Myrtle warbler

The Myrtle warbler is a migratory songbird that becomes a stark measure of pesticide damage in Rachel Carson’s account of elm spraying: in Whitefish Bay, Wisconsin, observers who had counted at least a thousand during migration in earlier years could find only two in 1958. Its sudden scarcity makes visible the reach of a spray program timed to coincide with a heavy wave of migrating birds.

Migration and Abundance

In Whitefish Bay, the Myrtle warbler was part of a substantial seasonal passage. During former years, at least a thousand could be seen in migration. The comparison is not between a thriving population and a distant estimate, but between familiar abundance and an almost empty sky: after the elms were sprayed, observers in 1958 found only two.

The Spraying and Its Timing

The broader spraying was timed to coincide with an exceptionally heavy wave of warbler migration. Nearly all warbler species present in the area were represented in the heavy kill that followed. The Myrtle warbler’s collapse in the count therefore belongs to a larger episode in which a control measure directed at trees exposed migrating birds as they passed through.

Significance in Carson’s Account

Carson uses the contrast between the earlier count and the two birds found in 1958 to show how indiscriminate spraying can reach creatures that are not its intended targets. The specific loss also gives scale to the wider record of warblers killed by the spray: ecological harm appears not as an abstraction, but as the disappearance of birds once observed by the thousand.