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As humans continue to change the landscape, migratory connectivity becomes increasingly important. Understanding the affects of proposed zoning changes or infrastructure projects must take into account migratory routes, breeding-wintering population dynamics, and the cascading effects of disrupting one or more of these areas. Considerations include:

  • Direct impacts like fatal collisions with infrastructure
  • Indirect effects like increased vulnerability imposed by seasonal interactions

Infrastructure collision

Collision of aerial migrants with buildings (particularly windows) and other structures is a worldwide problem (approximately one billion annual birds kills in the United States alone). Resident urban species rarely strike buildings, and migratory songbirds are disproportionately affected.

  • January, 2001 5,000 red-winged blackbirds collide with buildings and are killed in Arkansas
  • Night-migrating birds become “trapped” by the bright lights of cities and die from collision or exhaustion
  • Consequences of collision mortality is not fully known because we do not know where individuals breed
  • Impacts could be diffused throughout the entire range of a species, or may be focused on a handful of populations
  • Understanding where, when, and how birds migrate can help us to plan infrastructure and know when to keep the lights off


A side-effect of urbanization is pollution. Many cities around the world have poor infrastructure and few regulations to deal with human and industrial waste, particularly in developing and undeveloped regions (e.g. Tamilnadu, India and Accra, Ghana).

  • Water pollution can damage habitat and lead to severe mortality among waterbirds and aquatic animals
  • Some migrant animals (e.g. great white cranes and salmon) will reject outright polluted or otherwise human-altered environments. Ultimately, this reduces breeding success for the population and can cause mortality
  • Knowing where migratory populations are coming from and going to will help us elucidate population impacts from pollution, long-term toxicity, and how pollutants are moved from urban environments to other locales

Vehicular collisions & roadway-induced habitat fragmentation

While the effects of infrastructure and pollution appear to be localized, roadways are ubiquitous and widespread. Vehicular strikes with wildlife may cause significant damage to migratory populations as well as to humans involved in these accidents.

  • Habitat quality near roads is poor
  • Culverts may be impassable to migratory fish
  • Wildlife passages for ungulates are often avoided in favor of traditional migratory corridors
  • Migratory connectivity can help us know where to place wildlife corridors and reserves that protect important habitat for migratory populations
  • Governments must account for migratory pathways and address the stress of roads and traffic on wildlife populations.
  • A highway proposed for the Serengeti would severely disrupt wildebeest migratory route


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HOME | connecting populations | seasonal interactions | climate change | disease | urbanization

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