The tiny, iridescent birds that spend their summers feeding on nectar throughout Pennsylvania are entirely migratory and leave the state once the weather cools. This annual departure is necessary to find a stable climate where their specialized diet of floral nectar and small insects remains consistently available. This journey initiates one of the most remarkable feats of endurance in the avian world.
Identifying Pennsylvania’s Hummingbirds
The sole species of hummingbird that breeds in Pennsylvania is the Ruby-throated Hummingbird (Archilochus colubris). This bird, weighing less than a nickel, cannot tolerate the changing seasons of the northeastern United States. The lack of reliable food sources, such as flowering plants and flying arthropods, once temperatures drop below freezing, makes remaining in the state impossible. These hummingbirds must seek tropical environments where their high-energy diet can be sustained year-round.
The Winter Destination
The destination for these small travelers is a vast geographic range extending from the southern coast of Mexico through Central America. The largest concentration of the population winters in countries such as Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama. They seek environments where the climate remains consistently warm and humid.
These wintering grounds are generally located in coastal lowlands and tropical forests. The birds tend to inhabit the edges of second-growth forests and thickets rather than deep jungle, which provides a reliable interface between protective cover and open areas with abundant flowering plants. The stable environment, with its predictable supply of nectar and protein-rich insects, supports their survival until their return journey north.
Fueling the Migration
The journey requires the birds to store large amounts of energy before departure. Hummingbirds enter a period of intense feeding called hyperphagia, consuming constantly to accumulate fat reserves. They can nearly double their body mass, with a typical 3-gram bird adding up to 2 grams of fat in the weeks leading up to migration. This stored fat is the primary fuel for the flight ahead.
Many of these birds undertake a non-stop flight directly across the Gulf of Mexico, a distance of approximately 500 to 600 miles. This marathon flight can take 18 to 22 hours, powered by the efficient burning of their accumulated fat. Their highly specialized metabolism allows for this sustained effort, transforming the tiny bird into a miniature flying engine capable of long-distance travel without rest or refueling.
Timing the Seasonal Journey
The southward journey from Pennsylvania begins in late August and continues through September, triggered by environmental cues like decreasing daylight hours. Adult males initiate the departure first, followed by the females and the newly fledged juveniles several weeks later. By mid-September, most of the population has left the breeding grounds, though a few stragglers may be observed into October.
The return trip north starts in late winter, with the birds moving up the continent to arrive back in Pennsylvania in the spring. Their arrival is timed for mid-to-late April or early May, coinciding with the blooming of early native nectar sources. The presence of flowers like wild columbine and the emergence of flying insects mark the renewal of the food supply necessary for them to establish territories and begin the breeding cycle.