Results of monitoring surveys are difficult to analyze and interpret for this irruptive and nomadic species. No single monitoring program offers the full coverage or intensity of sampling required to allow a reliable assessment of status. However, the Breeding Bird Survey (BBS) provides good coverage and precision of results in the southern portion of the Pine Siskin's range, while the Christmas Bird Count (CBC) covers a large portion of the species' wintering range in Canada and the United States. Although CBC data are combined for all of North America, results include a good portion of Canadian birds. BBS results suggest that the population in Canada has shown a large decrease since the early 1970s. CBC results for the entire North American range suggest a more moderate decrease of some 33%. In contrast, CBC results for the resident population in Canada suggest an increase in numbers, though the precision of the trend estimate is low. Both surveys show wide year-to-year fluctuations in the abundance of birds, complicating the determination of overall change. Furthermore, the CBC is largely based in urban areas, where bird feeding activities have increased over the years and the increasing presence of Pine Siskin at feeders may influence results. The BBS covers the more stable breeding population and is used as the primary indicator of population status, but its results are moderated by the CBC results. Considering both surveys, the Pine Siskin is perhaps best assessed as having shown a moderate decrease in population since the early 1970s, but the differing trends among surveys and lack of BBS coverage in the north means that the reliability of this assessment is considered low. The Pine Siskin is currently considered to be below the lowest acceptable level relative to its national population goal, based on BBS results (see BBS Canada graph below).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
