Killing Traps and Snares in North America: The Need for Stricter Checking Time Periods

Simple Summary In this review, we make the point that current checking times for killing traps and snares are inadequate or nonexistent in most North American jurisdictions. We use Conibear 120 rotating-jaw traps and killing neck snares as examples of trapping devices that may fail to consistently and humanely kill furbearers. Because these killing devices are not powerful enough for the target species, the trigger systems do not properly position the animals in traps, or trappers are inexperienced and improperly set traps or snares, these killing devices become restraining devices, and animals suffer long and painful deaths. Because trappers use a variety of trigger configurations and trap sets, all killing devices, even those certified by trapper organizations or governments, should be monitored at least once every 24 h on traplines, but preferably every 12 h, because one cannot know a priori whether traps will strike animals in appropriate locations for a quick kill. However, when using trapping devices such as killing neck snares that are legal and allowed by government agencies despite being inhumane, trappers should check them every 12 h. When traplines are situated near urban areas, e.g., within 10 km, checks should be done every 12 h to release pets and non-target animals. Abstract In this review, we make the point that current checking times for killing traps and snares are inadequate or nonexistent in most North American jurisdictions. We use Conibear 120 rotating-jaw traps and killing neck snares as examples of trapping devices that may fail to consistently and humanely kill furbearers. Because these killing devices are not powerful enough for the target species, the trigger systems do not properly position the animals in traps, or trappers are inexperienced and improperly set traps or snares, these killing devices become restraining devices, and animals suffer long and painful deaths. Because trappers use a variety of trigger configurations and trap sets, all killing devices, even those certified by trapper organizations or governments, should be monitored at least once every 24 h on traplines, but preferably every 12 h, because one cannot know a priori whether traps will strike animals in appropriate locations for a quick kill. However, when using trapping devices such as killing neck snares that are legal and allowed by government agencies despite being inhumane, trappers should check them every 12 h. When traplines are situated near urban areas, e.g., within 10 km, checks should be done every 12 h to release pets and non-target animals.


Introduction
Since 1995, organized efforts to reform animal trapping were aimed primarily at reducing cruelty to animals, particularly by outlawing the steel-jawed leghold trap [1]. In the last 40 years, however,

Checking Times of Kill Traps and Snares in North American Jurisdictions
We consulted the trapping regulations of Canadian Provinces and Territories, and of American States, to determine checking times for killing traps and killing neck (body) snares (Appendix A). These regulations are subject to revision from year to year. At time of writing, in Canada, there are no legal requirements to check killing traps and snares in most Provinces and Territories (Appendix A). In nearly 35% of American jurisdictions, checking times for killing traps and snares exceed 24 h. In approximately 55% of American States, checking times for submersed killing devices exceed 36 h (Appendix A). In both countries, checking times for killing traps and snares often are longer than those of restraining traps which usually are 24 h (Appendix A).

Animals Restrained in Killing Traps and Snares: Three Case Studies
Killing traps and snares do not always kill animals quickly. Animals that are being restrained in such trapping devices may take hours or even days to die depending on the trapping device, the capture location, the physical condition of the animals, and the environmental conditions. In the following, we review examples of traps and snares that have been found to be ineffective to consistently kill animals humanely, even though they are either "AIHTS-certified" as being humane for some species in Canada or considered in Best Management Practices (BMPs) in the United States. BMPs are educational guides designed to address animal welfare and increase trappers' efficiency and selectivity.

