The Piping Plover (Charadrius melodus) and Killdeer (Charadrius vociferus) are two small North American shorebirds that bear a superficial resemblance to each other. Both have sand-colored upperparts, white underparts, and a black breast band. However, they belong to different sub-groups within the plover family Charadriidae and are not very closely related. In this article, we will take a deep dive into the taxonomic classification, physical characteristics, behavior, breeding habits, habitat preferences, conservation status, and evolutionary history of Piping Plovers and Killdeer to understand their similarities and differences.
Taxonomic Classification
Piping Plover
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Charadriidae
Genus: Charadrius
Species: C. melodus
The Piping Plover is one of two species in the Charadrius genus endemic to North America, the other being the Semipalmated Plover (C. semipalmatus). It belongs to the subfamily Charadriinae, which includes other plovers like the Snowy Plover.
Killdeer
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Charadriidae
Genus: Charadrius
Species: C. vociferus
The Killdeer is the only member of the Charadrius genus in the subfamily Vanellinae, which includes lapwings and other noisy plovers. It is the most widespread and common plover across North America.
While both birds belong to the same family Charadriidae, they are placed in different subfamilies that diverged over 20 million years ago. This indicates they are not very closely related within the plover family.
Physical Characteristics
Size and Shape
The Piping Plover is a small, stocky shorebird reaching about 7 inches in length with a wingspan of 15 inches. The Killdeer is slightly larger at 10-11 inches in length with a wingspan of 20-24 inches. Piping Plovers have proportionally large rounded heads and short bills, giving them a pudgy appearance compared to the more slender, long-billed Killdeer.
Plumage
Adult Piping Plovers are pale sandy brown on the crown, back, and upper wings. The face, sides of breast, and belly are white. There is one black breast band, white tail with a black tip, and orange legs.
Killdeer adults have two black breast bands, a brown back, and a white belly. Their tail and rump are reddish-orange in color. The crown and sides of the face are brown. Their legs are flesh-toned.
Behavioral Differences
Piping Plovers tend to be very still, calmly foraging in the wet sand. They rarely call except during breeding season. In contrast, Killdeer are energetic birds that frequently bob their heads and vocalize loudly with their signature “kill-deeeer” call.
Breeding and Nesting
Habitat
Piping Plovers nest on wide, flat, open, sandy beaches with very little grass or other vegetation. They prefer areas with dunes and beach ridges that provide shelter.
Killdeer nest in a wider variety of habitats, including gravel roads, parking lots, athletic fields, golf courses, agricultural fields, wetlands, and shorelines. They are flexible and often nest near human disturbance.
Nesting
Piping Plovers scrape out small depressions in the sand to create their nests. Killdeer nest on open ground with little to no nest construction. Their speckled eggs provide camouflage against pebbles or gravel.
Parental Behavior
Piping Plover parents both incubate the eggs and protect the young after hatching. To protect the nest, adults will frequently perform distraction displays like faking a broken wing to lure predators away.
Killdeer hatchlings are precocial and mobile soon after hatching. The parents do not feed the young directly. Instead, the chicks feed themselves while following their parents around prime feeding territory.
Habitat and Range
Piping Plover
Piping Plovers breed in three geographic regions: the Northern Great Plains, the shores of the Great Lakes, and the Atlantic Coast. They winter along the Atlantic and Gulf coasts from North Carolina to Mexico.
Killdeer
Killdeer breed across almost all of North America, from southern Canada to northern Mexico. They are the most widespread and common plover. Killdeer also winter along the Atlantic and Gulf Coasts but have a broader southern range stretching all the way down through Central and South America.
While both birds occupy shoreline habitat, the Piping Plover has a much more restricted range concentrated in a few sensitive beach nesting areas. The Killdeer thrives across a diverse array of habitat types and ranges.
Conservation Status
The Piping Plover is federally listed as Threatened and Endangered due to habitat loss, predation, and disturbance at breeding sites. Their population reached an all-time low of fewer than 2,000 pairs in 2001. Intensive conservation efforts have helped boost numbers to over 6,000 pairs as of 2019.
Meanwhile, the Killdeer remains common and widespread with an estimated 1 million individuals. Their population is considered stable and they are classified as a Species of Least Concern. Habitat loss does not pose a major threat as Killdeer readily adapt to human-altered environments.
Evolutionary History
Piping Plovers likely evolved as a distinct species specializing in undisturbed Atlantic Coast beach habitat 2 million years ago during the Pleistocene epoch. After the last glacial retreat, Piping Plovers expanded their breeding range inland to Great Plains alkali lakes.
Killdeer originated as an ancient migratory plover over 10 million years ago, splitting from a common ancestor shared with the Ringed Plover. Unlike coastal-nesting plovers, Killdeer evolved to thrive in a wide array of open habitats across the Americas, giving them a survival advantage.
Conclusion
While Piping Plovers and Killdeer may look similar at first glance, important differences in their taxonomy, behavior, habitat preferences, conservation needs, and evolutionary history show they are not closely related shorebirds. Piping Plovers are beach specialists with a small, threatened population. Killdeer are habitat generalists with abundant, widespread populations across North America. Understanding these differences is key for targeting conservation efforts to protect the sensitive Piping Plover while managing the common Killdeer.