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
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.