Osmoregulation in rock doves
The rock dove, Columbia livia, has a number of special adaptations for regulating water uptake and loss. Challenges C. livia pigeons drink directly by water source or indirectly from the food they ingest. They drink water through a process called double-suction mechanism. The daily diet of the pigeon places many physiological challenges that it must overcome through osmoregulation. Protein intake, for example, causes an excess of toxins of amine groups when it is broken down for energy. To regulate this excess and secrete these unwanted toxins, C. livia must remove the amine groups as uric acid. Nitrogen excretion through uric acid can be considered an advantage because it does not require a lot of water, but producing it takes more energy because of its complex molecular composition. Pigeons adjust their drinking rates and food intake in parallel, and when adequate water is unavailable for excretion, food intake is limited to maintain water balance. As this species inhabits arid environments, research attributes this to their strong flying capabilities to reach the available water sources, not because of exceptional potential for water conservation. C. livia kidneys, like mammalian kidneys, are capable of producing urine hyperosmotic to the plasma using the processes of