Food use by an insular population of coyotes

Comparison of helicopter and ground surveys of waterfowl broods in southern Ontario

Managers often employ aerial survey information to manage waterfowl. Results of surveys by helicopter and from elevated platforms were compared to determine the accuracy of helicopters to detect waterfowl broods on beaver ponds in southern Ontario in 1996 and 1997. Fewer broods were detected from the helicopter than by observers in elevated platforms at wetland margins. When broods were detected by helicopter crews, >90% were correctly enumerated and >80% were correctly aged. A second helicopter survey, the day following the first survey, did not change the Visibility Correction Factor (VCF) substantially (1.79 vs. 1.53). Data from the 2 helicopter surveys combined (without ground counts) resulted in greater VCFs (2.17) than when a single helicopter survey and ground count was used (VCF = 1.79). In general, VCFs for most waterfowl broods were lower in forested or closed (emergent and scrub-shrub) wetland habitats than on open wetlands. When multiple broods were present on a wetland, sightability of the additional broods (second, third, etc.) was lower for the helicopter crew than ground crew. Surveys by helicopter are likely most useful to develop indices for waterfowl broods of diver species in large inaccessible areas. If accurate information is required on dabbler brood densities, age, and number of ducklings, quiet observation by crews in elevated platforms should be used.