Mortality Patterns in Endangered Hawaiian Geese (Nene; Branta Sandvicensis)

Free-ranging feral cats (Felis catus) are increasingly found in colonies loosely managed by people. These colonies increase cat densities and, hence, pose threats to wildlife via disease and predation, particularly in insular ecosystems where native species have smaller populations and reduced pathogen exposure compared to continental systems. Given such concerns, our objectives were to: (a) identify feral cat colonies on the island of O'ahu in the vicinity of important native bird sites;and (b) test for Toxoplasma gondii, a parasite-causing disease (Toxoplasmosis) of concern to native birds, at cat colony sites. We identified 32 important native bird locations and surveyed public lands near these sites to determine presence of cat colonies. Where cat colonies were present, we collected feces and used molecular tools to identify the presence of T. gondii. We identified 25 cat colonies near an important bird area and collected feces at four of these colonies, with three testing positive for T. gondii. The presence of cats near a majority of native bird areas suggests that cats may impose a serious threat to bird species. Our finding of T. gondii at three of the four colonies where cat feces were collected raises serious health concerns for humans, birds, and many other terrestrial and aquatic organisms. Native birds in Hawai'i, including highly endangered species, are susceptible to both predation and T. gondii, and finding its presence in locations relatively near to important native bird areas provides further evidence that reducing freeranging feral cat numbers is critical for reducing impacts on birds. K E Y W O R D Scat colony, Felis catus, invasive species, island ecosystems, Toxoplasma gondii

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“…Indeed, T . gondii is the most common infectious disease in nēnē (Work, Dagenais, Rameyer, & Breeden, ). The impact of T .…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, T . gondii has been identified in nēnē carcasses from the islands of Hawai'i, Moloka'i, Kaua'i, and Maui (Work et al, , ). Taken together, our results highlight the potential threat of feral cats and the non‐native parasites they shed to the native wildlife of Hawai'i.…”

Section: Discussionmentioning

confidence: 99%

Quantifying the presence of feral cat colonies and Toxoplasma gondii in relation to bird conservation areas on O'ahu, Hawai'i

Lepczyk

Haman

Sizemore³

et al. 2020

Conservat Sci and Prac

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“…Currently the statewide population is estimated at over 3,000 individuals [13], but the species still faces many challenges to recovery. A survey of 300 opportunistically collected Nēnē carcasses in Hawai‘i found that vehicle collisions accounted for 5.7% of all deaths where the cause of mortality could be identified [14]. Notably, these mortality figures are unlikely to be representative of overall mortality rates because they were based on opportunistic sampling, and carcasses from vehicle mortalities are rarely sent in for necropsy as the source of mortality is known.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, increased adult mortality may have serious implications for the population. Evaluating and understanding causes of mortality are critical for developing and improving management methods that can contribute to species recovery [14].…”

Section: Introductionmentioning

confidence: 99%

Long-term history of vehicle collisions on the endangered Nēnē (Branta sandvicensis)

et al. 2019

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Millions of birds in the United States die annually due to vehicle collisions on roads. Collisions may be of particular interest for species of conservation concern, such as the endangered Hawaiian goose (Nēnē), which is endemic to Hawai‘i. Using a nearly 40-year dataset of Nēnē road mortality in and around Hawai‘i Volcanoes National Park, we sought to answer the following research questions: 1) has Nēnē mortality changed over time? 2) are there times of the year in which mortality is greatest and does it relate to specific events in the species’ lifecycle? 3) does age at mortality differ over time, space, or sex? 4) given that existing mortalities appear to occur only in certain locations, do the number of mortality events differ across these locations; 5) does mortality rate show any density dependence? and, 6) are mortality rates related to numbers of visitors or vehicles? Between 1977 and 2014, a total of 92 Nēnē died from vehicle collisions; while absolute mortality increased over this time, the mortality rate remained the same. Similarly, average age of mortality increased over time, but did not differ by location or sex. Between 1995 and 2014, Nēnē population size and mortality rates were not correlated. Mortality was greatest in November and December (breeding season) and lowest in June. Most of the mortality occurred along just three stretches of road in and around the park, with the number of mortalities split about evenly inside and outside of the park. Furthermore, Nēnē mortality was unrelated to the number of visitors or traffic volume in the park. These findings suggest vehicle collisions are a growing concern for Nēnē, but that management actions to reduce mortality can be targeted at specific road segments and times of the year.

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“…Considerable research has explored differences between captive and wild populations in terms of their health, genetics, nutrition, behavior, physiology, and reproduction (for examples see refs. 7 – 13 ). However, far less attention has been given to differences that may exist between wild-born and captive-born animals when both are considered in a captive environment.…”

Section: Introductionmentioning

confidence: 99%

A meta-analysis of birth-origin effects on reproduction in diverse captive environments

2018

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Successfully establishing captive breeding programs is a priority across diverse industries to address food security, demand for ethical laboratory research animals, and prevent extinction. Differences in reproductive success due to birth origin may threaten the long-term sustainability of captive breeding. Our meta-analysis examining 115 effect sizes from 44 species of invertebrates, fish, birds, and mammals shows that, overall, captive-born animals have a 42% decreased odds of reproductive success in captivity compared to their wild-born counterparts. The largest effects are seen in commercial aquaculture, relative to conservation or laboratory settings, and offspring survival and offspring quality were the most sensitive traits. Although a somewhat weaker trend, reproductive success in conservation and laboratory research breeding programs is also in a negative direction for captive-born animals. Our study provides the foundation for future investigation of non-genetic and genetic drivers of change in captivity, and reveals areas for the urgent improvement of captive breeding.

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Mortality Patterns in Endangered Hawaiian Geese (Nene; Branta Sandvicensis)

Cited by 17 publications

References 26 publications

Quantifying the presence of feral cat colonies and Toxoplasma gondii in relation to bird conservation areas on O'ahu, Hawai'i

Quantifying the presence of feral cat colonies and Toxoplasma gondii in relation to bird conservation areas on O'ahu, Hawai'i

Long-term history of vehicle collisions on the endangered Nēnē (Branta sandvicensis)

A meta-analysis of birth-origin effects on reproduction in diverse captive environments

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