High-frequency marine radar was used to estimate the numbers of Marbled Murrelets entering 19 watersheds in the Clayoquot Sound in 1996 (14 watersheds sampled), 1997 (19) and 1998 (13). The radar study was part of a multi-year study of Marbled Murrelets in Clayoquot Sound, which included audio-visual surveys linked with inland habitat analysis and at-sea boat surveys. The two primary goals of the radar study in Clayoquot Sound were: (1) to count the total numbers of Marbled Murrelets using each of the watersheds, and hence get an estimate of the total population using the sound; (2) to compare the numbers of murrelets with macro-habitat features in each watershed, and hence identify the important watershed-level habitat needs for the bird. Since radar censusing is a new technique, and there is considerable variation in murrelet activities, important secondary goals were: (3) to determine the most appropriate measure of counting murrelets per watershed; (4) to examine diurnal, seasonal and annual variations in murrelet counts, and determine the most accurate census protocol; (5) to examine the effects of weather on radar counts and murrelet behaviour and take this into account in making accurate counts and comparisons; (6) to document the species and number of birds likely to be confused with murrelets on radar at each radar station; and (7) to compare the radar inventory with audio-visual RIC surveys made inland in selected watersheds.
Burger, Alan E.. 1999. Radar Inventory of Marbled Murrelets in Clayoquot Sound, 1996-1998. Ministry of Environment, Lands and Parks