The answer to whether hawks migrate is complex, varying significantly across the many raptor species. Many hawks undertake long, seasonal journeys, but this behavior depends heavily on the specific species and the climate of its breeding grounds. Their movements are driven by the necessity of finding reliable food sources throughout the year. The distance and timing of their travels are evolutionary responses to resource availability and weather patterns.
Resident and Migratory Species
The decision to migrate is primarily governed by the hawk’s diet and the severity of the winter in its northern range. Species relying on prey available year-round, such as rodents, often exhibit resident behavior. Many populations of Red-tailed Hawks, for instance, remain in the same territory throughout the year, especially where snow cover does not hide their prey.
In contrast, species that feed on insects, reptiles, or smaller migratory birds are obligate migrants, meaning they must travel long distances to survive the winter. Broad-winged Hawks, for example, travel thousands of miles from North America to Central and South America. This movement is triggered by cooling weather and the disappearance of their primary food sources. The seasonal passage of cold fronts acts as a cue, signaling the end of the breeding season and providing favorable winds for the southward journey.
The length of the journey is highly variable, with some species being short-distance migrants. These hawks may only move from higher elevations to lower valleys, or travel just far enough south to escape deep snow.
Harnessing the Wind: Migration Techniques
Hawks conserve energy during long-distance flights by relying almost entirely on air currents rather than sustained flapping. This strategy utilizes two specific types of lift: thermal soaring and ridge lift. Thermal soaring involves finding and riding rising columns of warm air, known as thermals, which are created when the sun unevenly heats the earth’s surface.
By circling within a thermal, a hawk gains altitude with minimal physical effort, forming large, swirling groups of birds sometimes called a “kettle.” Once they reach the top, the birds glide toward their destination, losing altitude until they intercept the next thermal. This technique dictates that most soaring hawk migration occurs during midday hours, when solar energy is strongest and thermals are most abundant.
The second technique, ridge lift or slope soaring, is employed along topographical features like mountain ranges. When wind strikes a ridge, it is deflected upward, creating a continuous updraft that hawks can ride. By flying close to the edge, they use this deflected air to propel themselves forward at speeds reaching 40 to 60 miles per hour without energy-intensive wing beats.
Navigating the Continent: Established Flyways
Hawk migration follows established corridors known as flyways, which are defined by geographical features. Hawks use “leading lines” such as coastlines and major mountain chains, like the Appalachian Mountains, to guide their travel and maximize access to energy-saving air currents. These linear features concentrate migrating birds, making the routes predictable.
Hawks that rely on soaring generally avoid crossing large bodies of water, such as the Great Lakes or the Gulf of Mexico. Water heats and cools slowly, preventing the formation of the thermals necessary for lift, which forces the birds to fly around these expanses. This avoidance creates significant “bottlenecks” where large numbers of raptors are funneled into narrow passages of land.
One spectacular example is the “River of Raptors” in Veracruz, Mexico, where the Sierra Madre Oriental mountains constrict the coastal plain. Millions of hawks, including nearly the entire global population of Swainson’s Hawks, pass through this narrow corridor each autumn. Similarly, sites like Hawk Mountain in Pennsylvania are famous observation points because the Appalachian ridge forces the concentration of thousands of migrating birds.