Good Biosecurity can be the difference between life and death for your birds if you or your flock ever come in contact with a contagious pathogen potentially infecting your flock.
A little background on WHY it's important, and HOW it can help you:
About a decade ago when Exotic Newcastle Disease (END) swept across California, backyard flocks and pets (including parrots, finches & more) were completely depopulated (killed) in an effort to stop the harmful spread of disease.
Out of this experience, two of the national avian groups (American Federation of Aviculuture and Aviculutural Society of America) both helped to enact legislature to protect bird owners against future depopulations if another outbreak of similar nature should happen.
Sure enough, Virulent Newcastle Diseased (VND) reared its ugly head and put a dampener on many businesses, hobbyists and owners, BUT this time there wasn't the same mass depopulations at private homes like there had been before. Why?
Two reasons; the first was the state had new ways and legislature in effect for how to deal with testing and actions. The second is people who practiced EXCELLENT biosecurity stood a far greater chance of protecting their birds.
Now, granted, not everyone has to prepare their biosecurity set-up with Newcastle in mind, but some everyday practices can be easily implemented into your everyday routine and poultry keeping practices.