Egg Production Decreasing

My girls all appear to be healthy.  They eat a good, nutritionally balanced diet and have plenty of water available.  There are no obvious stressors.  But shorter days and advancing age are contributing to a decrease in the number of eggs I collect.

 After two or three years, many hens naturally decline in productivity.  Typically, hens will lay efficiently for two laying cycles.  This is the third laying season for the "charter members" of our small flock, and that includes everyone but First Lady!  I've also noticed more thin-shelled eggs, a problem associated with older hens.

The days are short between October and February.  Hens require 14 hours of day length to sustain egg production. Once day length drops below 12 hours, egg production will naturally decrease and frequently stop.   Last year, egg production went down to nothing in the first couple weeks of January, then promptly picked up again in February.  I could provide artificial light to extend the short days, but I've never set that up.  Maybe the chickens deserve a vacation.