Human Health and Ecological Risk Assessment

for the Use of Wildlife Damage Management Methods

by USDA-APHIS-Wildlife Services

Chapter III

USE OF CABLE DEVICES

IN WILDLIFE DAMAGE MANAGEMENT

May 2017

Peer Reviewed Final

September 2019
i

THE USE OF CABLE DEVICES IN WILDLIFE DAMAGE MANAGEMENT

EXECUTIVE SUMMARY

Snares and cable restraints such as neck snares, foot cable restraints, foot-nooses, and catch-poles, 

collectively termed cable devices, are used by USDA-APHIS-Wildlife Services (WS) Program for specific 

wildlife damage management projects, mostly involving wildlife that are causing damage to property, 

agriculture, and natural resources or protecting human health and safety. Implementation of WS-specific 

measures designed to reduce human interactions with cable devices reduces the risk of these types of 

management tools to the public and workers, and WS will continue to evaluate and implement, where 

appropriate, new protection measures. Advancements in cable device use and design have resulted in more 

effective and humane capture of target animals while reducing the potential for nontarget species captures. 

In fact, nontarget capture by WS has decreased over the last 25 years. For example, the use of break-away 

cable devices, stops, and exclosure cages for neck snares and consistent use of pan tension devices for foot 

cable restraints has reduced nontarget captures in cable devices by WS. The annual average target take of 

individual animals with cable devices by WS from FY11 to FY15 increased about five-fold over the annual 

target take in FY88 indicating that cable devices are being used more, which mirrors the reduced use of 

foothold traps and other devices over the 25-year period. During the same time, the take of nontarget species 

has decreased, which reflects the fact that cable devices are more selective. WS will continue to support and 

conduct research and education that supports more humane and effective cable device methods and will 

implement these measures in programs, where appropriate, to further reduce risk to nontarget animals.

Overall, the evaluation of risks to human health and safety and the environment from the use of cable devices 

are minimal. WS personnel are professional with their use of cable devices and try to minimize the identified 

potential risks. The issue of humaneness is minimized by WS using the Best Management Practices as 

guidelines for cable devices (AFWA 2017).

TABLE OF CONTENTS

1 INTRODUCTION...........................................................................................................................................................1

1.1 Use Pattern ........................................................................................................................................................5

2 HAZARDS ....................................................................................................................................................................9

2.1 Human Health and Safety ..................................................................................................................................9

2.2 Environmental ...................................................................................................................................................9

3 RISKS........................................................................................................................................................................12

3.1 Human Health and Safety ................................................................................................................................12

3.2 Environmental .................................................................................................................................................15

4 UNCERTAINTIES AND CUMULATIVE EFFECTS..........................................................................................................15

5 SUMMARY ................................................................................................................................................................15

6 LITERATURE CITED...................................................................................................................................................16

7 PREPARERS..............................................................................................................................................................18

7.1 WS Methods Risk Assessment Committee .....................................................................................................18

7.2 Internal Reviewers ..........................................................................................................................................19

7.3 Peer Reviewers ...............................................................................................................................................19

7.3.1 Peer Reviewers Selected by the Association of Fish and Wildlife Agencies ...........................................20

7.3.2 Comments............................................................................................................................................20

Appendix 1. “Other Species” Included in Tables ...........................................................................................................22
1

1 INTRODUCTION

Cable devices including snares, cable restraints, foot nooses, and catch poles are used by the United States 

Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Wildlife Services 

(WS) Program for specific wildlife damage management (WDM) projects, mostly involving wildlife that are 

causing damage to property, agriculture, and natural resources or protecting human health and safety. Cable 

devices1

, or snares, cable restraints, and foot nooses for this document, are typically made of wire, cable, or 

monofilament line consisting of a loop, which would be positioned to close around the neck, torso, leg, or 

foot of a target animal as the animal moves through the loop or the loop is thrown and tightened with a springloaded throw-arm. A neck snare may be placed in a vertical position to capture an animal as it passes through 

the loop (Figure 1) or a foot cable restraint may be used horizontally with a trigger and spring activated throwarm to capture the animal by the foot or leg when it steps in the loop (Figures 2, 3, and 4). With monofilament 

line, many loops are set on traps or mats to capture the animal, generally birds, by the foot (Figures 5 and 6).

When an animal moves forward into a loop formed by the cable or monofilament line, it tightens and the 

animal is held. Catch poles, which are used by WS and a cable restraint, are not discussed in this document.1

Cable devices may be used as lethal (snare) or livecapture (cable restraint) devices depending on how 

or where they are used. Snares are typically set to 

close around the neck of an animal (Figure 1) and are 

usually intended to be a lethal method, whereas cable 

restraints are set and positioned to capture the 

animal around the leg or foot and intended to livecapture the animal (Figures 2, 3, and 4). 

Monofilament line traps (e.g., bal-chatri and noose 

mats), which are live-capture devices, are used to 

snare the foot or feet of a bird and usually placed so 

that they alight on the ground without injuring 

themselves (Figures 5 and 6). Terms and illustrations 

of the different parts of a cable device as well as sets 

can be found in Olson and Tischaefer (2004), but are 

generally depicted in Figure 2. Cable devices are also 

placed so that the animal, especially if it is to be livecaptured, does not become entangled into an 

exposed root, woody vegetation, or post within reach 

of the animal that is on an extended cable;

entanglement with an item usually larger than a half 

 1 Cable devices (snares, cable restraints, and foot nooses) in this document refers to any type of loop meant to be tightened around an animal 

whether it is a standard neck snare, foot cable restraint, or foot noose (animal moves through and tightens loop) or a mechanical neck or foot cable 

restraint that is spring-activated (the loop is thrown up around the head or limb). A cable restraint that is actively placed by a person around the 

animal (catch pole) is not discussed in this document, but in “The Use of Hand Capture and Disease Sampling in Wildlife Damage Management” 

risk assessment because animals are close at hand to use them. A cable device is a type of capture device that uses a loop of wire, stranded wire, or 

wire rope designed and set to close around the neck, torso, foot or leg of an animal. In the 1990s, it more often is associated with a cable device 

that is set with the intention of being lethal (i.e., snare). Cable restraint is a term used for those devices meant to live-capture an animal. In this 

document, we use the terms more interchangeably because the same device can often be used as a lethal or live-capture device depending on the 

species being targeted or by slightly modifying the device (e.g., addition of a stop) or set. The WS Management Information System (MIS) does 

not differentiate between cable restraints and snares, and has always combined the two categories under the term “snares.” Thus, WS does not 

differentiate whether a snare or cable restraint was set. Snare is the more common term for cable devices used to capture animals. For this document, 

we try to use the most appropriate term, but realize that it may not be possible. 

