Food selection by skylarks: the effect of a pesticide on grazing preferences.

Abstract

Skylarks foraging in sugar beet fields in spring graze the crop seedling cotyledons causing economic damage in some cases. The birds also take weed seeds and beetles from the soil surface and graze weed seedlings. Counts of grazed seedlings, and micro-analysis of bird faeces, both showed that skylarks preferred sugar beet seedlings to the available weed seedlings. However, where crops were treated with aldicarb, a seed furrow granular pesticide, this preference was less apparent. In cage studies, captive skylarks grazed fewer aldicarb-treated seedlings than untreated seedlings. A survey of commercial plantings of sugar beet also showed significantly less grazing on aldicarb-treated than untreated crops.