Mapping Physical Characteristics of the Columbia River Mouth Using Transmittered Diving Waterbirds, 2014

This study investigated the local movements, foraging dive behavior, and foraging habitat selection by breeding adults of 2 closely related cormorant species, double-crested cormorants, Nannopterum auritum and Brandt’s cormorants, Urile penicillatus. These species nest sympatrically at East Sand Island in the Columbia River estuary at the border of Oregon and Washington states, USA. Breeding individuals of each species were tracked using GPS tags with integrated temperature and depth data-loggers. Complete TDR and GPS instrument data were obtained from 15 Brandt’s cormorants and 17 double-crested cormorants in 2014. Datasets will be in ".csv" format. TDR data were collected at a one-second sampling frequency for two Brandt’s and three double-crested cormorants, while the remaining TDR instruments sampled at a two-second frequency. For the five one-second frequency deployments, processed files were generated for 1) the original one-second frequency data, and 2) the original data with every-other observation subsampled, matching the temporal resolution of the two-second data. This yielded a total of 37 separate deployments/frequencies for analysis.