Justification of Red List Category
This species underwent rapid historical declines. Its moderately small remaining population continues to decline and as a result it is considered Near Threatened.
Originally numbering in the hundreds of thousands to millions (1890s-1900s), the species was brought to near extinction in the early 1920s by habitat destruction and hunting. It has not recovered, with the current population estimated at 23,000-84,000 individuals (Jorgensen et al. 2008, Norling et al. 2012), which equates to 15,333-56,000 mature individuals, rounded here to 15,300 - 56,000 mature individuals. Andres et al. (2012) suggest using a population estimate of 56,000 individuals with an estimated range of 35,000 to 78,000.
A moderate and on-going decline is suspected based on surveys at staging posts. This is thought to be driven by habitat loss and conversion, but contaminants may also have an impact. The species is difficult to monitor, as it is not faithful to breeding sites (although it is more faithful to wintering sites (Almeida 2009)), but data from North American migration sites suggest that declines are continuing (L. Wolfenbarger and J. McCarty, pers. comm.). Repeated counts on the wintering grounds however have not indicated a decline (Southern Cone Grasslands Alliance, pers. comm.), although counts at Estancia Medaland, Argentina showed a decline from approximately 2000 individuals in 1973-4 (J. P. Myers, in litt.) to 56-300 in 2007 (BirdLife International, 2016). New population estimates are being generated for the Rainwater Basin of Nebraska, the Flint Hills of Kansas, and the Gulf Coast of Texas and will allow a more complete assessment of current trends.
Calidris subruficollis breeds sporadically along Arctic coasts from central Alaska, U.S.A., to Devon Island, Canada, with a population on Wrangel Island and west Chukotka, Russia. It has also been reported from St Pierre and Miquelon (to France) as a non-breeder. Birds winter in eastern South America including Argentina, Brazil and Uruguay, after passing through the Greater and Lesser Antilles or around the Gulf coast of Central America.
This species breeds in the high Arctic on well drained tundra with tussocks and scant vegetation. It is generally not found near the sea and avoids marshes. It appears to depend heavily upon intensive grazing by livestock in its wintering grounds to create short grassland (Lanctot et al. 2002, Aldabe 2016), but also uses flooded pampas grasslands (Blanco et al. 2004, Lanctot et al. 2004). During migration it is found on many short grass habitats (McCarty et al. 2009, Norling et al. 2012). At the internationally important Rainwater Basin stopover site in Nebraska, U.S.A., it was observed to feed primarily in agricultural land (soybeans, corn), and use wetlands for resting (McCarty et al. 2009). It is a lekking species.
The species was severely overhunted in the late 1800s and the early part of the 1900s, reportedly declining to near extinction from a population which may have numbered in the hundreds of thousands to millions. The breeding grounds may be affected by habitat loss and degradation, and environmental contaminants (R. Lanctot in litt. 2003). Previously, on-going declines were attributed to widespread and continuing destruction of grasslands in the wintering range (Lanctot and Laredo 1994, Lanctot 1995), but there seems to be little evidence to support this, although environmental contaminants may be playing a part there (R. Lanctot in litt. 2003). Exposure on migration to toxic chemicals and pollutants in its agricultural feeding grounds may pose a threat, and is being investigated further (Lanctot 2006, McCarty et al. 2009).Conservation threats faced by the species vary throughout the annual cycle. On the breeding grounds, habitat is being lost or degraded due to energy production (extraction of oil and gas and associated development) and climate change (Lanctot et al., 2010). Climate change may also be affecting demographic parameters but the overall effects are unclear. Negative effects on Buff-breasted Sandpiper productivity may occur due to the decoupling of the apparent synchrony between the breeding chronology of the birds and food availability (Lanctot et al., 2010). Alternatively, climate change could lengthen the growing season, providing flexibility for birds to initiate or replace lost clutches (although this may be more common in Calidrids that do not have a lek mating system), as well as promote survival of chicks – enhancements that could provide an overall positive or neutral effect (Lanctot et al., 2010).
During migration, Buff-breasted Sandpipers may be negatively impacted from wind energy installations in the Great Plains/Midwest of the central United States and in coastal portions of the Gulf of Mexico (Lanctot et al., 2010). The short vegetation required by the species is being lost through management of native grasslands for medium to tall vegetation, a reduction in the size of intact grassland units and the conversion of native grasslands or pastures to agriculture and other human development (Lanctot et al., 2010). Agricultural conversion could lead to altered prey availability and increased exposure to pesticides and herbicides. However, little to no quantitative data are available to suggest birds using human-altered habitats have altered migration abilities, lowered survival rates, or affected any other measurable demographic trait. Climate change may also affect the species during migration by increasing the severity of storms over the western Atlantic that could directly impact survival rates of juveniles, which predominately use this pathway during southbound migration (Lanctot et al., 2010).
On the non-breeding range, Buff-breasted Sandpipers are threatened by conversion of historic grasslands into agriculture, wood plantations, mines, and tourist locations. Pastures are also being “improved” by ranchers planting exotic vegetation with a different vegetation structure that appears to be less preferred. Such improvements frequently involve applications of fertilizer and other contaminants that may negatively affect the species. Buff-breasted Sandpipers are also vulnerable to changes in ranch management that reduce grazing levels and result in pastures with tall vegetation. Finally, climate change may result in sea-level rise and greater precipitation, which will inundate the many low-lying areas used by the species during the non-breeding season.
Conservation Actions Underway
CMS Appendix I and II. Several symposia have been held, most recently in 2015, to identify priority actions for the conservation of the species. A conservation plan was prepared for the species in 2010 that lists priority actions for the species (Lanctot et al., 2010). Intensive field surveys are on-going in Texas and Nebraska, and a range-wide tracking study is underway to document migration routes and key staging, breeding and wintering locations. Intensive range management and site conservation are underway in Argentina, Brazil, Uruguay and Bolivia.
Text account compilers
Wheatley, H., Butchart, S., Bird, J., Benstead, P., Taylor, J., Khwaja, N.
Dowsett, R.J., Harrington, B., Russell, B., Lanctot, R., Casañas, H.
BirdLife International (2018) Species factsheet: Calidris subruficollis. Downloaded from http://www.birdlife.org on 23/09/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/09/2018.