Invasive Mammals of the Pacific Completed
The terrestrial biota of the Central Pacific is primarily defined by its degree of isolation. At the center lies the Hawaiian Archipelago, which is more than 3,200 km from any continental land mass. After tens of millions of years of evolutionary isolation from all mammals except bats, islands of the Central Pacific were quite suddenly besieged by a number of alien rodents, carnivores and both large and small herbivores. The first mammals were introduced by early canoe voyagers of the Pacific more than 1,000 years ago. The discovery of the Hawaiian Islands by Cook in 1778, like many other islands of the Pacific, marked the second wave of introductions of many hoofed animals for beasts of burden, milk, hides and meat as well as small predators to keep an assortment of stowaway rodents at bay.
Overview:
The terrestrial biota of the Central Pacific is primarily defined by its degree of isolation. At the center lies the Hawaiian Archipelago, which is more than 3,200 km from any continental land mass. After tens of millions of years of evolutionary isolation from all mammals except bats, islands of the Central Pacific were quite suddenly besieged by a number of alien rodents, carnivores and both large and small herbivores. The first mammals were introduced by early canoe voyagers of the Pacific more than 1,000 years ago. The discovery of the Hawaiian Islands by Cook in 1778, like many other islands of the Pacific, marked the second wave of introductions of many hoofed animals for beasts of burden, milk, hides and meat as well as small predators to keep an assortment of stowaway rodents at bay.
Rapid ecological degradation ensued and whole groups of endemic plants and animals suffered extinctions, including virtually all flightless birds, and roughly nine percent of all Hawaiian flora. After a century of settlement by westerners, the concept of eradicating non-native species came about as a solution to primarily agricultural, public health, or economic problems, and only more recently to solve ecological problems. Reversing the devastating effects of alien mammals has proven to be difficult, but limited successes have resulted in the dramatic recovery of native biota.
Mammals General Overview
Most of the isolated islands of the Pacific existed for tens of millions of years in the absence of terrestrial mammals except for bats, which were able to fly over vast oceans and establish themselves. The first human colonists of these islands brought with them domestic pigs (Sus scrofa) from island southeast Asia and Polynesian rats (Rattus exulans). European colonists brought an assortment of other mammals with them nearly 1,000 years later, including domestic goats (Capra hircus), sheep (Ovis aries), cattle (Bos taurus), other types of wild and domestic pigs, cats (Felis catus), rabbits (Oryctolagus cuniculus), rats (R. rattus and R. norvegicus), and mice (Mus musculus). In the absence of natural predators and competitors, these species became abundant on nearly every island, which caused rapid ecological degradation. Native plants of the islands were poorly defended against the newly established herbivores, and native wildlife were naïve to tree-climbing predators with teeth. Species which had never been previously domesticated such as axis deer (Axis axis), European mouflon sheep (O. musimon), and mongooses (Herpestes javanicus) were brought to the islands later and proved to be particularly challenging to manage. Diseases associated with introduced mammals such as toxoplasmosis (Toxoplasma gondii), bovine tuberculosis (Mycobacterium bovis), and bubonic plague (Yersinia pestis) have all caused major problems for wildlife, livestock, and human health in Hawai‘i. Invasive mammals have caused the decline and extinction of numerous native plants and animals, but researchers and land managers have developed progressively more effective strategies for managing these species, allowing the recovery and restoration of native species in increasingly larger natural areas.
Small Mammal/Toxoplasmosis Overview
Many factors have contributed to the decline and extinction of birds in Hawai‘i, not the least of which has been introduced mammalian predators like rats, mongooses, and cats. These predators take eggs, kill nestlings, or nesting adults, but are also sources of diseases that kill birds. One such disease known as toxoplasmosis can cause severe developmental disabilities and occasional mortality in humans but can also have lethal consequences for marine mammals. The infectious agent of the disease, Toxoplasma gondii, is a protozoan, a single-celled organism which behaves like an animal. It is considered a parasite, causing infection directly rather than by producing toxins. It is a zoonosis because it is a disease of animals that can also be transmitted to humans. Only cats –regardless of whether they are domestic or wild species– can support sexual reproduction of this parasite, and thereby serve as the definitive host of the disease. Any other warm-blooded animal, most commonly rodents, can also carry the parasite but can only serve as an intermediate host. Intermediate hosts of the parasite and may sometimes be consumed by people, leading to infection. Known intermediate hosts include feral pigs (Sus scrofa) and mouflon sheep (Ovis musimon), both popular game mammals in Hawai‘i. Birds can also be intermediate hosts, and populations that have been infected and killed by T. gondii include the critically endangered ‘Alalā (Corvus hawaiiensis), the endangered Nēnē (Branta sandvicensis), Red-footed Booby (Sula sula), and Erckel’s Francolin (Pternistis erckelii), a common gamebird. Flowing water may transport T. gondii oocysts –hardy, thick-walled, environmentally resistant spores– in runoff from land to streams and then into marine environments. Thus, T. gondii represents a land-based pathogen that can pollute nearshore marine ecosystems and infect a wide variety of animals in this environment including whales, seals dolphins, and sea otters. The leading cause of death of the endangered Hawaiian monk seal (Monachus schauinslandi) is now known to be T. gondii infection. Many aspects of T. gondii are poorly understood, but current research may soon lead to more effective management strategies to protect native wildlife from both toxoplasmosis and predation.
