Strategies for survival: Stellar sea lions, harbor seals and sea otters Chapter 4.9
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Book chapter↗
Geology topics
Alan M. Springer
Publications and source records attributed to Alan M. Springer.
Small boats disturb fish-holding marbled murrelets
Disturbance of seabirds by people at nesting colonies can reduce reproductive success and alter population demographics (Vermeer and Rankin 1984). In response to disturbance, adult seabirds may increase the incidence of alarm postures and alarm calling (Burger and Gochfeld 1993), increase heart and breathing rates (Culik and others 1990; Wilson and others 1991), reduce attendance of nest sites (Olsson and Gabrielsen 1990; Wilson and others 1991), and completely abandon nests and chicks (Boellstorff and others 1988; Evans and Kampp 1991). Daily or frequent handling of chicks can reduce their growth rates and survival (Harris and Wanless 1984; Pierce and Simons 1986; Piatt and others 1990).
Northwestern Naturalist↗
Deciphering the social structure of Marbled Murrelets from behavioral observations at sea
We surveyed Marbled Murrelets ( Brachyramphus marmoratus ) daily from small boats in Auke Bay and Fritz Cove, Alaska, from May through August 1992 and 1993. Differences in numbers of juveniles and in the timing of their presence in the study area between the two years indicated that breeding phenology was late and productivity was low in 1992 compared to 1993. This difference was consistent with variability in the physical environment. Of 99 fish identified in the bills of fish-holding adult murrelets, 81 (82%) were Pacific Sand Lance ( Ammodytes hexapterus ). Counts of fish-holding adult murrelets were significantly higher in the evening than at any other time of day. Time of day had no significant effects on counts of fledglings, indicating that juveniles were moving into and out of the study area during the day. Murrelets were predominantly found in groups of two or more, even during incubation, suggesting that murrelets incur an appreciable benefit, such as increased foraging efficiency, from foraging in groups. For both summers, there was no correlation between counts of murrelets on the water and numbers of murrelet detections in the adjacent forest. We suggest that many behavior patterns of the Marbled Murrelet (displaying, choosing of mates, and pair-bonding, finding of nest sites and successful foraging of juveniles) may be socially facilitated.
Waterbirds↗
Temporal variability in abundance of Marbled Murrelets at sea in southeast Alaska
We examined effects of season, time of day, tide stage, tidal oscillation, and sea surface temperature on Marbled Murrelet ( Brachyramphus marmoratus ) abundance and distribution at sea. We also evaluated whether constraining surveys to specific time periods or tide stages would reduce temporal variability in counts. Murrelets were surveyed daily from small boats and from shore in Auke Bay and Fritz Cove, Alaska, from May through August in 1992 and 1993. Murrelet numbers were high before egg-laying, declined by more than half during egg-laying and incubation and were highly variable during chick-rearing and fledging. Murrelet numbers were highest in early and late morning and declined throughout the day, sometimes increasing slightly in the evening. Peak murrelet numbers occurred on high or falling morning tides, especially in shallow areas where Pacific sand lance ( Ammodytes hexapterus ) were abundant. Differences between years in murrelet abundance and breeding phenology probably resulted from interannual differences in the pattern of seasonal warming and subsequent effects on production at lower trophic levels. We recommend that surveys for trends in abundance in Southeast Alaska be conducted in early morning, in June, at high or falling tides. Power analyses indicated that surveys conducted in this manner would minimize the number of years required to detect a significant change in abundance.
Alaska↗