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Santa Clarita Outdoor Report:  21-Second Rule

Santa Clarita Outdoor Report: 21-Second Rule

Growing up in Wisconsin, I had the good fortune to spend part of my summers on my Aunt and Uncle’s dairy farm.  There, I discovered a fundamental principle of four-legged mammals – they all pee.  Dogs, cats and especially cows all need to get rid of the waste products produced by their bodies.

Santa Clarita Outdoor Report: Cow

So imagine my surprise when I learned that scientists from the Georgia Institute of Technology are proposing another principle of pee, The describe it as the “Law of Urination”:  “animals empty their bladders over nearly constant duration of average 21 seconds (standard deviation 13 seconds), despite a difference in bladder volume from 100 mL to 100 L”. 

But we’re not talking about all mammals, just larger mammals.  When researchers measured flow rates of both laboratory animals and animals from the Atlanta zoo, they identified two styles of peeing – “dripping” and “jetting”.  (Click here to see examples.)  Small mammals “drip” and larger mammals “jet”. The difference has to do with the size of their plumbing.  Small mammals have a small urethra, so it makes sense that the output resembles an eye dropper.  But larger mammals have a larger urethra, so their output resembles that of garden hose (without the nozzle).

Santa Clarita Outdoor Report: California Ground Squirrel

Just as large mammals vary greatly in size, so do the sizes of their bladders.  For example, “an elephant can urinate about 42.3 gallons in one go…almost 1.5 gallons of liquid launching from the urethra every second”.   Let’s see…42.3 divided by 1.5…equals 28.2 seconds, well within the “Law’s” limits.

Santa Clarita Outdoor Report: Elephant

Meanwhile, a 20-pound dog has a bladder about the size of 1/2 cup, which it can empty in about 20 seconds, again within the limits.  These examples provide evidence that larger mammals “take the same time to empty their bladder, despite the difference in bladder size”. 

Because the research was done on laboratory and zoo animals, I’m not if their findings can be extended to animals who live in the wild.  It does makes sense, however, that a quicker pee is a better pee.  After all, it may be more difficult for wild animals to “attend to their business” while “doing their business”.

So for now, I think I’ll place this “21-second rule” in the same category as the “5 second rule”:  an interesting theory but yet to be determined.


Upcoming Outdoor Events: 

Trail Maintenance Schedule.  Come join our volunteers as they help maintain our trails.  Contact Steve at for time and place.

Wednesday mornings, January 8, 15, 22, & 29.
Saturday mornings, January 18.

Saturday, January 18, 8-10 AM.  TowsleyCanyon. “Up, Up and Away”.   Along with the weather changes, find out which birds leave our region, and which birds migrate in for a visit. Beginning birders are welcome. Binoculars optional. Meet at the Towsley Canyon front parking lot.

It’s not too late to enroll in Placerita Canyon Natural Area’s Volunteer-Naturalist training program.  Classes are currently meeting at PlaceritaCanyon on Tuesdays and Thursdays from 9AM to 12 Noon.  The cost for the 9 week training session is $45.  For more information, click here for the flyer, call (661) 259-7721 or e-mail  But contact them soon – the deadline for enrollment is 1/16/14.

New trail maps available.  If you’d like to explore a bit on your own, the City of Santa Clarita has a website with trail maps of our local open spaces.

There’s also a new website for bicycle riders.  

Ask Dr. Norm:  Do you have questions about the flora, fauna, animals, rocks, etc. in our Santa Clarita Valley?  Here’s a place for you to ask your questions. Dr. Norman Herr, Ph.D., is a professor of science and computer education at CaliforniaStateUniversity, Northridge.

Tell Us About Your Hike: Here’s a new website where you can post pictures, provide feedback and make suggestions about the City of Santa Clarita’s trails and open spaces.


You can listen to stories like this every Friday morning at 7:10 a.m. on “The SCV Outdoor Report”, brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.

For the complete MRCA hike and activity schedule and for trail maps, click here or go to    

Or check out our Facebook page  – L.A. Mountains.




Source: Santa Clarita News

Santa Clarita Outdoor Report: 21-Second Rule

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