Figure 1. A mountain lion neck snare made with 3/32” cable 

with a cage to exclude nontarget animal such as bighorn 

sheep and deer. 
2

inch in diameter can result in injuries, 

which can be inhumane (Olson and 

Tischaefer 2004) and result in the loss of a 

target animal because it may be able to 

apply pressure to the cable to break it or

cause the swivel not to work. Thus, the 

area around the set is surveyed to 

determine if entanglement could occur and 

to minimize the opportunity for such 

events. 

On standard cable devices, J-locks (Figure 

2), relaxing locks, or snare locks (Figure 1) 

are used to maintain the loop and to 

prevent the loop from opening again once 

the loop has closed around an animal. The 

lock tightens as it is pulled and is

stationary or relaxed when no tension is on 

it. Most cable devices are also equipped 

with a swivel(s) to minimize twisting and 

breakage of the cable as well as minimize 

injuries to captured animals (Figure 2); 

foot nooses do not typically have any form 

of swivel. Other additions can be made to 

improve the selectivity of cable devices 

and minimize the capture of nontarget 

species. Loop size and placement are 

strategies often used to reduce capture of 

nontarget animals (Phillips 1996); 

breakaway devices are incorporated into 

snares that allow the loop to break open 

and a nontarget animal to escape when a specific amount of force is applied, typically much more than what 

a target animal is capable of producing because they are larger than the target animal. Loop stops can also 

be incorporated which are mostly used to reduce capture of animals smaller than the target animal, but can 

also be used to reduce the capture of larger animals such as deer, which are typically snared around the legs; 

cable device stops are clamped onto the cable to prevent the loop from either opening or closing beyond a 

minimum or maximum loop circumference and are very effective (Etter and Belant 2011).

Cable devices can be effectively used wherever a target animal routinely travels through a restricted lane, such 

as a trail through brush or a crawl space under a fence. For example, cable devices can be set in “crawl holes,”

an area under a fence that was dug out to allow access to the other side, hunting or perch sites for birds, in 

water near beaver2 slides, at the entrance to burrows, or anywhere a target animal is expected to travel. Cable 

device set placement varies according to species targeted, habitat type, and the presence of nontarget species.

Most terrestrial sets, excluding bird noose traps, are disguised by brush (e.g., twigs, leaves, and natural 

 2 See the Introduction to Risk Assessments – Chapter I for scientific names of animals. These are only provided if not used in that Chapter.

Figure 2. A foot cable restraint with an Aldrich® throw-arm. A standard 

set for this can be found in Hygnstrom (1994).
3

vegetation) for neck snares and covered with natural debris 

(e.g., sifted crushed leaves, pine needles, and small twigs) for 

foot cable restraints. Bait, scents, lures, or carcass “draw 

stations” are often used as attractants to draw the target 

species to the area. Snares in aquatic sets are typically placed 

in shallow water where animals come and go from land or near 

lodges or burrows; scent may be used for aquatic mammals, 

especially for beaver. Many bird noose traps such as the balchatri, a trap designed in India by falconers, incorporate an 

attractant such as a live prey bird or rodent or are placed on 

frequently visited perching structures. 

Use-pattern data indicate cable devices are used throughout 

the year by WS. Placement of cable devices is dependent upon 

target species habits and habitat conditions such as snow.

Placement location is selected to minimize exposure to and 

capture of nontarget animals. Dependent upon cable device

type and circumstances, use may occur in rural or urban areas 

and on privately or publicly owned properties.

Most cable devices are passive capture methods that are only 

activated by an animal moving through the loop and causing it

to close (Figures 1, 5, and 6). However, some systems use 

power-activation to propel the cable loop onto the body of an 

animal or increase the speed of loop closure (Figures 2, 3, and 

4). When setting a power-activated cable device, a spring is 

generally held compressed by a trigger or pan, and positioned 

with the arm set so that the spring throws the cable over the 

target species appendage. Springs are set to open away from 

the body of the animal to minimize the likelihood of hitting it, 

which could cause it not to function properly. Power-activated 

cable devices rely on the animal to step on a pan (i.e., footdepressed trigger) or for the target animal to pull the trigger 

with their mouth or foot. When an animal trips the trigger, the 

compressed spring releases and pulls the cable loop closed 

around the animal quickly. Similar to passive cable devices, 

power-activated cable devices may be used for either live- or 

lethal-capture. One commonly used power-activated cable 

device is the foot cable restraint, which consists of a flexible 

loop of cable placed on the ground along active trails or near 

bait sites, and covered with dirt or snow (Figures 2, 3, and 4).

The foot cable restraint is set as a spring-power-activated

nonlethal device, activated when an animal places its foot on 

the trigger or pan. Several styles of foot cable restraints are 

available (Figures 2, 3, and 4) and some can include an in-line 

Figure 3. A mechanical foot cable restraint, the 

“Hold-a-Hog Device,” with a disengaging jaw.

Figure 4. A coyote WS-T foot cable restraint with 

a WS-T throw-arm, which incorporates a 

foothold trap pan and pan-tension device. 
4

spring (shock spring) to minimize the 

amount of force applied by lunges.

However, no data are available to quantify 

the effects (AFWA 2009). WS uses in line 

springs for some devices, but it is not a 

standard use.

Foot noose traps are different from other 

cable devices because they incorporate 

many foot nooses made of monofilament 

fishing line (usually 20-100# test weight

dependent on the target species). These 

are attached to a cage (Figures 5 and 6) 

with a live lure (prey), mats that are set 

along shoreline or perches, or pigeons 

tethered to a one-pound weight (heavier 

for eagles) fitted with a harness covered 

in nooses. Unlike snares, these are 

monitored frequently when in use. Birds, 

especially raptors, pigeons, or shorebirds, can be live 

captured with foot-nooses made of monofilament lines on 

different types of trap designs. The nooses are typically nonlocking.

In 1996 the Association of Fish and Wildlife Agencies 

(AFWA), working cooperatively with federal and private 

partners, embarked on a goal to develop voluntary Best 

Management Practices (BMPs) for trapping furbearers in 

the United States (Batcheller et al. 2000). The stated 

purpose and intent of AFWA in developing the BMPs was 

to: “Scientifically evaluate traps and trapping systems

used for capturing furbearers in the United States.”

