Use of Radio-Telemetry to Test for Investigator Effects on Nesting Mallards, Anas platyrhynchos

Abstract

We examined the effects of investigator activity on hatching rates of radio-marked wild female Mallards (Anas platyrhynchos), and evaluated the efficacy of radio-telemetry to minimize nest disturbance, characterize vegetation at nest sites, and mark nests for later relocation. Differences in hatching rates between birds that were flushed once (experimental) and those never flushed (control) approached significance (P = 0.086). However, hatching rates did not differ (P = 0.588) between the two groups when nests where investigator activity caused abandonment (30% of experimental nests) were removed from analysis. If the nest remained active, flushing the bird and visiting the nest once did not appear to increase the likelihood of the nest being depredated. We were able to locate 92% of radio-telemetry marked nests (control) after the female was no longer tending the nest. Radio-telemetry provides a technique to collect relatively unbiased nesting data for Mallards without disturbing the female.