Bird Distribution Surveys at Carpinteria Salt Marsh, California USA, January 2012 to March 2013

We collected detailed spatial data on birds as part of a broader effort to understand food webs in California Estuaries. The survey area was Carpinteria Salt Marsh, California USA, which comprises 9 Ha tidal channels, 2 Ha salt flats, 17 Ha upland habitat, 6 Ha tidal pans, 52 Ha vegetated marsh, and 2 Ha tidal flats. In 30 surveys, we mapped 21,486 birds comprising 88 species interacting with the intertidal habitat. Each full survey represents a unique month-year-tide combination (but not necessarily a unique day). Specifically, for each of 15 months between January 2012 and March 2013 we conducted separate, but temporally adjacenthigh-tide and low-tide bird surveys (30 in total) throughout the intertidal habitats. Back to back surveys within the same month are not meant to be independent measures of bird abundance and should be averaged to get an idea of bird abundance in a particular month. Birds were observed along a 12.2 km walking transect designed so that an observer would pass within 50m of all habitat in the estuary. However, to approximate a census, observers were allowed to deviate from the transect to obtain clear views of features like tidal channels. Birds were counted if they were in the intertidal habitat. We also counted some species, like raptors, if they were perched in adjacent upland habitats, but potentially interacting with the estuary.