AFWA determined the best methods by species3

, but 

primarily targeted harvest by private fur trappers and not 

WDM take. Evaluations of trap and snare performance 

were based on animal welfare, efficiency, capture rate, 

selectivity, practicality, safety, mechanical function, cost, 

quality, durability, weight, and maintenance requirements 

(Fall 2002). Scientific research on the variety of traps and 

snares was used by AFWA to develop the BMPs. The 

evaluation of BMPs continues and BMPs are updated as 

research results warrant (AFWA 2017). The BMPs were 

provided to state and federal wildlife agencies, trappers,

 3 Furbearers with AFWA (2017) trapping BMPs include Virginia opossum, beaver, muskrat, nutria, Canada lynx, bobcat, coyote in Eastern U.S., 

coyote in Western U.S. (both eastern and western United States populations have own BMPs since eastern coyotes are larger as a result of 

hybridizing with wolves), gray wolves, red fox, swift/kit fox, arctic fox, gray fox, river otter, fisher, American marten, weasel (least, long-tailed, 

and short-tailed), mink, American badger, ringtail, raccoon, and striped skunk. 

Figure 5. Typical bal-chatri trap, a foot noose trap with monofilament line 

at top and on sides. The trap is baited with a live mouse or bird.

Figure 6. A flat topped bal-chatri, showing the 

variation in styles, which could be used for birds as 

large as eagles.
5

and the public in the form of a general overview for traps and trapping, and specifically the most efficient 

and humane methods for trapping 24 furbearer species in the United States (AFWA 2017). The goals 

were to promote regulated trapping as a modern wildlife management tool, identify practical traps

and trapping techniques while continuing to improve efficiency, selectivity, and the welfare of trapped

animals through research, to provide specifications for traps that meet BMP criteria for individual

species in various regions of the United States, to provide wildlife management and trap industry 

professionals with information to evaluate trapping systems in the United States, and to instill public

confidence in and maintain public support for wildlife management and trapping through distribution

of science-based information. The BMP program uses international humane trapping standards 

consistent with the Agreement on International Humane Trapping Standards among Russia, Canada, 

and the European Union. WS has adopted these standards, where feasible, for trapping in the United 

States and conducts research on different trapping systems.

WS Policy (WS Directive 2.450, 09/24/2014)4 states that the use of the BMP trapping guidelines developed 

and promulgated by AFWA (2017) for private fur harvest and other trapping activities are valuable and should 

be followed as practical. WS uses the BMP guidelines as the basis for policy formulation, but recognizes that

some devices used in WDM are not commercially available and that not all devices recommended in the BMP

guidelines for general public-use meet the more stringent performance requirements, particularly efficiency

and durability, for use in federal WDM activities. AFWA (2017) recognized that trapping for depredation 

control was different than trapping for fur harvest, but focused their recommendations on private 

trappers. The Directive also states that cable devices should be set so that captured animals are not 

conspicuous to the public, particularly along public roads and trails; this reduces the possibility of theft or a 

member of the public attempting to free an animal and getting injured. Cable devices are typically placed in 

areas where the public will not randomly stumble onto a device or captured animal. The Directive also states 

that cable devices are not to be set closer than 30 feet from any exposed animal carcass, or part thereof, to 

reduce the potential of capturing raptors or other nontarget animals attracted to it5

. Foot cable restraints

incorporate pan-tension devices to prevent or reduce the capture of nontarget animals, unless such use would

preclude capture of the intended target animal. The Directive also notes that agency cable device replacements 

are to be selected from the various commercially available devices or equivalents listed in BMP regional 

guidelines for each species (AFWA 2017), unless changes are authorized by a WS Regional Director. WS 

checks cable devices as frequently as possible and in accordance with state law, which helps minimize injuries 

and unintended fatalities, especially with cable restraints; foot noose traps are checked frequently during the 

day.

1.1 Use Pattern

Cable devices are used by WS primarily to manage damage caused by mammals, whereas foot noose traps 

are generally used to manage bird damage (Tables 1 and 2). Neck snares are used mostly for coyotes6

, feral 

swine, beaver, raccoons, red and gray foxes, and bobcats (Table 1). Additionally, though few are taken, they 

are effective for mountain lions (Figure 1). The Collarum® and other similar devices have almost strictly been 

 4 All WS Policy Directives referenced in this document can be found at http://www.aphis.usda.gov/wps/portal/aphis/ourfocus/wildlifedamage

under Wildlife Damage – WS Program Directives. 5 If an animal carcass could be dragged or moved by scavengers to within 30 feet of set foothold traps, the carcass has to be secured to restrict 

movement (WS Directive 2.455, Scents, Baits, and Attractants). These restrictions do not apply to animal carcasses used to attract bear (foothold traps 

cannot be used to capture bear) or mountain lion for approved capture devices, including foothold traps. 6 See the Risk Assessment Introduction (Chapter 1) for scientific names of animals. These are only provided if they are not used in that Chapter.
6

used for coyotes (Table 1). From FY11 to FY15, WS took an annual average of 24,660 target individuals

(96.5%) of 44 species, and 898 nontarget individuals (3.5%) of 55 species (Table 1) with neck snares.

Table 1. The annual average number of target and nontarget animals captured by Wildlife Services in wildlife damage 

management from FY11 to FY15 with neck snares including power-activated neck snares such as the Collarum®

throughout the United States.

ANIMALS TAKEN WITH STANDARD AND POWER-ACTIVATED NECK SNARES 

TARGET NONTARGET

Species Killed Freed Killed Freed

NECK SNARE

Virginia Opossum 22 0 7 0.8

Bobcat 432 1 14 0.6

Mountain Lion 45 0 4 0.4

Coyote 14,657 3 10 0.8

Northwestern Gray Wolf 6 0.4 0.2 0

- Great Plains WolfT&E 11 3 0 0

- Feral/Free-Roaming Dog* 103 5 18 21

Red Fox 442 0 15 0.4

Common Gray Fox 436 0.4 16 2

Black Bear 11 0 2 1

River Otter 3 0 15 1

Badger 83 0.4 72 10

Raccoon 882 0 117 5

Striped Skunk 83 0 13 0

Other Predator (3T, 5NT – 7 sp.)1 5 2 4 0.8

Feral Swine* 4,560 0.8 14 0

Collared Peccary (Javelina) 0.4 0 178 8

Mule Deer (incl. Black-tailed Deer) 0 0 16 3

White-tailed Deer 0.2 0 81 14

Philippine (Sambar) Deer* 31 0 0 0

Other Hoofed Mammal (7 NT – 7 sp.) 1** 0 0 9 3

Beaver 2,499 3 0.6 0.2

Nutria* 57 0 1 0

Muskrat 12 0 0 0

Woodchuck 24 0 2 0.4

Porcupine 45 2 104 8

Eastern Cottontail 6 0 9 11

White-tailed Jackrabbit 7 0 3 0

Black-tailed Jackrabbit 30 0 26 0.2

Other Rodent and Rabbit (8T, 2NT – 8 sp.) 1 14 0 3 0.2

Nine-banded Armadillo 2 0 13 6

Unidentified Domestic Animal 0 0 0 0.2

Bald Eagle 0 0 0.4 0

Golden Eagle 0 0 1 0

Other Raptor (2T, 5NT – 5 sp.) 1 0.4 0 3 0.4

Waterbird-fowl/Larid/Gallinaceous (3T, 6NT – 8 sp.) 1 2 0 7 2

Common Snapping Turtle 0 0 6 9

Other Reptiles (3T**, 2NT – 4 sp.) 1 0.4 0.6 0.6 3

ANIMALS TAKEN W/ NECK SNARES (46T, 51NT, 68 sp.) 24,511 22 785 112

POWER-ACTIVATED NECK SNARES (e.g., COLLARUM®)

