The breeding population of the Ipswich sparrow (Passerculus sandwichensis princeps), Sable Island’s endemic passerine, was censussed in spring 2006 using two methods: one used from 1968-1995 that had yielded a population of up to 3400 birds, and another developed in 1998 (slightly modified here) that had yielded nearly 6000 birds. In this 2006 census, the methods yielded 6700 and 6800 sparrows, respectively, well within the margin of error of the 1998 census. These results suggest that the difference between pre-1998 and 1998 censusses represents a real increase in the sparrow population, and not just a difference in censussing technique. The Discussion evaluates the methods based on such features as how well they cover different habitats, how well they detect birds, and practicality.
Grains of Sand