Summary (AGH): Conserving any population requires regular monitoring, which in turn requires an accurate estimate of the population’s size, or at least a precise index of its relative abundance, which can then be compared from one year to the next. The Ipswich Sparrow population on Sable Island was censused nearly every year in the late 60s and early 70s, then more irregularly thereafter, so there is good information on its ups and downs that has been helpful in its conservation and understanding the role of harsh winters and mild summers in population regulation. These counts, however, were based on thorough searches of hand-picked areas judged to be representative of habitats on Sable Island, and thus were possibly biased and might not have changed together with changes across the island as a whole. To address these possible problems, a new census method was devised, in which observers walked across the island along north-south routes that were randomly selected within sections of the island that differed in their habitats. The random selection allowed an estimate of the precision of the count, which was impossible with the previous census method. The count estimated that 5960 + 555 individuals breed on Sable Island, an estimate nearly double any previous count.