Coyote 126 0 0 0

Other Predators/Hoofed Mammals* (3T, 2NT – 3 sp.) 1 0 0 1

ANIMALS TAKEN W/ MECH. N. SNARES (4T, 2NT, 4 sp.) 127 0 0 1

TOTAL TAKEN IN ALL NECK SNARES (46T, 51NT, 68 sp.) 24,638 22 785 113

% OF ALL TARGET AND NONTARGET SPECIES TAKEN 96.4% 0.1% 3.1% 0.4%

1 Individual accounts of species are only given for those species that had an annual average of more than 10 killed and freed or a sensitive or T&E 

species. Animals listed in “Other Animals” are given in Appendix 1.

* Introduced species ** Introduced Species except pronghorn/alligator T – Target NT - Nontarget
7

Of the targets taken with neck snares, 22 were relocated or freed after sampling (0.1% of targets); this is 

mostly because neck snares are rarely used nonlethally. Of the nontargets, 113 were freed (12.5%) following 

capture, if it was deemed that the animal would survive; those that would not survive were euthanized. It 

should be noted that one unidentified domestic nontarget animal7 was freed from a neck snare and was most

likely either a dog or a cow which would not have changed the take number (0.2 freed).

Foot cable restraints have mostly been used for feral swine, black bears, and coyotes (Table 2). They have 

also been used to take some grizzly bears. Foot noose traps have been mostly used for raptors including redtailed hawks, American kestrels and Swainson’s hawks (Table 2). From FY11 to FY15, WS took an annual 

average of 1,050 target individuals (99.0%) of 42 different species, and 10 nontarget individuals (1%) of 18

species (Table 2). Of the targets, 447 were relocated or freed after sampling (42.6% of targets). Of the 

nontargets, 8 were freed (80.0%) following capture and deemed that they would survive (those that would 

not survive were euthanized). It should be noted that noose mats were used to capture many shorebirds to 

monitor for highly pathogenic avian influenza in FY06 and FY07 which could occur again and increase the 

number of shorebird species taken (most all of these were sampled for disease and freed).

Table 2. The annual average number of target and nontarget animals captured with foot cable restraints and foot noose 

traps by Wildlife Services in wildlife damage management from FY11 to FY15 throughout the United States.

ANIMALS CAPTURED WITH FOOT CABLE RESTRAINTS AND FOOT NOOSES

Species

TARGET NONTARGET

Killed Freed Killed Freed

CABLE RESTRAINTS

Coyote 164 0 0 0

Northwestern Gray Wolf 0.2 0.2 0 0

- Feral/Free-Roaming Dog* 4 1 0.6 1

Mountain Lion 19 0 0.2 0.4

Black Bear 178 14 0 2

Grizzly BearT&E 0.2 6 0 0

Other Predator (7T, 5NT – 8 sp.) 1 15 0 0.6 2

Feral Swine* 183 0.2 0 0.4

Philippine (Sambar) Deer* 17 0 0 0

Other Hoofed Mammal (3T, 3NT – 5 sp.) 1 1 0.2 0.4 1

All Rodents (2T - 2 sp.) 1 4 0 0 0

All Birds (3T, 1NT – 4 sp.) 1 0.4 0.4 0 0.2

ANIMALS TAKEN IN FOOT SNARES (22T, 13NT – 26 sp.) 586 22 2 7

FOOT NOOSE

Bald Eagle 0 0.4 0 0

Swainson's Hawk 0.2 110 0 0

Red-tailed Hawk 8 160 0 0.2

Ferruginous Hawk 0 12 0 0

American Kestrel 3 113 0 0

Other Raptor (12T – 12 sp.) 1 0 30 0 0

Other Bird Species (4T, 4NT - 7 sp.) 1 6 3 0.4 0.6

ANIMALS TAKEN IN FOOT NOOSES (21T, 5NT – 24 sp.) 17 425 0.4 0.8

TOTAL TAKEN IN ALL FOOT SNARES (42T, 18 NT, 49 sp.) 603 447 2 8

% OF ALL TARGET AND NONTARGET SPECIES TAKEN 58.1% 40.9% 0.2% 0.8%

1 Individual accounts of species are only given for those species that had an annual average of more than 10 killed and freed or a sensitive or T&E 

species. Animals listed in “Other Animals” are given in Appendix 1.

* Introduced Species T – Target NT - Nontarget

 7 In MIS the animal was listed as “domestic animal” and the species was not provided.
8

Nontarget capture by WS has decreased in the last 25 years from a nontarget capture rate of 19.1% in FY88 

(USDA 1997, Appendix P, pp. 23-27) to 6.5% annual average between FY11 and FY15 in the 6 states (AZ, 

CO, NM, OK, TX, and UT) analyzed. The use of pan tension devices for foot cable restraints, break-away 

snares, stops, exclosure cages, and others improvements, most being implemented in the 1990s, likely 

accounted for the largest portion of the decrease. Target take by WS increased almost five-fold from FY88 to 

FY11-FY15 in the six states, from an annual average of 6,944 to 32,241 (464% increase in USDA 1997, 

Appendix P, pp. 23-27).

Animal capture snare nights is a standard comparison measurement of effectiveness or selectivity for cable 

devices that remain in place for one or more nights, and was determined from MIS data. Noose traps for birds 

were not included since these are almost always set and taken down daily and checked frequently, at least 

twice daily if not more, when in use. From FY11 to FY15, WS used standard neck snares for an annual average 

of 8,222,413 snare nights (snare nights includes neck snares and cable restraints in this standard 

comparison). An annual average of 25,431 animals were captured in neck snares for a total of 3.1 

animals/1000 snare nights8 with 96% target species and 4% nontarget species. Thus, target mammal take 

was 3.0/1000 snare nights and nontarget take was 0.1/1000 snare nights. Of the 24,533 target captures with 

neck snares, 0.1% were relocated. Of the 898 nontarget captures, 12.5% were released at the capture location.