Below are publications associated with this project.
Anatomy of an eradication effort: Removing Hawaii's illegally introduced axis deer
Evaluating the long-term management of introduced ungulates to protect the palila, an endangered bird, and its criticial habitat in subalpine forest of Mauna Kea, Hawai'i
Strength of evidence for the effects of feral cats on insular wildlife: The Club Med Syndrome Part II
How much land is needed for feral pig hunting in Hawai'i?
Locking horns with Hawai‘i’s non-native ungulate issues
Environmental conditions associated with lesions in introduced free-ranging sheep in Hawai‘i
Biology and impacts of Pacific island invasive species 9. Capra hircus, the feral goat, (Mammalia: Bovidae)
Abundance and distribution of feral pigs at Hakalau Forest National Wildlife Refuge, 2010-2013
Videographic evidence of endangered species depredation by feral cat
The effects of feral cats on insular wildlife: the Club-Med syndrome
The history of mammal eradications in Hawai`i and the United States associated islands of the Central Pacific
Survival of European mouflon (Artiodactyla: Bovidae) in Hawai'i based on tooth cementum lines
Below are partners associated with this project.
- Overview
The terrestrial biota of the Central Pacific is primarily defined by its degree of isolation. At the center lies the Hawaiian Archipelago, which is more than 3,200 km from any continental land mass. After tens of millions of years of evolutionary isolation from all mammals except bats, islands of the Central Pacific were quite suddenly besieged by a number of alien rodents, carnivores and both large and small herbivores. The first mammals were introduced by early canoe voyagers of the Pacific more than 1,000 years ago. The discovery of the Hawaiian Islands by Cook in 1778, like many other islands of the Pacific, marked the second wave of introductions of many hoofed animals for beasts of burden, milk, hides and meat as well as small predators to keep an assortment of stowaway rodents at bay.
Overview:
The terrestrial biota of the Central Pacific is primarily defined by its degree of isolation. At the center lies the Hawaiian Archipelago, which is more than 3,200 km from any continental land mass. After tens of millions of years of evolutionary isolation from all mammals except bats, islands of the Central Pacific were quite suddenly besieged by a number of alien rodents, carnivores and both large and small herbivores. The first mammals were introduced by early canoe voyagers of the Pacific more than 1,000 years ago. The discovery of the Hawaiian Islands by Cook in 1778, like many other islands of the Pacific, marked the second wave of introductions of many hoofed animals for beasts of burden, milk, hides and meat as well as small predators to keep an assortment of stowaway rodents at bay.
Rapid ecological degradation ensued and whole groups of endemic plants and animals suffered extinctions, including virtually all flightless birds, and roughly nine percent of all Hawaiian flora. After a century of settlement by westerners, the concept of eradicating non-native species came about as a solution to primarily agricultural, public health, or economic problems, and only more recently to solve ecological problems. Reversing the devastating effects of alien mammals has proven to be difficult, but limited successes have resulted in the dramatic recovery of native biota.
