Conservation and Management

Not globally threatened. Currently considered Near Threatened. Global population 891,000–979,000 individuals WetlandsInternational 2015 Wetlands International (2015). Waterbird Population Estimates. Wetlands International, Wageningen, The Netherlands. Close .

The U.S. Shorebird Conservation Plan (Brown et al. 2000b Brown, S., C. Hickey, and B. Harrington (2000). The U.S. Shorebird Conservation Plan. Manomet, MA: Manomet Center Conserv. Sci. Close ) outlines numerous issues that impact Red Knot, but does not focus on this species. Arctic-breeding shorebirds like knots have low fecundity and are subject to substantial annual variation in breeding productivity. On the other hand, they have relatively high survival rates (Boyd 1962b Boyd, H. (1962b). Mortality and fertility of European Charadrii. Ibis 104:368-387. Close ). Modeling (Baker et al. 2004 Baker, A. J., P. M. González, T. Piersma, L. J. Niles, I. D. S. do Nascimento, P. W. Atkinson, N. A. Clark, C. D. T. Minton, M. K. Peck and G. Aarts. (2004). Rapid population decline in Red Knots: Fitness consequences of decreased refuelling rates and late arrival in Delaware Bay. Proceedings of the Royal Society B-Biological Sciences 271 (1541):875-882. Close , McGowan et al. 2011b McGowan, C. P., D. R. Smith, J. A. Sweka, J. Martin, J. D. Nichols, R. Wong, J. E. Lyons, L. J. Niles, K. Kalasz and J. Brust. (2011b). Multispecies modeling for adaptive management of horseshoe crabs and Red Knots in the Delaware Bay. Natural Resource Modeling 24 (1):117-156. Close , Hitchcock and GrattoTrevor 1997 Hitchcock, C. L. and C. GrattoTrevor. (1997). Diagnosing a shorebird local population decline with a stage-structured population model. Ecology 78 (2):522-534. Close ) suggests that population sizes of arctic sandpipers with these characteristics are strongly influenced by adult survival and recruitment rates, food supplies at non-breeding and stopover sites, and snow depth during incubation in the Arctic.

A major concern is with global climate change, unpredictability of weather conditions and possible contraction of Arctic breeding habitat (Piersma and Baker 2000). Thus shorebirds breeding in high Arctic tundras and polar deserts can serve as sentinels of the effect of climate change on these species (Piersma and Lindstrom 2004, Meltofte et al. 2007). The rapid and worrying decline of Red Knots in Tierra del Fuego (TdF) since 2000, and the associated drop in Delaware Bay censuses, suggest that key factors modulating population size include fattening rates in Delaware Bay as well as breeding conditions in the Arctic (McGowan et al. 2011b).

Additionally, much effort has been made in protecting major non-breeding and stopover sites in the Americas under the umbrella of the Western Hemisphere Shorebird Network since its inception in 1985, and this is a critical initiative for the future. Shorebird conservation plans in Canada and the USA -- as well as specific recovery plans for Red Knots formulated by the USFWS and CWS -- require long-term monitoring and research across the hemispheric flyway. Interpretation centers focused on shorebird conservation in San Antonio Oeste and Rio Gallegos in Argentina, Bahia Lomas in Chile, and in Mispillion Harbor in Delaware USA have been very effective in changing public awareness of the need for conservation of this knot, and of shorebirds generally across the flyway.

Shooting And Trapping

Heavily hunted for both market and sport during the second half of the 19th and first quarter of the 20th centuries. Mackay (Mackay 1893 Mackay, G. H. (1893). Observations on the knot (Tringa canutus). Auk 10:25-35. Close ) noted that market hunters, working at night with flares, sent a single shipment of knots from Cape Cod to Boston, MA, that filled 6 barrels. If each barrel held 60 dozen knots, then perhaps more than 4,000 knots were taken in a single night. Bent (Bent 1929 Bent, A. C. (1929). Life histories of North American shorebirds, Part 2. United States National Museum Bulletin 146. Close ) noted that excessive shooting and market hunting had reduced the species to “a pitiful remnant of its former numbers.” It is unclear today whether the population has regained its historical numbers. It is clear, however, that numbers on the Massachusetts coast are far lower today than they were when Mackay (Mackay 1893 Mackay, G. H. (1893). Observations on the knot (Tringa canutus). Auk 10:25-35. Close ) wrote his accounts.