From FY11 to FY15, WS captured an annual average of 128 animals in power-activated neck snares in 22,400

snare nights for a capture rate of 5.7 animals/1000 snare nights with 99% target species and 1% nontarget 

species. Thus, target mammal capture was 5.7 animals/1000 snare nights and nontarget take was 0.04/1000 

snare nights. Of the 127 target captures with power-activated neck snares, none were relocated; the 1 

nontarget animal captured was freed. These figures represent a high effectiveness rating for target mammal 

capture with low nontarget take (especially considering that most neck snares were used passively).

Standard neck snares are light-weight and easy to set out. Power-activated neck snares are not as light-weight 

as standard neck snares and require two to three times the amount of time to set. Even though fewer animal 

are captured per 1000 snare nights than compared to foothold traps (10.3 target and 0.7 nontarget 

animals/1000 trap nights)9

, these are very effective tools because more can be carried and set in the field in 

a short amount of time. Power-activated neck snares had a higher relative capture rate, but it is likely due to 

the ability to use scents at bait sites more efficiently for coyotes. 

From FY11 to FY15, WS used foot cable restraints, not including noose traps, for an annual average total of 

74,700 snare nights. An annual average of 617 animals were captured in foot cable restraints for a total of 

8.3 animals/1,000 snare nights with 98.5% target species and 1.5% nontarget species. Thus, target mammal 

take was 8.1/1000 snare nights and nontarget take was 0.1/1000 snare nights. Of the 608 target captures 

with foot cable restraints, 3.6% were relocated. Of the 9 nontarget captures, 77.8% were released at the 

capture location. These figures represent a very high effectiveness rating for target mammal capture with a 

very low nontarget take. In the hands of a skilled trapper, foot cable restraints are a very selective means 

available for removing problem animals.

 8 Capture per 1000 snare nights is the standard for comparison, where snare equals any cable device set for overnight use. 

9 See Chapter IV, The Use of Foothold Traps in Wildlife Damage Management risk assessment.
9

2 HAZARDS

2.1 Health and Human Safety

Hazards would primarily occur to WS employees that create, handle, and set cable devices. Abrasions, 

bruises, and minor cuts to the fingers, hands, and arms of users may result from inadvertent release of the 

spring mechanism of power-activated snares. Minor cuts to hands and fingers may also occur from broken 

strands of cable or frayed cable ends. Injuries to employees could also occur from animals that are livecaptured in cable deivces from bites, scratches, lacerations, and disease threats. In extreme cases, serious 

injury to employee or even death could occur from large animals (e.g., bear, feral swine) live-captured in 

snares or cable restraints.

Similar hazards could occur to the public if they purposefully handled devices placed by WS. Members of the 

public may come into contact with cable devices set by WS, but are most likely to inadvertently trigger poweractivated sets hidden from view. Because foot cable restraints are set underground and “camouflaged” under 

sifted leaves or other debris, if stepped on, the loop could close on a person’s foot or ankle. If a person was 

wearing shoes, the cable loop would likely close around the shoe but the person would suffer no injuries to 

the foot. If barefoot or if the cable device closed around the ankle, abrasions, bruises, minor cuts, and swelling

potentially could occur. To reduce such possibilities, WS personnel post signs at entrances to properties or 

on roads in the area to alert the public that cable devices are present. Finally, it is possible for someone to 

find a captured animal and attempt to free it which could expose them to bites or scratches. WS Policy (WS 

Directive 2.450, 09/24/2014) states that cable devices should be set so that captured animals are not 

conspicuous to the public, particularly along public roads and trails; this reduces the possibility of a member 

of the public getting injured while attempting to free an animal. 

2.2 Environmental

Environmental hazards associated with the use of cable devices include the injury or death of animals, 

including target and nontarget animals. Animals may die from the cable device, exposure to the elements 

such as heat or cold, other causes associated with capture, or euthanasia by the WS employee. Cable devices

may accidentally capture nontarget animals including other wildlife species, domestic animals, or livestock

(Tables 1 and 2 list nontarget species captured from FY11 to FY15). Injuries generally would involve 

abrasions, cuts, and bruises or constriction of blood flow. Abrasions, cuts, and bruises could occur if an 

excessively loose loop repeatedly slides or turns on a captured animal, and extensive swelling could occur if 

the cable were tight enough to partially restrict blood circulation, but not tight enough to kill (AFWA 2009).

Shivik et al. (2000) found that injuries to coyotes live-captured in several power-activated cable devices

included slight swelling, some hemorrhaging, cutaneous lacerations, and minor abrasions around the area of 

capture, along with tooth damage or loss. Similar injuries were noted for red fox live-captured using poweractivated cable devices in Spain with nearly all of the foxes captured showing minor swelling or hemorrhaging

(Munoz-Igualada et al. 2008). However, Munoz-Igualada et al. (2008) did note that a small number of foxes

live-captured also had major cutaneous lacerations, severance of minor tendon or ligament, minor skeletal 

muscle degeneration, and fractures. Canids caught in neck snares that have been necropsied have shown low 

incidence of significant injury and surpass international humaneness standards (Olson and Tischaefer 2004, 

Munoz-Igualada et al. 2008, Defra 2012). The trapping BMPs (AFWA 2017) provided standards for trapping 

that looked at much of this literature and new research to develop the best methods to minimize injuries.

Much research has been done on selectivity, injuries, humaneness, and other characteristics related to traps 

which provided AFWA good data to determine BMPs that would minimize problems. WS personnel check 
10

equipment as required by state laws, but as often as possible, which reduces injuries associated with being 

in cable devices for long periods of time.

