by Ben Johnson, Rice University (Class of 2018)
We humans have the power to force animals to choose their own extinctions. Most people are not even aware we possess such power. We’re all well aware that human actions can cause great harm to the natural world, but many people might not be aware that our actions can cause animals to become unable to distinguish between suitable habitats. Humans impact habitats so rapidly that environmental cues indicating suitable habitats become unreliable. These areas are called “ecological traps,” because, in essence, human activities are trapping animals in detrimental spaces.
A 2015 study out of the University of Melbourne published in Proceedings of the Royal Society looked at the consequences of ecological traps on groups of nearby animal populations—what ecologists call a metapopulation. Such a large scale for the study indicates that ecological traps affect habitats across a wide range of land. In fact, one of the study’s main findings is that traps are most harmful when they encompass many habitats. This might seem intuitive, but it is still a stark reminder that human activities are detrimental to nature at large scale levels. Animals can roam but cannot always hide from our harmful effects.
An easily understood example of an ecological trap is that of certain insect species that are attracted to the polarized light from bodies of water (where they lay their eggs). There have been many sightings of doomed insects attempting to land on sources of polarized light such as roads or even oil spills. They believe they are entering a situation beneficial to their reproductive success, but they instead find themselves unable to lay eggs or even at risk of death. These situations are essentially caused by human influences that distort natural cues.
Species most susceptible to these traps are those that are migratory and/or have large ranges. This means that many of the charismatic animals we all love and want to conserve, such as the Monarch butterfly or African wild dog, may be most at risk to this kind of human-induced confusion in habitat selection.
(Personal Photo taken on a trip to Namibia)
Species with requirements for expansive habitats, such as the African wild dog, are particularly susceptible to ecological traps
Furthermore, sick or injured animals are more inclined to be affected by ecological traps. They don’t have the time to wander about in search of the most favorable habitats. Even healthy individuals, however, can be easily deceived by misplaced or anachronistic environmental cues. When these individuals select an unfavorable habitat, they’ll likely in turn have fewer available resources or find themselves in imminent or indirect danger. The point is that these animals could easily become sick or injured, and thus even more likely to fall prey to these traps. These are cycles difficult to escape from. The consequences are not just mortality or discomfort, but also lessened reproductive success (fitness is one of the key concepts that permeates every discipline of ecology).
A particularly important factor to consider when discussing ecological traps is that some species select habitats that closely resemble their birth sites. These are behavioral preferences so innate that they are difficult for species to ignore or compensate for. For example, some aquatic species may settle down in a habitat with a similar pH as the habitat they were born in (or lived in as a juvenile). These inclinations are common in many species across many groups.
The authors of the study declare that “Ecological traps are likely to become increasingly common as humans continue to dramatically alter the landscape, and therefore have important implications for the management of animal populations worldwide.” Conservationists must be highly cognizant of these behaviors and preferences, especially in the light of ecological traps; hardwired behavioral preferences can be transformed into deleterious decisions through human-induced environmental changes.
Climate change is a widely spoken of mechanism by which human actions have detrimental impacts on the natural world. Ecological traps are a more localized, but perhaps equally potent, way in which humans are distorting the natural order. The solutions to this problem are highly context-specific and will be different for every species and ecosystem. In general, though, we can make the declaration that we owe it to animal populations to become more aware of how our actions are impacting their lives in ways they don’t deserve.
Hale, R., E. A. Treml, and S. E. Swearer. “Evaluating the Metapopulation Consequences of Ecological Traps.” Proceedings of the Royal Society B: Biological Sciences 282.1804 (2015): 20142930. Web.