When wildlife avoids perfectly good habitat: the perceptual trap

Lesser prairie chicken (Tympanuchus pallidicinctus). Credit, Dominic SheronyWhat should we do when perfectly good habitat exists but certain species of wildlife decide to avoid it anyway?

In a new article in the journal Ecological Applications, Michael Patten and Jeffrey Kelly from the University of Oklahoma grapple with this potential mismatch between wildlife perception and habitat quality - a phenomenon they call the "Perceptual Trap." 

Past research on this issue has largely focused on the related problem of "Ecological Traps" in which wildlife select for habitat that is bad quality even though better habitat may exist.

Scientists believe that ecological traps occur when human disturbance to the ecosystem throws off the cues for wildlife behavior. For example, polarized light pollution created by surfaces such as asphalt, windows, and oil slicks can be more attractive to some aquatic insects for mating than bodies of water.

However, very little research has looked specifically at the phenomenon of species avoiding high quality habitat. In this new study, though, Patten and Kelly find some empirical evidence for a perceptual trap in lesser-prairie chickens in eastern New Mexico.

The researchers looked at a region of oak-grasslands where areas have been treated with herbicides to prevent the encroachment of woody vegetation. They found that nesting prairie-chickens tended to avoid the treated sites in favor of locations with more woody vegetation even though nesting success, clutch size, and fledgling production were equal in both types of areas. 

The researchers conclude that the birds perceive that the treated areas are lower reproductive quality even though the data suggests that they are not.  The authors contend that perceptual traps can be problematic for the viability of populations. In the case of prarie chickens they write,

"Reducing shrub cover may force female prairie-chickens to move farther to find what they perceive to be suitable nesting habitat, but increased motility leads to increased mortality. If the practice of herbicide application spreads, then nesting prairie-chickens may abandon areas where their perception of habitat quality drops below some threshold, [and] populations and ranges [may] shrink as a result of fragmentation."

Of course other factors may be at work. The prairie chickens may know more about the quality of the habitat that they are avoiding than we do. For example, it is possible that the removal of woody vegetation has negative effects on the long-term viability of populations that the researchers were not able to observe.

Nevertheless, this study makes an important contribution to conservation science. Perceptual traps are potentially very problematic but they also are very difficult to demonstrate empirically or even to recognize. Hopefully, this study will spur more research activity on this important topic.

--Reviewed by Rob Goldstein

Patten, M., & Kelly, J. (2010). Habitat selection and the perceptual trap Ecological Applications DOI: 10.1890/09-2370