IT'S MARKATHON TIME IN THE VALLES GRANDE, and John is back on site with a crew of assistants capturing and marking prairie dogs who have molted over the late summer. Our prairie dogs are now sporting thicker winter coats, and with them they have lost their semi-permanent dye markings. If we didn't return in the fall to mark our study subjects before winter, they would be unrecognizable upon our return for research in the spring. And with the mating season starting almost immediately, trapping to re-mark them in March would be too invasive and interruptive for the prairie dogs. And so, John brings a team to the site every Fall to make sure every prairie dog is dyed again. This is also a good time to take stock of the research colony, determine how many members (especially juveniles) are still alive, and survey what's happened since we've been gone.