Conservation, Migrations, Wildlife

A Twisted Tale of Red Knot Survival

By Joanne Garton


It has happened countless times: I walk into my favorite restaurant only to find that it is out of breakfast burritos. The manager points me to the tamales without ever explaining if it was a lack of eggs, a problem with the oven, or an angry mob of hungry burrito-eaters that wiped out the supply this weekend. I leave hungry and find somewhere else to eat.

These days, the red knot birds in Delaware Bay are similarly exasperated, but with no other food to eat when their seasonal feast of horseshoe crab eggs are gone, the migratory birds are starving. Horseshoe crabs are the favored bait for a growing market of eel and conch farms, diminishing the supply and diversity of breeding horseshoe crab pairs left in the bay.

However, red knot survival is likely not tied only to ample food supply. Also important are changes in wetland habitats critical to red knots, the weight and overall fecundity of red knot populations, or the male to female horseshoe crab ratios left after harvest. Scientists now assign numerical values to these variables in order to determine when management decisions are being impeded by too many uncertainties. The ideal management solution utilizes an adaptive framework that relies on known, or “perfect”, information, while also expecting outcomes with measured uncertainty.

Curiously, after the systematic incorporation of so many relevant environmental and anthropogenic variables, the survival of 45,000 annually migrating red knots ultimately depends on a population of about 11 million horseshoe crabs. The size, shape, and breeding rates of red knots are variable but inconsequential pieces of this numbers game. Without the luxury of a second choice for breakfast, the red knots need a restaurant manager that knows how to keep the clientele satiated and happy.

A review of: Smith, D.R., McGowan, C.P., Daily, J.P., Nichols, J.D., Sweka, J.A. and Lyons, J.E. (2013) Evaluating a multispecies adaptive management framework: must uncertainty impede effective decision-making? Journal of Applied Ecology, doi: 10.1111/1365-2664.12145.

Joanne Garton is an active eater in the Montpelier Farmers’ Market where she searches for weekly breakfast burritos amidst mounds of root vegetables. She spends her academic time somewhere between the first and second year of the Ecological Planning program at UVM.

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