Dave Leatherman worked for the Colorado State Forest Service as an entomologist from 1974-2005. He has discovered at least five insect species new to science. An active birder, Dave has found a unique way to combine his interests in entomology and ornithology. Dave recently wrote an article for the June 2010 issue of Winging It titled “Fresh Fruit, Aisle 3B”.
1. How did you become interested in bird diets? Have you always had a joint interest in birds and insects?
My parents tell me I was always interested in nature while growing up in Columbus, Ohio. All my childhood books with animals in them show a thick outline of pencil where I used carbon paper to transfer their silhouettes to fresh white paper so they could be colored with crayons. If I wasn't playing baseball during the summer, I was at the river catching insects or frogs. My father brought me a cecropia moth cocoon. When it hatched in our living room and performed its miracle of pumping up its wings over the course of an entire afternoon, I was hooked for life. At some point around 1959 or 1960, I got my first Peterson Field Guide and binoculars. From the Lane Avenue Bridge over the Olentangy River near the Ohio State football stadium, I saw large numbers of eastern warblers in the tree crowns at eye level. A Blackburnian male was one I remember being impressed by, both because of its spectacular beauty and because it actually matched the tiny image on Peterson's plate. I apparently quit insect collecting for a time as a teenager, but had the fires restoked in an undergraduate course at Marietta College. My Bachelor's Degree was in biology. Through no great plan of my own, I ended up at Forestry School at Duke and declared a specialization in "Forest Protection" (basically a concentration in entomology and pathology). Upon receiving a Master's Degree, I considered myself a forest entomologist and a 32-year career with the Colorado State Forest Service followed. I still think of myself that way, just don't get paid a regular salary. On a spring day in the 1980's, while birding along the Poudre River in downtown Fort Collins, it struck me that an Orange-crowned Warbler eating a Boxelder Leafroller caterpillar might be a predator-prey combination nobody had ever specifically written down. That seemed like a logical thing to do for an entomologist deeply interested in birds, and all of nature, really. Thus began my obsession to try and figure out what birds eat. In the mid-1990's there was a ten-part series listing accumulated food anecdotes (and anybody else's who provided them) in the CFO Journal (now Colorado Birds). My interest in this aspect of bird biology continues to grow and it's been heartening to see other birders are intrigued by it also. There is so much to learn that none of us could ever do more than scratch the surface, but that's part of the excitement – absolutely no chance of the investigations ending or burn-out.
2. Have you ever identified a bird solely by observation of its diet? Can you give an example in which a bird's diet would help clinch identification?
Many, many bird-watching episodes begin with my attention being drawn to a particular feeding thing, and, as such, the identification of the bird was "because of" the food procurement activity. But I can't really think of a case where I identified the bird solely on the basis of what it was eating. If somebody in Florida saw a big dark raptor fly off unidentified, and while it was disappearing it dropped something that proved to be an Apple Snail, I suppose perhaps they could be pretty certain the bird was a Snail Kite. I have, on the other hand, been shown many interesting insects, some of them important range extensions or first state records, by birds. Downy Woodpeckers whacking away at branches, and then scared off by me and the insects retrieved, have led to at least three state record wood borers. One that I specifically remember was a cerambycid beetle which the book says doesn't occur north of Texas tunneling in a Russian-olive branch at Prewitt Reservoir. Another such episode was a mile-long stretch of barbed wire fence near Riverside Reservoir decorated every 20 feet or so with a particular species of sand-treader cricket that we didn't know lived on the northeastern plains, and that we thought was nocturnal. How could the young Northern Shrike newly arrived at a winter territory have found them? Astonishing.