Intimidated by Diversity

By Michael R. Cornish

          Birds come in many shapes and sizes, this I know. Years spent in my backyard growing up continues to tell me so. Flipping through the book Birds of North America, I would try to memorize what each looked like. Walking in the small patch of woods behind my house, I would then try to identify as many as I could. I would hang bird feeders to attract songbirds, and nail oranges to trees near a swamp I knew were frequented by Baltimore Orioles frequented. It became a game of sorts, always trying to identify as many species as I could, until I eventually knew all but the rarest species.  I really liked birds.  

            Before my coming to Costa Rica this fall, I spent the summer working on a research boat in the Gulf of Maine. One of our tasks was bringing ornithologists to and from island field sites where they were studying birds. While motoring between islands, it was always a treat to hear from them about their work and adventures around the world. I can recall a conversation with a well-known researcher, during which I mentioned that I would be in Costa Rica for the fall semester. He told me that he had just been in that country a few weeks earlier, and said that the amount of bird diversity “down there” “would frighten me”.  I didn’t believe him; I was out on the ocean every day, routinely seeing puffins, razorbills, shearwaters, and many other rare and beautiful species. I knew that it would be impressive, but frightening? I thought not.

            Three months later, I sit here nestled in the premontane wet forests of Las Cruces Biological Station in southern Costa Rica. Of course, at first hand, the bird life here is amazing. But, after many walks looking for birds, the diversity is quite intimidating indeed. Black-mandibled Toucans call, sounding like a weird flute as they fly over the forest canopy. Rufous-tailed and Magnificent Hummingbirds fly through the vegetation, crested caracaras up in palm trees, and brilliantly colored scarlet-thighed dacnis look like blue lights strung up in the trees. The diversity was astounding; everywhere I looked a bird I had never seen popped into view. Now that I think about it, I cannot recall having seen the same species more than twice. Trying to keep a simple species list was downright overwhelming.

             A really interesting observation I made was the number of different species within the same family.  Tanagers, for example, also occur in my native Vermont but only one species, the scarlet tanager. Within the span of three hours walking through the Wilson botanical garden at Las Cruces, I recorded more than five different tanagers; cherries tanagers, bay-headed tanagers, silver-throated tanagers, and golden crowned tanagers to name a few. Lead by the expertise of Jason Figueroa, a local guide, we saw over thirty species in a single bird walk through the garden one morning, including a cherries tanager male (top left),  a black-mandibled toucan (top right),  a green honeycreeper female (bottom left), and a blue-crowned motmot (bottom right).  Experiencing first-hand the products of niche partitioning from intense competition was an amazing experience. Frightening may not be the right word (but it makes for good effect), the diversity and sheer number of bird species in this place is truly astounding and something I wish more people could experience.