural populations of aquatic birds in central California. Arch. Environ. Contam. Toxicol. 17:519–525.
Ludwig, J. P., H. Kurita Matsuba, H. J. Auman, M. E. Ludwig, C. L. Summer, J. P. Glesy, D. E. Tillitt, and P. D. Jones. 1996. Deformities, PCBs, and TCDD-equivalents in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) of the upper Great Lakes 1986–1991: testing a cause-effect hypothesis. J. Great Lakes Research 22:172–197.
Ohlendorf, H. M., D. J. Hoffman, M. K. Saiki, and T. W. Aldrich. 1986. Embryonic mortality and abnormalities of aquatic birds: apparent impacts by selenium from irrigation drainwater. Sci. Total Environ. 52:49–63.
Pomeroy, D. E. 1962. Birds with abnormal bills. Brit. Birds 55:48-72.
Pravosudov, V. V., and N. S. Clayton. 2002. A test of the adaptive specialization hypothesis: population differences in caching, memory, and the hippocampus in Black-capped Chickadees (Poecile atricapilla). Behav. Neuroscience 116:515–522.
Pravosudov, V. V., and J. R. Lucas. 2000. The costs of being cool: a dynamic model of nocturnal hypothermia by small food-caching birds in winter. J. Avian Biol. 32:463–472.
Ritchie, B. W., G. J. Harrison, and L. R. Harrison. 1994. Avian medicine: principles and application. Wingers Publishing, Inc., Lake Worth, FL.
Sharbaugh, S. M. 2001. Seasonal acclimatization to extreme climatic conditions by Black-capped Chickadees (Poecile atricapilla) in interior Alaska (64° N). Physiolog. Biochem. Zool. 74:568–575.
Smith, S. M. 1991. The Black-capped Chickadee: behavioral ecology and natural history. Comstock Publ. Assoc., Ithaca, NY.
Smith, S. M. 1993. Black-capped Chickadee. In Poole, A., P. Stettenheim, and F. Gill, eds. The Birds of North America, No. 39. Academy of Natural Sciences, Philadelphia, PA, and American Ornithologists’ Union, Washington, DC.
Tully, T. N., Jr., M. P. C. Lawton, and G. M. Dorrestein. 2000. Avian medicine. Reprinted in 2003. Butterworth Heinemann, New York.
Vannucci, F. A., D. C. Linhares, D. E. Barcellos, H. C. Lam, J. Collins, and D. Marthaler. 2015. Identification and complete genome of Seneca Valley virus in vescilur fluid and sera of pigs affected with idiopathic vesicular disease, Brazil. Transbound Emerg Dis 62:589-593.
West, G. C. 1959. Effects of high air temperature on the bill and claw keratin structures of the Tree Sparrow. Auk 76:534-537.
Below are other science projects associated with this project.
Beak Deformities in Landbirds
Over the past 20 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.
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 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.
Physical Description of Beak Deformities
The most commonly observed physical abnormalities among Alaskan birds are overgrown or crossed beaks. 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.
Prevalence, Distribution and Timing of Beak Deformities in Birds
The rates of beak deformities documented in Black-capped Chickadees and Northwestern Crows in Alaska are the highest ever recorded within a wild bird population anywhere.
Beak Deformity's Effects 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.
Possible Causes for Beak Deformities
Beak deformities can be caused by a variety of factors, including contaminants, nutritional deficiencies, disease, parasites, blunt trauma, or genetic abnormalities. We recently 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...
Links Related to Beak Deformity Research
Links, videos and news articles related to beak deformity research
Below are multimedia items associated with this project.
Black-capped Chickadee with a deformed crossed beak
A Black-capped Chickadee with a beak that has grown long and crossed
Boreal Chickadee with a mildly deformed beak
A Boreal Chickadee with a mildly deformed beak.
A Boreal Chickadee with a mildly deformed beak.
A Red-breasted Nuthatch captured at an Anchorage banding station
A Red-breasted Nuthatch captured at an Anchorage banding station
A Red-breasted Nuthatch captured at an Anchorage banding station
Black-capped Chickadee with lower elongated and upper curved beak
A 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. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
A 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. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Black-capped Chickadee with lower elongated and upper curved beak
A 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
A 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 a mildly deformed beak
A 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.
A 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 captured at an Anchorage banding station
A black-capped chickadee with a normal beak captured at an Anchorage banding station.
A black-capped chickadee with a normal beak captured at an Anchorage banding station.
