Now a chicken ain't nothing but a bird and birds have been used for sentinel duty for many years. You have sentinel canaries in the deep coal mines, birds who would alert the miners to the presence of invisible and deadly levels of CO2 or other gasses by falling off of there perches. I'm not totally sure these lovely songsters perished or if they could be revived. I do know, however, many human lives were spared and since canaries cant dig coal, the trade off was a plus for mankind and any other animals who had the benefit of a warm and bright place to weather the elements. Then we have sentinel geese. These boisterous flocks were turned out at night to alert the small hamlet or farm if a stranger might appear i.e. a chicken thief. That gray honker, the barnyard goose, is perfect for the job while a duck would be too small and your Canadian Goose proper don't march around in flocks or have the reputation for meanness necessary for this gig. I've heard that swans can be right nasty too, but I think a slick crook could tie the bunch up by the neck and effectively put them out of commission. So the Sentinel Chicken? Well her job is unique in that she just hangs about waiting for a skeeter to bite. That's it and she doesn't have to kick up a ruckus about it either. Nope, she just goes n about her business of scratching and pecking, laying and even brooding. Then every so often a person will come along and take a blood sample and they check that out for signs of various insect born disease. Like what? Well, West Nile Virus and St. Louis Encephalitis and Western Equine Encephalitis are three big time diseases that can lay humans down and if the chickens are bitten by mosquito carriers their blood will show anti bodies and that will cause the local health department to take action. Such as? OK, they might step up mosquito control and maybe get some airplane spraying going, that sort of thing. And the chickens? The sentinel chickens are an important part of disease prevention and control and as such are treated very well. They are happy hens hardly ever harvested for the human hearth. Sentinel chickens! Animals on the job salutes you and hopes that you fare well.