Abstract: The U.S. Geological Survey (USGS), in partnership with U.S. Fish and Wildlife Service and the Bureau of Ocean Energy Management, Resources, and Enforcement set forth to compile all available data from seabird observation datasets from the Atlantic Outer Continental Shelf into a single database. This product characterizes the survey effort and bird observations that have been collected across space and time. Currently, the database contains ~60 datasets from 1906-2009 with over 260,000 records of seabird observations. The web mapping services provided for these observational data represent processed data, as described elsewhere in this document. The layers are titled beginning with "Atlantic Offshore Seabird Dataset Catalog": 1. Total Survey Effort - all years' effort data represented in "five minute equivalent" units. 2. Seasonal Survey Effort, all years - like the Total Survey Effort, but divided by season 3. Seasonal Effort Background for Species Maps - derived from previous layer, but designed to show as background for a species map, showing empty grid cells with effort but no detections. 4. Decadal Survey Effort, all seasons - breaks out effort by decade. 5. Seasonal Naive Species Occurrence - this is the species data layer. Species counts were adjusted using the five-minute equivalent effort units; however due to biases in methods, etc (see elsewhere in this document) these maps combining multiple surveys should be used with caution. 6. Seasonal Effort Adjusted Counts of Focal Species - this is a summary layer essentially "stacking" the naive species occurrence maps for 24 selected species. This list of species is not inclusive of all important species, but was selected as a representative list for discussion purposes for a June 2011 workshop. The species are: (Audubon's Shearwater, Black-capped Petrel, Black Scoter, Common Loon, Common Murre, Cory's Shearwater, Double-crested Cormorant, Dovekie, Great Black-backed Gull, Great Cormorant, Greater Shearwater, Long-tailed Duck, Northern Fulmar, Northern Gannet, Razorbill, Red Phalarope, Red-necked Phalarope, Roseate Tern, Red-throated Loon, Surf Scoter, Unidentified Cormorant, Unidentified Scoter, White-tailed Tropicbird, White-winged Scoter) Purpose: Currently, the mapping products available from the database are based on ~60 datasets from 1906-2009 with over 260,000 records of seabird observations. These maps include representations of survey effort and bird detections. Effort was standardized into "five minute equivalents" so that both discrete and continuous transect data could be combined. This unit is essentially "five minutes of survey effort from a vessel traveling 10 knots." Species data were prepared for occurrence maps by adjusting counts using these five minute equivalents. The resulting species maps are referred to as "Naive occurrence maps" because, although some effort standardization has been applied, there are no corrections for biases introduced by differences in survey methodology, observers, and species detectability.