For Birds & Blooms, Timing is Everything

Northern Parula (Setophaga americana)

N. Lewis

Species tune into key seasonal signals to thrive

by Smokies Life

Humans seem to be the only forms of life in the Smokies that rely on a calendar. For the other 21,000+ species discovered in these mountains so far, knowing when to sing, bloom, or set out in search of food depends on paying close attention to environmental cues.

In spring, as days lengthen, temperatures climb, and rains soak the ground, a whole host of plants known as “spring ephemerals” receive their signal to flower. Over millennia, these early risers have adapted to attract pollinators within the brief window of springtime when most deciduous trees have yet to put out their leaves and direct sunlight is still plentiful on the forest floor. Spring ephemerals generally peak in early to mid-April in the Smokies with some persisting into May at the cooler higher elevations.

Songbirds also take note of these seasonal signals and the growing availability of food. Resident birds establish their territories, sing more frequently, and develop colorful plumage in hopes of attracting a mate. Meanwhile, migrant songbirds start to move and arrive daily throughout spring from their wintering grounds elsewhere to join in the chorus of song and set to building their nests.

When we humans decide to study these changes, we call it phenology. Every year, park biologists and community volunteers organized by the Great Smoky Mountains Institute at Tremont visit designated phenology plots to measure the progress of the seasons. By carefully collecting data about natural events over time, we can reveal fascinating interconnections and better understand how everything from blooming wildflowers to migrating songbirds will respond to change as they set their busy schedules.