Assessing Mammalian Predator Control to Protect Endangered Birds at Haleakalā National Park

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USGS researchers assessed trends in non-native mammalian predator trapping methods designed to protect endangered ʻuaʻu and nēnē at Haleakalā National Park, Hawaiʻi.

Predation and habitat degradation by non-native mammal species are principal terrestrial threats to endangered ʻuaʻu (Hawaiian Petrel, Pterodroma sandwichensis) and nēnē (Branta sandvicensis). The invasive mammal species found in the park that prey on nesting birds and eggs include feral cat (Felis catus), Indian mongoose (Herpestes javanicus), black rat (Rattus rattus), Norway rat (Rattus norvegicus), Polynesian rat (Rattus exulans), and house mouse (Mus musculus), with cats, mongoose, and black rats being the most commonly observed predators1. High-priority recovery actions for ʻuaʻu include predator control, habitat restoration, and population monitoring. In collaboration with Haleakalā National Park, USGS evaluated seasonal, annual, and environmental patterns and factors that influence small mammal trap events throughout a 15 year period (2000–2014).

A dark grey and white bird ('ua'u) lies on the ground in a grassy area

Haleakalā volcano is an important breeding location for the endangered Hawaiian Petrel (Pterodroma sandwichensis), or 'Ua'u in Hawaiian.  The predator control efforts at Haleakalā National Park help protect this important 'Ua'u colony on  Haleakalā.  This photo was taken by Maui Nui Seabird Recovery Project.

(Credit: Maui Nui Seabird Recovery Project)

The results, published in a 2019 USGS Open-File Report, showed temporal and spatial trends in trap events within Haleakalā National Park during 2000–14. The probability of predator capture was influenced by ʻuaʻu breeding season (off-season, pre-laying, incubation or nestling), month, year, and seasonal rainfall, with the highest probabilities of capture during the ʻuaʻu nestling period (July–October) and when rainfall was low. Rats were the most frequently caught predator in the traps and cats were the least frequently caught. The results indicated that vegetation cover and elevation were also factors affecting the probability of predator capture. Researchers found that bait was often taken without the trap being triggered.

These analyses will help the Haleakalā National Park Endangered Wildlife Management staff evaluate existing methods for predator control and inform future predator control efforts. The trends outlined by this project inform park personnel to focus trapping efforts in the most effective time periods and locations to protect ʻuaʻu and nēnē. The results reveal gaps where additional study could be implemented to improve predator trap efficiency, i.e., reduce untriggered trap events.

 

 

 

Products

Kelsey, E.C., Adams, J., Czapanskiy, M.F., Felis, J.J., Yee, J.L., Kaholoaa R.L., and Bailey, C.N., 2019, Trends in mammalian predator control trapping events intended to protect ground-nesting, endangered birds at Haleakalā National Park, Hawaiʻi: 2000–14: U.S. Geological Survey Open-File Report 2019–1122, 27 p., https://doi.org/10.3133/ofr20191122

 

Maps of Trapping Locations and Trapping Effort

Topographic map of Haleakala, on Maui, showing trap locations

Haleakalā National Park, Maui, Hawaiʻi, property and current trap lines 2000–14 (map provided by the National Park Service, Haleakalā National Park, Endangered Wildlife Management program). Inset map shows Maui, with Haleakalā National Park in red.  “Front Country” traplines (A – H) are located in the northwest section of the park near the access road. “Back Country” traplines (Waikau, Halemauu, Kapalaoa, NaMana, Kaupō, Lā‘ie and Palikū) are located in the eastern portion of the park, within the crater and only accessible by trail.

Map showing number of traps per week in Haleakala

Trapping effort in HALE during 2000–2014. Colors and values in cells indicate the number of traps per week per 100 m2. Given spatial layout of the traps, some cells represent multiple traps for the 15-year period, while others represent one trap used for a shorter interval.

(Public domain.)

Collaborator

Haleakalā National Park Endangered Wildlife Management 

 

Banner photos: The crater of Haleakalā volcano in Haleakala National Park, Maui Hawai’i;  The crater rim in Haleakalā.  This rocky landscape is the dominant nesting habitat for 'Ua'u within  Haleakalā National Park. Photos by E. Kelsey, USGS

 

[1] Kaholoaa, R. L., Bailey, C.N., Kekiwi, E.K., Purdy, K.K., Judge, S.W., Tamayose, J.A., and Schwarz, C.J., 2019, Predator control management plan Haleakalā National Park: Natural Resource Report NPS/HALE/NRR—2019/2005, National Park Service, Fort Collins, Colo. 

 

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