The Conibear 120 Rotating-Jaw (Bodygrip) Trap Model to Kill Marten
According to AIHTS [3], a killing trap would meet the standards if 80% of 12 tested animals are unconscious and insensible within a pre-determined time limit (e.g., 2 min for small mammals like martens), and remain in this state until death. This means that, on the basis of the normal approximation to the binomial distribution (one-tailed test) [11], a humane trap would, with 95% confidence, render ≥58% of captured animals irreversibly unconscious within the prescribed time limit.
The Conibear 120 trap (Woodstream Corp., Lititz, PA, USA; Figure 1) is the most commonly used trap to harvest American martens (Martes americana) in North America [7]. It is not certified as humane for marten in Canada [12], but is part of the USA BMPs [13].
Animals 2019, 9, x FOR PEER REVIEW 4 of 16 120 trap models may be, if they are equipped with two-prong triggers, improperly struck martens risk suffering for long periods of time.  The impact and clamping energies of this trap are lower than the kill threshold standards of the Canadian General Standards Board (CGSB) for American martens [14] where animals must be rendered irreversibly unconscious in ≤3 min. Mechanical evaluations showed that the Conibear 120 trap does not have the potential to render animals unconscious in ≤3 min [15] and thus to meet AIHTS' 2-min time limit. This was further demonstrated in tests with wild animals in simulated natural environments [7] where 2 out of 6 tested animals did not lose consciousness within 5 min (the time limit was 3 min but the research protocol allowed researchers to prolong it to 5 min to learn more about traps). This result suggests that, based on the normal approximation to the binomial distribution (one-tailed) [11], the Conibear 120 trap would then be expected to humanely kill (by rendering animals unconscious in ≤3 min as per CGSB), with 95% confidence, >20% of all captured martens of a true population. The poor performance of the Conibear 120 trap to humanely kill martens was further determined on working traplines [9]. At least 4 out of 13 martens captured in Conibear 120 traps were struck in non-lethal regions that would not result in a loss of consciousness in ≤3 min. Thus, on the basis of a one-tailed binomial test, the trap would, with 95% confidence, render <40% of captured martens unconscious in ≤3 min.
The Conibear 120 trap is still available on the market; it can be purchased at trapper supply stores and through the internet, and it is commonly encountered on traplines (Proulx, unpublished observations), simply because traplines are not being monitored by Conservation Officers, and standards are not being enforced. The inability of the Conibear 120 trap to humanely kill American martens led to the development of the more powerful, humane C120 Magnum [16] (Figure 1). Since then, a series of mechanically improved Conibear 120 trap models have also been developed and certified as humane by the Fur Institute of Canada [12].
All old and new Conibear 120 trap models are sold with a two-prong trigger; the tins of the trigger can be bent and shaped different ways to allow martens to enter the trap, and fire the trigger while attempting to reach a bait placed behind the striking bars. However, martens may bypass the prongs, and go far into the trap before firing the trigger, which results in strikes in non-lethal regions that do not cause an irreversible loss of consciousness in ≤3 min [9] (Figure 2). When animals are captured by the abdomen or legs, they do not die quickly, and killing Conibear 120 traps then become restraining traps. Animals stay alive and commonly die from exposure many hours after capture. Conibear 120 trap models should be equipped with a pitchfork trigger [16] (Figure 1) to ensure that martens are consistently struck in vital regions and die quickly. No matter how powerful Conibear 120 trap models may be, if they are equipped with two-prong triggers, improperly struck martens risk suffering for long periods of time.
Animals 2019, 9, x FOR PEER REVIEW 4 of 16 120 trap models may be, if they are equipped with two-prong triggers, improperly struck martens risk suffering for long periods of time.  In North America, at least 100,000 martens are trapped every year [17,18], but the number of captures may vary from year to year depending on pelt price. The number of martens captured in In North America, at least 100,000 martens are trapped every year [17,18], but the number of captures may vary from year to year depending on pelt price. The number of martens captured in the Conibear 120 traps is unknown, but due to the popularity of the trap model, it certainly amounts to several thousands of animals. If at least 30% of martens captured in Conibear 120 traps were struck in non-lethal regions [9], then a very large number of martens would likely experience pain and suffering for periods of time exceeding AIHTs' time limit of 2 min.

The Conibear 120 Trap Model to Kill Mink (Neovison vison)
There are no certified traps for mink in Canada [9] but the Conibear 120 rotating-jaw trap is most popular among trappers. In the USA, the Conibear 120 trap is recommended in BMPs for trapping mink, and neck strikes are identified as proper strike locations [19]. However, as we explained above, the Conibear 120 trap cannot consistently and humanely kill American martens. Mink have a greater cervical musculature and stronger bones than American martens [20], and cannot be humanely killed, i.e., lose consciousness in ≤3 min as per CGSB, by the Conibear 120 trap. In fact, even the mechanically superior and stronger C120 Magnum failed to humanely kill mink captured by the neck [21]. Furthermore, while the Conibear 120 trap is marketed with a two-prong trigger, its inability to properly strike mink in vital regions was reported nearly 50 years ago [22].
The stronger C120 Magnum trap equipped with a pan trigger humanely killed mink double-struck in the neck and thorax [21]. Because the two-prong trigger fails to ensure strikes in vital regions, and the Conibear 120 trap does not have the striking and clamping forces to produce a humane kill, many mink captured in this trap stay alive for many hours, and sometimes until the following day (Rodtka, unpublished data). Thousands of mink are trapped every year in North America [17,18], and many of those captured in the Conibear 120 trap must experience pain and suffering for periods of time exceeding AIHTs' time limit of 5 min.

