William Blake once wrote a poem, “The Little Girl Lost”, about two parents searching for their child through valley and desert. This week I have returned to Puerto Rico, on a much less pressing errand – the resurvey of a forest for the second year of a five-year study on forest dynamics. Last year, our team spent long weeks tagging and measuring thousands of trees through a broad landscape like the one you see here (the red-flowered tree is an African import Spathodea campanulata). This year our goal is to re-find all these trees, and re-measure every single one. This task can at times feel like the one given to Blake’s imagined family. In the poem, a lion confronts the parents, but leads them to a happy reunion with their daughter. I want to share one story of life in the forest with you, which is about this challenge of finding small things in large places.

We spent today re-familiarizing ourselves with the forest. I put down my measuring tools on the forest floor, and looked around. At first, all seemed ordinary – but then something caught my eye. Do you see it in this picture below?

It is a very small blue spot, towards the top right of the photograph. Blue is a very unusual color for organisms, especially plants. At first, I thought it was a discarded piece of plastic flagging tape, left behind by a careless researcher. But then I looked closer, and saw something very different.

This is a gastropod with a tag painted onto its shell. The whole organism is no larger than a penny, and the national forest we work in (El Yunque) covers twenty-eight thousand acres.

Blake ends his poem with a re-united family:

To this day they dwell
In a lonely dell,
Nor fear the wolvish howl
Nor the lion’s growl.

I don’t know how many organisms are being tagged, by whom, or to what scientific purpose – but seeing this little creature on a rock made me feel like our challenge will not be so difficult after all.