An Automatic Nest-Trap for Waterfowl

The results do not appear to be satisfactory, and implies the need for more controlled experiments and for more fundamental knowledge of the biology of the species.

Abstract

cartridges misfired, or 5 per cent of the total used. In total, 17 burrows required retreatment on the next or subsequent days. It may be noticed that on May 9th a fair number of burrows were treated which were missed on the previous day. Undoubtedly a few burrows were overlooked nevertheless. Twelve woodchucks were observed in the 100acre area from May 7 to 9. None were seen on the last day of treatment. On May 23 the 18.6-acre field was revisited, and four burrows were found to be opened up, two of which indicated recent burrowing activities of woodchucks. No woodchucks were sighted. Nine recently used burrow systems and one woodchuck were noticed on July 11, and eleven burrow systems were in use on July 23 (Fig. 2). This means that more than one-third of the burrows were opened up again. The field was plowed up immediately after July 23. A visit on September 26 disclosed that none of the burrows which had been plowed down were opened up. However, there were indications of possible use in three burrows situated along the fences. The three visits made after the control experiment was discontinued indicate relatively high woodchuck activity. There are two possible explanations for this: first, that a relatively rapid influx took place from the surrounding fields which were not controlled; and second, that a certain number of woodchucks survived treatment. This second alternative seems to us improbable. Considering the size of the area treated, we feel that it would not take the average woodchuck very much time to infiltrate into the center field. Whatever the causes for woodchuck activity during late May and July may be, the results do not appear to be satisfactory. This implies the need for more controlled experiments and for more fundamental knowledge of the biology of the species. In total, 40 man hours were spent on the project. Since an ordinary control operation requires only one man, and since a fourth visit, such as we made on May 10, may not be necessary under average conditions, we estimate that one man could have done the operation in about 24 hours. If the average farmer earns $1.00 per hour, this would amount to $24.00. One hundred and sixty-six cartridges, selling at $0.065 each, would cost $10.78. The total expenditure for the operation would therefore be about $34.78, or approximately $0.35 per acre. Considering the results obtained, it is doubtful that this investment is warranted except in areas of valuable truck crops, orchards, etc.