Research

Conservation of Migratory Shorebirds

Migratory shorebirds are true wonders of the natural world. Each year, they undertake grueling migrations of up to 30,000 km from their wintering grounds in South America to their breeding grounds in the Canadian Arctic, and back again. Along the way, they stop at various staging points to rest and refuel. These highly productive stopover sites are critical to the survival and breeding success of these birds, and there are a number of factors that are reducing their viability, such as global climate change, over-harvesting of food supplies, and disturbance or destruction of habitat. As a result, most populations of migratory shorebirds are in serious decline and their future is tenuous.

One of the most important staging sites along the migration route for shorebirds is Delaware Bay, U.S.A. It is estimated that as much as 80 percent of the North American population of Red Knots (Calidris canutus), as well as numerous Sanderlings (Calidris alba) and Ruddy Turnstones (Arenaria interpres) use the bay during spring migration. What is the main attraction in this heavily-developed area? Horseshoe crabs—their eggs are a principal food source for the birds, which arrive exhausted and with their fat reserves and part of their muscle mass depleted after the long flight from South America. They gorge on these eggs, almost doubling their body mass over a period of approximately three weeks, until they depart en masse at the end of May. If they do not achieve the critical body mass to enable them to continue to the breeding grounds and survive an initial few days of snow cover, their survival and breeding success is jeopardized.

By trapping, banding and gathering data on shorebirds during their stopovers in Delaware Bay, scientists have noticed a decline in the refueling and annual survival of shorebirds, particularly in Red Knots, prior to their departure from the bay. This decline and the dramatic increase in the 1990s in the harvesting of horseshoe crabs are directly correlated. Furthermore, erosion of beaches in Delaware Bay has reduced the number of foraging areas. Unless a viable conservation plan is developed and implemented, Red Knots and other shorebird species face imminent endangerment and risk of extinction.

The ROM’s Allan Baker and Patricia Gonzalez, a conservationist with the Fundación Inalafquen in Argentina, have led the International Shorebird Banding Project for the past 15 years. Collaborating with Luis Benegas in Tierra de Fuego and with an international team of researchers, conservationists, students and volunteers throughout the hemispheric flyway, they are heavily involved not only in collecting data and estimating risks to red knots, but in assisting local conservation organizations to initiate programs to protect resources on which shorebirds depend. Continued monitoring will remain crucial in ensuring the survival of these long distance migrants.

Curator
Allan Baker

Recent Publications

2009	Baker, A.J.“The Plight of the Red Knot.” ROM Magazine, 41(4): 19-23.
2009	Gillings, S., P.W. Atkinson, A.J. Baker, et.al. "Staging behavior in Red Knot (Calidris canutus) in Delaware Bay: implications for monitoring mass and population size." The Auk, 126: 54-63.
2009	Niles, L.J. J. Bart, H.P. Sitters, A.D. Dey, K.E. Clark, P.W. Atkinson, A.J. Baker, et. al. “Effects of Horseshoe Crab harvet in Dleaware Bay on Red Knots: Are harvest restrictions working?” BioScience, 29:53-164.
2008	Niles, L.J., H.P. Sitters, A.D. Dey, P.W. Atkinson, A.J. Baker, et al. "Status of the Red Knot (Calidris canutus rufa) in the Western Hemisphere." Studies in Avian Biology No. 36, edited by Carl D. Marti. Cooper Ornithological Society, Pennsylvania, pp. 1-185.
2007	Atkinson, P.W., A.J. Baker, et al. "Using stable isotope ratios to unravel shorebird migration and population mixing: a case study with Red Knot Calidris canutus." In Waterbirds around the world , edited by G.C. Boere, C.A. Galbraith and D.A. Stroud. TSO Scotland Ltd., Edinburgh, UK, pp. 535-540.
2007	Atkinson, P.W., T. Piersma, A. Dekinga, A.J. Baker, et al. "Rates of mass gain and energy deposition in Red Knot on a staging site are both time - and condition - dependent." Journal of Applied Ecology, 44: 885-895.
2006	González, P.M., A.J. Baker and M.E. Echave. "Annual survival of Red Knots (Calidris canutus rufa) using the San Antonio Oeste stopover site is reduced by domino effects involving late arrival and food depletion in Delaware Bay." Hornero, 21(2): 109-117.
2005	Clark, N.A., S. Gillings, A.J. Baker, P.M. González and R. Porter. "The production and use of permanently inscribed leg flags for waders." Wader Study Bulletin, 108: 38-41.
2004	Baker, A.J. et al. "Rapid population decline in red knots: fitness consequences of decreased refuelling rates and late arrival in Delaware Bay." Proc. Roy. Soc. Lon. B., 271: 875-882.

 

 

 

A banded Red Knot. The number is clearly visible through a spotting scope, and identifies the individual so it can be tracked. © Mark Peck.

Team members work quickly to remove birds from the cannon net. © Mark Peck.

A horseshoe crab in Delaware Bay. The grey lines through the sand are eggs. © Mark Peck.