The Honolulu Field Station provides routine diagnostic support to state and federal agencies in order to determine cause of death in endangered and threatened native birds in Hawaii, US territories, and affiliated states in the Pacific. These activities have resulted in information that was important in the recovery of several species of endangered birds such as Laysan ducks, Nihoa millerbirds, Hawaiian ducks, and Hawaiian crows.

Surveillance
Doing necropsies on birds to determine cause of death permits us to keep tabs on the health of wild bird populations and allows for detection of new threats. For instance, the discovery of Toxoplasma gondii, a parasite transmitted by feral cats, as a cause of native Hawaiian crow declines in mid-elevation forests on the Island of Hawaii prompted removal of remnant crows from the wild. Present reintroductions of crows to their native range are coupled with aggressive management of feral cats to reduce impacts of this parasite to newly released crows. Likewise, the discovery of botulism, a bacteria-produced toxin in wetlands, as a cause of death in endangered waterfowl has resulted in management of environmental factors to reduce the impacts of this toxin on Hawaiian wetlands.
Research
Mariana crows are one of the most endangered crows in the world. Populations of this bird were historically on Rota and Guam but were extirpated from the latter because of predation by the brown tree snake. Since then, the only remnant population of this bird is on Rota where numbers have declined over 90% since the mid-1980s for unknown reasons. Introduced predators like rats, feral cats, and monitor lizards, as well as habitat destruction, human persecution, and disease are suspected causes of this decline. Crow habitat on Rota has been protected since 1994, and removal of non-native predators from core breeding habitat began in 2012; however high rates of mortality continue to affect the population.
We are working closely with the CNMI Department of Fish & Wildlife, the US Fish and Wildlife Service, and the University of Washington to better understand actual causes of crow declines. This process is complicated by the remoteness of the island, difficulty in detecting dead birds and shipping them to laboratories to determine cause of death. Recently, however, due to concerted efforts by field biologists on Rota, the HFS has received carcasses of immature Mariana crows in suitable post-mortem condition. Necropsies of crows have revealed a consistent pattern of massive inflammation of the liver and lung suggesting that crows might be dying from an infectious disease or, less plausibly, some sort of toxin. An infectious disease amongst immature Mariana crows may thus explain why the birds have been declining on Rota. HFS is currently collaborating with a variety of laboratories to determine what might be causing these lesions in immature Mariana crows.
Resources
Seabird Necropsy Manual
Below are other science projects associated with this project.
Avian Botulism
Toxoplasmosis
Below are publications associated with this project.
Toxoplasma gondii antibody prevalence and two new genotypes of the parasite in endangered Hawaiian Geese (nene: Branta sandvicensis)
Mortality patterns in endangered Hawaiian geese (Nene; Branta sandvicensis)
Infection by Haemoproteus parasites in four species of frigatebirds and the description of a new species of Haemoproteus (Haemosporida: Haemoproteidae)
Avian botulism: a case study in translocated endangered Laysan ducks (Anas laysanensis) on Midway Atoll
Translocation and disease monitoring of wild laysan ducks
Molecular phylogeny of Babesia poelea from brown boobies (Sula leucogaster) from Johnston Atoll, Central Pacific
Mortality in the endangered Laysan teal, Anas laysanensis: conservation implications
Mortality in Laysan ducks (Anas laysanensis) by emaciation complicated by Echinuria uncinata on Laysan Island, Hawaii, 1993
Toxoplasmosis in three species of native and introduced Hawaiian birds
Fatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii
Necrotizing enteritis as a cause of mortality in Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll, Hawaii
Description and epizootiology of Babesia poelea n. sp. in brown boobies (Sula leucogaster (Boddaert)) on Sand Island, Johnston Atoll, Central Pacific
- Overview
The Honolulu Field Station provides routine diagnostic support to state and federal agencies in order to determine cause of death in endangered and threatened native birds in Hawaii, US territories, and affiliated states in the Pacific. These activities have resulted in information that was important in the recovery of several species of endangered birds such as Laysan ducks, Nihoa millerbirds, Hawaiian ducks, and Hawaiian crows.
Sources/Usage: Some content may have restrictions. Visit Media to see details.A mating pair of adult nēnē (Branta sandvicensis) keep a close watch on three young goslings. An endangered species and the state bird of Hawai‘i, nēnē are affected by the parasite Toxoplasma gondii.(Credit: USGS.) Surveillance
Doing necropsies on birds to determine cause of death permits us to keep tabs on the health of wild bird populations and allows for detection of new threats. For instance, the discovery of Toxoplasma gondii, a parasite transmitted by feral cats, as a cause of native Hawaiian crow declines in mid-elevation forests on the Island of Hawaii prompted removal of remnant crows from the wild. Present reintroductions of crows to their native range are coupled with aggressive management of feral cats to reduce impacts of this parasite to newly released crows. Likewise, the discovery of botulism, a bacteria-produced toxin in wetlands, as a cause of death in endangered waterfowl has resulted in management of environmental factors to reduce the impacts of this toxin on Hawaiian wetlands.
