article at www.nature.com (http://www.nature.com):

"Kozorovitskiy suggests that studying rats in burrows is likely to be much more relevant to understanding human behaviour than tests carried out in standard cages. Standard laboratory housing may suppress individual variability,' agrees neuroscientist Larry Young from Emory University in Atlanta, Georgia. 'So the behaviour you see may be different from that you would observe in nature."

http://www.nature.com/news/2004/040802/full/040802-18.html