Participating in Warbler Weekend in Frontenac,MN, on the Mississippi River this past weekend was quite an experience. The total bird list seen by all 100+ observers at this gathering ran to 139 species; I think my husband and I saw about 70 of those. Some were old friends (e.g., Yellow-rumped and Yellow Warblers), and some were brand new to us, like the Cape May Warbler. It’s hard to pick a “most beautiful” among such colorful creatures, but the Cape May was my choice for this weekend.
The “best bird” was also the first bird I saw this weekend, highlighted in the golden light of our early morning (6:30 a.m.) departure on bird walks all over the wooded areas of Frontenac. This particular bird was so busy probing into the flowers of this tree that it completely ignored the exclamations and chatter of the dozens of people standing 20 feet away.
Cape May Warblers are spruce budworm specialists, but they do have an unusually curled and semi-tubular tongue that allows them to probe into the depths of flowers to lap up nectar, which they use as an alternative food source to their highly insectivorous diet.
These warblers are also unusual in having a larger than expected number of nestlings for a tiny warbler. Their clutch size might vary markedly depending on the density of spruce budworm available in a particular season, ranging from a low of 4 to a high of 9 nestlings per brood. This density dependent strategy allows the warbler population to expand rapidly and serves as an effective control of budworm outbreaks in the coniferous forests.