There’s a vine-covered tree mass beside the lab building which I’ve tried to tease apart, unsuccessfully, in botanical terms. It’s like untangling cables without using your hands. Two trees side stand by side in the clearing, one identified for me as Leuhea seemanii, the other still a mystery. Vines, lianas and bromeliads web the trees, fighting to smother each other under masses of tendrils, flowers, foliage and fruit. This vegetable war is aided and abetted by birds. I’ve been watching comfortably, sketching from the sidelines.
Flycatchers swarm over this plant mass like drosophila buzzing over a banana (of which, by the way, there’s a good patch nearby). They nest, they swoop, they dive into the wild tangle. They sing from the canopy, nest in the midstory and plummet for crawling bugs in the grass. I’ve checked off 9 species of flycatcher moored to this little island of diversity: yellow-crowned tyrannulets, common tody-flycatchers, Panama flycatchers, lesser kiskadees, great kiskadees, rusty-margined flycatchers, social flycatchers, streaked flycatchers, and tropical kingbirds. The plants benefit the flycatchers, but the flycatchers reciprocate, and not just by eating herbivorous insects, either. They’ve helped create their own ideal habitat.
From the lab balcony yesterday I watched a social flycatcher in the vine/tree complex. The bird parted its bill and disgorged a shiny white pearl of a seed, which hit the branch and stuck. After a moment of contemplation, the bird opened its bill and let another pearl drop. It rolled off the branch and was caught by a thread of saliva which stretched like a bungee cord from the branch to the seed, halting it in midair. The flycatcher wiped a third seed onto the branch, then a fourth and a fifth. By the time the flycatcher let go its final pearl, eight were glued to the branch or dangling below.
Flycatchers don’t just catch flies, they eat fruit, too, dispersing seeds around the forest. A seed attached by a bird’s spit to a bare branch might sprout and become the next fruiting vine or bromeliad. It’s a nice little positive feedback loop, one that nourishes future flycatchers and grows more plants. Sweet deal all around.