Updated: Apr 8
Water is the liquid key to the door of all life on Earth. While we know birds have high water requirements, just how long can they survive without water?
Birds, like most vertebrate species, require water for survival. However, just like their food requirements, there are limits to dehydration before birds can suffer severe consequences, such as death. In this post, we will explore the water requirements of birds, how they acquire water, and the limits their bodies can survive without water.
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The answers below are not suggestions for keeping and caring for birds. These are answers to questions about the limits wild birds may display during the extremes of survival. Do not attempt to dehydrate any birds, wild or captive.
What is a bird's water content?
The majority of a bird's mass consists of 60-70% water. The amount depends on multiple factors including species, size, sex, fat content, and muscle content. This high percentage requires constant water maintenance to prevent dehydration or salt-stress.
The water requirements of birds
The water requirement of a bird varies depending on its size and diet, however, the average wild bird can lose 15-25% of its body water to the environment or normal body processes. Small birds will typically lose more water as it relates to total mass, which leads to a constant need for water replenishment. During more extreme conditions, a bird can lose even more water, causing severe dehydration or an imbalance in their salt concentrations. How do birds solve these deficiencies? Read on.
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How do birds get water?
Birds can acquire and store water in a variety of ways, but the three most common ways are basic water consumption, water consumption from food, and the breakdown of molecules that release water (metabolizing fat and muscle). Carnivorous and insectivorous birds are able to obtain most of their water needs from their food sources, while seed and plant eaters likely have to acquire additional water from fresh sources. Some birds, such as sandgrouse, will actually use their feathers to store water to transport it away from the source. Other birds, will mitigate water loss by hyperconcentrating their excreta as uric acid instead of dilute urine.
How long can birds survive without water?
As with all of these answers, there are a variety of factors involved. However, for smaller birds like finches and warblers, major dehydration can occur in as little as 2-3 hours as temperatures peak. A research project looking at how major drought could impact bird populations ran several experiments and determined that a Lesser Goldfinch could survive:
10 hours at 86˚F (30C)
6-7 hours at 95˚F (35C)
5-6 hours at 104˚F (40C)
2-3 hours at 113˚F (45C)
Larger birds like pigeons can survive for 48+ hours at mild temperatures when deprived of water.
How do drought and extreme temperatures affect birds?
Dehydration is the most obvious threat to birds in high temperatures. However, high temperatures are also tied to drought and wildfires, which can lead to losses in food sources and habitat, further impacting birds in negative ways. Losses in food and habitat can lower a bird's ability to lay and raise young, and these negative impacts can also carry onto the wintering grounds, lowering a bird's ability to survive from season to season. These negative impacts can even compound on a bird, scientists will refer to it as the "carryover effect," leading to lower and lower productivity of young each year.
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The ability of birds will never cease to amaze us. Birds can survive on minimal water, using various adaptations to live in environments that are harsh and unforgiving.