This case study uses the brood parasitic relationship between the brown-headed cowbird (Molothrus ater) and the prothonotary warbler (Protonotaria citrea) to illustrate how complex species interactions can drive coevolutionary dynamics. Cowbirds benefit by laying eggs in warbler nests and avoiding costs of parental care, while warblers incur energetic and reproductive costs by hosting parasitic cowbird offspring. As part of this species interaction, cowbirds have evolved unique behaviors to “encourage” the warblers to host their offspring, including retaliatory nest destruction when parasitic eggs are rejected, resulting in higher failure rates for unparasitized nests. This case study is presented without initially revealing cowbird behavior, which challenges students to interpret ecological patterns, evaluate evolutionary trade-offs, and consider alternative explanations for observed data. Designed for sophomore-level biology majors but adaptable to introductory courses, the case study emphasizes critical thinking, experimental design, and the evolutionary implications of species interactions in natural systems.