Hazards associated with the use of cable devices would primarily be associated with injuries to animals and 

the humaneness of their use. Those hazards affect both target and nontarget animals. When used as a livecapture method, cable devices could cause injuries to target animals and to nontarget animals or they could 

cause the unintended death of those animals. When neck snares are used as a lethal method, their use should 

cause a rapid death by strangulation, which results in asphyxiation of the target animal. However, several 

factors can influence the performance of cable devices (Phillips 1996, Daoust and Nicholson 2004, AFWA 

2009, Short et al. 2012). Entanglement of the cable device cable with nearby objects (e.g., brush, trees, and 

fences) can increase the risk of injury to animals live-captured (Short et al. 2012). Short et al. (2012) also 

recommended that stakes used to anchor the snaring cable not protrude from the ground to avoid 

entanglement. Cable devices are inspected regularly and repaired or discarded to avoid risks of failure. For 

example, small kinks can weaken the cable, which could allow the cable to break easier or could prevent the 

lock from functioning correctly (Daoust and Nicholson 2004). Attaching a swivel to the lock can prevent the 

cable from kinking as the lock slides along the cable (Daoust and Nicholson 2004). Properly anchoring the 

snare or cable restraint can prevent an animal from pulling the cable loose. If a cable device is anchored too 

low, an animal could chew through the cable. During the use of three types of lethally set snares, Phillips 

(1996) noted that 17 of 131 coyotes caught managed to escape, one by breaking a lock and 16 by chewing 

through the cable. The failure of snares or cable restraints could lead to animals escaping with the cable 

device still constricted around the animal, which would likely lead to the death of the animal after several 

weeks or months (Daoust and Nicholson 2004). The use of diazepam tabs on necks snares has been used 

successfully to reduce the risk of injuries to coyotes when the coyotes chewed or removed the tab from the 

cable device (Pruss et al. 2002). Diazepam tabs can be used to sedate and calm captured animals, which can 

reduce aggression and the risk of injuries (Pruss et al. 2002), but are not approved for use at this point.

Death of an animal may occur from strangulation, predation by other animals (Short et al. 2012), or exposure 

to the elements. Target animals live-captured in a snare or cable restraint could be euthanized by an employee 

of WS. In addition, nontarget animals live-captured that were severely injured and unlikely to survive if 

released, could be euthanized by a WS employee. WS personnel with training, skills, and appropriate 

knowledge of cable devices can carefully select snaring components and designs that improve the selectivity 

and humaneness of the cable device selected for a particular damage situation, species targeted, and 

nontarget species in the area; additionally, site selection appropriate for the target animal without 

entanglement possibilities also improves selectivity and humaneness (Short et al. 2012). WS employees are 

required to participate in a trapper education course (WS Directive 2.450), which reduces many of the 

problems such as capture of nontarget animals.

Frey et al. (2007) used neck snares to live-capture red fox to be fitted with radio collars for telemetry studies 

and found that foxes were active the evening following capture and that all females captured reared young 

the following spring. Therefore, Frey et al. (2007) concluded that the use of neck snares to live-capture red 

fox did not affect their behavior following release. Over the three-year study period, Frey et al. (2007) used 

neck snares to capture 21 red fox with only two fatal injuries occurring from the snares used.

Environmental risks would be greatest for nontarget animals that frequent an area where cable devices are 

placed and travel along the same trails as the target species. Snares and cable restraints could be used in a 

variety of habitats; thus, many species of wildlife could be exposed to cable devices used by WS. As the 

amount of time between capture and checking the device increases, the risk of injuries also likely increases.
11

The selectivity of cable devices can be improved by cable device design and using techniques designed to 

reduce the risk to nontargets (AFWA 2009, Short et al. 2012). Several designs and techniques are used by 

WS to reduce the risk of capturing or killing nontarget animals.

One commonly used technique to minimize risk involves adjusting the loop size of cable devices. The loop 

size used when setting a snare or cable restraint can minimize the likelihood of capturing animals either larger 

or smaller than the intended species (AFWA 2009, Short et al. 2012). For example, when setting a cable device

to capture a coyote in areas where wolves could be present, using the smallest loop size necessary to capture 

a coyote could reduce the risk of capturing a wolf (AFWA 2009). Conversely, using the largest loop size 

possible to capture beaver increases the likelihood that an otter will pass through the loop without being 

captured (AFWA 2009). 

The height of the snare loop from the ground can also minimize risks of non-capture when using snares by 

positioning the loop at a level most apt to minimize risk of capture for other animals (AFWA 2009, Short et 

al. 2012). Adjusting the loop height can minimize capture of animals that are either taller or shorter than the 

target species. Raising the loop can allow smaller animals to pass under the under the snare. Conversely, 

lowering the height of the loop can allow larger animals to step over the loop. However, lowering the height 

of the loop too much could result in capturing a larger animal by the leg (AFWA 2009).

Various natural or other materials can be used as “guide sticks” to direct the target animal through a snare 

or to guide a nontarget animal over, under, or around the snare (AFWA 2009). Knowledge of the animal 

species in an area and the behavior of those animals can be critical in deciding whether to use guide sticks

when using cable devices. If guide sticks are used, appropriate placement and size must be considered 

because the placement and size or rigidity of the guide can influence animal behavior (AFWA 2009). For 

example, using a large rigid guide stick over a neck snare could cause deer to jump over it avoiding capture; 

however, placing a large rigid guide stick too high above the snare could encourage a deer to pass underneath 

the stick, which would increase the risk of capture (AFWA 2009). Gardner (2010) used a diverting wire with 

neck snares set for wolves to reduce the risk of moose captures; an additional wire was placed at a height 

that allowed moose to push the wire and push the snare out of the way to prevent its activation.

Baits or lures can be used to attract a target animal to the area where a device has been placed. When deciding 

on whether to use baits or lures and which ones, consideration is given to nontarget animals that may also 

be attracted to the bait or lure (Knopff et al. 2010). Selecting the appropriate bait or lure can increase or 

decrease risks of attracting nontarget animals to an area where a snare or cable restraint is set (AFWA 2017).

Loop stops can also be used to minimize the risk of capturing or killing nontarget animals in cable devices 

(AFWA 2009, Etter and Belant 2011). Minimum loop stops control the minimum diameter of the loop while 

maximum loop stops control the maximum diameter of the loop (AFWA 2009). Minimum loop stops allow 

animals smaller than the target animals to escape or allow animals captured in a specific body area, such as 

the leg, to escape since the loop could only close to minimum diameter, greater than the diameter of the leg.

As an example, a minimum loop stop could allow a red fox to be captured but let a marten escape because it 

is smaller than a fox. Similarly, a minimum loop stop could allow for the capture of a coyote but allow a deer 

caught by the leg to escape (AFWA 2009). Etter and Belant (2011) compared the efficiency and selectivity of 

cable restraints to live-capture coyotes based on minimum loop stop diameters of 8.9 centimeters and 10.8 

centimeters and found the smaller loop stop diameter was more effective at capturing coyotes and avoiding 

nontarget capture.
12

Adjusting trigger tension on power-activated cable devices can also increase selectivity and reduce risks to 

nontarget animals. Increasing the amount of force required to activate a foot-depressed trigger or a mouthpulled trigger could minimize the risk of capturing smaller animals or animals without the ability to apply the 

necessary force to trigger the device (AFWA 2009).

