Digital Imagery Used for Aerial Counts for Surface-Nesting Seabirds at Lehua Island and Moku Manu Islet and Ulupa'u Crater, O'ahu in 2019

This data release is a product of Atlas of Breeding Seabirds of the Main Hawaiian Islands (https://www.sciencebase.gov/catalog/item/5fc0045cd34e4b9faad7ef37). Specific results and details about methods and additional information useful for interpreting these data can be found in the data series report: Adams, J., Kelsey, E.C., Stenske, J., and Felis, J.J., 2022, Aerial counts for surface-nesting seabirds at Lehua Island and Moku Manu Islet and Ulupau Crater, Oahu in 2019: U.S. Geological Survey Data Report 1161, 20p., https://doi.org/10.3133/dr1161. We have incorporated the Hawaiian language spellings of place names however, software limitations did not allow for inclusion of the appropriate diacritical markings. Among important seabird breeding sites in the main Hawaiian Islands (MHI), Lehua Island off Niihau, and Moku Manu Islet off Oahu support diverse and abundant seabird breeding populations. Both offshore islands provide excellent nesting habitat for surface nesting boobies (Sula spp.) and Moku Manu also supports nesting habitat for relatively large breeding populations of Sooty Tern (Onychoprion fuscatus) and Brown Noddy (Anous stolidus). Additionally, Ulupau Crater, near Moku Manu on Oahu, is one of only a few main island sites and the only site on the main island of Oahu that supports a nesting population of Red Footed Boobies (Sula sula). In May 2019, we completed comprehensive digital aerial photographic surveys at these three sites for six surface-nesting seabird species: Brown Booby (Sula leucogaster), Red-footed Booby, Masked Booby (S. dactylatra), Great Frigatebird (Fregata minor), Sooty Tern, and Brown Noddy. We took oblique digital aerial photographs of Lehua during the late morning of 13 May from a H-65 Dolphin helicopter with the door open to provide the best viewing conditions. During the late morning on 16 May 2019, we worked with U.S. Coast Guard Auxiliary on-board a Piper Saratoga fixed-wing aircraft (single-engine, low-wing) to photograph the Red-footed Booby colony in Ulupau Crater and the entire surface of Moku Manu taken through a tinted, rear Plexiglas window. We used a Canon 5DSr camera (51-megapixel full frame) equipped with a Canon electro-focus (EF) ultra-sonic motor (USM) 135-mm telephoto lens for all photography. At all locations, we flew at an altitude of approximately 300 m above sea level and photographs were taken over distances of 150-850 m from bird subjects, resulting in pixel resolutions of 0.5-2.6 cm pixel-1 on the ground. Photographs were taken with overlap so that observers could later ensure locational reference and complete counting without double-counting. GPS coordinates of the location from where photos were captured were recorded from a GPS track recorded during photographic surveys. We reviewed photographs and counted birds using the program DotDotGoose (Ersts 2019). We estimated 5,782, 102, and 1,446 nesting pairs of Red-footed Boobies at Lehua, Ulupau Crater, and Moku Manu, respectively. At Lehua and Moku Manu we estimated 692 and 65 nesting pairs of Brown Boobies, respectively. At Moku Manu we estimated 95 nesting pairs of Masked Boobies, one of only 3 nesting locales for this species in the MHI. Based on photo counts of sampled areas and area-based extrapolation, we estimated 17,938 terns (mostly Sooty Tern and including Brown Noddy) on Moku Manu. We observed Great Frigatebirds (Fregata minor) roosting at the two island sites, but we did not detect any sign of nesting for this species. The nesting population sizes of boobies across the three colonies and number of terns present on Moku Manu presented here likely are minimum estimates because individuals among these species can exhibit asynchronous nesting phenologies, and not all members of the nesting populations would be expected to be attending the sites when we surveyed. The results of these surveys provide current and accurate abundance estimates for these species that can serve as benchmarks for future management and monitoring and as important components of population-level assessments aimed at quantifying seabird vulnerability to potential offshore wind energy development in the MHI. The DotDotGoose software interface requires that photos being counted are organized in a single folder and creates a .pnt output file referencing all photos in the folder and the locations (in pixel space) and classification of each object identified by the user. This data release maintains that structure for each unique colony photo set (Lehua, Moku Manu, and Ulupau Crater). The .pnt files in each folder can be opened in DotDotGoose to see classification results and locations of birds identified in each photo. The data are organized as: PhotoIndex: a tabular list of all photograph filenames and ancillary information (e.g., camera settings, location) used for the aerial photographs DigitalImages: digital photographic images used for conducting aerial photographic counts and output software files of count results; photographs are grouped by location References Ersts, P.J., 2020, DotDotGoose (version 1.5.1): American Museum of Natural History, Center for Biodiversity and Conservation, accessed May 30, 2020, at https://biodiversityinformatics.amnh.org/open_source/dotdotgoose/ Felis J.J., Kelsey E.C., Adams J., Stenske J.G. , White L.M., 2020, Population estimates for selected breeding seabirds at Kilauea Point National Wildlife Refuge, Kauai, in 2019: U.S. Geological Survey Data Series 1130, 32 p., https://doi.org/10.3133/ds1130.

