Geology topics

Martha Kawasaki

Publications and source records attributed to Martha Kawasaki.

2 recordsLinked to original sources

USGS2022

Hawaiian waterbird movement across a developed landscape

A key component for biologists managing mobile species is understanding where and when a species occurs at different locations and scaling management to fit the spatial and temporal patterns of movement. We established an automated radio-telemetry tracking network to document multi-year movement in 2016–2018 of 3 endangered waterbirds among wetlands on Oʻahu, Hawaiʻi, USA: ʻalae ʻula or Hawaiian gallinule (gallinule; Gallinula galeata sandvicensis ), ʻalae keʻokeʻo or Hawaiian coot (coot; Fulica alai ), and aeʻo or Hawaiian stilt (stilt; Himantopus mexicanus knudseni ), each with different ecological requirements. There were marked differences in the movement propensity of the species, with no movement among sites detected in gallinules, 31% of coots moving among wetlands, and very high levels of daily movement in stilts. A network analysis revealed strong evidence for fidelity among individual stilts to specific wetlands, indicating different groups of wetlands supported different birds. There was also strong evidence for patterns in daily and seasonal movement patterns of stilts. Our work indicates the importance of each wetland to the waterbirds they support, as each individual had strong fidelity to a single wetland. In addition, for Hawaiian coots and stilts, which were documented moving among multiple wetlands, a network of wetlands may be key for long-term persistence of these endangered species, and coordinated regional management of waterbirds as a shared resource could provide greater benefits to waterbirds than independent management of each wetland.

Hawaii↗

USGS2019

Frequent use of upland habitats by the endangered Hawaiian stilt (Himantopus mexicanus knudseni)

The Hawaiian Stilt, or Ae’o (Himantopus mexicanus knudseni), is an endangered waterbird endemic to the Hawaiian Islands. Loss of suitable wetland habitats due to anthropogenic development is a leading cause for decline, as well as the introduction of non-native predators and invasive wetland plants. This study fitted four Hawaiian Stilts with GPS satellite tags to document their use of wetland and surrounding habitats on Oahu Island. While other Hawaiian waterbirds are largely restricted to wetlands, we detected Hawaiian Stilts using heavily modified upland habitats, including developed areas, undeveloped fields, sports fields, as well as wetland habitats over a 6-month period. Overall, a high use of non-wetland habitat was observed (up to 58%), with significant differences in habitat occupancy among individual stilts and across different times of day. Wetlands were the dominant habitat occupied from morning to early afternoon, but non-wetland habitats were occupied at higher frequencies in the evening and early morning hours. Although only four birds were tracked, the extensive use of non-wetland habitat by these individuals indicates management of non-wetland habitats may be important for the conservation of this subspecies. However, more research is needed to understand how applicable these results are to other stilt popualtions across the Hawaiian Islands, and better understand the potential risks and benefits of these non-wetland habitats to stilt populations.

Hawaii↗