I'm aware that this is an old topic, but I'm reading here a some misleading information that I would like to clarify. Last weekend one my british show racer pigeon got killed and eaten by rats. During the night these pests dig a hole in the wooden cage and reached one of the females that was in the nest. So I went to search for more effective ways to deal with them and found this topic with some myths like the coca cola method that really seems some hoax spread by rat lovers.
I will use regular rat poison to deal with them in these poisoning stations: _ww.all-about-chickens.co.uk/killingrats.html
and also the method of leaving poison in their holes covered by a brick. I will also leave a water source reachable to the rats because they get thirsty after the poison and that way they won't drink in the birds water.
The spring traps are good but I can't put them near the holes in places were the chickens or cats/dogs might play.
Regarding the myths I found a study that might be usefull - MYTHOLOGY OF VERTEBRATE PEST CONTROL
Plaster/Cement and Rats
Boelter (1909) states that plaster of paris (calcium sulfate) mixed with sugar has long been recommended as a rat poison. This bait is placed near water. When the thirsty rat drinks, the plaster hardens in his intestinal tract and "literally stiffens him." Fitzwater (1990) fed caged rats (Rattus norvegicus) plaster of paris mixed 50% with their dry feed. He also fed a mixture of portland cement in the same ratio to a second set of rats. After 14 days on these diets, there was no mortality in either test and the animals appeared perfectly healthy except for sore rectums due to their large bowel movements. It is probably safe to assume the digestive fluids in the alimentary tract prevent these substances from hardening. Other suggestions along this line, such as dehydrated potatoes and bath sponge or cork pieces soaked in butter or bacon fat, can be presumed to be equally ineffective.
Carbonated Soft Drinks and Mice
Ingestion of carbonated drinks is supposed to cause mice to bloat up to the point of exploding. A university laboratory fed mice (Mus musculus) a liquid diet of a commercial cola for 8 days without any mortality. Once a bottle is opened it goes flat rapidly.
Electromagnetics
Devices claiming to put out an electromagnetic force capable of driving pest animals out of an area received great publicity a few years back (Fitzwater 1978). They supposedly drove out pest species, from aphids and cockroaches to coyotes and pocket gophers, with no effect on humans or domestic animals. While electromagnetic forces can change the behavior of animals, experimental support data are based on confined animals and higher intensities than is possible in the field units. The devices in use generate no more electromagnetic impulses than what is put out by a household refrigerator.
Ultrasonics
Sounds above the range of human hearing (over 20,000 Hz), as they can't be checked without special equipment, are difficult to evaluate. One such device is SAV-A-LIFE which, when mounted on the front bumper of an automobile going 45 mph or more, is supposed to send out a high-frequency sound alerting deer crossing the highway. Russell Reidinger (DWRC, pers. comm.) had this checked by A. L. Kolz. Using compressed air at different pressures, they concluded the device is no more complex than a whistle. The frequency was determined to be about 3,400 Hz, with no significant ultrasonic frequencies present. The amplitude was 65 dB at a distance of 6 feet, which is little better than a shout. There are also "ultrasonic" devices that reportedly repel birds. The author observed an unperturbed pigeon resting on a rafter within 3 feet of a commercial ultrasonic unit in an open barn. This is not exactly surprising as studies have shown the range of pigeon hearing to be between 200 and 7,500 Hz (Brand and Kellogg 1939). In a more specific test Woronecki (1988) was unable to repel pigeons from a vacant building after 20 days treatment with a commercial ultrasonic device. Some mammals we do know hear ultrasonic frequencies are bats and commensal rodents. Hill (1970) with highfrequency dog whistles (4,000 to 18,000 Hz) drove bats out of a building with 48 hours continuous play. Peterson (1974) found bats were initially disoriented and agitated when a commercial sonic device was turned on. However, by the end of the studies, counts showed no appreciable loss in numbers. There is considerable literature available on the use of ultrasonics to repel commensal rodents. While they may work under certain conditions, the cost/benefit ratio is questionable.
Mothball Repellencv
Mothballs (naphthalene) are registered repellents for bats, cats, dogs, house sparrows, pigeons, rabbits, starlings, and tree squirrels. Indoor use recommendations are 5 pounds per 2,000 cubic feet for attics, etc. (Fitzwater 1972b). Similarly PDB flakes (paradichlorobenzene) are registered as repellents for cats, dogs, ground squirrels, moles, pocket gophers, and Norway rats. The dog and cat registrations usually are combined with other chemicals and carry instructions that they need to be used with disciplinary action to reinforce the repellent effect. The efficacy data on these chemicals, despite a long history of use, are questionable. In test conditions naphthalene showed no repellency against (1) penned deer (Payne and Palmer 1985), (2) starlings in a nest box, though the naphthalene was well above the recommended concentrations for enclosed spaces (Dolbeer et al. 1988), or (3) bats exposed to direct sprays of 7% naphthalene or PDB...
