Western Hemisphere Shorebird Reserve Network

Predicting Shorebirds’ Vulnerability to Climate Change


Scientists and conservationists have long been concerned about how climate change may exacerbate population declines already occurring for individual species, and for shorebirds in general. A team of shorebird and climate-change experts in the United States collaborated recently to find answers to this question through the use of a predictive model. At the end of September 2014, they published the findings of their study, entitled “Predicting Vulnerabilities of North American Shorebirds to Climate Change,” in PLOS ONE, a peer-reviewed, web-based, science publication. In it, the team also explored whether relatively secure species might become “at-risk species.”

Shorebirds depend on the availability of horseshoe crab eggs when they land to refuel on migration. / © Jan van de Kam

The authors highlight how the life history of shorebirds poses inherent risks. Their lengthy, energetically expensive migrations may be vulnerable to changes in wind patterns; the coastal stopover sites they depend upon are vulnerable to sea-level rise; and the timing of food availability, such as emergence of invertebrates, is vulnerable to changes in average temperature. Climate-change vulnerability assessments often don’t take these factors into account, thus underestimating shorebirds’ vulnerabilities and their risk of extinction.

Therefore, the team created a categorical risk model based on the following four factors:
1. anticipated changes in breeding, migration, and wintering habitat;
2. degree of dependence on ecological synchronicities;
3. migration distance; and
4. degree of specialization on breeding, migration, or wintering habitat.

The team evaluated 52 shorebird taxa (49 species, and two distinct populations each for another three species). The model predicted that 90% (47 taxa) will have an increased extinction risk when adding these four factors to the current vulnerabilities estimated in the U.S. Shorebird Conservation Plan. No species was reclassified into a lower-risk category, although six species had at least one of their risk factors decrease in association with climate change. Whether a species moved to a different risk category (+/-) depended on how much of a climate-change effect was required to cause the shift. Even among the ‘high tolerance’ group, the model put 20 species in the highest-risk category for extinction. In short, the results of the predictive model confirmed, and will more deeply inform, the intuitive concern among scientists and conservationists—that shorebirds are likely to be highly vulnerable to climate change.

Of the 52 shorebird taxa evaluated, 47 are predicted to change to a higher risk category (positive values) for extinction due to climate change, and none to a lower one (negative values). Source: Figure 2 from Galbraith et al. 2014.

What is the conservation application of these findings? The authors recommend that the U.S. Fish and Wildlife Service use them to revise national shorebird priority scores, to better reflect shorebirds’ high vulnerability to climate change. The existing scoring system was developed nearly 15 years ago, without direct considerations for a changing climate. Revising it to account for this will benefit long-term shorebird conservation efforts.

Congratulations and appreciation to coauthors Hector Galbraith, supported by Manomet Center for Conservation Sciences and National Wildlife Federation, Massachusetts; David W. DesRochers, Department of Natural Sciences, Dalton State College, Georgia; Stephen Brown, Shorebird Recovery Program, Manomet Center for Conservation Sciences, Massachusetts; and J. Michael Reed, Department of Biology, Tufts University, Massachusetts; and to editor Grant Ballard, Point Blue Conservation Science, California.

For more information, please contact coauthor J. Michael Reed (michael.reed@tufts.edu), Department of Biology, Tufts University, Massachusetts