Chronic mercuric chloride: Behavioral effects in pigeons

The effects of daily doses (1, 3, 10 mg/kg, im) of mercuric chloride were studied in pigeons responding under multiple fixed-ratio, fixed-interval schedules of food presentation. The effects also were studied in pigeons responding under a multiple fixed-ratio schedule which had several intensities of a visual stimulus controlling the performance and under a repeated acquisition schedule which required the pigeon to learn a different four-step, three-position sequence every test day. Across all test conditions, the daily doses of 1 mg/kg produced some increases in the variability of the rates of responding, but no consistent decreases. Daily doses of 3 and 10 mg/kg reliably decreased responding, and these decreases disappeared gradually after daily dosing was discontinued. Daily 10 mg/kg doses in three birds which were not being tested killed two birds after 17 and 28 injections, but the third bird survived 60 injections.