Mammals General Overview
Most of the isolated islands of the Pacific existed for tens of millions of years in the absence of terrestrial mammals except for bats, which were able to fly over vast oceans and establish themselves. The first human colonists of these islands brought with them domestic pigs (Sus scrofa) from island southeast Asia and Polynesian rats (Rattus exulans). European colonists brought an assortment of other mammals with them nearly 1,000 years later, including domestic goats (Capra hircus), sheep (Ovis aries), cattle (Bos taurus), other types of wild and domestic pigs, cats (Felis catus), rabbits (Oryctolagus cuniculus), rats (R. rattus and R. norvegicus), and mice (Mus musculus). In the absence of natural predators and competitors, these species became abundant on nearly every island, which caused rapid ecological degradation. Native plants of the islands were poorly defended against the newly established herbivores, and native wildlife were naïve to tree-climbing predators with teeth. Species which had never been previously domesticated such as axis deer (Axis axis), European mouflon sheep (O. musimon), and mongooses (Herpestes javanicus) were brought to the islands later and proved to be particularly challenging to manage. Diseases associated with introduced mammals such as toxoplasmosis (Toxoplasma gondii), bovine tuberculosis (Mycobacterium bovis), and bubonic plague (Yersinia pestis) have all caused major problems for wildlife, livestock, and human health in Hawai‘i. Invasive mammals have caused the decline and extinction of numerous native plants and animals, but researchers and land managers have developed progressively more effective strategies for managing these species, allowing the recovery and restoration of native species in increasingly larger natural areas.
Small Mammal/Toxoplasmosis Overview
Many factors have contributed to the decline and extinction of birds in Hawai‘i, not the least of which has been introduced mammalian predators like rats, mongooses, and cats. These predators take eggs, kill nestlings, or nesting adults, but are also sources of diseases that kill birds. One such disease known as toxoplasmosis can cause severe developmental disabilities and occasional mortality in humans but can also have lethal consequences for marine mammals. The infectious agent of the disease, Toxoplasma gondii, is a protozoan, a single-celled organism which behaves like an animal. It is considered a parasite, causing infection directly rather than by producing toxins. It is a zoonosis because it is a disease of animals that can also be transmitted to humans. Only cats –regardless of whether they are domestic or wild species– can support sexual reproduction of this parasite, and thereby serve as the definitive host of the disease. Any other warm-blooded animal, most commonly rodents, can also carry the parasite but can only serve as an intermediate host. Intermediate hosts of the parasite and may sometimes be consumed by people, leading to infection. Known intermediate hosts include feral pigs (Sus scrofa) and mouflon sheep (Ovis musimon), both popular game mammals in Hawai‘i. Birds can also be intermediate hosts, and populations that have been infected and killed by T. gondii include the critically endangered ‘Alalā (Corvus hawaiiensis), the endangered Nēnē (Branta sandvicensis), Red-footed Booby (Sula sula), and Erckel’s Francolin (Pternistis erckelii), a common gamebird. Flowing water may transport T. gondii oocysts –hardy, thick-walled, environmentally resistant spores– in runoff from land to streams and then into marine environments. Thus, T. gondii represents a land-based pathogen that can pollute nearshore marine ecosystems and infect a wide variety of animals in this environment including whales, seals dolphins, and sea otters. The leading cause of death of the endangered Hawaiian monk seal (Monachus schauinslandi) is now known to be T. gondii infection. Many aspects of T. gondii are poorly understood, but current research may soon lead to more effective management strategies to protect native wildlife from both toxoplasmosis and predation.
- Publications
Below are publications associated with this project.
Filter Total Items: 37Anatomy of an eradication effort: Removing Hawaii's illegally introduced axis deer
In February 2011, a rancher in the rural southern part of Hawaii Island reported a large mammal on her land. Her call mobilized several agencies led by the Big Island Invasive Species Committee (BIISC), a partnership to prevent, detect, and control the establishment and spread of invasive species, to sit up and take notice. Agency biologists installed camera traps to identify the animal, and a fewAuthorsSteven C. Hess, Jake Muise, Jan SchipperEvaluating the long-term management of introduced ungulates to protect the palila, an endangered bird, and its criticial habitat in subalpine forest of Mauna Kea, Hawai'i
Under the multiple-use paradigm, conflicts may arise when protection of an endangered species must compete with other management objectives. To resolve such a conflict in the Critical Habitat of the endangered Hawaiian honeycreeper, palila (Loxioides bailleui), federal courts ordered the eradication of introduced ungulates responsible for damaging the māmane (Sophora chrysophylla) forest on whichAuthorsPaul C. Banko, Steven C. Hess, Paul G. Scowcroft, Chris Farmer, James D. Jacobi, Robert M. Stephens, Richard J. Camp, David L. Leonard, Kevin W. Brinck, J.O. Juvik, S. P. JuvikStrength of evidence for the effects of feral cats on insular wildlife: The Club Med Syndrome Part II
Various types of evidence have been promulgated as proof for the effects of feral cats on wildlife, typically including numerous studies on predation inferred from diet, mortality attributed to pathogens, and photographic or videographic documentation. The strength of these types of evidence is often short of conclusive. For example, studies of predation inferred from diet provide weak evidence foAuthorsSteve C. HessHow much land is needed for feral pig hunting in Hawai'i?
