Between 1974 and 1993, CWS staff divided the coast of Atlantic Canada into coastal blocks to serve as boundaries to count coastal waterbirds during aerial surveys.
The CWS coastal blocks divide coastal waterbird habitat: shoreline, rivers, and marshes, in to areas delimited by landmarks that are easily identified from the air. Each block contains mostly uniform habitat, and blocks usually end where a distinct change in habitat occurs. Discrete small bays or bodies of water are usually treated as a single block, and protected areas such as National Parks, National Wildlife Areas, or Provincial Wildlife Management areas are contained within single or multiple blocks which end at their boundaries.
With the use of GPS technology during aerial surveys, coastal blocks are no longer used to summarize observations of wildlife during aerial surveys. Coastal blocks are often referenced in other CWS datasets, and can serve as ecological boundaries to examine the coast of Atlantic Canada.