Sandpipers and killdeer are two types of shorebirds that are often seen together probing the mudflats and beaches of North America. Despite their similar habitats and behaviors, sandpipers and killdeer are not closely related within the shorebird family.
What are sandpipers?
Sandpipers are a large and diverse group of small to medium-sized shorebirds. There are over 20 species of sandpipers in North America alone. They are characterized by their slender bills and long legs, adaptations for wading in shallow water and probing mud for invertebrates. Most species have cryptic brown, gray, or buff-colored plumage. Sandpipers breed in the Arctic tundra and subarctic regions and migrate long distances to spend the winter along coastlines from temperate to tropical regions.
Some of the most common North American sandpiper species include:
- Western sandpiper
- Least sandpiper
- Pectoral sandpiper
- Semipalmated sandpiper
- Spotted sandpiper
- Solitary sandpiper
- Dunlin
There are also larger sandpipers known as “godwits” including the marbled godwit and Hudsonian godwit. The dowitchers are sandpipers with distinctive long, straight bills used to probe deeply in mud. The colorful Wilson’s phalarope is also classified as a type of sandpiper.
What are killdeer?
Killdeer are a distinct species of medium-sized, long-legged shorebird. Their scientific name is Charadrius vociferus. They are the only member of the genus Charadrius commonly found in North America. Killdeer get their name from their loud, shrill “kill-deer” call.
Killdeer have brown upperparts, white underparts, and two black breast bands. Their legs are reddish-orange. They are larger than most sandpipers, around 9-11 inches in length with a wingspan of up to 21 inches. Killdeer breed in open fields, pastures, golf courses, and other land habitats rather than the tundra breeding grounds used by most shorebirds.
How are sandpipers and killdeer adapted to their environments?
Sandpipers and killdeer exhibit a number of adaptations that allow them to thrive in coastal and wetland environments:
- Bills – Sandpipers have long, tapered bills for probing deeply into mud to find insects and other invertebrates. Killdeer have shorter bills better suited for picking food items off the surface.
- Legs – Long legs allow sandpipers and killdeer to wade into water and muddy areas without getting their bodies wet and cold.
- Cryptic plumage – Sandpipers’ dull brown, gray, and buff plumage provides camouflage from predators as they nest and feed.
- Widely spaced eyes – Both species have eyes placed high and wide on their heads, improving their vision while feeding with their face down near the ground.
- Shorebird metabolism – High metabolic rates allow sandpipers and killdeer to undergo long migrations and put on fat reserves quickly to fuel their journey.
How do sandpipers and killdeer feed?
Sandpipers employ a variety of feeding techniques to take advantage of their slender bills, some of which include:
- Probing deeply into mud or sand
- Rapidly pecking the surface to catch prey
- Stirring up the substrate to uncover hidden invertebrates
- Wading through shallow water while swinging their bills back and forth to catch small organisms
Their diet consists of worms, mollusks, crustaceans, insects, and other invertebrates. Some larger sandpiper species may occasionally eat very small fish.
Killdeer use a pick-and-peck feeding method characteristic of plovers. They run or walk along the ground, stopping to pick up food items visible on the surface. Their diet is more varied than sandpipers, consisting of insects, spiders, crustaceans, seeds, and other plant material.
What are the migration patterns and ranges of sandpipers and killdeer?
Most sandpipers undertake incredible long-distance migrations each year between their arctic breeding grounds and wintering areas scattered around the Americas. Some species fly nonstop transoceanic journeys of 4,000 miles or more. Their primary wintering habitat consists of coastal wetlands and mudflats with large concentrations occurring at certain sites like San Francisco Bay and the Pacific coast of Central America.
Killdeer migrate shorter distances than sandpipers. Northern killdeer populations retreat from the northernmost parts of their breeding range in winter while southern populations may remain in the same general region year-round. They mainly winter in open fields, agricultural areas, golf courses, and shorelines throughout the southern U.S. and Mexico.
How and where do sandpipers and killdeer breed and nest?
