: 35 Bats and swallows have been used to monitor pesticide contamination due to their diet of insects that may have been affected by the chemicals. These include honey bees for air pollution, bivalve molluscs for online water-quality survey and pigeons for atmospheric lead. The bird's rapid breathing rate, small size, and high metabolism, compared to the miners, led birds in dangerous mines to succumb before the miners, thereby giving the miners time to take action.Ī number of animals have been used to measure varying kinds of air pollution. Toxic gases Ĭanaries were iconically used in coal mines to detect the presence of carbon monoxide. Thornburg shows a small cage with a canary used for testing carbon monoxide gas in 1928. Some species may show effects of a contaminant before humans due to their size, their reproductive rate, or their increased exposure to the contaminant. : 35 By the same token, aquatic animals, or their direct predators, are used as sentinel species to monitor water pollution. : 35 Similarly both bats and swallows have been used to monitor pesticide contamination due to their diet of insects that may have been affected by the chemicals. Often the ideal species is determined by the characteristics of the hazard.įor example, honey bees are susceptible to air pollution. It is important that the species' range overlap with the range being studied. : 34 Many of these species are ideally unendangered and easy to handle. Yushō disease was discovered when poultry began dying at alarming rates due to polychlorinated biphenyl (BCP) poisoning, although not before approximately 14,000 people were affected.Īnimal sentinels must have measurable responses to the hazard in question, whether that is due to the animal's death, disappearance, or some other determinable aspect. Studies similarly found higher disease rates in animals exposed to tobacco smoke. Dogs ĭogs were recognized as early as 1939 to be more susceptible to tonsil cancer if they were kept in crowded urban environments. In Minamata Bay, Japan, cats developed ' dancing cat fever' before humans were affected due to eating mercury-contaminated fish. 'Canary in the coal mine' is now used as an idiom for a person or thing that warns people of danger. In some cases, the canaries were kept in cages with dedicated oxygen tanks so the birds could survive after their illness provided a warning. The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective respirators. Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide. Countries such as Britain, the United States, and Canada used canaries as a sentinel species.

The idea of placing a warm-blooded animal in a mine to detect carbon monoxide was first proposed by John Scott Haldane in 1895, and canaries were used as early as 1896.

The classic example is the ' canary in the coal mine'. Many observations of animals point to toxicity in food, water or air that would or could harm humans. Depiction of a miner with a canary in a cage

Canari bird