Band recoveries indicate that knots are killed commonly for food in some regions of South America, especially the Guianas (BAH). They also are shot for sport in Barbados. The overall take from these activities is unknown, but information from band recoveries (n = 17) in the Guianas (BAH) hints that the take may be substantial.

Pesticides And Other Contaminants/Toxics

No information.

Ingestion Of Plastics, Lead, Etc

No information.

Collisions With Stationary/Moving Structures Or Objects

Shorebirds, including Red Knots (Piersma et al. 1994 Piersma, T., Y. Verkuil and I. Tulp. (1994). Resources for long-distance migration of knots Calidris canutus islandica and C-c-canutus: How broad is the temporal exploitation window of benthic prey in the western and eastern Wadden Sea? Oikos 71:393-407. Close ), occasionally collide with stationary objects (e.g., McNeil et al. 1985a McNeil, R., J. R. Rodriguez and H. Ouellet. (1985a). Bird mortality at a power transmission line in northeastern Venezuela. Biological Conservation 31:153-165. Close ).

Climate Change

Global warming may have especially strong impacts on this species. Anticipated climate change will be greatest at polar and temperate latitudes, where Red Knots breed and winter, respectively. All known major migration staging sites, and most of the major wintering range, are on temperate coastlines of both the New and Old World, where sea level change is predicted to be greatest.

Degradation Of Habitat

Tendency to concentrate at traditional migration staging sites and wintering areas may render populations vulnerable to loss of strategic habitats critical to the well-being of their populations (Myers et al. 1987 Myers, J. P., R. I. G. Morrison, P. Z. Antas, B. A. Harrington and T. E. Lovejoy. (1987). Conservation strategy for migrating species. American Scientist 75:19-26. Close ). According to studies by Harrington et al. (Harrington et al. 1989 Harrington, B. A., J. P. Myers and J. S. Grear. (1989). Coastal refueling sites for global bird migrants: Coastal Zone 89. Proc. Sixth Symp. on Coastal and Ocean Manage. 5:4293-4307. Close ), which evaluated the relative concentration of 24 shorebird species at migration staging sites, Red Knots were the most heavily concentrated of all shorebirds, with 98% in the spring and 97% in the fall concentrated at key sites, virtually all of which were coastal locations. Similarly, during aerial surveys of South American coastlines where Red Knots spend the boreal winter, Morrison and Ross (Morrison and Ross 1989a Morrison, R. I. G., and R. K. Ross (1989). Atlas of Neararctic shorebirds on the coast of South America. Volume 1. Canadian Wildlife Service Special Publication. Ottawa, Ontario, Canada. Close : Vol. 1) tallied roughly 76,000 individuals, >50% at a single bay, Bahía Lomas on the n. Chilean coast of TdF. Concern is growing that vastly increased harvesting of horseshoe crabs during 1980s and 1990s on mid-Atlantic Coast of U.S. will hinder use of Delaware Bay as a critical migration staging area by Red Knots during spring (Tsipoura and Burger 1999 Tsipoura, N. and J. Burger. (1999). Shorebird diet during spring migration stopover on Delaware Bay. Condor 101 (3):635-644. Close , Piersma and Baker 2000 Piersma, T. and A. Baker. (2000). "Life history characteristics and the conservation of migratory shorebirds." In Behavior and conservation., edited by L. Gosling and W. Sutherland, 105-124. Cambridge, U.K: Cambridge Univ. Press. Close ).

Vulnerable to extensive land reclamation projects, encroaching on relatively few staging areas, especially in W Europe, where virtually the entire adult population of race canutus and most of population of islandica stage in Wadden Sea, where up to 433,000 birds counted at one time. Human overexploitation of shellfish stocks in the Wadden Sea directly leads to reduction of food supply and indirectly to alterations in sediment characteristics, which reduce prey availability.