Most sandpipers nest in the Arctic tundra, taking advantage of the burst of insect activity that occurs during the short arctic summer. Females lay four eggs directly on the ground in a shallow depression or hidden cup nest. Sandpiper chicks are precocial, able to walk and feed themselves soon after hatching while both parents help protect and brood them.
The killdeer breeding habitat overlaps the northern part of the sandpiper’s range but extends much farther south into temperate regions. Killdeer nest in open fields, gravel parking lots, golf courses, and shorelines with gravel or sand. Their nest is a shallow scrape lined with pebbles, sticks, and debris. The female lays four eggs that are incubated by both parents. The speckled chicks leave the nest within hours after hatching.
What are some key differences between sandpipers and killdeer?
Some of the main differences between sandpipers and killdeer include:
| Trait | Sandpipers | Killdeer |
|---|---|---|
| Size | Small to medium | Medium |
| Bill shape | Long, thin, and straight or slightly curved | Shorter and straighter |
| Plumage | Cryptic gray, brown, or buff colors | White belly, brown back, black breast bands |
| Habitat | Coastal wetlands and mudflats | Beaches, open fields, human-made environments |
| Migration | Long distance over oceans | Shorter distances over land |
| Breeding | Arctic tundra | Temperate and arctic regions |
| Nest | Cup nest on tundra | Scrape on open ground |
| Diet | Small invertebrates | Insects, other invertebrates, seeds |
How are sandpipers and killdeer classified by taxonomists and ornithologists?
Sandpipers, killdeer, and other shorebirds belong to the diverse order Charadriiformes. However, sandpipers and killdeer are placed in separate families within this order:
- Sandpipers belong to the family Scolopacidae, the typical shorebirds.
- Killdeer are members of the family Charadriidae, which includes plovers and lapwings.
The Scolopacidae are then divided into multiple genera and species such as Calidris sandpipers, Tringa sandpipers, phalaropes, and snipes. Killdeer comprise their own single-species genus, Charadrius.
This taxonomic separation indicates that sandpipers and killdeer are only distantly related within the diverse order of shorebirds. Their similar coastal habitats and probing feeding behaviors represent examples of convergent evolution rather than close ancestry.
When and where are sandpipers and killdeer found together?
There are some locations and times of year where sandpipers and killdeer can be observed feeding and resting alongside each other, including:
- Coastal migration stopover sites, such as mudflats and estuaries along the U.S. Atlantic and Pacific coasts
- Inland wetlands, lakeshores, and river shores used as migration stopovers
- Wintering grounds along the southern U.S. coast
- Overlap in breeding range in subarctic regions of Alaska and Canada
Both groups converge on prime feeding areas along muddy shorelines during migration. During the winter, the killdeer’s range extends along the length of the U.S. coastline where they mix with wintering sandpipers.
How can you distinguish a sandpiper from a killdeer in the field?
There are several features birdwatchers can look for to identify a shorebird as either a sandpiper or a killdeer:
- Size and shape – Sandpipers have very thin, upright bodies and are smaller than the more robust, full-breasted killdeer.
- Bill shape – The long probing bills of sandpipers differ from the shorter pick-and-peck bill of the killdeer.
- Plumage patterns – Killdeer have two bold black breast bands; sandpipers have camouflage gray/brown patterns.
- Leg and eye-ring color – Killdeers’ orange legs and red eye-rings distinguish them from yellow-green-legged sandpipers.
- Behavior – Sandpipers do more probing while killdeers pick food from the surface.
- Vocalizations – The loud “kill-deer” call is diagnostic for the killdeer.
Conclusion
Sandpipers and killdeer have adapted in similar ways to take advantage of shoreline habitats. However, killdeer are more terrestrial while sandpipers are more specialized for aquatic environments. Taxonomists place them in entirely different families within the diverse order of shorebirds. So while overlapping in habitat and behavioral habits in many ways, sandpipers and killdeer are not actually closely related.
Careful attention to details like bill shape, leg color, plumage patterns and vocalizations allows birders to distinguish between these two types of shorebirds. So the next time you see a small brown shorebird probing the mud or a boldly-patterned killdeer running along the beach, take a closer look at whether it is one of the many sandpiper species or their lookalike cousin, the killdeer.
