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The #WildAg team is currently working on a little side-project to measure the diets of barn owls nesting in boxes provided by the Turkovich Family around their farm property. We're interested in finding out if barn owls nesting in row crop habitat have diets that differ from those nesting in perennial crops like orchards and vineyards.
When I first arrived in California and started talking to farmers about beneficial birds, many immediately brought up the idea of raptors controlling pest mammals and birds. While my main #WildAg experiment is looking at the ability of songbirds to control insect pests, before moving to California I spent 6 years in New Zealand studying whether reintroducing the threatened New Zealand Falcon into vineyards would be an effective means of reducing the damage that pest birds cause to wine grapes in Marlborough. (It turns out, vineyards with resident falcons had close to 70% less grape damage than those without falcons). So, my ears perked up as soon as growers here started mentioning their interest in learning more about the ability of native raptors to control rodent pests.
The study we are running now is a great opportunity for the many undergraduates on the #WildAg team to get more experience with conducting scientific research. Joshua Heasell was involved in early discussions with Mike Turkovich and located and collected the owl pellets from most of the boxes in our study. Ryan Bourbour has been doing a lot of the initial owl pellet analysis and, along with Breanna Martinico, has worked out the bulk of the methods we're using. Sara Remmes and Jeffery Haight are also going to join us to dissect pellets and analyze data. We're in the early days yet, but the plan right now is for this small team of very capable undergraduates to work together to dissect pellets, analyze data, and write a scientific paper together. This will give these grad-school prospects a taste of the entire scientific process, from experimental design to submitting and revising a peer-reviewed publication.
Dissecting barn owl pellets is a common activity at nature centers and in classrooms around the world. Because owls often swallow their prey whole, and don't have digestive systems that break down bones very well, pellets are composed of undigestible material (fur, bones, and some feathers). We're using counts of diagnostic features such as lower jaw bones to determine the minimum number of individuals of each species in each pellet. This process is initially slow, but as we get through more pellets we're becoming good at noticing the identifiable features from each species (and with the help of a loan of reference skulls from the Museum of Wildlife and Fish Biology and advice from Professor Dirk Van Vuren).
The Turkovich family is famous for their progressive farming methods and they have a wide variety of different crops in their growing portfolio, including vineyards where they estate-grow grapes for the family's winery. We worked closely with Mike Turkovich to plan our bird exclusion experiments on alfalfa and tomato fields, and have gotten lots of advice from Mike and his brother Chris on methodology and the logistics of running an experiment on a working farm.