News Flash: I just now received the paper "An Evaluation of Breakaway Snares for Use in Coyote Control" [Phillips, R. L., F. S. Blom, and R. E. Johnson. 1990. An evaluation of breakaway snares for use in coyote control. Pages 255-259 in L. R. Davis and R. E. Marsh, eds., Proceedings Fourteenth Vertebrate Pest Conference
(March 6-8, 1990, Sacramento, CA)] These were the tests done at the Denver Wildlife Research Center in 1990. The only thing I had wrong was the diameter of the pipe. In the Denver test it was 3" not 2.4". I'll do some retesting at a later date.)
And "Evaluation of 3 Types of Snares for Capturing Coyotes" (Phillips, R. L. 1996. Evaluation of 3 types of snares for capturing coyotes. Wildlife Society Bulletin 24(1): 107-110). This field study was done 1992-1994.
Tom: "…those out there that would prefer to fashion their own equipment…"
Yes, there are folks who may want to be inventive. We don't want to stifle innovation. HOWEVER, Pennsylvania regulations require a "commercially produced" BAD. So PA trappers are not allowed to make their own BADs. (This regulation may be in the same vein as the Maximum Loop stop. Evidently the Pennsylvania Game Commission considers PA trappers too untrustworthy and too dumb to make these determinations.)
Mike: Actually the difference I quoted above was 1/64 of an inch not 1/32. That may be cause for glee in a lawyer, but those with a scientific background would be unimpressed. In this case 1/64" represents a 5% difference and it yields roughly a 5% difference in break away strength. Believe me, in this application, fractions of a millimeter make a difference. Thusly, you can come up with a range of BADs, of various strength"I realize DWRC tested some BADS years ago...but alot has changed since then."
Exactly what has changed? Coyotes are still coyotes, and deer are still deer. The main thing that has "changed" is that more and more states are allowing snares, and more and more states are requiring
BADs."Like discussion on how valid the testing procedure was!"
I've read that material. I can see no invalidity in the testing procedure. They hooked some coyotes, deer, and livestock up to a testing machine, via a snare cable, to see how much pressure they could exert. They used two different lengths 11 feet and 4.5 feet. Obviously there was less force with the 4.5' of cable. (FYI the figures for neck snared coyotes were 302 lbs and 192 lbs respectively).
The snares in question were tested for break away by cinching them around a 3" dia. steel pipe. While no mention is made giving a reason for this choice, I will assume that a 3" diameter is roughly representative of a coyote's neck.
The field component of this comes later (Phillips, R. L. 1996. Evaluation of 3 types of snares for capturing coyotes. Wildlife Society Bulletin 24(1): 107-110) Three snares were used. Tested by the above means their BA was: 118 kg (260 lbs), 123 kg (271 lbs) and 154 kg (339 lbs)
The "capture rate" for these devices was 89%, 97%, and 87% respectively. However
, the majority of the escapes were from "chew outs". As far as the BAD releasing the numbers are 11, 1 and 1, respectively. Now bear in mind there was no effort to set these snares I a non-lethal manner. You might consider the capture rate to be lower in a non-lethal application, because of more chew outs but not necessarily through release of the BAD.
As for leg snared deer, the release rate was approximately 73%, 100%, and 70% respectively. (Note: the 260 lb device with 100% release rate was the Amberg, but only 8 deer total were leg snared in that device.) Keep in mind that this study was done throughout
the year over a 2 year period, by people doing "control" work. While no mention is made, I think it is safe to assume that some of these deer were in fact fawns, and just not big enough to break out. There is a quote that says: "Phillips et al. (1990) demonstrated that coyotes and deer fawns (<34 kg) generate a similar force on the snare. Hence it will be difficult to design a breakaway system that holds all coyotes and releases all deer."
The "deer" in question here were western mule deer. For our purposes, fur trappers will primarily be using snares during the fall and winter, when "fawns" are not a great problem. Still, there can be some very small whitetail deer around during the fall. So, I basically agree with the quote above.
Where is the concern with this test?