Snare “loading” is the process of altering the curvature of the snare loop to increase the sensitivity of the loop 

to closure and once closure of the loop is initiated by the target animal, the loop closes more rapidly. Snare 

loading is often used to improve the efficiency of capturing a target animal when using passive snares but 

may not be suitable for use in all situations, especially when nontarget animals that may encounter the snare 

are smaller than the target animal (AFWA 2009). If a smaller animal was passing through the loop of the snare 

and bumped or brushed the snare loop, the modified snare loop could close more rapidly, not allowing enough 

time for the smaller animal to pass completely through the loop. Adjusting the position of a lock can increase 

or decrease the sensitivity of the loop to closure, which can be used to reduce risks of capturing or killing a 

nontarget animal (AFWA 2009).

Breakaway devices on snares allow the snare loop to break open when a certain amount of force is applied, 

which allows the animal to escape from the snare (AFWA 2009). The devices can be used to prevent holding 

a nontarget animal that generates more force than the target animal. For example, when setting snares to 

capture coyotes, breakaway locks or other devices could be used that allow deer to break the device and 

escape if captured, since deer are able to generate more force than coyotes.

3 RISKS

3.1 Health and Human Safety

The risk of human injury from cable devices is mainly to WS field personnel placing them. Injuries related to 

neck snares and foot cable restraints, including power-activated cable devices accidentally triggered and 

striking a person, are relatively minor. One laceration (0.3 annually) from a neck snare being set for feral 

swine occurred from FY13 to FY15 as documented in WS Office of Worker’s Compensation Program (OWCP)

claims. Additionally, WS annually had 6.3 lacerations/punctures per year, but we were unable to determine 

the method in use when the injuries occurred. WS employees engaged in trapping receive trapper education 

training to reduce risk of injury. WS personnel are encouraged to use gloves10 and other appropriate protective 

equipment to minimize injury risk.

WS employees filed an annual average of 79 OWCP claims from FY13 to FY1511 for strained backs, 

lacerations, animal bites, burns, and other injuries that occurred on the job. It is unknown how many of the 

injuries were from cable devices. However, only 59 of these claims occurred in the field. Many of the types of 

injuries and other maladies that occurred happen over time from using many different WDM techniques (e.g., 

back issues from bending down to work on sets). It is possible that injuries involving strained muscles or 

ligaments, compression or contusion injuries, animal bites, laceration and punctures, fractures, insect bites, 

or foreign body injuries could have occurred as a result of setting cable devices, but we were unable to 

determine that exact number (these are discussed in detail in the Introduction to the Risk Assessments, 

Chapter 1).

 10 Setting snares may sometimes require free hands and gloves may not be worn at all times. 11 FY13 was the first year OWCP claims were managed at a national level rather than at the state level, thus only FY13-FY15 was used. Due to

reporting requirements and privacy concerns, data is not tracked by activity, and therefore, all the data as a whole is discussed for injuries on the 

more than 2,000 personnel employed, but we may not have been able to ascertain all information.
13

The risk of injury from captured animals is also minimal. Typically, employees dispatch captured target 

animals slated for lethal removal with a gunshot to the brain. However, most animals targeted for lethal 

removal with neck snares are killed by the snare relatively quickly and, therefore, would not cause these types 

of injuries. The highest risk is typically from animals that are trapped in foot cable restraints that are not 

staked, but are attached to drags; employees may unexpectedly encounter an animal that is snared when 

approaching the set. Few employees over many years have been injured by such captured animals (most of 

the few incidents that have occurred over the last 20 years have been with bears). WS personnel enter trapping 

areas cautiously and know where traps with drags versus stakes are placed, using extra caution in the former

situation. A more obvious risk is associated with the release of captured animals. WS employees usually carry 

a catch-pole (a pole with a cable loop that can hold an animal prior to release). Catch-poles are very effective 

in handling wildlife, but an animal’s behavior following release, though mostly predictable, is a primary 

concern. If an animal is too large or is being trapped for a research project, an animal may be immobilized 

with drugs. Though usually not a problem, drugged animals are a risk which will be discussed under the 

Immobilization Risk Assessment.

From FY13 to FY15, WS operational field personnel averaged 3 bites or injuries annually from animals and 

some of these were from trapped animals, but not in cable devices. However, they illustrate the potential 

dangers of getting close to live animals in any type of capture device. Of the average of 3 animals per year, 

one was a coyote captured in a foothold trap that bit the employee before it was euthanized. Another was 

from a feral cat that had been caught in a foothold trap, and bit the employee while it was in the process of 

being turned over to a local animal shelter. Another feral cat was captured in a cage trap and bit the WS 

employee while transferring custody. A black bear in a culvert trap bit a WS employee on the hand before

being released after relocation. Two WS employees were bitten by feral or free-roaming dogs being hand 

gathered, but one escaped capture. Finally, a bat that was caught by another agency, bit a WS employee while 

the bat was being sampled for a variety of diseases (primarily rabies). Two other dog bites were from property 

owners’ dogs while responding to a request for assistance. For context, WS operations annually killed 43,576 

and released 11,432 predators with methods conducive to being bitten from FY13 to FY15. Thus, an average 

of 2.3 bite incidents per year were related to animal capture, including hand gathering (0.7), transferring 

custody to another agency after capture (0.7), relocating an animal (0.3), euthanizing a live-captured animal 

(0.3), and handling an animal for disease sampling (0.3). For bite incidents that occurred from released 

animals (2.0 per year), WS had a ratio of one bite per 5,700 releases. For animals to be euthanized, the ratio 

was much less at 1 bite for 145,000 animals killed. Overall, the bite ratio was 1 bite for every 18,000 animals 

captured with methods where the animal could be captured alive. This is a low risk.

It should be noted that 2 bites in three years occurred as dog attacks. This again is a minimal number as the 

Centers for Disease Control (2015) estimates 4.5 million dog bites occur annually throughout the United 

States. Thus again, we believe these risks are low.

In addition to field personnel, from FY13 to FY15, NWRC personnel received an annual average of 1.0 animal 

bites or injuries from research animals, including bites from a skunk (0.3 ave.) and a rat (0.3 ave.), and a 

bone fracture from feral swine (0.3 average). Lab animal bites typically come from caged animals during 

routine maintenance or research. It is not known whether these particular animals were from animals captured 

with cable devices during field research.

WS personnel could be exposed to animals carrying diseases such as rabies. All recorded bites from FY13 to 

FY15 and an annual average of two lacerations/splashes were from potentially diseased animals (rabies). No 
14

known animal exposures occurred as a result of an animal captured in a cable device, but this has occurred.

