Bats in Agroecosytems around California's Central Coast

Thursday, 18 December 2014
Alex Wayne, UC Santa Cruz HSSI Program, Santa Cruz, CA, United States
Bats in agroecosystems around California’s Central Coast:

A full quarter of California’s land area is farmland. Crops account for $32.5 billion of California’s GDP. Insect control is a big problem for farmers, and California bats eat only insects, saving farmers an estimated $3 to $53 billion a year.

As farmers maximize crop yield, they use more pesticides, herbicides, and fertilizers, which contaminate runoff streams that bats drink from. Also, pesticide use kills bats’ sole food source: insects.

My research objective was to find out how farm management practices and landscape complexity affect bat diversity and activity, and to see which one affects bat activity more. We monitored 18 sites, including conventional, organic, and low and high-complexity landscapes. We noted more bat activity at sites with high complexity landscapes and organic practices than at sites with either low-complexity landscapes or conventional farming practices. I captured and processed bats and recorded data. I also classified insects collected from light traps.

I learned how to handle bats and measure forearm length and weight, as well as how to indentify their gender. I took hair clippings and fecal samples, which yield data about the bats’ diet. Their diet, in turn, gives us data about which pests they eat and therefore help control. I also learned about bats’ echolocation: they have a special muscle over their ears that closes when they echolocate so that they don’t burst their own eardrum. Also, some insects have evolved a special call that will disrupt bats echolocation so bats can’t track it.