The buff-breasted sandpiper (Calidris subruficollis) is a small shorebird that breeds in the Arctic tundra and migrates long distances to wintering grounds in inland South America. Estimating populations of migratory shorebirds like the buff-breasted sandpiper can be challenging, but conservation groups have made efforts to monitor their numbers over time.
Quick Answer
The global population of buff-breasted sandpipers is estimated to be about 15,000 birds. Their numbers have declined significantly since the late 19th century due to threats on their migratory routes and wintering grounds.
Overview of the Buff-Breasted Sandpiper
The buff-breasted sandpiper is a medium-sized shorebird measuring 7.5-9.5 inches in length with a wingspan of 16-20 inches. As their name suggests, they have distinctive buff-colored underparts that contrast with their gray/brown upperparts and wing coverts. During the breeding season, they exhibit bold black and chestnut brown markings on their heads and necks. Their long wings allow them to undertake an extraordinary migratory journey each year.
Breeding Range
The buff-breasted sandpiper breeds in the high Arctic tundra, above latitude 67°N. Their breeding range includes:
- Northern Alaska
- Northern Canada
- Coasts of the Chukchi and Beaufort Seas
They nest on the ground in dry upland tundra relatively far from water. The female typically lays 4 eggs in a shallow scrape lined with grasses and lichens. The eggs hatch after around 21 days of incubation by both parents. The chicks are precocial, leaving the nest within days to feed themselves.
Migration Route
After breeding, buff-breasted sandpipers undertake an immense clockwise loop migration from the Arctic down to South America. They fly a staggering 9,300 miles from their Arctic breeding grounds to their wintering grounds in central Argentina, Uruguay, Paraguay and southern Brazil. Their migration route includes key stopover sites in the interior of North America along the Mississippi and Missouri River floodplains.
Wintering Range
The buff-breasted sandpiper winters in the grasslands and agricultural fields of central South America, mainly:
- Central Argentina
- Uruguay
- Paraguay
- Southern Brazil
They forage mostly in grasslands, grazing on insects, arthropods and seeds. The return migration north begins in February. They stop over again in the interior plains of North America before returning to the Arctic in late May to early June.
Population Status and Trends
Due to their inaccessible breeding areas and huge migration routes, estimating population numbers for buff-breasted sandpipers has always been difficult. What is known is that their populations have declined substantially since historical times.
Historic Population
In the late 19th century, buff-breasted sandpipers were described as “abundant” and one of the most plentiful shorebirds in North America during migration. Early 20th century estimates presumed a population in the hundreds of thousands or even millions of birds. Though these very high historical numbers are speculative, it is almost certain that their populations used to be much larger than they are today.
Current Population
The most recent estimate for the global population of buff-breasted sandpipers is around 15,000 birds. The primary survey that arrived at this estimate is the USFWS Breeding Bird Survey along with an estimate of the percent of the population that passes through North America during migration. Though still considered tentative, 15,000 birds is the widely cited figure used today for total global population.
Population Decline
It is evident that buff-breasted sandpiper numbers have declined drastically since historical times. The magnitude of decline is difficult to quantify given the lack of concrete historical data. Various estimates indicate their numbers may have declined by anywhere from 65 to 90 percent since the 1800s. They likely began declining rapidly in the late 19th to early 20th century. Even since the 1970s, Breeding Bird Survey data shows evidence of a 50 percent decline in their population numbers.
Current Conservation Status
Due to significant ongoing population declines, the buff-breasted sandpiper is listed as Near Threatened on the IUCN Red List of Threatened Species. It is listed as a Species of Special Concern under the Migratory Bird Act in Canada. In the United States, it is listed as one of the top 20 most highly imperiled migratory bird species.
Threats and Conservation Efforts
Understanding the key threats facing buff-breasted sandpipers allows conservation groups to target efforts to protect the species where they are needed most. The main threats include:
Habitat Loss on Wintering Grounds
The rapid conversion of grasslands to agriculture in South America has substantially reduced habitat on their wintering grounds. They have lost an estimated 50% of critical habitat in parts of Argentina and Uruguay.
Habitat Loss on Migration Route
Wetland drainage and changes in river management have degraded stopover habitat in the interior United States. For example, over 90% of Missouri River floodplain habitat has been lost.
Climate Change Impacts
Climate change could alter Arctic breeding habitat and the availability of prey. It may also create mismatches between food availability and migration timing.
Hunting
Historically, buff-breasted sandpipers were hunted for sport and food in North and South America, which contributed to early population declines.
Conservation Efforts
Key conservation efforts to protect buff-breasted sandpipers include:
- Protecting and restoring grasslands and wetlands on their migration routes and wintering grounds
- Research into their migration ecology using new tracking technologies
- Working with farmers and ranchers to sustainably manage grazing lands used by the birds
- Raising public awareness and support for grassland conservation
In the United States, conservation groups have worked to conserve and restore important stopover areas for buff-breasted sandpipers along the Mississippi and Missouri Rivers. The Western Hemisphere Shorebird Reserve Network aims to preserve a network of key shorebird habitats across their range.
Research Techniques to Estimate Population
Estimating the population of buff-breasted sandpipers presents challenges due to the remoteness of their Arctic breeding grounds and the sheer scale of their migration across continents. However, researchers employ various techniques to study and estimate their populations:
Aerial Surveys
Aerial surveys of breeding areas are used to estimate densities and extrapolate total population size. However, these remote surveys only cover a portion of the breeding range.
Migration Counts
Tallies at migratory stopover sites provide minimum counts during migration. Combined with mark-recapture and modeling, these counts help estimate overall population.
Telemetry Tracking
Using tiny transmitters or tags, individual birds can be tracked throughout their migrations to elucidate migratory connectivity and better understand threats during the annual cycle.
Genetic Analyses
Genetic analysis of birds can identify population units and genetic diversity to focus conservation efforts.
Habitat Assessments
Analyzing changes in habitat coverage and quality across the range helps identify drivers of declines.
Importance of Continued Monitoring
Ongoing monitoring and research will be crucial to accurately track buff-breasted sandpiper populations over time. This will require international cooperation across their vast range. Continued monitoring will allow conservationists to:
- Detect any future population changes or sudden declines
- Evaluate the success of conservation initiatives in protecting the species
- Refine population estimates as new data is gathered
- Identify key sites or regions that may warrant greater habitat protection
Technological advances like satellite telemetry and drones may help improve monitoring coverage and efficiency for buff-breasted sandpipers. Only with robust monitoring can conservationists gather the information needed to ensure the future survival of these long-distance migrants.
Conclusions
In summary:
- The current best estimate for the global population of buff-breasted sandpipers is around 15,000 birds
- Their numbers have declined substantially from much higher historical populations
- Loss of habitat on wintering grounds and migration routes are major threats
- Ongoing conservation efforts aim to protect critical habitats across their range
- Better research and monitoring is still needed to accurately assess their populations
The buff-breasted sandpiper faces considerable threats on its migration between Arctic tundra and South American grasslands. Conservation groups are working to maintain essential habitats and reverse historical declines. With improved monitoring and habitat management, the charming buff-breasted sandpiper can once again thrive across its epic migratory range.