ABSTRACT
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 (Nene), which is endemic to Hawai'i. Using a nearly 40-year dataset of Nene road mortality in and around Hawai'i Volcanoes National Park, we sought to answer the following research questions: 1) has Nene 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 Nene 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, Nene 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, Nene mortality was unrelated to the number of visitors or traffic volume in the park. These findings suggest vehicle collisions are a growing concern for Nene, but that management actions to reduce mortality can be targeted at specific road segments and times of the year.
Subject(s)
Accidents, Traffic , Endangered Species , Geese , Animals , Hawaii , Population DensityABSTRACT
Although West Nile Virus (WNV) has not been reported in Hawai'i, eventual introduction appears unavoidable with potential adverse effects on avian species. Nene (Branta sandvicensis) are endemic endangered Hawaiian geese that are susceptible to WNV. We demonstrate that a vaccine developed against WNV for humans (WN-80E) is also highly immunogenic in Nene and does not produce adverse biologic effects. Six captive, nonbreeding Nene were immunized with two 10-µg doses (4 wk apart) of the WN-80E recombinant protein adjuvanted with Montanide ISA720. Two Nene were similarly injected with "mock" preparation as controls. Blood samples were collected before the first dose, then 2 wk and 6 mo after the second dose. WNV-specific antibody titers were determined by an endpoint enzyme-linked immunosorbent assay. An unpaired t-test demonstrated significantly higher geometric mean titers for immunized vs. control groups 2 wk after dose 2 (4,129 and 100, respectively, P=0.010) and 6 mo after dose 2 (246 and 63, respectively, P=0.002). Daily observations revealed no swelling at the site of injection and no serious adverse biological effects from the immunization. The vaccine containing the WN-80E and Montanide ISA720 adjuvant appears to be safe and immunogenic in Nene. This protein-based WNV vaccine may be safer for use in Hawai'i than killed virus and live chimeric or recombinant canarypox-vectored vaccines because it cannot cause disease.
