Edited by Dr. Bob Dittmar, Wildlife Veterinarian, Texas Parks and Wildlife Department

The water needs of different wildlife species vary widely. Even within a species, an animal’s water needs may differ depending on climate, body size of the animal, reproductive status, and other factors. This is why the daily water intake of a particular species is usually given as a range of values. Below are some of the factors that can influence the specific water needs of a given animal.

Physiology
Different animals are adapted to different climates and habitats. Species found in dry climates tend to have adaptations that allow them to use water more efficiently. For example, deer (Odocoileus spp.) and pronghorn (Antilocapra americana) produce feces that are relatively dry compared to cattle (Bos taurus) feces. This is because deer and pronghorn can extract more water from their food than cattle, and then use this water inside their bodies rather than losing it when excreting waste. Animals can also use behavioral adaptations to reduce water loss. Many desert-dwelling species are nocturnal, meaning they are active at night when cooler temperatures help them conserve water.

Size
Larger individuals of a particular species will need to intake more water than smaller individuals of the same species, given that all other factors are equal. A 35-pound coyote (Canis latrans) simply needs more water to run its body’s processes than a 25-pound coyote.

Reproductive status
Lactating mammals require more water to make up for the water content of the milk they produce. However, males can also be affected by water availability. For example, small mammals may produce less sperm during drought conditions.

Diet
As discussed in an earlier post, food can be a significant source of water for some animals. For example, javelina (Pecari tajacu) are well-adapted to eating the pads and fruits of prickly pear (Opuntia spp.), which have high water content. Other animals, such as deer, might prefer to eat other plants, but will eat more prickly pear in drought conditions as a way to get water.

Ambient temperature
Animals with an endothermic metabolism (that is, animals that generate their own body heat, also called “warm-blooded,”) can expend energy to keep their body temperature optimal when the air temperature is high or low. When air temperatures are high, maintaining an optimal body temperature requires a higher water intake. One excellent way to cool down is via evaporative cooling, because water absorbs energy (and thus, heat) as it evaporates off the body surface. Most animals do not sweat, but panting is an example of evaporative cooling from the tongue. Because water is being lost, additional intake is needed.