Tessa N. Campbell
Department of Biology University of Victoria, Box 3020, Station CSC, Victoria, B.C. V8W 3N5
Abstract: The traditional point count survey method of population size estimation was tested on breeding Red-winged Blackbird (Agelaius phoeniceus) and Yellow-headed Blackbird (Xanthocephalus xanthocephalus) populations at Myers Wetlands, British Columbia. Initial counts of the two icterids totalled seven male and five female red-wings and 32 male and eight female yellow-heads. The polygynous nature of both species may result in underestimates of population size if the population size is estimated by multiplying the number of males counted by two to include their mates. At Myers Wetlands, traditional methods produced estimates of 14 red-wings and 64 yellow- heads; yet, 67 active red-wing and 178 active yellow-head nests were found. Thus, results of traditional point count surveys should be interpreted with caution, even when attempting to estimate minimum rather than actual population sizes.
Key words: Agelaius phoeniceus, British Columbia, point count survey, population estimation, Red-winged Blackbird, Xanthocephalus xanthocephalus, Yellow-headed Blackbird
Campbell, T.N. 1999. Preliminary test of point count survey method of population size estimation on breeding Red-winged and Yellow-headed blackbirds at Myer’s wetlands, British Columbia. British Columbia Birds 9:11-14.
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