HCSU Quantitative Ecologist
Pacific Island Ecosystems Research Center
Email:
mgorresen@usgs.gov
Office Phone:
808-985-6407
Fax:
808-967-8568
ORCID:
0000-0002-0707-9212
Location
PIERC Office Bldg 344
P.O. Box 44
Bldg. 344
Hawaii National Park
, HI
96718
US
Supervisor:
Robert N Reed
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Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2019 to October 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. In 2019, three maternity roosts were identified however only two were suitable for video recording. Thermal video recording at two maternal roosts was used to identify the time of bat departure and arrival at a roost. We examined an average of 2 hours during sunset and sunrise (range = 0.9 to 5.4 hours). The time of bat departure from a roost ranged from 53 minutes before sunset to 20 minutes after sunset (n = 48, mean = 2.7 minutes...
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The yǻyaguak (Mariana swiftlet; Aerodramus bartschi) is an endangered cave-nesting species historically found on Guam and the southern Mariana Islands, Micronesia. The population on Guam has been severely impacted by the introduction of the brown treesnake (Boiga irregularis). Population status assessments have, however, been challenging due to the limitations of traditional counting methods, which rely on visual observations at cave entrances and are prone to inaccuracies. To improve count accuracy, we estimated yǻyaguak population size and relative nesting activity using thermal and near-infrared videography at Mahlac, Maemong and Fachi Caves from April 2019 to April 2023. This study demonstrates the potential...
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Hawaiian hoary bats ('ōpe'ape'a; Lasiurus semotus) were captured and tracked back to roosting locations on Hawaiʻi Island from 2018-2021. We examined resource selection at multiple spatial scales - perch location within a roost tree, roost tree, and forest stand. We used a discrete choice modeling approach to investigate roost selection and describe attributes of day-roost trees including those used as maternity roosts. ‘Ōpe‘ape‘a were found roosting in a variety of tree species and in an assortment of habitat types including native and non-native habitats. This data release consists of six tabular datasets: (1) Hawaiʻi Island ʻōpeʻapeʻa roost perch metrics, 2019–2021, (2) Hawai‘i Island ʻōpeʻapeʻa roost tree metrics,...
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Hawaiian hoary bats (Lasiurus cinereus semotus) were captured at multiple locations on the east side of Hawaii Island from May 2018 through September 2019. Radio transmitters were affixed to captured bats and, when possible, radio telemetry was used to locate bats in trees used for day-roosts. A total of 23 bat day-roosts were identified to tree and used by 18 bats (10 male; 8 female; 17 adult; 1 juvenile). Three maternity roosts were confirmed. One maternity roost was determined to be a bat that was not captured or radio-tagged but was visually located in a roost tree that was also in use by a radio-tagged bat. During the period of monitoring of telemetered bats (less than one month), multiple roosts were located...
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The Yǻyaguak (Mariana Swiftlet; Aerodramus bartschi) is an endangered cave-roosting species native to Guam and southern Mariana Islands, Micronesia. On May 24-25, 2023, Guam was hit by the category-4 Typhoon Mawar, which brought wide-spread destruction to the island. Approximately 6 weeks prior to the typhoon in April 2023 we conducted surveys of the three known colonies of Yǻyaguak at Mahlac, Maemong, and Fachi caves. This April 2023 pre-Mawar survey provided a baseline population estimate prior to Typhoon Mawar’s landfall. In July 2023, we re-surveyed the caves to estimate colony size and assess whether the cave colonies experienced significant declines in the immediate aftermath of the storm. In November 2023,...
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