Electronic Activity Recorders for Aquatic Wildlife

Abstract

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