Trade-offs in performance of six lightweight automated tracking devices for birds

Abstract

Researchers should consider the costs and benefits of using tracking devices and choose devices that will optimize information gained with minimal effects on study organisms. With numerous technological advancements and devices marketed for avian research, selecting an optimal device and data collection interval (i.e., duty cycle) can be difficult. We evaluated six tracking-device types from two manufacturers (Pinpoint 10 [1-g; Lotek], Pinpoint Argos 75 [4-g; Lotek], Pinpoint Argos Solar S [6-g; Lotek], Ornitrack-10 [10-g; Ornitela], Ornitrack-15 [15-g; Ornitela], and Ornitrack-N35 [35-g; Ornitela]) and varied duty cycles to quantify (1) fix success rate for all units, (2) precision of location information for all units, and (3) battery voltage given the effects of duty cycle and reduced light for solar-rechargeable units (Ornitrack-10, Ornitrack-15, and Ornitrack-N35). Fix success rates for Pinpoint 10, Pinpoint Argos 75, Ornitrack-10, Ornitrack-15, and Ornitrack-N35 units were overall > 0.95. However, the Pinpoint Argos Solar S units had a lower fix success rate that varied with duty cycle intensity. The Pinpoint Argos 75, Pinpoint Argos Solar S, and Ornitrack-10 units were more precise (≥ 99% points were collected within 20 m of each other) than the Pinpoint 10, Ornitrack-15, and Ornitrack-N35 units (> 80% of points collected within 20 m of each other). For all devices, batteries maintained a high charge (i.e., battery charge lost during the dark hours was recovered or mostly recovered during the day) under high and intermediate light levels, and low and intermediate duty cycles. Light explained more variation in battery voltage than duty cycle. We encourage investigators to evaluate devices prior to deployment on birds to maximize data quality relative to their research questions.