More Water for Mule Deer? - Mojave National Preserve (U.S. National Park Service) In addition to springs, there are also stock tanks fed by wells throughout the preserve, principally (and historically) used for watering cattle. It’s not known which of these water sources deer used regularly, or whether they depend upon such artificial water sources of survival. Furthermore, is it water availability that limits the number of deer, or is it something else, such as food availability or predators? To learn more, up to 80 deer will be captured, tagged and released. In January 2008, the first eighteen deer were trapped and transported to a field site where researchers and volunteers efficiently gathered data: blood samples were collected; does were checked for pregnancy using ultrasound; weight, temperature, and other tests were conducted as quickly and safely as possible to minimize trauma to the animals.