Broad-winged Hawk

The fall migration of Broad-winged Hawks is one of the great avian spectacles of eastern North America. If you find yourself on a hilltop with good visibility in mid-September, and there’s a favorable northwest wind, you might be treated to the sight of hundreds – if not thousands – of hawks rising in “kettles” on pockets of warm air. In many years the bulk of the migrants detected at New Hampshire hawk watches are seen on only a handful of days, even though the migration lasts from late August to early October. As they work their way south, the Broad-wings we see here are joined by others from farther south and west, and eventually they all funnel into the coastal plain of the Gulf of Mexico. Concentrated by mountains to the west, over a million Broad-wings pass over Veracruz, Mexico each fall on their way to wintering grounds in Central and South America.

Broad-winged Hawks are far less concentrated in the summer, but they remain the most common forest raptor in New Hampshire. They nest in most forest types, although less commonly in uniform spruce-fir, and generally require larger forest areas than the Red-shouldered Hawk. The nest is typically in a large crotch of a deciduous tree (especially yellow birch), built of sticks, and lined with bark. If you find a suspected Broad-wing nest, a good sign that it is active is the presence of fresh green sprigs of conifer branches (e.g., hemlock) along the rim. The birds add these when the nest is near completion and continue to refurbish the nest as the season progresses.

Forest raptors are hard to survey because they occur in low densities (compared to songbirds) and are not as active early in the day when most surveys take place. Data from such surveys show slow but steady increases across most of the Broad-wing’s range, perhaps reflecting gradual reforestation in many areas. In contrast, data collected from hawk migration sites indicate stable or decreasing trends. Migration data are harder to interpret because of the effects of weather and the possibility of changes to migration routes, so it’s likely that the breeding data, despite their shortcomings, are a more accurate reflection of population trends in this species.