2. Digital Images to Support Aerial Counts for Surface-Nesting Seabirds at Lehua Island and Moku Manu Islet and Ulupa'u Crater, O'ahu in 2019

Dates

Publication Date: 2022-07-20
Start Date: 2019-05-13
End Date: 2019-05-16

Citation

Kelsey, E.C., Adams, J., Felis, J.J., Stenske, J.G., and Horton, C.A., 2022, 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: U.S. Geological Survey data release, https://doi.org/10.5066/P9P434NO.

Summary

We have incorporated the Hawaiian language spellings of place names however, software limitations for metadata files did not allow for inclusion of the appropriate diacritical markings. Among important seabird breeding sites in the main Hawaiian Islands (MHI), Lehua Island off Niʻihau, and Moku Manu Islets off O'ahu 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, Ulupa'u Crater, near Moku Manu on O'ahu, is one of only a few main island sites and the only site [...]

Summary

We have incorporated the Hawaiian language spellings of place names however, software limitations for metadata files did not allow for inclusion of the appropriate diacritical markings.

Among important seabird breeding sites in the main Hawaiian Islands (MHI), Lehua Island off Niʻihau, and Moku Manu Islets off O'ahu 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, Ulupa'u Crater, near Moku Manu on O'ahu, is one of only a few main island sites and the only site on the main island of O'ahu that supports a nesting population of Red Footed Boobies (Sula sula). In May 2019, we completed comprehensive aerial photographic surveys (using a Canon 5DSr camera equipped with a Canon electro-focus ultra-sonic motor 135-mm telephoto lens) 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. 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 between individual photos.

We reviewed photographs and counted birds using the program DotDotGoose (Ersts 2019) and avoided double-counting individual birds seen in more than one image by identifying areas of overlap among sequential photos. For each photo, we evaluated image quality (Poor, Fair, Good, or Excellent), geographical location of the image, the degree of overlapping areas between images, other general observations, and the species and behavioral classification of each bird present. Behavioral classifications were broken down as nesting, roosting, flying, or unknown (e.g., for Red footed Booby, we used RFBO_Nesting, RFBO_Roosting, RFBO_Flying, and RFBO_Unknown). Birds on nests or displaying nesting posture (e.g., sitting bird with horizontal posture) were counted as RFBO_Nesting. We classified Red-footed Booby adults sitting with tails down, chest out, and an extended body with no visible nest as RFBO_Roosting. If a Red-footed Booby was present, but showed no definitive roosting or nesting cues, we classified it as RFBO_Unknown. We used similar classifications for Brown Boobies at Lehua and Moku Manu and Masked Boobies on Moku Manu. The presence of a well-defined guano ring or chicks assisted in identifying ground nests for these two species; regardless of the number of adults and chicks present, we counted each nest singularly as BRBO_Nesting or MABO_Nesting.

At Moku Manu where poor photo quality and a complex surface made identification challenging, we did not specify Roosting (included within _Unknown) for BRBO, RFBO, MABO, and GRFR and included a category with prefix alpha code and suffix _Undetermined to indicate a potential bird with a best guess species identification (based on color and habitat) which could also have been a rock, shadow, or guano. Undetermined classifications are reported but were not used to estimate nesting pairs. In additional, some targets on Moku Manu were labeled as Unknown, with no species prefix, on the first pass of photo review if the object had no definitive species identification and was not discernable from a rock, landscape feature, shadow, or guano. This additional, alternate classification facilitated clarification for uncertain identifications by the additional reviewers and thus helped us to scrutinize species identifications and improve final counts. While the overall approach for reviewing photographs and counting species were similar, there were some slight differences by site and species. Detailed methods on how we counted and reviewed counts for each species in each colony are presented in the Data Quality, Process Step section. We estimated 5,782, 102, and 1,446 nesting pairs of Red-footed Boobies at Lehua, Ulupa'u 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 Ulupa'u Crater). The pnt file in each folder can be opened in DotDotGoose to see classification results and locations of birds identified in each photo.

Additional information useful for interpreting these data can be found in the data 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 Ulupaʻu Crater, Oʻahu, in 2019: Data Report 1161, 20 p., https://doi.org/10.3133/dr1161.

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., and White L.M. 2020, Population estimates for selected breeding seabirds at Kīlauea Point National Wildlife Refuge, Kaua'i, in 2019: U.S. Geological Survey Data Series 1130, 32 p., https://doi.org/10.3133/ds1130.

Contacts

Point of Contact :: U.S. Geological Survey, Western Ecological Research Center
Originator :: Emily (Emma) C. Kelsey, Josh Adams, Jonathan J Felis, Jennilyn G. Stenske, Cheryl A Horton
Metadata Contact :: Josh Adams
USGS Mission Area :: Ecosystems
SDC Data Owner :: Western Ecological Research Center
Distributor :: U.S. Geological Survey - ScienceBase

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Digital images to support aerial counts for surface-nesting seabirds at Lehua Island and Moku Manu Islet and Ulupau Crater, Oahu in 2019.xml Original FGDC Metadata	View	29.44 KB	application/fgdc+xml
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Related External Resources

Type: Related Primary Publication

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 Ulupaʻu Crater, Oʻahu, in 2019: Data Report 1161, 20 p., https://doi.org/10.3133/dr1161.	https://doi.org/10.3133/dr1161

Purpose

This data release provides supporting data used to count or estimate population sizes of six surface-nesting seabird species: Brown Booby (Sula leucogaster), Red-footed Booby (S. sula), Masked Booby (S. dactylatra), Great Frigatebird (Fregata minor), Sooty Tern (Onychoprion fuscatus) and Brown Noddy (Anous stolidus) present at one or more of three nesting sites in the Main Hawaiian Islands (Lehua Island, Moku Manu Islet, and Ulupa'u Crater) during the 2019 breeding season.

2. Digital Images to Support Aerial Counts for Surface-Nesting Seabirds at Lehua Island and Moku Manu Islet and Ulupa'u Crater, O'ahu in 2019

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