Water metabolism of desert mammals

Measured every route of water gain and loss in desert rodents kept on dry seed with no drinking water, including metabolic water production, urine concentration, faecal water and respiratory loss.

Studied in

Dipodomys, Mammalia

Sample size

desert rodents under measured water regimes

Kangaroo rats survive indefinitely without drinking, on water produced by metabolising their food, because losses are cut on every route at once: extremely concentrated urine, nearly dry faeces, no sweating, and recovery of water from exhaled air.

• Laboratory conditions with controlled humidity; the burrow humidity that matters so much in the field was reproduced rather than measured in situ.
• A small number of species from one desert region.

• Desert survival

  Desert animals are not enduring the desert. They are keeping accounts — cutting losses on every route at once, and mostly arranging not to be out in the conditions at all.

• Kangaroo rat

  A kangaroo rat can live its whole life without drinking, on water released by metabolising dry seed. It manages it by losing almost none — including by cooling its own exhaled breath to condense the water back out.