Loss of intertidal stopover habitats due to reclamation in Yellow Sea region of the East Asian–Australasian Flyway is thought to be driving declines in shorebird populations Amano et al. 2010 Amano, T., T. Székely, K. Koyama, H. Amano, and W. J. Sutherland (2010). A framework for monitoring the status of populations: an example from wader populations in the East Asian–Australasian flyway. Biological Conservation 143(9):2238–2247. Close Yang et al. 2011 Yang, H.-Y., B. Chen, M. Barter, T. Piersma, C.-F. Zhou, F.-S. Li, and Z.-W. Zhang (2011). Impacts of tidal land reclamation in Bohai Bay, China: ongoing losses of critical Yellow Sea waterbird staging and wintering sites. Bird Conservation International 21(3):242–259. Close Choi et al. 2015 Choi, C.-Y., P. F. Battley, M. A. Potter, K. G. Rogers, and Z. Ma (2015). The importance of Yalu Jiang coastal wetland in the north Yellow Sea to Bar-tailed Godwits Limosa lapponica and Great Knots Calidris tenuirostris during northward migration. Bird Conservation International 25(1):53–70. Close . Up to 65 percent of intertidal habitat in the Yellow Sea region of East Asia has been lost over the past 50 years, and more than 1% of remaining habitat is being lost per year to reclamation for agriculture, aquaculture, and other development Murray et al. 2014 Murray, N. J., R. S. Clemens, S. R. Phinn, H. P. Possingham, and R. A. Fuller (2014). Tracking the rapid loss of tidal wetlands in the Yellow Sea. Frontiers in Ecology and the Environment 12(5):267–272. Close . Disturbance outside breeding season from recreational activities and overflying aircraft reduces size of foraging areas. In New Zealand, some illegal shooting persists.

Baker (Baker 1992 Baker, A. J. (1992). Molecular genetics of Calidris, with special reference to knots. Wader Study Group Bulletin 64 (Suppl.):29-35. Close ) and Baker et al. (Baker et al. 1994 Baker, A. J., T. Piersma and L. Rosenmeier. (1994). Unraveling the intraspecific phylogeography of knots Calidris canutus: a progress report on the search for genetic markers. Journal of Ornithology 135:599-608. Close ) noted that levels of genetic variation in Red Knots and most other calidridine sandpipers are seriously depleted, presumably because of population bottlenecks during Pleistocene (or later) glaciations; species that have lost genetic variability may be more vulnerable to extinction from stochastic ecological factors and small population size (Baker 2006).

Direct Human/Research Impacts

See Management, below.

Conservation Status

Not considered of conservation concern until 2015, when population declines triggered uplisting to Near Threatened BirdLife International (2015) Species factsheet: Calidris canutus. Downloaded from http://www.birdlife.org on 31/10/2015. .

Measures Proposed And Taken

A key management goal in shorebird conservation efforts in the New World is to identify important migration staging sites and wintering areas of these birds and to work for their voluntary inclusion in the Western Hemisphere Shorebird Reserve Network (WHSRN). At many of the WHSRN sites, local conservation initiatives are focused on better protection of key habitats of Red Knots. One such area is Delaware Bay, which is included in WHSRN. Similar initiatives are under way elsewhere in the world, notably including some international treaties, such as the Ramsar Convention (Anonymous 1971 Anonymous. (1971). Convention on wetlands of international importance, especially as waterfowl habitat. Ramsar, Iran: Int. Convention on the Conserv. of Wetlands and Waterfowl: final act and summary record. Close ).

