Figure 1

Unrooted UPGMA clustering tree based on microsatellite allele frequency differences. Only breeding sites with greater than 20 individuals were included; we assessed support using 10,000 bootstrapped data sets. Nodes with greater than 50% bootstrap support are indicated. The results shown here are consistent with previous research that found support in UPGMA clustering for a distinction between B. j. calurus and B. j. borealis breeding and migration sites [22].