Search

Kleptoparasitic behaviour of Arctic Skuas was studied at a Black Guillemot colony in northeastern Hudson Bay, Canada. Skuas procured fish in 7-2% and 19-9% of attacks, and Black Guillemots lost fish in 7-2% and 21-2% of chases in 1982 and 1983, respectively. In 1983 chase outcome was related to distance between birds at the end of a chase and number of skuas in pursuit. The skuas' foraging efficiency (energy intake/energy expended during hunting) was estimated at 45 for 1982 and 5–8 for 1983, and total daily energy expenditure was estimated at 2–4 and 2-1 × b.m.r. for these years. Energetic calculations suggested that skuas obtained sufficient food to meet their daily needs in 3–6 h of hunting in 1982 and 2–7 h in 1983. The absence of intensive kleptoparasitic activity by breeding skuas in North America is attributed to the paucity of colonies suitable for both feeding (due to available host species and colony topography) and nesting (due to presence of arctic foxes and/or polar bears).

Leach's Storm—Petrels (Oceanodroma leucorhoa), the smallest and most abundant seabirds that breed in the northwest Atlantic, are not usually included in avian energetics models. To round out an energy analysis of seabirds spanning the full range of body sizes in the northwest Atlantic, the field metabolic rates (FMRs) of breeding Leach's Storm—Petrels were measured using doubly labeled water techniques (DLW). Metabolic, dietary and, demographic data were used as inputs in a populations energetics model to estimate the energy requirements and prey harvests of the Leach's Storm—Petrel population of eastern North America. FMRs of storm—petrels that remained in burrows averaged 83.3 ± 19.4 KJ/d. FMRs increased significantly with time (i.e., x in hours per day) at sea (y = [85.8 ± 6.5] + [3.13 ± 0.48]x), and metabolism at sea was estimated to be 161 ± 18 KJ/d. FMRs integrated over activity on land and activity at sea averaged 124 KJ/d during incubation and 142 KJ/d during chick rearing. Incubating adults weighed significantly more than adults rearing chicks, although adult mass did not vary with age of chick. Basal metabolic rate (BMR, measured as O2 flux) averaged 2.02 ± 1.01 cm3°g—1°h—1, equivalent to 45.4 ± 30.4 KJ/d, very similar to values obtained for breeding conspecifics in the Bay of Fundy and in the Bering Sea. Thermal conductance averaged 0.124 ± 0.065 cm3°g—1°h—1°°C—1. FMR/BMR ratios averaged 2.73 for incubating birds and 3.13 for birds rearing young. Population energetics modelling indicated that during a 7—mo breeding period Leach's Storm—Petrels at colonies in the northwest Atlantic Ocean consume >74 000 Mg of prey, mostly myctophids and amphipods (mostly Hyperia galba), as wall as euphausiids (mostly Meganyctiphanes norvegica) and other prey (decapods, copepods, isopods). Leach's Storm—Petrels make up °80% of the breeding seabird population in eastern Canada, but owing to small body size and metabolic efficiency, they account for comparatively little of the energy that flows through the avian assemblage of the northwest Atlantic. An intra—specific, inter—colony difference in FMR is suggested: FMRs measured in a Newfoundland colony were significantly higher than those determined with the same DLW procedure in the Bay of Fundy near the southern limit of the species' breeding range in the northwest Atlantic. Differences in ambient temperatures and wind speed associated with different oceanographic regimes may generate energetic differences. Like inter—colony differences in feeding ecology, inter—colony differences in FMR need to be considered in population and community energetics models and in meso— and mega—scale extrapolations.