Hunting is often considered to be incompatible with conservation of native biota and watershed functions in Hawai'i. Management actions for conservation generally exclude large non-native mammals from natural areas, thereby reducing the amount of land area available for hunting activities and the maintenance of sustainable game populations. An approach which may be useful in addressing the necessaAuthorsSteven C. Hess, James D. JacobiLocking horns with Hawai‘i’s non-native ungulate issues
Conservation and management interests for sustained-yield hunting of non-native ungulates in Hawai‘i have conflicted with the conservation of native biota for several decades. Hawaiian ecosystems evolved in the absence of large mammals and all currently hunted animals in Hawai‘i are non-native species. The best-studied aspects of Hawai‘i’s ungulates have dealt primarily with direct negative effectAuthorsSteve C. HessEnvironmental conditions associated with lesions in introduced free-ranging sheep in Hawai‘i
Wildlife species which have been translocated between temperate and tropical regions of the world provide unique opportunities to understand how disease processes may be affected by environmental conditions. European mouflon sheep (Ovis gmelini musimon) from the Mediterranean Islands were introduced to the Hawaiian Islands for sport hunting beginning in 1954 and were subsequently hybridized with fAuthorsJenny G. Powers, Colleen G. Duncan, Terry R. Spraker, Bridget A. Schuler, Steven C. Hess, Jonathan K.J. Faford, Hans SinBiology and impacts of Pacific island invasive species 9. Capra hircus, the feral goat, (Mammalia: Bovidae)
Domestic goats, Capra hircus, were intentionally introduced to numerous oceanic islands beginning in the sixteenth century. The remarkable ability of C. hircus to survive in a variety of conditions has enabled this animal to become feral and impact native ecosystems on islands throughout the world. Direct ecological impacts include consumption and trampling of native plants, leading to plant commuAuthorsMark W. Chynoweth, Creighton M. Litton, Christopher A. Lepczyk, Steve A. Hess, Susan CordellAbundance and distribution of feral pigs at Hakalau Forest National Wildlife Refuge, 2010-2013
The Hakalau Forest Unit of the Big Island National Wildlife Refuge Complex has intensively managed feral pigs (Sus scrofa) and monitored feral pig presence with surveys of all managed areas since 1988. Results of all available data regarding pig management activities through 2004 were compiled and analyzed, but no further analyses had been conducted since then. The objective of this report was toAuthorsSteven C. Hess, Christina R. Leopold, Steven J. KendallVideographic evidence of endangered species depredation by feral cat
Feral cats (Felis cafus) have long been implicated as nest predators of endangered 'Ua'u (Hawaiian Petrel; Pterodroma sandwichensis) on Hawaii Island, but until recently, visual confirmation has been limited by available technology. 'Ua'u nest out of view, deep inside small cavities, on alpine lava flows. During the breeding seasons of 2007 and 2008, we monitored known burrows within Hawai'i VolcaAuthorsSeth Judge, Jill S. Lippert, Kathleen Misajon, Darcy Hu, Steven C. HessThe effects of feral cats on insular wildlife: the Club-Med syndrome
Domestic cats have been introduced to many of the world‘s islands where they have been particularly devastating to insular wildlife which, in most cases, evolved in the absence of terrestrial predatory mammals and feline diseases. We review the effects of predation, feline diseases, and the life history characteristics of feral cats and their prey that have contributed to the extirpation andAuthorsSteve C. Hess, Raymond M. DannerThe history of mammal eradications in Hawai`i and the United States associated islands of the Central Pacific
Many eradications of mammal taxa have been accomplished on United States associated islands of the Central Pacific, beginning in 1910. Commonly eradicated species are rabbits (Oryctolagus cuniculus), rats (Rattus spp.), feral cats (Felis catus), and several feral ungulates from smaller islands and fenced natural areas on larger Hawaiian Islands. Vegetation and avifauna have demonstrated dramatic rAuthorsS.C. Hess, J.D. JacobiSurvival of European mouflon (Artiodactyla: Bovidae) in Hawai'i based on tooth cementum lines
Reliable techniques for estimating age of ungulates are necessary to determine population parameters such as age structure and survival. Techniques that rely on dentition, horn, and facial patterns have limited utility for European mouflon sheep (Ovis gmelini musimon), but tooth cementum lines may offer a useful alternative. Cementum lines may not be reliable outside temperate regions, however, beAuthorsS.C. Hess, R.M. Stephens, T.L. Thompson, R.M. Danner, B. Kawakami - Partners
Below are partners associated with this project.