Abstract |
An assessment of bird utilization patterns of the intertidal soft sediment and low marsh habitats of the Yaquina estuary, Oregon was conducted from December 2007- November 2008. Daylight censuses of all birds utilizing selected estuarine intertidal habitats in the Yaquina estuary were conducted by a single observer from shoreline observation sites in each of five intertidal habitats (Zostera marina (eelgrass), Upogebia (mud shrimp)/mudflat, Neotrypaea (ghost shrimp)/sandflat, Zostera japonica (Japanese eelgrass), low marsh), and during five tide levels (<0.3, 0.6-0.9, 1.2-1.5, 1.8-2.4 and >2.4 m above MLLW). Censuses were designed to determine the spatial and seasonal utilization patterns of estuarine habitat by birds, and how these patterns changed during the tidal cycle. The estuary was divided into four sectors for surveying, Idaho Flat, Sallys Bend, Raccoon Flat and Upriver. Field census data were collected for a one year period, during six, two-month count cycles. A total of 49,015 birds consisting of 79 distinct species and 10 composite taxa were recorded from the surveys. Gulls and terns comprised 42% of the total birds and, together with ducks, shorebirds, corvids and geese, accounted for about 92% of the total abundance. The addition of herons/egrets, rails (i.e. coots), and pelicans/cormorants comprised just over 98% of all birds observed. The remaining birds consisted of songbirds, loons/grebes, raptors and alcids. |