Download the pdf of this lesson!
When the felt on the head of the sealed glass bird is wet with water, the bird pivots back and
forth into a glass of water. It gives the appearance of drinking!
Wet the head of the Drinking Bird, and place a full glass of water near it so that when the head
tips forward, only the beak comes in contact with the water. Most Drinking Birds work without
adjustment! Sometimes a small adjustment to the pivot point of the bird is needed. Carefully
move the metal clip up or down the glass tube, (ca. a millimeter), until the Drinking Bird just
balances in a vertical position.
Water requires heat to evaporate. In this demonstration, water from the wet felt on the outside of the head evaporates, causing the vapor inside the head of the bird to cool. This reduces the
pressure of the vapor at the top, allowing the higher pressure in the lower bulb to push up the column of liquid. The pressure of the vapor in the top bulb decreases for two reasons:
- As the vapor cools, the vapor contracts. Notice the top volume of gas decreasing, and
- As the rising liquid near the top cools, less liquid evaporates into the head and more vapor returns to the liquid state. Since this demonstration only works with a sealed liquid that has a high vapor pressure, this is a major factor.
As the head cools further and more liquid inside the bird rises, the center of gravity of the bird rises, causing the bird to become unstable and tip forward.
Eventually, the beak of the bird tips forward enough to rewet its head. When this happens, the bottom end of the glass tube in the lower bulb is above the remaining liquid. Vapor from the bottom travels to the top until the pressure is equalized. At the same time, liquid in the column flows to the bottom. As the center of gravity of the bird is lowered, the bird tips vertical and the cycle starts over.
Suggested Classroom Activities:
I) Classroom Discussion
Q. Is this an example of perpetual motion?
A. No. The cycle repeats itself only as long as the water evaporates from the head
Q. What is needed in order for the Drinking Bird to work?
A. A difference in temperature between the head and body.
II) Student Challenges
- Observe the operation of the Drinking Bird and explain how it works.
- Discover a way to make the Drinking Bird cycle faster.
- Predict what will happen if a fan blows air toward the Drinking Bird. Does it
make a difference which direction the air blows?
- Predict the result of using warmer or cooler water in the glass.
- How long will the bird cycle without needing a refill of the water in the open
container? Can you find a way of causing the bird to cycle longer?
- Is there a difference in the cycle rate on a humid day vs. a dry day? Can the bird
be used to determine the relative humidity in the air?
- Predict the result of placing a small inverted aquarium over the bird. Does this
cause the bird to cycle more or less? (Note: as soon as the water in this closed
system reaches its vapor pressure, water from the felt can no longer evaporate
and the bird stops.)
- Can you attach a thread to the bird so that it does useful work, e.g. lifting a small
Write a review
Feb 5, 2015 | By Janie M. of Beaumont, TX United States
Sixth Grade Social Studies Teacher
Apr 2, 2014 | By Ruth Beller of Dalhart, TX United States
Owner Response:Ruth, someone from customer service will be contacting you today. Sometimes the bird's fulcrum needs to be adjusted by sliding the bird's neck up or down through the metal sleeve, which changes the center of gravity. If this doesn't work, we will send you out a replacement.
Dec 19, 2013 | By Dr. Ann Abraham of Ashtabula, OH United States
Aug 2, 2013 | By Rfletch of altamont, NY United States
Owner Response:We are terribly sorry for any inconvenience. One of our customer service representatives will contact you regarding your purchase of the Drinking Bird. The problem is most likely with the placement of the fulcrum, however, if we cannot get your bird to work, we will replace it immediately!
Awesome item from the past!
Apr 4, 2013 | By Ruth of Dracut, MA United States
Jan 23, 2013 | By Christine of Stanwood, WA United States
Romantic Drinking Birds
Jan 18, 2013 | By Sweet Perfume of Casper, WY United States
Awesome Dippy Bird
Sep 17, 2012 | By Kim Dickey of Greenbrier, AR United States
As a child, as an adult
May 30, 2012 | By Guillermo Nery of Bayamon, PR United States
May 29, 2012 | By Kim of Murfreesboro, TN United States
Class is Stumped
May 29, 2012 | By Stacey Militello of Shrewsbury, MA United States
Fun to watch
May 22, 2012 | By C Chino of San Marcos, CA United States
We love our bird!
May 22, 2012 | By Diane W of Minneapolis, MN United States
Great Focus activity
May 22, 2012 | By Rebecca Absher of Troutdale, VA United States
May 22, 2012 | By constance maxwell of oxford, MS United States
May 19, 2012 | By Margaret Flack of Jasper, IN United States
Drinking birds spark creative hypothesizing
May 18, 2012 | By Dave Beedell of Ottawa, ON Canada
Great thought provoker
May 18, 2012 | By Charles Zierzow of Barkhamsted, CT United States
Great Item to challnge thinking!
May 17, 2012 | By Ashley Dyson of Brandon, MB Canada
A great buy
May 17, 2012 | By D Doherty of Dublin, AL Ireland
Nothing dippy about these birds!
May 17, 2012 | By Jason H. of Zeeland, MI United States
Drinking bird rocks
May 16, 2012 | By Candy Sykes of Fremont, CA United States
Beautiful Bird Breaks Easily
May 16, 2012 | By RJAD of Jacksonville, FL United States
A great introduction to heat of vaporization
May 16, 2012 | By Cathy of Richland, WA United States
Old toy, always fun
May 16, 2012 | By Martin Roy of St-Georges, QC Canada
May 16, 2012 | By LaDawn Haws of Chico, CA United States
May 16, 2012 | By Charla O'Brien of Ferris, TX United States
May 16, 2012 | By Diedre Adams of West Terre Haute, IN United States