Kure Atoll is the final land mass in the Hawaiian Archipelago, within Papahānaumokuākea Marine National Monument
Management
The State of Hawaii’s Department of Land and Natural Resources (DLNR) Division of Forestry and Wildlife manages the atoll and has a mission to eradicate the invasive plant Verbesina encelioides. Widespread monotypic stands covered 120 acres (64%) of the atoll1 (Map) and caused heat stress and habitat loss in ground-nesting boobies1,2
Before restoration - 2009
Ongoing Restoration - 2014
Biosecurity
Quarantine measures have been implemented since the 1990s to prevent the introduction of new species to the atoll. Measures include only using gear previously used on Kure, purchasing new gear as needed, visually inspecting for seeds and insects, freezing soft items and food, preventing invasive food seed introduction, fumigating gear prior to transport, and treating wood products. Habitat restoration is successful in this remote location due to adherence to these strict preventative measures.
Brown Booby (Sula leucogaster, BRBO) breeding biology
Mid-century surveys estimated 50-60 breeding pairs1
Peak nesting occurs in spring to early summer, and peak fledging is from summer to early fall (Figure 1)
Figure 1. 2014-2017 mean nesting and fledging counts
BRBO Monitoring
Year-round surveys conducted to census atoll
- Confirmed nest sites GPS marked
- Pairs, eggs and chicks counted monthly
Vegetation Monitoring
Areas previously monotypic V. encelioides
- Randomly selected quadrats
- Percent cover quantified annually – summer and winter
2012-2014, restoration efforts were monitored with vegetation plots (Figure 2)
- V. encelioides cover decreased 21.6% in winter 2012 to 0.4% in winter 2014
- Low-lying native plant cover increased from 8.4% to 44.5% over same time period
- Post-2014, other non-native plant cover reduced
Figure 2. Vegetation monitoring plots: native vs. non-native plant cover 2012-2014
Fledglings increased 19.8% over 4 years
- From 86 chicks (2014) to 103 (2017)
- 76% (± 1.4% SD) productivity (egg to fledging) success (Figure 3)
Figure 3. 2014-2017 BRBO Active Nests and Fledging counts
Nest sites 2014-2017 (Map, color dots) projected on pre-2010 V. encelioides distribution (Map, white hash area)
- Nesting in areas previously V. encelioides
- Over four years, confirmed nests increased (114 to 135)
- Nesting range expanded (detail in expanded view maps)
- BRBO responded to habitat restoration by moving into areas replaced by low-lying native groundcover
- V. encelioides eradication requires ongoing maintenance to ensure permanent booby habitat
- Adherence to strong biosecurity protocols for this remote location are crucial to the success of this project
- Example of ambitious invasive plant eradication effort to benefit seabirds long-term
Mahalo to:
- National Fish and Wildlife Foundation for funding V. encelioides eradication & booby monitoring
- Staff and Volunteers of habitat restoration and seabird monitoring on Kure Atoll
- Michelle Hester (Oikonos), Martha Brown (KAC) for input & review of NFWF grant
- Dr. K. David Hyrenbach and Pelagicos lab for input and advising
Citations:
1. DLNR Internal Reports 1997-2013
2. Woodward. P.W., 1972. Natural History of Kure Atoll, Northwestern Hawaiian Islands. Atoll Rsrch. Bull 164.