Research
Mariana crows are one of the most endangered crows in the world. Populations of this bird were historically on Rota and Guam but were extirpated from the latter because of predation by the brown tree snake. Since then, the only remnant population of this bird is on Rota where numbers have declined over 90% since the mid-1980s for unknown reasons. Introduced predators like rats, feral cats, and monitor lizards, as well as habitat destruction, human persecution, and disease are suspected causes of this decline. Crow habitat on Rota has been protected since 1994, and removal of non-native predators from core breeding habitat began in 2012; however high rates of mortality continue to affect the population.
Sources/Usage: Public Domain. Visit Media to see details.Mariana crows. (Credit: Phillip Hannon, University of Washington Rota Avian Behavioral Ecology Program.) We are working closely with the CNMI Department of Fish & Wildlife, the US Fish and Wildlife Service, and the University of Washington to better understand actual causes of crow declines. This process is complicated by the remoteness of the island, difficulty in detecting dead birds and shipping them to laboratories to determine cause of death. Recently, however, due to concerted efforts by field biologists on Rota, the HFS has received carcasses of immature Mariana crows in suitable post-mortem condition. Necropsies of crows have revealed a consistent pattern of massive inflammation of the liver and lung suggesting that crows might be dying from an infectious disease or, less plausibly, some sort of toxin. An infectious disease amongst immature Mariana crows may thus explain why the birds have been declining on Rota. HFS is currently collaborating with a variety of laboratories to determine what might be causing these lesions in immature Mariana crows.
Resources
Seabird Necropsy Manual
- Science
Below are other science projects associated with this project.
Avian Botulism
Botulism is a natural toxin produced by a bacterium ( Clostridium botulinum ) commonly found in the soil. There are several types of botulism toxin some of which can affect humans who eat improperly canned foods. Birds get their own kind of botulism (Type C in Hawaii) that does not affect humans. Botulism type C is concentrated in aquatic invertebrates that filter feed sediments or water. When...Toxoplasmosis
Toxoplasmosis is caused by a microscopic parasites called a protozoan. The specific name of the protozoan that causes toxoplasmosis is Toxoplasma gondii. T. gondii reproduces in the gut of cats (all members of the Felidae are susceptible). Cats shed the parasite in their feces, and the parasite is ingested by other animals (intermediate hosts) causing disease. Cats can acquire the parasite from... - Publications
Below are publications associated with this project.
Filter Total Items: 15Toxoplasma gondii antibody prevalence and two new genotypes of the parasite in endangered Hawaiian Geese (nene: Branta sandvicensis)
Toxoplasma gondii is a protozoan parasite transmitted by domestic cats (Felis catus) that has historically caused mortality in native Hawaiian birds. To estimate how widespread exposure to the parasite is in nene (Hawaiian Geese, Branta sandvicensis), we did a serologic survey for T. gondii antibody and genetically characterized parasite DNA from the tissues of dead birds that had confirmed infectAuthorsThierry M. Work, Shiv K. Verma, Chunlei Su, John Medeiros, Thomas Kaiakapu, Oliver C. Kwok, Jitender P. DubeyMortality patterns in endangered Hawaiian geese (Nene; Branta sandvicensis)
Understanding causes of death can aid management and recovery of endangered bird populations. Toward those ends, we systematically examined 300 carcasses of endangered Hawaiian Geese (Nene; Branta sandvicensis) from Hawaii, Maui, Molokai, and Kauai between 1992 and 2013. The most common cause of death was emaciation, followed by trauma (vehicular strikes and predation), and infectious/inflammatoryAuthorsThierry M. Work, Julie Dagenais, Robert Rameyer, Renee BreedenInfection by Haemoproteus parasites in four species of frigatebirds and the description of a new species of Haemoproteus (Haemosporida: Haemoproteidae)
Among seabirds, the fregatids stand out with a high prevalence of blood parasites. Four of 5 species in this family have been found to be infected with Haemoproteus; however, complete species descriptions with molecular phylogeny are lacking. Seventy-five samples from 4 species of frigatebirds, i.e., Fregata andrewsi, Fregata minor, Fregata magnificens, and Fregata aquila, were screened for infectAuthorsSantiago Merino, Janos Hennicke, Javier Martinez, Katrin Ludynia, Roxana Torres, Thierry M. Work, Stedson Stroud, Juan F. Masello, Petra QuillfeldtAvian botulism: a case study in translocated endangered Laysan ducks (Anas laysanensis) on Midway Atoll
