Evaluation of nest temperatures to assess female nest attendance and use of video cameras to monitor incubating waterfowl

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Wildlife Society Bulletin 2004, 32(2):581–587 Peer refereed Quantifying avian incubation provides insight into reproductive strategies and potential constraints on reproduction. Methods to assess nest attendance by parent birds include direct observations, mechanical devices, time-lapse photography, radiotelemetry, weight scales, changes in temperature in nests and eggs, and a multiple-sensor system of weight scales and infrared beams (e.g.,Afton and Paulus 1992). In recent years, monitoring changes in nest and egg temperatures has been used to study waterfowl attendance patterns in redheads (Aythya americana;Yerkes 1998), blue-winged teal (Anas discors; Loos 1999), northern shovelers (A. clypeata; MacCluskie and Sedinger 1999), spectacled eiders (Somateria fischeri; Flint and Grand 1999),wood ducks (Aix sponsa;Manlove and Hepp 2000), and greater snow geese (Chen caerulescens atlantica; Poussart et al. 2000). Researchers discretely hid temperature-sensing probes, or thermistors, inside artificial eggs placed in the nest bowl and recorded temperature data at specified time intervals on microcomputers or data loggers. Data loggers can collect data for extended periods of time; their small size allows them to be hidden next to nests or hundreds of meters away. Low cost,ease of setup in the field, minimal investigator disturbance to the incubating female, and ability to monitor many nests during a breeding season likely have led to the increased use of temperature sensors with data loggers to monitor nest attendance. However, detecting movements of incubating females on and off the nest with temperature data appears subjective and may contain observer error. Female movements off the nest may not be detected, especially when ambient temperature approaches incubation temperature (Afton and Paulus 1992). Furthermore, despite the method’s recent popularity, the reliability of temperature data to quantify nest attendance has not been adequately tested. Limited validation of temperature recordings involved flushing females from their nests (Loos 1999), and direct observations of females leaving and returning to nests (Manlove and Hepp 2000, Poussart et al. 2000) to provide comparisons of these times to temperature changes recorded by data loggers. Although these studies failed to find differences between real movements of the female and temperature data, they have not provided a thorough validation of the use of temperature data to assess nest attendance for prairie-nesting dabbling ducks. Manlove and Hepp (2000) validated female wood ducks using nest boxes,Poussart et al. (2000) monitored colonially nesting greater snow geese, and Loos (1999) provided only a known exit time from the nest. Our primary objective was to examine the accuracy of using temperature data to assess female nest attendance by monitoring northern pintail (A. acuta, hereafter pintail) and mallard (A. platyrhynchos) nests on the prairie breeding grounds. We continuously monitored nests using closed-circuit video recordings to provide true times of female presence or absence, while simultaneously monitoring the same nests with 2 different types of temFrom the Field: Evaluation of nest temperatures to assess female nest attendance and use of video cameras to monitor incubating waterfowl