Hamilton, C.D., Golightly, R.T. & Takekawa, J.Y. 2005. Characteristics of diving in radio-marked Xantus’s Murrelets. Marine Ornithology 33: 155-159.

We monitored diving activity of radio-marked Xantus’s Murrelets Synthliboramphus hypoleucus near Anacapa Island, California, during the breeding season. Thirteen radio-marked murrelets were remotely monitored from Anacapa Island with a hand-held antenna and radio receiver for 29 h in three sample periods in April and May 2003. Mean dive duration in each sample period was 18 ± 2 s, 28 ± 2 s, and 24 ± 4 s, respectively, suggesting that dives were less than 21 m from the surface. Dive duration and subsequent time on the surface differed between the sample periods. Dive duration and subsequent time on the surface were not correlated in observations stratified by individual bird, or by sample period. Further, dive duration and subsequent time on the surface were not correlated within foraging bouts. Dive characteristics measured near Anacapa Island suggested that Xantus’s Murrelets have the ability to capture prey found at varying depths, but will feed on prey that is most available near the surface of the water.

Key words: Xantus's Murrelet, Synthliboramphus hypoleucus, Anacapa Island, radio telemetry, dive duration, dive depth, surface times