Management efforts to protect Delaware Bay staging sites involve local, state, and federal agencies. Major initiatives include reduction of risks of industrial and maritime accidents to knots and the resources they use. A greatly increased commercial harvest of gravid, female horseshoe crabs during 1990s also is thought to be threat to knots (Tsipoura and Burger 1999 Tsipoura, N. and J. Burger. (1999). Shorebird diet during spring migration stopover on Delaware Bay. Condor 101 (3):635-644. Close ). Crab eggs are a primary food resource for Red Knots at Delaware Bay and were less abundant in the late 1990s and early 2000s than in 1980s, owing to greatly increased harvests of female crabs, and had a major effect on the decline of the knot population in TdF (Niles et al. 2009). Modeling in an adaptive management framework, considering both the harvest levels of horseshoe crabs and needs of Red Knots, showed that restrictive harvest would benefit recovery of the knot population (McGowan et al. 2011a).

Disturbance associated with the collection of gravid crabs on beaches also flushes knots. Chronic human disturbance at marine and estuarine nonbreeding habitats is thought to reduce suitability of habitats for Red Knots (Pfister et al. 1992 Pfister, C., B. A. Harrington and M. Levine. (1992). The impact of human disturbance on shorebirds at a migration staging area. Biological Conservation 60:115-126. Close , Burton et al. 1996 Burton, N. H. K., P. R. Evans and M. A. Robinson. (1996). Effects on shorebird numbers of disturbance, the loss of a roost site and its replacement by an artificial island at Hartlepool, Cleveland. Biological Conservation 77:193-201. Close ). Modeling of the energetic costs of chronic disturbance to knots also indicates that such disturbance at migration sites could affect the species' ability to gain fat at migration staging sites (BAH).

Elsewhere in the world, key food resources of Red Knots also are demonstrably vulnerable to human activities—e.g., shell fishing activities depleting bivalve populations and destroying important habitats for a decade or more (Piersma et al. 1997 Piersma, T., A. Hedenstrom and J. H. Bruggemann. (1997). Climb and flight speeds of shorebirds embarking on an intercontinental flight: do they achieve the predicted optimal behaviour? Ibis 139:299-304. Close Piersma et al. 2001). This lead to a large loss of Red Knots, and emigration of substantial numbers to the United Kingdom. In South America, wintering and migration staging areas are also vulnerable to human population growth and economic development. The Red Knot population spending the non-breeding season at Rio Grande in TdF declined from about 6,000 in 1995 to ~300 in 2012, partly because of destruction of roosting sites, economic development on the shore, and erosion of the restinga leading to decline of food supplies. In Río Negro Province, a key migration staging area near San Antonio Oeste is a WHSRN site, as are other smaller stopover sites at Rio Gallegos, Peninsula Valdes, Bahia Blanca and Punta Rasa. San Antonio Oeste has developed a management plan to protect sites used by shorebirds, and has rangers that protect sites during migration. A social marketing campaign there by RARE sigificantly raised public awareness of shorebird conservation. The major migration staging area of knots at Lagoa do Peixe in Rio Grande do Sul in s. Brazil was established as a national park by the Brazilian federal government. During southward migration, substantial fractions of the rufa population visit coasts of Suriname; 3 major sections of this national coastline are included in the WHSRN.

Effectiveness Of Measures

Most of the measures described in the preceding section were designed to prevent population declines among shorebird populations by protecting key resources needed during winter and migration. The long distance migrant population in TdF saw a 30% increase to 13,000 in the Austral summer of 2011-2012, indicating that measures taken in the flyway to better protect non-breeding sites and in Delaware Bay to limit the horseshoe crab harvest, and thus increase the proportion of red knots reaching high body masses before migrating to the Arctic to breed, has been successful. Field studies during the southward migration at the important stopover site at the Mingan Archipelago in Quebec showed that the 2011 breeding season was very good as many males were late arriving there because they stayed in the Arctic until young fledged, and were followed by much higher numbers of juveniles than in the previous 5 years. A ground census at Delaware Bay in late May recorded a count of 26,000 Red Knots (L. Niles, pers. comm.), confirming a population recovery had begun. If adaptive management is continued to limit horseshoe harvest then it may be possible to restore the Red Knot population to the 60,000 threshold used in the model, providing ecological conditions in other parts of the annual cycle remain favorable.