Pandas Pandas come together for breeding only once a year, but are otherwise solitary animals in the wild. Ann Batdorf, Smithsonian's National Zoo

Billionaire private equity exec David Rubenstein, the co-founder of The Carlyle Group, recently compared lawmakers in Washington, D.C. working to resolve the "fiscal cliff" issue to pandas trying to mate. 

Rubenstein, who donated $4.5 million to the National Zoo's panda reproduction program last year, told The Atlantic at the Washington Ideas Forum last month that it's very difficult for pandas to reproduce.

The reason, the private equity tycoon explained, is that pandas can only mate four hours a day, one day a year.  In addition, female and male pandas live separately in captivity and in the wild.

"Well they get together in the appointed four hour period of time and they're very inexperienced.  If you only do this one day a year, you don't have experience.  So the parts don't often go where they're supposed to go." 

Rubenstein added that this often results in the pandas fighting and it just doesn't work out so well. 

"The point is that they know what they're supposed to do, they don't know how to do it and it's not unlike members of congress.  They know what they're supposed to do, they know they have to solve the fiscal cliff, they don't know quite how to do it.  Hopefully they'll get it resolved."