The killdeer, a familiar bird across the Americas, is often recognized by its distinctive call. Killdeer exhibit varied migratory behaviors; some populations undertake seasonal journeys, while others remain in their territories year-round. Understanding these patterns reveals a complex picture of their movement.
Understanding Killdeer Migration Patterns
Killdeer display “partial migration,” meaning not all individuals or populations migrate. This behavior contrasts with species where all members undertake long-distance seasonal movements. In the southern parts of their range, such as much of the contiguous United States, killdeer often remain resident throughout the year.
In contrast, killdeer populations breeding in northern areas, including parts of the United States and Canada, typically migrate south to escape harsh winter conditions. These migratory populations often bypass areas where other killdeer reside year-round, a phenomenon sometimes called “leapfrog migration.” This variability in migratory strategy allows the species to adapt to diverse climates across its wide distribution.
Seasonal Journeys: Destinations and Timing
For killdeer that migrate, their journeys are timed with the changing seasons, linking their breeding and wintering grounds. Their breeding range extends across North America, from central Alaska and southern Canada down through the United States and into Mexico. They often choose open fields, pastures, gravelly areas, and even rooftops for nesting, rather than being strictly tied to water bodies.
As winter approaches in northern regions, these migratory killdeer move south. Their wintering grounds span the southern United States, Mexico, Central America, the Caribbean, and northern parts of South America, including Colombia, Ecuador, and Venezuela. Fall migration typically begins after mid-July, peaking from August to September, with some birds still moving south as late as November. Spring migration, the return journey to breeding territories, can start early, with some individuals arriving in northern areas as early as February or March, continuing through mid-May.
The Drivers of Killdeer Movement
The motivations behind killdeer migration are linked to environmental conditions and resource availability. A primary factor prompting southern movement for northern populations is the diminishing food supply as temperatures drop. Killdeer primarily feed on insects and other invertebrates, which become scarce or inaccessible when the ground freezes or is covered by snow.
Avoiding harsh winter weather, characterized by snow and extreme cold, is also a driver for migration. While some killdeer can endure mild winters in their resident ranges, severe conditions necessitate a move to warmer climates where foraging is easier. The return journey in spring is driven by the need to access suitable breeding territories and abundant food resources for raising their young. This movement ensures their survival and reproductive success across their extensive range.