Owls, Weeds and Bees: Interactions on a Squash Farm

Ximena's Farm Records

1The Quispe family runs a 30-hectare farm in a river valley. They grow squash and hay and raise a small flock of sheep. For a science project, seventh grader Ximena Quispe spent two years studying how living things on the farm affect one another, using her own tests and the farm's records.

2Voles are small rodents that eat roots, stems and seeds, and they dig burrows in the hay field. Early in 2022, Ximena's father put up 4 nest boxes for barn owls, and he added 4 more in 2023. Barn owls hunt at night and feed mostly on small rodents, which they also carry back to their chicks. Every June, Ximena counted the active vole burrow openings in ten 10 m by 10 m plots of the hay field and found the average per plot. The farm's records also list how many owl chicks were raised in the boxes each year (Table 1).

3In the squash field, fast-growing weeds such as pigweed can grow taller than the squash vines. Ximena marked 8 plots of the same size, planted with the same kind of squash and watered the same way. She pulled the weeds from 4 plots every week and left the other 4 alone. At midsummer she used a light meter to measure how much sunlight reached the squash leaves, and in the fall she weighed each plot's harvest (Table 2).

4A squash flower opens for just one morning. A squash forms only if pollen is carried to a female flower from a male flower. Bumblebees and squash bees visit the flowers to drink nectar and to gather pollen, which they carry back to feed their young, and pollen sticks to their hairy bodies as they move from flower to flower. The evening before 100 female flowers were due to open, Ximena tied mesh bags over 50 of them to keep insects out and left the other 50 uncovered. Later she counted how many of each group grew into squash (Table 2).