Slate-colored Junco
A Slate-colored Junco on Middleton Island, Alaska.
A Slate-colored Junco on Middleton Island, Alaska.
Black-capped Chickadee with a deformed beak that has grown long and curved down
A 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.
A 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 branch.
Black-capped Chickadee with a crossed beak on a branch.
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, 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. 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 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. 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 maxilla.
Black-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.
Black-capped Chickadee with a long upper beak in the brush
Black-capped Chickadee with a long upper beak in the brush. 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 upper beak in the brush. 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 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. 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.
Literature Cited in the Beak Deformity web pages
Return to Ecosystems >> Terrestrial Ecosystems or Wildlife Disease and Environmental Health >> Beak Deformities
Sources/Usage: Public Domain. View Media Details
- Beak Deformity and Banded Bird Observation Report
- Beak Deformity Home
- Background
- Species Affected
- Physical Description
- Prevalence, Distribution and Timing
- Effects on Birds
- Possible Causes
- Photo Gallery - see the Multimedia tab
- Publications - see the Publications tab
- Links
- Literature Cited
Altman, R. B. 1986. Noninfectious diseases. Pp. 379–385 in Fowler, M. E., ed. Zoo and wild animal medicine, second edition. W. B. Saunders Co., Philadelphia.
Altman, R. B., S. L. Clubb, G. M. Dorrestein, and K. Quesenberry. 1997. Avian medicine and surgery. W. B. Saunders Co., Philadelphia.
Bailey, R., L. A. Barrie, C. J. Halsall, P. Fellin, and D. C. G. Muir. 2000. Atmospheric organochlorine pesticides in the western Canadian Arctic: evidence of transpacific transport. J. Geophys. Res. 105:11805–11811.
Blais, J. M., D. W. Schindler, D. C. G. Muir, L. E. Kimpe, D. B. Donald, and B. Rosenberg. 1998. Accumulation of persistent organochlorine compounds in mountains of western Canada. Nature 395:585–588.
Chaplin, S. B. 1974. Daily energetics of the Black-capped Chickadee, Parus atricapillus, in winter. J. Comp. Physiol. B. 89:321–330.
Chaplin, S. B. 1976. The physiology of hypothermia in the Black-capped Chickadee Parus atricapillus. J. Comp. Physiol. B. 112:335–344.
Craves, J. A. 1994. Passerines with deformed bills. N. Am. Bird Bander 19:14-18.
Custer, T. W., J. W. Bickham, T. B. Lyne, T. Lewis, L. A. Ruedas, C. M. Custer, and M. J. Melancon. 1994. Flow cytometry for monitoring contaminant exposure in Black-crowned Night Herons. Arch. Environ. Contam. Toxicol. 27:176-179.
Easton, M. 1999. A report to the United States Fish and Wildlife Service on an investigation of DNA damage in Black-capped Chickadees. Unpublished report. International EcoGen, Inc., North Vancouver, BC.
Gilbertson, M., T. Kubiak, J. Ludwig, and G. Fox. 1991. Great Lakes embryo mortality, edema, and deformities syndrome (GLEMEDS) in colonial fish-eating birds: similarities to chick-edema disease. J. Toxicol. Environ. Health 33:455–520.
Harrison, G. J., and L. R. Harrison. 1986. Nutritional diseases. Pp. 397–407 in Harrison, G. J., and L. R. Harrison, eds. Clinical avian medicine and surgery. W. B. Saunders Co., Philadelphia.
Hitchcock, C. L., and D. F. Sherry. 1990. Long-term memory for cache sites in the Black-capped Chickadee. Anim. Behav. 40:701–712.
Hoffman, D. J., H. M. Ohlendorf, and T. W. Aldrich. 1988. Selenium teratogenesis in natural populations of aquatic birds in central California. Arch. Environ. Contam. Toxicol. 17:519–525.
Ludwig, J. P., H. Kurita Matsuba, H. J. Auman, M. E. Ludwig, C. L. Summer, J. P. Glesy, D. E. Tillitt, and P. D. Jones. 1996. Deformities, PCBs, and TCDD-equivalents in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Hydroprogne caspia) of the upper Great Lakes 1986–1991: testing a cause-effect hypothesis. J. Great Lakes Research 22:172–197.
Ohlendorf, H. M., D. J. Hoffman, M. K. Saiki, and T. W. Aldrich. 1986. Embryonic mortality and abnormalities of aquatic birds: apparent impacts by selenium from irrigation drainwater. Sci. Total Environ. 52:49–63.
