Birds often prey on agricultural pests, potentially making them effective pest management agents; thus, changes in bird populations may have impacts on plant health. Using an exclosure treatment, we test whether birds reduce herbivore damage and increase crop yield on the island of Luta in the Mariana Island chain. We focused on Luta because the nearby island of Guåhan has experienced widespread bird loss due to an invasive snake, and thus, this experiment simulating bird loss could provide an indication of potential cascading impacts to agriculture on Guåhan. We planted two crops—eggplant and long bean—within bird exclosure and control treatments at three working farms, and measured herbivore damage, crop yield, and spider web abundance in the presence and absence of birds. The influence of birds varied among crops and farms. Herbivore damage did not differ between treatments in long bean, but damage was greater for eggplant in the absence of birds at one farm (“Farm 3”). Yield of eggplant did not differ between treatments, but yield and weight of long bean was lower in the absence of birds at Farm 1. Spider webs were 270% greater in the absence of birds at Farm 1, whereas spider webs were more abundant in the presence of birds at the other two farms. These results suggest that birds may control pest populations, but the effects vary depending on the crop and environmental context.