A Traveller’s Guide to Feathers, Article 85 – Brave Birds

A Traveller's Guide to Feathers

Some birds are willing to take on tasks that would make a human stagger. Consider the American Golden-plover. Each year, these shorebirds migrate from their breeding grounds in Arctic Canada to spend the non-breeding season on the treeless plains of Argentina and Uruguay, and fly back again. Covering these huge distances, the American Golden-plover weighs about as much as a baseball or a cricket ball. That is an impressive feat.

These brave birds cannot cover those distances in a single long flight. They must stop along the way to rest, feed, and replace some of their feathers. On their northward migration, American Golden-Plovers may stop for two weeks or more to replenish themselves on the previous year’s leftovers in corn and soybean fields. It has been estimated that, at the peak of migration, a single county in a state south of the Great Lakes might host 25,000 individuals.

We all recognize the importance of renewable and non-depletable sources of energy. Parts of the globe seem ideally suited for wind-energy turbines, for instance. Even though the wind cannot be used up, those turbines might come with an environmental cost. Might those structures have an impact on migrating birds?

Wesley Homoya and his colleagues at Purdue University studied the responses of American Golden-plovers to wind energy facilities in west-central Indiana. More than four hundred turbines were constructed on their study site between 2008 and 2009, where none existed before. This sort of development seems likely to continue, and so an understanding of potential impact is crucial, particularly since the bird is a species of special concern in Indiana. Might turbines cause American Golden-plovers to avoid prime habitat? Might collisions with turbine blades kill birds?

Homoya and his crew surveyed agricultural fields in Benton County twenty-five times through the spring migration period. They estimated the number of individuals in each flock, and noted the time and location of each flock, as well as the type of crop from the previous season. The team spotted more than 100 flocks containing nearly 10,000 individuals. The distribution and abundance of American Golden-plovers was apparently only modestly influenced by the presence of turbines, and the research did not reveal strong avoidance on the geographic scales that they tested.

Some earlier studies found that wind-energy developments had negative consequences for migratory birds, but others were unable to demonstrate a significant impact. Until we have a better understanding of the full effects of wind-energy developments on bird populations, Homoya et al. suggest that we set aside those regions that have been identified as being particularly important to migrants. This might give many brave birds a better probability of survival.

Homoya, W., J. W. Moore, P. J. Ruhl and J. B. Dunning, Jr. 2017. Do American Golden-plovers (Pluvialis dominica) avoid wind-energy turbines in agricultural fields in Indiana during spring migration? Wilson Journal of Ornithology 129:863-871.

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