Killing Neck Snares for Wild Canids
Killing neck snares are killing devices where the animals, or one or two springs, provide the energy necessary to tighten the noose. These are the most popular kill trapping devices used by trappers because they are cheap, lightweight, easy to set and camouflage, and are efficient at capturing a diversity of furbearers [10]. They are popular in Canada where they are set on traplines to harvest canids, i.e., gray wolves (Canis lupus), coyotes (Canis latrans) and red foxes (Vulpes vulpes) [2,23,24]. Although killing neck snares were originally considered for inclusion in ISO standards [25], which required that snares render captured animals unconscious within 5 min, these trapping devices are not covered under AIHTS [3]. A footnote to Article 7 of the Agreement stipulates that the standards do not prevent individuals from constructing and using traps (which may not pass AIHTS' time limit test), provided that such traps comply with designs approved by the relevant competent authority. Although killing neck snares are commercially manufactured and sold on the open market [10], they are deemed by competent authority to be non-commercial devices. Certified or not, killing neck snares do not have the ability to quickly and humanely render canids unconscious [26]. Less than 50% of canids captured by the neck in killing neck snares lose consciousness within 300 s [8,27]; death may come after hours or days [28], depending on the killing efficacy of the snare and the frequency of visits by trappers [8,26]. Trail video-cameras set on a working trapline showed that one neck-captured coyote and one wolf lost consciousness after 14 h 16 min and 3 h 39 min of repeated escape attempts, respectively [10] (Figure 3). These videos confirmed years of research showing that killing neck snares do not have the ability to quickly and humanely kill canids [8,26,27]. Although neck snares are sold as devices that are intended to kill, they behave like restraining trapping devices.
More than 100,000 red foxes, coyotes, and wolves are trapped every year in Canada [18], mostly in killing neck snares [10]. Thousands more are snared in the United States [17]. In a previous study of 65 snared coyotes, 59% were neck catches, 20% flank, and 10% foot [29]. Also, nearly half of the animals were alive the morning after being snared. Another study also reported that 5% to 32% of animals captured in various killing neck snare models were still alive when found [28]. While it is best to snare canids behind the jaw where the carotid artery and the trachea are maximally exposed [26], snare location on an animal is influenced by many factors such as the behaviour of the animal when entering the loop [8], snare height and loop diameter, positioning of the lock, preload on the loop (i.e., a little tension is put into the loop to force it to close quicker), and environmental and maintenance factors (rust, twists in the snare cable, snowfall), etc. [26]. Not surprisingly, the percentage of animals found alive in killing neck snares is relatively high [10]. Canids kept alive in killing neck snares die hours or days after being captured, with injuries akin to those recorded with steel-jawed leghold traps [30].
Animals 2019, 9, x FOR PEER REVIEW 6 of 16 when entering the loop [8], snare height and loop diameter, positioning of the lock, preload on the loop (i.e., a little tension is put into the loop to force it to close quicker), and environmental and maintenance factors (rust, twists in the snare cable, snowfall), etc. [26]. Not surprisingly, the percentage of animals found alive in killing neck snares is relatively high [10]. Canids kept alive in killing neck snares die hours or days after being captured, with injuries akin to those recorded with steel-jawed leghold traps [30]. Finally, snared animals may break the snare lock or chew through the cable if the lock does not tighten sufficiently to cause death [28,30]. The likeliness of an escape increases with the length of time an animal is restrained in the killing snare. A 2-year-old male coyote was found in a moribund state on Prince Edward Island, one month after the official end of the trapping season, with a snare deeply embedded in the ventral portion of its neck [31]. Two wolves that had been snared outside Denali National Park and Preserve, Alaska, and had then escaped with the tightened loops around their necks, were spotted by park staff a few days before one of them was immobilized with a tranquilizer dart [32]. The snare was deeply embedded in the wolf's neck. In both cases, such escapes and injuries could have possibly been avoided with relatively short check time periods [10].

Stricter Checking Times Are Needed for Killing Traps and Snares
On the basis of past research work, we believe that Conibear 120 traps with two-prong triggers and killing neck snares should be banned altogether [2,26]. However, all killing traps, even those that have been certified as being humane [12], should be monitored frequently because environmental conditions and trappers' modifications can impact on their killing performance, and one cannot guarantee that all animals will be struck in appropriate locations for a quick kill [2]. Even with certified traps, some animals will not lose consciousness within AIHTS' time limits and may suffer for long periods of time. When traplines are too long for frequent trap visits, they should be subdivided into smaller sections. Trappers would then be able to check their traps every 24 h, e.g., at sunrise, or even more often. However, when using trapping devices such as killing neck snares that are not considered to be humane by experts who assessed them [26,27,30] but are still being allowed by government agencies, trappers should check them every 12 h. Most carnivores are nocturnal or crepuscular, and the chances to find animals still alive in killing neck snares are greater at dusk and dawn. For example, in Proulx's video recordings [10], a coyote snared at 11:50 h could have been killed humanely at 17:00 h the same day (trap visit at dusk), instead of 09:00 h the following day (trap visit at dawn, 24 h later). Finally, snared animals may break the snare lock or chew through the cable if the lock does not tighten sufficiently to cause death [28,30]. The likeliness of an escape increases with the length of time an animal is restrained in the killing snare. A 2-year-old male coyote was found in a moribund state on Prince Edward Island, one month after the official end of the trapping season, with a snare deeply embedded in the ventral portion of its neck [31]. Two wolves that had been snared outside Denali National Park and Preserve, Alaska, and had then escaped with the tightened loops around their necks, were spotted by park staff a few days before one of them was immobilized with a tranquilizer dart [32]. The snare was deeply embedded in the wolf's neck. In both cases, such escapes and injuries could have possibly been avoided with relatively short check time periods [10].

