Maybe, they follow the mottos "You have to speculate to accumulate " or "You reap what you sow". Even though this is obviously not a cognitive effort on ther part, if they follow an automatic behaviour pattern of pulling plant matter into the ground they can make their environment more moisture-retentive, easier for personal transport and aerobically more hospitable in the long term. Eventually they can graze on the matter they pulled down, which will be in various states of decomposition, ensuring continuous nutrition. It looks to me like an evolutionarily advantageous strategy.