Migratory Airspaces
Migratory airspaces consist of the dynamic, three-dimensional, aerial corridors through which bats, birds, and insects migrate. This ecosystem is crucial for the survival of migratory individuals and their populations because it connects distant habitat segments used across different life-stages of a species to feed, mate, and overwinter. While not limited to a particular set of geographical features, these ecosystems are influenced by ecological, geographical, and meteorological factors, encompassing the horizontal and vertical extent of the flight paths of these animals. Many Species of Greatest Conservation Need make use of these ecosystems, including birds such as piping plovers (Charadrius melodus) and black-crowned night-herons (Nycticorax nycticorax), and migratory bats such as hoary bats (Lasiurus cinereus) and eastern red bats (Lasiurus borealis).
- Ecosystem Services and Human Benefits
Many important species travel the migratory corridors of Indiana. Indiana sits within the Mississippi Flyway, one of the four major North American migration corridors. The Flyway is used by an estimated 40% of waterfowl and shorebirds on the continent. This makes Indiana airspace a necessary habitat for many birds and makes the state a destination for birdwatchers. Migratory airspaces also connect pollinator habitats for species of bats and insects. Pollinators improve the health of other ecosystems nearby and are necessary for the health of many crops. Maintaining Indiana’s migratory airspaces is crucial to many species and ecosystems and yields benefits to agriculture.
- Ecosystem Status
Migratory airspace is increasingly impacted by humans through physical structures, pollution, and habitat changes. Significant contributors to the mortality of many migratory species include buildings, towers, and wind turbines. Better understanding how these structures and factors like light pollution impact migration will better inform how the migratory airspace ecosystem can be better managed. In regard to air pollution, the 2025 State of Air report from the American Lung Association ranked the Indianapolis metro area 54th out of 228 cities nationally for ozone pollution, and 21st for particle pollution. In this urban area, industrial activity, car emissions, and outdated plants contribute greatest to these pollutants.
- Ecosystem Pressures
Recent increases in residential and commercial expansion have led to decreases in open air space and increased light pollution. New structures and buildings in these areas increase the risk of collisions in the air. With a positive correlation between structural strikes and bird mortality, this presents a major challenge to urban areas. Large expanses of glass with reflection or transparency alongside buildings have the highest rates of collision, killing hundreds to millions of birds each year. Recent building and road construction also increases the amount of artificial light produced within an area. Nocturnal birds that rely on the darkness for safe activity are at particular risk for behavioral alterations, competition for resources, and predation. Feeding and breeding patterns can be negatively affected by the untimely light, leading to decreased survival. Similarly, migrating birds are at risk for deterred flight patterns and flock fragmentation upon the introduction of artificial light. These birds use the natural light cycle for navigation as the sun’s position aids in direction orientation. Without their sun-compass, many birds may be misled or drawn into urban settings, leading to higher rates of building collisions and bird confusion.
Migratory birds that rely on local forests, wetlands, and grasslands for habitat may overarchingly lose parts of these ecosystems due to development. Consequences include ecological traps where birds begin nesting in unsuitable habitat, unknowing that the number and quality of resources present will not allow them to thrive and reproduce successfully.
Additional pressures that affect the migratory airspace ecosystem in Indiana can be explored here.
- Ecosystem Conservation Opportunities
Conservation professionals highlighted two opportunities for reducing pressures in migratory airspace ecosystems. The first is to promote better management practices from energy, utility, and service companies. Attention to habitat buffers and integrated vegetative management will improve environmental outcomes while still serving infrastructure needs. Optimized maps can help direct this movement, and the development and adherence to rights-of-way (ROWs) for priority wildlife corridors can further guide management for infrastructure companies and contractors. It is clear that more research, data collection, and case study compilation is necessary to positively educate these key stakeholders on the benefits of these management practices. Goals of discussions would be to empower stakeholders not only to adopt the changes, but also to believe in their environmental impacts and public benefits.
The second opportunity is to incentivize landowners to conserve state-listed species. As much of Indiana’s lands are already developed, maximizing species conservation in these spaces will be crucial to support native species habitat needs and migration patterns. There is an opportunity to create incentive programs that provide landowners with benefits for adopting conservation practices. Research into conservation programs will be needed to improve management on private lands with provisions to allow researchers access to landowner properties for data collection.