Wednesday, July 8, 2009

What do hawks drink?

In all the time that I've been watching these hawks - since they hatched, being fed by the haggards, and now hunting and feeding themselves - I realized that I have never seen them drink, and have not a clue about how they hydrate themselves.

John Blakeman to the rescue:

"Red-tails and many other hawks, and virtually all falcons, drink water. They walk out into shallow water, lean over, and dip their mouths into the water. They have no lips and so cannot easily create a swallowing reflex in soft, flexible mouth and throat tissues as can mammals. Instead, the water is literally scooped into the mouth, and then is quickly drained back into the esophagus by lifting the head and neck. It’s a bit awkward, but it works. The birds don’t get more than a few milliliters in each drinking session.


With red-tails these drinks can be rather infrequent. Peregrines, accipiters (Cooper’s hawks, sharp-shinned hawks, and goshawks), and a few other species prefer to drink and bathe each day. Red-tails aren’t so thirsty. I studied some red-tail nests in Nevada where there was virtually no available ponded water for the birds to drink or bathe in. They did well, nevertheless. If water is not available, red-tails can survive very well. Not so with falcons and accipiters. They require almost daily bathes and drinks.

Drinking varies from hawk to hawk. Some of my falconry red-tails seldom drank. Others seemed always thirsty. It’s an individually variable trait with red-tails.

Some of the water the birds use originates in the blood of their prey, but unless the animal is swallowed whole, as with mice and very small rats, very little blood is swallowed. It simply drains away, unconsumed by the hawk. She’s interested in pulling off pieces of flesh, unconcerned with swallowing any blood. Any swallowed blood is merely incidental to that soaked into fir or feathers, and does not provide a significant source of water to the bird.

Actually, birds can’t be drinking and carrying around excess water. Their physiology, from highly efficient kidneys to the unique low-water urinary waste (the concentrated white uric acid, not the clear and copious urea of mammals), is adapted to operate on little water. Flying around with a bladder heavy with water doesn’t work well. So water is conserved and used carefully."

- John Blakeman

5 comments:

  1. Really interesting (although I could have done without the bloody picture!) I see on facebook you are planning to go down to see them tomorrow- I'm going to try and get up early enough to meet you- probably about 8:30 or 9- are you hanging out in front of the library at 20th street or thereabouts? Hope that I get down there and find you and I hope Kay is there with her camera and Carditoo! If I can't make it, I'll look forward to reading your latest blog.

    mmggolfer

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  2. Thank you for keeping us (that don't live nearby) updated!! It is so exciting to see that they all made it - but then again, this family had a lot of prayers behind them. Thanks Sunny!

    Evelyn (from Florida)

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  3. Most birds and reptiles use water very efficiently. As mentioned in the article, they excrete uric acid. This compound takes more energy to produce, but it saves on water. Thanks, the article is interesting and informative.

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  4. Just got a hawk, so i think this will really help. Thanks for the information.

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