Why "Yellow Canary"?
Sensitive to noxious gases such as carbon monoxide, the yellow canaries were used as organic "early-warning" devices to detect gases that are colorless, odorless and tasteless.
Gases were easily formed underground during a mine fire or after an explosion. It was important that those going back into the mines had a way to detect any noxious gases. Although mice were also used, yellow canaries were more sensitive and the canaries' distress was more readily observable to the miners.
A canary would waver on its perch at the first sign of danger - and - lose consciousness and drop to the bottom of their cages before the levels of toxins in the air affected the miners. If the canary hit the deck, the miners hit the exits.
Once electronic gauges were developed to measure levels of these gases, the use of the canaries stopped. (Mostly because, over time, the electronic devices proved to be cheaper.
Over time, to call someone or something a "yellow canary" took on a wider meaning. To be a "yellow canary" a "canary in a cage" or a "canary in the mine" meant being an "early-warner". Certainly, the use of the concept is apt when used in conjunction with the field of environmental pollution of any kind. In a wider interpertation, being a "yellow canary" is to be sensitive to changes in the environment, to be aware of and affected by dangerous elements wherever and however they exist.
About Canaries as Harbingers of Danger
Creatures as Sentinels of Dangerous Environments
Canary Database: Aims to overcome scientific barriers which limit the use of animal sentinel data for early recognition of human environmental health hazards. These barriers include difficulty in locating animal sentinel studies in current biomedical databases and a lack of communication between human health and animal health professionals. The Canary Database will overcome such barriers by making the scientific literature on animals as sentinels of human environmental hazards more accessible in a single location.
Conservation Medicine Consortium: The Consortium for Conservation Medicine is a unique collaborative institution that strives to understand the link between anthropogenic environmental change, the health of all species, and the conservation of biodiversity.
Federation of American Scientists policy initiative calling for global monitoring of emerging diseases.
USGS National Wildlife Health Center: The National Wildlife Health Center is one of eighteen science and technology centers in the Biological Resources Division (BRD) of the U.S.
Geological Survey, a bureau of the Department of the Interior. The NWHC was established in 1975 as a biomedical laboratory dedicated to assessing the impact of disease on wildlife and to identifying the role of various pathogens in contributing to wildlife losses.
Wildlife Disease Information Node: The Wildlife Disease Information Node is a Web-based monitoring and information system, providing state and federal resource managers, animal disease specialists, veterinary diagnostic laboratories, physicians, public
health workers, educators, and the general public with access to near real-time data in wildlife mortality events and other critical related information.
WildPro: WildPro is an electronic encyclopedia and library providing information on the natural history, health and management of captive and free-ranging wild animals.