本数据集成果源自《夏威夷主群岛繁殖海鸟图集》（https://www.sciencebase.gov/catalog/item/5fc0045cd34e4b9faad7ef37）。如需了解本数据集的具体结果、方法细节及辅助解读信息，请参阅以下数据系列报告：Adams J.、Kelsey E.C.、Stenske J.与Felis J.J.，2022年《2019年雷胡阿岛、莫库马努岛礁及瓦胡岛乌鲁帕乌火山口地表筑巢海鸟航拍统计》：美国地质调查局（U.S. Geological Survey）数据报告1161，共20页，https://doi.org/10.3133/dr1161。

我们已采用夏威夷语地名拼写，但受软件限制未能添加相应的变音符号。夏威夷主群岛（Main Hawaiian Islands, MHI）的重要海鸟繁殖地中，尼豪岛周边的雷胡阿岛与瓦胡岛周边的莫库马努岛礁拥有多样且庞大的海鸟繁殖种群。两座离岸岛屿均为鲣鸟属（Sula spp.）地表筑巢提供了优质栖息环境，其中莫库马努岛礁还为乌燕鸥（Onychoprion fuscatus）与褐玄燕鸥（Anous stolidus）的大型繁殖种群提供了筑巢场所。此外，瓦胡岛邻近莫库马努岛礁的乌鲁帕乌火山口是为数不多的主岛繁殖地之一，也是瓦胡岛主岛上唯一存有红脚鲣鸟（Sula sula）繁殖种群的区域。

2019年5月，我们针对6种地表筑巢海鸟在上述三处地点完成了全面的数码航空摄影调查，涉及物种包括：褐鲣鸟（Sula leucogaster）、红脚鲣鸟、蓝脸鲣鸟（S. dactylatra）、大军舰鸟（Fregata minor）、乌燕鸥及褐玄燕鸥。

5月13日上午晚些时候，我们搭乘舱门敞开的H-65海豚直升机对雷胡阿岛进行了斜向数码航拍，以获取最佳拍摄视野。2019年5月16日上午晚些时候，我们与美国海岸警卫队辅助队合作，搭乘派珀萨拉托加单引擎低翼固定翼飞机，通过着色后部有机玻璃舷窗拍摄了乌鲁帕乌火山口的红脚鲣鸟种群，以及莫库马努岛礁的全域区域。我们全程使用佳能5DSr相机（5100万像素全画幅），搭配佳能电子对焦（EF）超声波马达（USM）135毫米长焦镜头进行拍摄。

所有拍摄均在海拔约300米的高度进行，拍摄距离鸟类主体150至850米，地面像素分辨率达0.5至2.6厘米每像素。我们采用重叠拍摄模式，以便后续观察员能够准确定位并完成计数，避免重复统计。航拍拍摄时记录的GPS航迹将用于提取照片拍摄地点的坐标。

我们使用DotDotGoose软件（Ersts，2019）对照片进行审阅与鸟类计数。经估算，雷胡阿岛、乌鲁帕乌火山口及莫库马努岛礁的红脚鲣鸟繁殖对数量分别为5782对、102对及1446对。雷胡阿岛与莫库马努岛礁的褐鲣鸟繁殖对数量分别为692对与65对。莫库马努岛礁的蓝脸鲣鸟繁殖对数量为95对，该物种在夏威夷主群岛仅存3处繁殖地之一。

基于抽样区域的照片计数与面积外推法，我们估算莫库马努岛礁的燕鸥种群数量为17938只（主要为乌燕鸥，包含褐玄燕鸥）。我们观察到大军舰鸟（Fregata minor）在两座离岸岛屿栖息，但未发现该物种存在繁殖迹象。

本次公布的三处海鸟种群数量及莫库马努岛礁燕鸥数量大概率为最低估计值，因为这些物种的繁殖物候存在异步性，并非所有繁殖个体都会在调查时段出现在繁殖地。本次调查结果可为上述物种提供当前准确的种群丰度估计值，可作为未来管理与监测的基准，同时也是量化夏威夷主群岛海鸟对潜在近海风电开发脆弱性的种群水平评估的重要组成部分。

DotDotGoose软件界面要求待计数照片需整理至单个文件夹，并生成.pnt输出文件，记录文件夹内所有照片的相关信息，以及用户识别的每个物体在像素空间中的位置与分类。本数据集保留了每个独立繁殖地照片集（雷胡阿岛、莫库马努岛礁及乌鲁帕乌火山口）的该结构。各文件夹内的.pnt文件可在DotDotGoose中打开，以查看每张照片中识别出的鸟类分类结果与位置。

本数据集的组织形式如下：
PhotoIndex：包含所有航拍照片文件名及辅助信息（如相机设置、拍摄位置）的表格列表
DigitalImages：用于航拍计数的数码照片及计数结果的输出软件文件；照片按拍摄地点分组

参考文献
Ersts P.J.，2020年，DotDotGoose（版本1.5.1）：美国自然历史博物馆，生物多样性与保护中心，2020年5月30日访问，https://biodiversityinformatics.amnh.org/open_source/dotdotgoose/
Felis J.J.、Kelsey E.C.、Adams J.、Stenske J.G.、White L.M.，2020年，《2019年考艾岛基拉韦厄角国家野生动物保护区部分繁殖海鸟种群估计》：美国地质调查局数据系列1130，共32页，https://doi.org/10.3133/ds1130。