Not-quite-so-old Hats


Despite my best efforts to explore new scientific frontiers as a graduate student, I have stumbled into Piper ecology. Piper is a plant genus familiar to most Neotropical ecologists because of their diversity and the diversity of their main disperser, the leaf-nosed bats. Pipers and their bats are but one classical tale in the annals of Neotropical ecology. Others stories include the use of bromeliads as nurseries by certain poison dart frogs, and evolutionary battles of deception between passion vines and Heliconius butterflies. Perhaps the most colorful story is that of hummingbirds and Heliconia plants. It was with great pleasure that I was able to capture this last example of Neotropical beauty (pictured below) while visiting La Selva Biological Station.

La Selva has a suspension bridge that provides an ideal vantage point for admiring of a small patch of Heliconia. As I stood on this bridge, a scene from a Neotropical guidebook unfolded. A crowned woodnymph (Thalurania colombica) buzzed into a fluorescent orange Heliconia bract with fighter jet precision. It was clear that this hummingbird was here to refuel on the Heliconia sp.’s high-octane nectar. Later, as I was reviewing my pictures, I realized I may have incorrectly assumed the crowned woodnymph was collecting Heliconia nectar. Closer inspection of my photos revealed the hummingbird wasn’t visiting the flowers at all! Instead, the bird appeared to be stuffing its head into a bract that recently filled with rainwater. It is possible that this bird was grabbing a quick drink.

Crowned woodnymph  (Thalurania colombica) visiting a Heliconia sp. at La Selva Biological Station

A crowned woodnymph (Thalurania colombica) visiting a Heliconia sp. at La Selva Biological Station, Cost Rica.

I am no ornithologist, but to me, this hummingbird looked quite vulnerable. Why would the hummingbird engage in such risky behavior for water that is abundant everywhere in the rainforest? My hypothesis is that this hummingbird was visiting the bract not to drink, but to eat. When hummingbirds aren’t slurping down nectar, they are supplementing their diets with insects. If one peers into a Heliconia bract they are likely to find insect larvae, like mosquitos. Rather than nectar or water, I think that the hummingbird in the pictures above was visiting this Heliconia sp. in search for protein-rich insects. With one week remaining in our OTS course, I hope to explore potential reasons or hummingbird visitation – if not via brief experimentation, then through casual observation.

For me, this accidental hummingbird observation reinforces the importance of natural history in generating new research questions. Like other grad students in the Summer ‘15 OTS Tropical Biology course, I have spent the last year scouring primary literature in search of neglected ideas, knowledge gaps, and new questions to pursue in graduate school. But if there is one lesson OTS has taught me, it is that even in well-studied systems many questions have yet to be asked, let alone tested.


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