37 
weather, and when placed in muskegs where the water is close to the 
surface. He has also found that holes made with an 8-inch post-hole 
digger are satisfactory. The earth from the pit should be placed on either 
side of it. The mice will go to play on the sand piles or pass between them 
and fall in. Grain or oatmeal may be scattered about the pits, but this is 
not required if the pits are placed in the right place. If the animals are 
wanted alive it is well to place a tin can of meat and other food in the pits. 
Pits should always be visited the last thing at night and as early as 
possible in the morning. Mice may also be caught alive by tying a sheet 
of paper over a wide-mouthed jar or pail, and cutting two long slits in the 
paper, crossing at the middle. Crumbs or other bait are placed on top of 
the paper and the weight of the animal causes it to fall through. C. E. 
Johnson has seen a variation of this method used in Quebec, for catching 
rabbits. A keg or barrel with lid on a swivel hinge in the middle is buried 
in a snowdrift and a piece of cabbage suspended over the lid. He also 
notes a method of catching muskrats used at St. Thomas, Ontario, in which 
a keg with a small amount of water and some apples in the bottom is sunk 
with rocks until the top is near the water-level. 
Clarke (1938) describes a method of using “water-traps” that is 
inexpensive, and for some species, particularly shrews, jumping mice, etc., 
was strikingly more effective than the use of ordinary mouse traps. The 
water-trap is made by sinking a bucket, tub, or large tin in a hole dug in 
ground deeply enough to have the rim of the vessel below ground level. 
If the ground is high and dry the bucket must be tight and have its own 
water supply. In low sites holes may be punched in the bucket and w'ater 
allowed to seep in. The advantages of the water-trap may be listed: (1) 
means of collecting small mammals with a different selectivity from mouse 
traps; (2) trapping may be repeated, except in winter, under identical 
conditions; (3) no bait is required; (4) once established, a set runs itself; 
(5) if the weather is cool the hair of specimens is kept from slipping for 
some time; (6) no specimens damaged and no traps robbed; would-be rob- 
bers are themselves taken; (7) they may be used for moles and in other 
runways. The main disadvantages are in being cumbersome, and that the 
collector of ectoparasites can not be sure of his host records. Water-traps 
w r ere more efficient in certain situations, such as along streams. Dr. Clarke 
suggests that water-traps could be made in portable units, with the traps 
nested, a bottom on the outermost, and then every second or third trap 
bottomless. Those lacking bottoms could be set where there is a natural 
w r ater supply. The depth of metal in the trap need not exceed 1 foot. 
POISONING MAMMALS 
The use of poisons is not recommended for killing mammals for speci- 
mens. The animal often wanders away after taking the bait, and many 
are never found, or if found are usually spoiled. There is also danger of 
killing other harmless and useful mammals and birds. The only justifiable 
use of poisons is in control of injurious rodents such as ground squirrels, 
pocket gophers, etc., that are damaging crops, and possibly in some cases 
for certain species of predatory mammals. At the proper season and by 
exercising care poison may be used on infested farming areas without doing 
much damage to other forms of life, but the possibility of destroying 