Pomeroy, D. E. 1962. Birds with abnormal bills. Brit. Birds 55:48-72.
Pravosudov, V. V., and N. S. Clayton. 2002. A test of the adaptive specialization hypothesis: population differences in caching, memory, and the hippocampus in Black-capped Chickadees (Poecile atricapilla). Behav. Neuroscience 116:515–522.
Pravosudov, V. V., and J. R. Lucas. 2000. The costs of being cool: a dynamic model of nocturnal hypothermia by small food-caching birds in winter. J. Avian Biol. 32:463–472.
Ritchie, B. W., G. J. Harrison, and L. R. Harrison. 1994. Avian medicine: principles and application. Wingers Publishing, Inc., Lake Worth, FL.
Sharbaugh, S. M. 2001. Seasonal acclimatization to extreme climatic conditions by Black-capped Chickadees (Poecile atricapilla) in interior Alaska (64° N). Physiolog. Biochem. Zool. 74:568–575.
Smith, S. M. 1991. The Black-capped Chickadee: behavioral ecology and natural history. Comstock Publ. Assoc., Ithaca, NY.
Smith, S. M. 1993. Black-capped Chickadee. In Poole, A., P. Stettenheim, and F. Gill, eds. The Birds of North America, No. 39. Academy of Natural Sciences, Philadelphia, PA, and American Ornithologists’ Union, Washington, DC.
Tully, T. N., Jr., M. P. C. Lawton, and G. M. Dorrestein. 2000. Avian medicine. Reprinted in 2003. Butterworth Heinemann, New York.
Vannucci, F. A., D. C. Linhares, D. E. Barcellos, H. C. Lam, J. Collins, and D. Marthaler. 2015. Identification and complete genome of Seneca Valley virus in vescilur fluid and sera of pigs affected with idiopathic vesicular disease, Brazil. Transbound Emerg Dis 62:589-593.
West, G. C. 1959. Effects of high air temperature on the bill and claw keratin structures of the Tree Sparrow. Auk 76:534-537.
Below are other science projects associated with this project.
Beak Deformities in Landbirds
Over the past 20 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.
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 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.
Physical Description of Beak Deformities
The most commonly observed physical abnormalities among Alaskan birds are overgrown or crossed beaks. 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.
Prevalence, Distribution and Timing of Beak Deformities in Birds
The rates of beak deformities documented in Black-capped Chickadees and Northwestern Crows in Alaska are the highest ever recorded within a wild bird population anywhere.
Beak Deformity's Effects 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.
Possible Causes for Beak Deformities
Beak deformities can be caused by a variety of factors, including contaminants, nutritional deficiencies, disease, parasites, blunt trauma, or genetic abnormalities. We recently 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...
Links Related to Beak Deformity Research
Links, videos and news articles related to beak deformity research
Below are multimedia items associated with this project.
Black-capped Chickadee with a deformed crossed beak
A Black-capped Chickadee with a beak that has grown long and crossed
A Black-capped Chickadee with a beak that has grown long and crossed
Boreal Chickadee with a mildly deformed beak
A Boreal Chickadee with a mildly deformed beak.
A Boreal Chickadee with a mildly deformed beak.
A Red-breasted Nuthatch captured at an Anchorage banding station
A Red-breasted Nuthatch captured at an Anchorage banding station
A Red-breasted Nuthatch captured at an Anchorage banding station
Black-capped Chickadee with lower elongated and upper curved beak
A 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. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
A 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. Avian keratin disorder (AKD) is a disease characterized by debilitating beak overgrowth and other abnormalities of keratinized tissues.
Black-capped Chickadee with lower elongated and upper curved beak
A 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
A 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 a mildly deformed beak
A 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.
A 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 captured at an Anchorage banding station
A black-capped chickadee with a normal beak captured at an Anchorage banding station.
A black-capped chickadee with a normal beak captured at an Anchorage banding station.
Slate-colored Junco
A Slate-colored Junco on Middleton Island, Alaska.
A Slate-colored Junco on Middleton Island, Alaska.
Black-capped Chickadee with a deformed beak that has grown long and curved down
A 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.
A 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 branch.
Black-capped Chickadee with a crossed beak on a branch.
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, 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. 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 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. 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 maxilla.
Black-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.
Black-capped Chickadee with a long upper beak in the brush
Black-capped Chickadee with a long upper beak in the brush. 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 upper beak in the brush. 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 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. 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.