EXPERIMENT   Researchers observed that the population collapse of the greater prairie chicken was mirrored in a reduction in fertility , as measured by the hatching rate of eggs. In 1992, researchers began experimental translocations of prairie chickens from Minnesota, Kansas, and Nebraska in an attempt to increase genetic variation.

 RESULTS   After translocation (blue arrow), the hatching rate rapidly improved, and the population rebounded.

 CONCLUSION   The researchers concluded that lack of genetic variation had started the Jasper County population of prairie chickens down the extinction vortex.