Northern gannets, Sula bassanus, and possibly other seabird species nesting on Funk Island off northeastern Newfoundland preyed on postsmolt Atlantic salmon, Salmo salar. Salmon comprised less than 1% of 2928 regurgitated food samples collected from gannets at the colony. Ten smolt tags were recovered in and near the gannetry during August or September in 1984 through 1986. The tags were from smolts released 3–4 mo earlier in the Penobscot River (Maine) (n = 7) and one each from the Saint John River (New Brunswick) and the Lower Clyde and LaHave rivers (Nova Scotia). These recoveries provide evidence that postsmolt Atlantic salmon from rivers in New England, the Bay of Fundy, and the Atlantic coast of Nova Scotia migrate off eastern Newfoundland This migratory pattern contrasts with that of postsmolts from the Gulf of St. Lawrence, which tend to move northwards along Newfoundland's west coast and through the Strait of Belle Isle.

There has been considerable controversy over the existence of serum albumin in fish. One of the physiological functions of albumin is to bind free fatty acids. This characteristic was used to screen the plasma of seven species of salmonids. Each species contains a protein fraction that (i) binds palmitate, (ii) has a molecular mass similar to that of human serum albumin, and (iii) is one of the most rapidly migrating proteins when salmonid plasma is subjected to anodal polyacrylamide gel electrophoresis. We conclude therefore, that salmonids have serum albumins that are homologous to the serum albumin of higher vertebrates.

An activity recorder is described that can be used to determine time spent by aquatic animals diving, at the surface of the water, and out of the water. Time spent flying also can be calculated for volant aquatic birds if time on land is measured by direct observation. Data are displayed on a digital screen that can be read from a distance through binoculars or a telescope or directly from an animal in hand. The recorder is simpler to use than other nontransmitting activity recorders and has wide application in timeenergy studies of aquatic wildlife. J. WILDL. MANAGE. 51(2):395-399 The allocation of time to various activities is an important element of life history strategy and energy balance in animals. Several studies have measured activity budgets of aquatic birds, mammals, and reptiles through direct field observation (Titman 1981, Maxson and Bernstein 1984, Cooper 1985) and radio telemetry (Siniff et al. 1971, Obbard and Brooks 1981, Melquist and Hornocker 1983). Direct observation is unsuitable for cryptic, nocturnal, or widely mobile species, and determination of activity budgets from telemetry may be hampered by limited transmitter range and difficulties of interpreting signal patterns (Harrison and Stoneburner 1981, Wanless et al. 1985). Recently, Wilson and Bain (1984) and Wilson and Achleitner (1985) developed auto-radiographic meters for marine birds and mammals, which can be used to calculate time budgets (Nagy et al. 1984), and Prince and Francis (1984) devised an immersion timer that uses electrolyte deposition to measure the time albatrosses (Diomedea spp.) spend on the water. These devices do not require that the animal remain within visual or transmission range of the observer, but they require careful calibration before use and laboratory equipment to decode results. We have developed a new type of activity recorder for aquatic wildlife that is inexpensive, gives directly readable results, operates for long periods without maintenance, and, in some circumstances, yields activity data without need to recapture the animal. This paper outlines design and construction of this recorder and describes its application to 2 marine birds, the common murre (Uria aalge) and the northern gannet (Sula bassanus). We are grateful to K. G. Adams, D. L. Cairns, and G. F. Pierce for essential background information. F. Anderka of Holohil Systems Ltd. gave valuable advice and suggestions. We thank R. MacLellan and the staff of Mem. Univ. Tech. Serv. for assistance with many construction details, and W. Jacobs of Mem. Univ. Faculty Eng. for testing electronic designs. Thanks are also due to S. Parent of the Montreal Aquarium for arranging timer trials on captive birds and to G. Chaisson of Mem. Univ. Mar. Sci. Res. Lab. for pressure-testing prototype timers. Fieldwork in the Witless Bay and Funk Island Ecol. Reserves was authorized by the Newfoundland and Labrador Wildl. Div. This research was funded by Can. Dep. Fish. and Oceans Subvention Grants (DKC and WAM), Natl. Sci. and Eng. Res. Counc. Can. Grants A0687 and E6828 (WAM), and the Newfoundland Inst. for Cold Ocean Sci. and Psych. Dep. Mem. Univ. This is Rep. 116 from the Newfoundland Inst. Cold Ocean Sci. DESIGN AND PRINCIPLE OF