Census of the Willow Ptarmigan in Newfoundland

Abstract

The accuracy of direct counts, the King strip census, the Lincoln index, and a becking census were tested for willow ptarmigan (Lagopus lagopus alleni) in a 2.6-square-mile study area on Brunette Island, Newfoundland, from 1962-65. In 1962 a minimum direct count was made of a dense population by totaling (1) birds killed in the summer and fall, (2) birds dying in winter, and (3) birds still alive in spring 1963. Compared to this statistic the King census and Lincoln index based on the hunter kill gave satisfactory results, while a Lincoln index based on July and August observations greatly underestimated the population. Direct counts in 1963, 1964, and 1965 were believed to estimate the true population within 5 percent. Compared to these direct counts the Lincoln index provided reliable statistics; the King census was accurate in 1964, but overestimated the population in 1963 and underestimated it in 1965. The becking count was accurate in 1965 and underestimated the cocks in 1963 and 1964. A further test of these techniques plus an aerial census trial on the Avalon Peninsula suggested that the becking and aerial counts were sufficiently accurate for management purposes on the mainland of Newfoundland.