Laysan Ducks are endemic to the Hawaiian archipelago and are one of the world’s most endangered waterfowl. For 150 yr, Laysan Ducks were restricted to an estimated 4 km2 of land on Laysan Island in the northwestern Hawaiian Islands. In 2004 and 2005, 42 Laysan Ducks were translocated to Midway Atoll, and the population increased to approximately 200 by 2007. In August 2008, mortality due to botuliAuthorsThierry M. Work, John L. Klavitter, Michelle H. Reynolds, David S. BlehertTranslocation and disease monitoring of wild laysan ducks
The Laysan duck (Anas laysanensis), also known as the Laysan teal because of its small size, is a critically endangered waterfowl species that once occurred widely across the Hawaiian Archipelago. For the past 150 years, however, it was restricted to a single population on Laysan, a 4-square-kilometer (1.5-square-mile) island with a hypersaline shallow lake. Laysan is part of the Hawaiian IslandsAuthorsMichelle H. Reynolds, Thierry M. WorkMolecular phylogeny of Babesia poelea from brown boobies (Sula leucogaster) from Johnston Atoll, Central Pacific
The phylogenetic relationship of avian Babesia with other piroplasms remains unclear, mainly because of a lack of objective criteria such as molecular phylogenetics. In this study, our objective was to sequence the entire 18S, ITS-1, 5.8S, and ITS-2 regions of the rRNA gene and partial ß-tubulin gene of B. poelea, first described from brown boobies (Sula leucogaster) from the central Pacific, andAuthorsMichael J. Yabsley, Thierry M. Work, Robert A. RameyerMortality in the endangered Laysan teal, Anas laysanensis: conservation implications
The Laysan Teal Anas laysanensis is an endangered anatid of the Hawaiian Islands, currently restricted to an emergent atoll, Laysan Island. Laysan Island lacks terrestrial mammalian predators, which permits the examination of mortality rates and causes without the anthropogenic effects of introduced predators. Mass and morophometrics were measured during the colour-marking of 297 Laysan Teal betweAuthorsM.H. Reynolds, Thierry M. WorkMortality in Laysan ducks (Anas laysanensis) by emaciation complicated by Echinuria uncinata on Laysan Island, Hawaii, 1993
In November 1993, unusual mortality occurred among endangered Laysan ducks on Laysan Island, one of the remote refugia of the Northwestern Hawaiian Islands National Wildlife Refuge (USA). Ten live ducks were emaciated, and blood samples documented anemia, heterophilia, and eosinophilia. Pathology in 13 duck carcasses revealed emaciation, marked thickening of the proventricular wall, abundant mucusAuthorsThierry M. Work, Carol U. Meteyer, Rebecca A. ColeToxoplasmosis in three species of native and introduced Hawaiian birds
Toxoplasma gondii was found in endemic Hawaiian birds, including 2 nene geese (Nesochen sandvicensis), 1 red-footed booby (Sula sula), and an introduced bird, the Erckels francolin (Francolinus erckelii). All 4 birds died of disseminated toxoplasmosis; the parasite was found in sections of many organs, and the diagnosis was confirmed by immunohistochemical staining with anti–T. gondii–specific polAuthorsThierry M. Work, J. Gregory Massey, D. S. Lindsay, J. P. DubeyFatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii
The ‘Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging ‘Alala. One ‘Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measureAuthorsThierry M. Work, J. Gregory Massey, Bruce A. Rideout, Chris H. Gardiner, David B. Ledig, O. C. H. Kwok, J. P. DubeyNecrotizing enteritis as a cause of mortality in Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll, Hawaii
A necropsy survey of Laysan albatross, Diomedea immutabilis, chicks on Midway Atoll in June 1993, 1994, and 1995 revealed 54% (21/39), 67% (49/71), and 93% (15/16), respectively, to have enteritis as the most severe pathologic finding. The lesion was limited to the ileum, ceca, and large intestine. We were unable to attribute a single infectious etiology to this lesion. Many birds with enteritis aAuthorsThierry M. Work, M. R. Smith, R. DuncanDescription and epizootiology of Babesia poelea n. sp. in brown boobies (Sula leucogaster (Boddaert)) on Sand Island, Johnston Atoll, Central Pacific
We describe a new species of piroplasm from brown boobies (Sula leucogaster) on Sand Island, Johnston Atoll National Wildlife Refuge, central Pacific. Mean parasitemia in adults and chicks was less than 1%, with the parasitemia in chicks significantly greater than in adults. There was no significant relation between the age of chicks and the degree of parasitemia. Parasitized red cells and red celAuthorsThierry M. Work, Robert Rameyer