As a general aviation pilot, a story about increasing conflicts among fliers sharing the skies overhead carries an intrinsic interest with a safety overtone. As a biologist and a birder, realizing the story is about wildlife-human aerial interactions awakens quite a different interest, still with a safety overtone.
Sergio Lambertucci, a wildlife ecologist at the National University of Comahue in Argentina, along with Emily Shepard, and Rory Wilson, wildlife scientists at Swansea University in the UK, outline the evidence in a thorough review of where and when human and wildlife uses of airspace can lead to problems (see Science magazine, 1 May 2015, 348(6234), pp. 502-504).
Lambertucci et al. include on the human side what you would expect, fixed-wing airplanes, helicopters, and of course, unmanned aerial vehicles (UAVs) or drones. But you may be surprised that human use of the near-surface airspace extends beyond aircraft. Buildings, wind turbines, power lines, and antennae also project well into the lowest hundred meters of airspace within which most flying animals operate.
These three inclusive thinkers also remind their readers that less visible life forms exploit earth’s airspace; bacteria, algae, and fungi. I must admit, even wearing my biologist hat I never considered the impact of our use of airspace on microbial life. But aerial microorganisms can serve as condensation nuclei promoting cloud formation. Changes in the abundance and distribution of these organisms as a result of air pollution and wind flow patterns altered by tall buildings can impact precipitation and weather.
Bald eagle over Jordan Lake dam, North Carolina
Key to mitigating adverse impacts of human activities is a better understanding of just how and where and when wildlife use airspace. Beyond the obvious bird migration patterns that can extend across continental and oceanic boundaries, think about the more mundane, daily use of airspace by our avian friends to find food, mates, and nesting space. These smaller scale dynamics require understanding animal movements in the horizontal and vertical dimensions at scales from meters to kilometers, and how these uses change during the course of a 24-hour day.
Great blue heron over the Apex Reservoir, North Carolina
Armed with better knowledge of wildlife habits of airspace utilization we can design and place buildings and other structures to minimize conflicts. Windows can include markers to alert flying animals, the newest technologies employing ultraviolet lights highly visible to birds. Radar can detect approaching flocks of birds and enable structural modifications to limit impacts, such as reducing wind turbine speeds. In selected instances, full-time or time-sensitive airspace reserves might provide the best alternatives.
With over 500 hours in the left seat of single engine aircraft, I’ve only come close to a vulture or other bird a handful of times, almost always in the landing or take-off pattern. But as Lambertucci et al. report, there have been over two hundred people killed by birds striking aircraft, and the cost of bird strikes in the U.S. alone exceeds $900 million per year. One year, 2013, saw 11,315 bird strikes. Better understanding of wildlife use of airspace at small and large scales should enable us to reduce these and the variety of more subtle human-wildlife conflicts in our skies.