Long-term history of vehicle collisions on the endangered Nene (Branta sandvicensis).
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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 (N?n?), which is endemic to Hawai'i. Using a nearly 40-year dataset of N?n? road mortality in and around Hawai'i Volcanoes National Park, we sought to answer the following research questions: 1) has N?n? 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 N?n? 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, N?n? 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, N?n? mortality was unrelated to the number of visitors or traffic volume in the park. These findings suggest vehicle collisions are a growing concern for N?n?, but that management actions to reduce mortality can be targeted at specific road segments and times of the year.
SUBMITTER: Lepczyk CA
PROVIDER: S-EPMC6382094 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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