Post-Typhoon Mawar population counts of the endangered yǻyaguak (Mariana swiftlet) on Guam

dc.coverage.spatial Marianas Islands
dc.coverage.temporal April to November 2023
dc.creator Eben H. Paxton
dc.creator P. Marcos Gorresen
dc.creator Paul Cryan
dc.creator Megan Parker 2024-05-15T16:39:14Z 2024-05-15T16:39:14Z 2024-05-15
dc.description.abstract The yǻyaguak (Mariana swiftlet, Aerodramus bartschi) is an endangered cave-roosting species native to Guam and southern Mariana Islands, Micronesia. The population on Guam has declined substantially over the last half century, likely due to the introduction of the brown treesnake (Boiga irregularis), but other factors have been proposed including habitat loss, pesticides, reduced food resources, and powerful storms. 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 survey provided a baseline population estimate prior to Typhoon Mawar’s landfall. In July 2023, we resurveyed 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, we conducted our regularly scheduled biannual surveys which provided a longer-term assessment of potential impacts from the typhoon. Our counts indicated that in the immediate aftermath (~6 weeks) there was a 7–8% reduction in size of colonies compared to the April 2023 counts, but in November there were larger, 19–35% reductions in the cave colonies from pre-Mawar surveys. These results suggest that the long-term effects of the storm were more detrimental to the yǻyaguak populations than the immediate impacts if these colony size reductions are a result of the storm. Continued monitoring of the yǻyaguak cave colonies will allow for documenting the pace of recovery from the storm.
dc.format Technical Report
dc.format.extent 11 pages
dc.identifier.citation Paxton, E. H., P. M. Gorresen, P. Cryan, and M. Parker. 2024. Post-Typhoon Mawar population counts of the endangered yǻyaguak (Mariana swiftlet) on Guam. Hawai‘i Cooperative Studies Unit Technical Report HCSU-110. University of Hawai‘i at Hilo. 11 pages.
dc.language eng
dc.language other
dc.publisher University of Hawai'i at Hilo
dc.subject Aerodramus bartschi
dc.subject brown treesnake
dc.subject conservation
dc.subject Guam
dc.subject Mariana swiftlet
dc.subject Typhoon Mawar
dc.subject yǻyaguak
dc.title Post-Typhoon Mawar population counts of the endangered yǻyaguak (Mariana swiftlet) on Guam
dcterms.rights Creative Commons
dcterms.type Text
prism.endingpage 8
prism.number 110
prism.publicationname Hawai'i Cooperative Studies Unit Technical Report Series
prism.startingpage i
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