Oregon Coast NWRC: Surface Nesting Seabirds - Aerial Photographic Colony Surveys - 1997 GIS Raw Count Databases

This reference archives metadata about the collection of geospatial data which may be stored in a variety of file formats (e.g. shapefile, geodatabase) for the Oregon Coast NWRC: Surface Nesting Seabirds - Aerial Photographic Colony Surveys survey (PRIMR ID: FF01RORG00-002 and FF01RTAR00-002). Early records are not recorded digitally, these counts were done by projecting the slide image and manually counting birds on hardcopy. The metadata file will display where counts were done on hardcopy (analog) as well as those done digitally (GIS). Counts (from photographs) were initially started in 1997 but were not completed until 2020.

These geospatial files represent the raw count of seabirds from non-georeferenced images. These raw point counts are not registered to any geospatial coordinates. They only line up with the image from which they were derived, no geospatial coordinates are attached to the raw images. Results of the counts are put through a secondary check and then numbers are entered into the complete Seabird Colony Count Catalog (Database) which can be downloaded from <https://ecos.fws.gov/ServCat/Reference/Profile/125358>, which is the authoritative source for bird count data collected by the U.S. Fish and Wildlife Service (USFWS).

Oregon Coast National Wildlife Refuge Complex manages an Imagery Program for collecting refuge-wide aerial imagery datasets that are used to monitor nesting seabirds on offshore islands. Aerial flights are generally conducted annually to monitor population status and trends, but the imagery is used for other resource monitoring purposes.

Aerial photography has served as the primary means for monitoring populations of nesting seabirds (Census years include 1988, 1994, 2006, and 2014), and the subsequent analysis of long-term seabird colony legacy data in the Pacific Northwest as a regional baseline. The 1997 set of photographs have been used to complete a refuge-wide colony subsample count for 1997, where each photograph in the subsample has a digital point file (hand count) of nesting seabirds stored in a geodatabase format. 

We counted a subsample of Oregon coast colonies using a size- and geographical-based stratified random sampling approach for all other survey years. The subsample was selected based on common murre populations, therefore no inferences can be drawn about Brandt’s cormorants without additional colony subsampling. The subsampling approach was informed by recommendations from bio-statistical experts based on colony size and location. We subsampled 45 colonies, which were counted over time. Including census year counts, our subsample years were 1988, 1994, 1997, 2000, 2003, 2006, 2009, 2012, and 2014.

A power analysis for the sampling design recommended for the Protocol Framework indicated that a minimum of 16 common murre within each region needed to be counted each year in order detect an average decline of 3.35% per year over a 15-year period (cumulative 40% decline) with 80% probability. With guidance from two statisticians, we randomly selected 6 small and 9 medium/large colonies per region for a total of 45 colonies to be counted each year to detect changes across the Oregon Coast.

For more information about the long-term monitoring of seabirds along the Oregon Coast, go to The Service Catalog (ServCat) at the following link: https://ecos.fws.gov/ServCat/Reference/Profile/125347

Tags: brandts-cormorant, breeding-colonies, common-murre, distribution, ff01rorg00-002, ff01rtar00-002, general-biology-species-birds, general-management-inventory, general-management-monitoring, gulls, ivory-gulls, kittiwakes, larus, phalacrocorax-penicillatus, population-trends, primr, ross-gulls, sabines-gulls, uria-aalge
Organization: Department of the Interior