Stricter Checking Times Are Needed for Killing Traps and Snares
On the basis of past research work, we believe that Conibear 120 traps with two-prong triggers and killing neck snares should be banned altogether [2,26]. However, all killing traps, even those that have been certified as being humane [12], should be monitored frequently because environmental conditions and trappers' modifications can impact on their killing performance, and one cannot guarantee that all animals will be struck in appropriate locations for a quick kill [2]. Even with certified traps, some animals will not lose consciousness within AIHTS' time limits and may suffer for long periods of time. When traplines are too long for frequent trap visits, they should be subdivided into smaller sections. Trappers would then be able to check their traps every 24 h, e.g., at sunrise, or even more often. However, when using trapping devices such as killing neck snares that are not considered to be humane by experts who assessed them [26,27,30] but are still being allowed by government agencies, trappers should check them every 12 h. Most carnivores are nocturnal or crepuscular, and the chances to find animals still alive in killing neck snares are greater at dusk and dawn. For example, in Proulx's video recordings [10], a coyote snared at 11:50 h could have been killed humanely at 17:00 h the same day (trap visit at dusk), instead of 09:00 h the following day (trap visit at dawn, 24 h later).
When traplines are situated near urban areas, checks should be done every 12 h to release pets and non-target animals. In suburban areas, if traps cannot be checked easily, they should be equipped with a monitor [33][34][35][36] that allows false positives but not false negatives, and that notifies a trapper when battery power is low or when a trap has misfired [37].
Our recommendation to frequently check, preferentially every 12 h, killing traps and snares which act like restraining traps is in line with other scientists who recommended that live-holding devices be checked at least daily or more frequently depending upon target species, the potential for capture of nontarget species, and environmental conditions [38]. It is also in agreement with recommendations for the humane and efficient capture of carnivores [2]. Checking traps within a 24-h period on traplines, and within 12 h in urban and sub-urban areas or when using legal but inhumane trapping devices, would minimize pain and discomfort of animals kept alive in killing devices. It would also be advantageous to trappers as it allows them to retrieve captured animals before they are scavenged upon by animals, maintain trap sets that may have been disturbed by animals that avoided capture or by weather conditions, release non-target animals that have not suffered serious injuries during capture, or humanely kill those that are too badly injured to be released.
The concept of humane trapping involves more than just developing devices that meet standards. It also entails changes on how trappers carry out their activities. Shortening trap check times, and using only trapping devices that can consistently and humanely kill animals, would significantly minimize injuries, pain and suffering of trapped animals.
Author Contributions: G.P. and D.R. were involved in the writing of the paper. G.P. reviewed Canadian and American trapping regulations, and did corrections in the revised paper.
Funding: This research received no external funding.

Acknowledgments:
We thank Editor Sandra Baker and three anonymous referees for their helpful comments on an earlier version of this manuscript.

Conflicts of Interest:
The authors declare no conflicts of interest.  Page 25-All animals or animal carcasses caught in any type of trap or snare, except those that are placed entirely under water and designed to drown the animal immediately, must be removed from the trap or snare by the trap or snare user immediately upon discovery and within 24 h of the time the animal is caught. Mechanically powered snares are prohibited. All traps set in organized towns must be tended daily, except for killer-type traps, drowning sets, and under-ice drowning sets. Each killer-type trap or drowning set, except under-ice drowning sets, in organized towns must be tended at least once every three calendar days except if the drowning set is within 1 2 mile of the built up section of town, then it must be checked every 24 h. All traps set in unorganized towns must be tended daily, except for killer-type traps, drowning sets, and under-ice drowning sets. Each killer-type trap or drowning set, except under-ice drowning sets, in unorganized towns must be tended at least once in every 5 calendar days. During November, December, March and April if a drowning set is under-ice there will be no tending requirement. However, if a trap set is in open water the trap tending requirements are:    (a) All leg-hold traps and live traps shall be checked by the owner a minimum of once during each seventy-two (72) h period. (b) All snares and quick-kill body-grip traps shall be checked by the owner a minimum of one time each week, except during the initial week the snares or quick-kill bodygrip traps were set.

Appendix A
* Daily: the checking period could exceed 24 h if a kill trap/snare was set or checked on a morning of one day and rechecked in the afternoon or evening of the following day. ** Once per week: the checking period could be as long as 13 days if a kill trap/snare was set or checked on a Monday of one week and rechecked on the Sunday of the next week.