DOI: 10.5061/dryad.jsxksn0mn
title: 2024 Oregon and Washington double-crested cormorant (Nannopterum auritum) colony surveys – aerial photos and count data

description: Aerial surveys were undertaken to monitor selected double-crested
 cormorant (DCCO; Nannopterum auritum) colonies in Oregon to fulfill
 monitoring requirements associated with the United States Fish and
 Wildlife Service (USFWS) final environmental impact statement: Management
 of Conflicts Associated with Double-crested Cormorants (USFWS 2020).
 Survey methods follow guidelines established by the Pacific Flyway Council
 monitoring strategy: A Monitoring Strategy for the Western
 Population of Double-crested Cormorants within the Pacific Flyway (PFC
 2013). This dataset presents high resolution aerial imagery and
 corresponding nest counts from areial surveys of double-crested cormorant
 (DCCO; Nannopterum auritum) colonies in Oregon and Washington. Survey
 results are intended for use by USFWS and Pacific Flyway Council members,
 including ODFW and other state and federal agencies, to determine
 population size and evaluate long-term trends in abundance of DCCO within
 the Pacific Flyway. Additionally, colonies in coastal Washington were
 surveyed opportunistically and aerial photos were shared with WDFW.
 Monitoring DCCO numbers is essential for evaluating effects on population
 size of permitted management actions currently underway across the western
 United States.
description: We conducted aerial surveys at focal double-crested cormorant
 (DCCO; <em>Nannopterum auritum</em>) colony sites in Oregon
 and Washington during May and June of 2024. Colony sites were photographed
 if cormorants were present, or if there were any signs of nesting activity
 (i.e., nest structures). We also opportunistically surveyed and
 photographed four supplemental cormorant colony sites along our survey
 route. Flight timing was based on a best estimate of peak nesting activity
 from monitoring conducted in previous years and from available published
 literature. We surveyed and photographed each colony from a fixed-wing
 aircraft (Cessna 180 Skywagon) at altitudes between 700 and 1,500 feet
 above ground level. The pilot circled above each target colony, and we
 used a mirrorless digital camera (Canon R5) with an image-stabilized lens
 (Canon 100 – 500mm; f/4.5-7.1) to photograph the colonies. Photographs
 were taken from the front right window of the aircraft, which was opened
 at survey speeds to reduce potential distortion. For
 Oregon colonies, we followed protocols and procedures identified in the
 Cormorant Management Plan to measure colony size as the number of apparent
 active nests at each colony at the time that the oblique aerial
 photography was taken. Colony counts were performed by two independent
 reviewers using Dot Dot Goose software (Version 1.7.0) to analyze aerial
 imagery taken during survey flights. We estimated the number of breeding
 pairs at each DCCO colony as the average nest count of the two photography
 reviewers. When counting colony photography, reviewers identified active
 nests by the presence of adults on nest structures in incubating or
 brooding posture. Nests were considered active if they were unattended but
 contained eggs and/or chicks. All counts were obtained from aerial photos
 and no ground visits were conducted as part of this project. Washington
 colony photos were not counted or analyzed by Oregon State University for
 this project.
description: # 2024 Oregon and Washington double-crested cormorant (Nannopterum
 auritum) colony surveys Aerial photos and count data
 [https://doi.org/10.5061/dryad.jsxksn0mn](https://doi.org/10.5061/dryad.jsxksn0mn) ## Description of the data and file structure This README file describes the data package for the 2024 Oregon and Washington double-crested cormorant (*Nannopterum auritum*) colony aerial surveys. Description: This dataset consists of high-resolution aerial images and corresponding nest counts of double-crested cormorant (DCCO; *Nannopterum auritum*) colonies surveyed in Oregon during 2024. Additional photos of Washington colonies are also provided. Aerial surveys were undertaken to monitor selected double-crested cormorant colonies in Oregon to fulfill monitoring requirements associated with the United States Fish and Wildlife Service (USFWS) final environmental impact statement, Management of Conflicts Associated with Double-crested Cormorants (USFWS 2020). USFWS (U.S. Fish and Wildlife Service). 2020. Management of Conflicts Associated with Double-crested Cormorants: Final Environmental Impact Statement, November 2020. Portland, Oregon.[https://www.fws.gov/media/record-decision-management-conflicts-associated-double-crested-cormorants](https://www.fws.gov/media/record-decision-management-conflicts-associated-double-crested-cormorants) ### Files and variables #### File: 2024\_DCCO\_Aerial\_Survey\_Counts.xlsx Description: This excel spread sheet contains colony names, location, including latitude and longitude, species counted, individual count estimates, final colony size estimates, and the reference for the corresponding photos which were counted. Only photos for Washington colonies are included in this dataset, where counts were not made N/As are present in the spreadsheet. ##### Variables Colony_Name = The assigned colony name. State = The US state in which the colony is located. Region = The general region of the colony within the US state. Lattitude = Colony latitude. Longitude = Colony longitude. Count_Type = Details what subject was counted, nest, adults, or chicks. Counter_1 = Counter name code. C1_Affiliation = Counter 1 affiliation. Count_1 = Total count from counter 1 Counter_2 = Counter 2 name code. C2_Affiliation = Counter 2 affiliation. Count_2 = Total count from counter 2 Count_Mean = The mean of count 1 and count 2 Survey_Date = Date of the survey (MM/DD/YY). Survey_Type = The survey type used, for these surveys only aerial fixed wing surveys were conducted. Photos_Used = Gives the name of the image/s which were used for thecorresponding nest counts or in the case for Washington state colonies the names of the image/s included in this dataset, which could be used to obtain a nest count. Notes = Additional count information. N/As present if no notes are included #### File:Oregon\_DCCO\_Colonies\_2024.zip This file contains the photos from aerial surveys of double-crested cormorant colonies. The images included were used to determine number of nests and relate to the corresponding count data from 2024_DCCO_Aerial_Survey_Counts.xlsx. Images are saved a .jpg and .pnt files. #### File: Washington\_DCCO\_Colonies\_2024.zip This file contains the photos from aerial surveys of double-crested cormorant colonies. The images included are listed in the 2024_DCCO_Aerial_Survey_Counts.xlsx. Images are saved a .jpg and .pnt files. ## Code/software #### File Types: Software * .xls Files: Microsoft Excel * Zip Files: Unzip software, built-in software on your operating system or installable software such as WinZip or 7-Zip * JPG and .pnt files: Most standard image viewers, including Windows Photo Viewer on Windows, Preview on Mac, or third-party options like Adobe Photoshop, FastStone Image Viewer, ACDSee, or XnView