Specialization for life underground has evolved multiple times in mammals as a strategy for foraging, avoiding predators, storing food and nesting; however, researchers know very little about burrowing behaviors because it is difficult to visualize animals as they move through soil. This project focuses on burrowing behavior in Eastern moles because they are specialized diggers that have evolved extreme morphological specializations for powerful burrowing and exhibit two different burrowing behaviors in response to the type of soil they encounter. This study will investigate how and why Eastern moles change their burrowing behavior in response to soils of different compactness. This work will connect morphological specializations for burrowing to burrowing performance, and set the stage for broader investigations of the convergent evolution of burrowing in other species of moles and other mammals. In addition, this research will promote education by providing animations of burrowing useful in teaching evolution and comparative anatomy at all academic levels, benefit the general public by providing crucial kinematic data for improving the design of mole-inspired robots that are used in urban search and rescue, engage the public by recruiting local community members to help identify mole habitats, and lastly, will support the researchers continued participation in the Science Cafe program, which hosts accessible scientific talks for the public that spotlight local scientists.
In this study, the researchers intend to extend upon preliminary data by asking how burrowing behavior changes in response to soils that differ in compactness and how changes in behavior balance the trade-off between force, speed and the trajectory of force used to displace soils. The researchers hypothesize that lateral stroke and scraping movements involve different joints and are used with different frequencies and that lateral strokes are more efficient in displacing loose soil while scraping movements are most efficient in displacing compact soil. Bi-planar x-ray video and force plates will be used to visualize and quantify how Eastern moles change the movements of their limbs in order to meet the challenges of moving through soft and compact substrates. Force and video data will be made available to the public through Dryad.org and the XMA portal (http://xmaportal.org/webportal/), respectively.
