Proceedings of the Vertebrate Pest Conference

Performance of three models of sodium cyanide (NaCN) ejectors was evaluated at Port O'Connor, Texas, early in 1982. M-44s, M-50s, and coyote getters were test-pulled and reset at 7-day or 21-day intervals for 42 days. Each pull was recorded as good if, in our judgment, it would have taken a coyote. Based on 402 to 430 test pulls of each ejector model, the percentages of good pulls were 40% for M-50s, 73% for M-44s, and 99% for coyote getters. M-44s with shortened plungers performed better than standard M-44s. Most pulls of M-50s resulted in ejection failure due to corrosion between the plunger and ejector body. The greatest problems with M-44s were mechanical defects, particularly of triggers, and caking of NaCN in the capsules. Condition of NaCN was evaluated in 1,354 M-44 capsules that had been weathered for one to six weeks. Eighty-five percent contained normal, dry powder after one week and only 49% were normal after six weeks' exposure. Addition of a beeswax seal decreased capsule deterioration. Based on these results, we recommended that the Service discontinue the M-50 and concentrate on improving the M-44. The Service's Pocatello Supply Depot has shortened the M-44 plunger and added a beeswax seal to M-44 capsules made for use by the Animal Damage Control program.