The animal bites (average of 5.0 per year) had the potential for transmitting the rabies virus. None of the 

animals involved in the incidents was subsequently identified as rabid, with the exception of fluids from tissue 

from a known rabid skunk that splashed into the eye of a researcher. Thus, a potential for 5 animals per year 

caused concern potentially for exposure to rabies from FY13 to FY15. Personnel that have the potential for 

exposure to rabid animals have the option of obtaining the rabies prophylactic series with follow up boosters 

to reduce the potential for contracting the disease if bitten, lacerated, or exposed to bodily fluids. General 

exposure to animals is common for many WS employees, but considering the number of animals captured 

or handled, the risk of contracting a wildlife-borne disease is minimal.

The placement of cable devices in urban and rural recreational areas may expose the public to these same 

hazards; however, WS conducts WDM mostly on private lands where the risks are principally to WS 

employees and the landowners that receive WS assistance. Cable devices are mostly placed in areas not 

visible or visited by the public. WS personnel consider the potential for the public to be in an area, and 

generally do not use cable devices where people would frequent for three reasons: 1) the potential for the 

public to be exposed to a captured animal, 2) the potential for persons, particularly small children, accidentally 

stepping on a power-activated foot cable restraint, or 3) the possibility of theft or vandalism. Additionally, 

neck snares are set in brushy areas or are brushed in to camouflage them and foot cable restraints are 

frequently set underground with leaves or other natural debris over them, camouflaging the sets from both 

animals and humans. Someone with knowledge of cable device sets could, however, disturb the sites or steal 

the cable devices. Since cable devices are often set in remote areas, mostly on private lands, and camouflaged, 

the likelihood of incidental public contact is minimized. Additionally, WS has received no reports of members 

of the public being injured by a cable device set by WS, or injured by an animal captured in one. Considering 

the number of snare nights in a given year (8.3 million), the risk of public exposure is negligible.

Snares and cable restraints are passive or power-activated methods that require direct contact to activate; 

therefore, if left alone, risks to the public would be non-existent. However, the potential exists for a person to 

inadvertently encounter a snare or cable restraint if that person was unaware that the devices are being used

in an area. Appropriate warning signs are posted at main entrances or commonly used access points to areas 

where cable devices are in use (see WS Directive 2.450). Signs are routinely checked to ensure that they are

present, obvious, and readable. Signs are removed when the equipment is no longer in use. The locations 

where cable devices are placed reduces the risk of the public inadvertently encountering them. Those locations 

where cable devices could be placed for target animals (e.g., under fences, dense vegetation, or semisubmerged in aquatic habitats) would generally not be areas where people frequently travel. 

Flaa et al. (2009) indicated that using substandard components and the improper use of foot cable restraints

designed for bears could result in device failure, leading to increased risks to personnel from bears that 

escape as personnel approach to immobilize the bear. One WS employee injury was directly attributable to a 

snare or cable restraint, a laceration, and was the only report from FY13 through FY15 where the method was

positively identified; this is why all injuries are discussed because some of the other injuries could have been 

associated with cable devices, but we could not determine the method being used for many of the injury 

reports. Training, experience, and the use of gloves to protect hands and fingers helps ensure the safety of 

employees.
15

3.2 Environmental

WS recognizes that cable devices result in some risk of injury or death for nontarget wildlife and domestic 

animals (3.1% chance in neck snares and 0.2% chance in foot cable restraints of catching a nontarget species 

– Tables 1 and 2). WS supports efforts to make cable devices as humane as possible for species captured in 

them as well as minimize the potential to capture nontarget species. WS is actively involved in research efforts 

to increase humanness while minimizing impacts to nontarget species (Fagerstone and Keirn 2012). WS 

recognizes the BMPs for trapping as developed by AFWA (2009, 2017) that emphasize animal welfare, 

efficiency, selectivity, practicality, and safety. Whenever practical, WS will utilize these guidelines when using 

cable devices. The risk of capturing nontarget animals is minimized by the selection of the suitable cable and 

loop size, use of pan-tension devices for foot cable restraints, proper cable stops, proper attractants, and 

appropriate placement location. All of these issues are addressed in trapper education programs required of 

WS personnel, and reinforced during meetings and discussions with experienced trappers.

The home ranges, habitat preferences, travel corridors, and population densities of both target and nontarget 

species are considered when selecting locations for the placement of cable devices. WS policy (WS Directive 

2.450, 09/24/2014) requires that cable device placement be a minimum of 30 feet away from animal carcasses 

used as draw stations, to minimize the risk of capturing scavengers such as vultures or eagles. Signs warning 

of the placement of foothold traps in the area alert people to the presence of traps. Warning signs advise 

people to restrain pets and limit pet and livestock access in areas where cable devices are being used to 

minimize the risk of accidental capture. From FY11 to FY15, an annual average 49 feral/free roaming nontarget 

animals were captured in cable devices nationwide. This includes 41 dogs, 3 cats, and 5 livestock; of these,

18 dogs, 2 cats, and 4 livestock were killed (50%). It is unknown how many of these were feral versus freeroaming pets and livestock. However, this is a minimal number and low risk considering the amount of 

equipment in the field (8.3 million snare nights per year on average). 

4 UNCERTAINTIES AND CUMULATIVE IMPACTS

Uncertainty in this risk assessment is negligible as WS has 100 years using cable devices for WDM activities 

and understands potential risks of using the variety of available devices. The knowledge gained from this 

experience has helped reduce uncertainties. 

Cumulative impacts could occur to target and nontarget animals. However, cumulative impacts are addressed 

in National Environmental Policy Act (NEPA) documents (USDA 2017) such as WS (2017)12. To date, no WS 

NEPA document has found any significant impact to any native species population. Additionally, the 

“Introduction to Risk Assessments for Methods Used in Wildlife Damage Management” looks at all take from 

all WDM activities by WS and none of the Risk Assessments shows a significant level of take for any native 

species. From a human health perspective, the use of cable devices in WDM will not have any known 

cumulative impacts.

5 SUMMARY

In the hands of a skilled professional, cable devices are a very selective tool available for removal of specific 

problem animals. WS uses cable devices as tools in its wildlife damage management programs, typically as 

a component of an integrated approach. WS works cooperatively with natural resource agencies at the state, 

 12 WS NEPA documents are available @ https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/programs/nepa.
16

national, and international level to develop effective and humane trapping measures while minimizing 

exposure to people, pets, and nontarget animals. Implementation of program-specific protective measures 

designed to reduce human interactions with cable devices reduces the risk of these types of management 

tools to WS employees and the public. WS will continue to evaluate and implement, where appropriate, new 

protective measures. In addition, advancements in cable device use and design have resulted in more effective 

and humane capture of target animals while reducing the potential for nontarget captures. As discussed, 

nontarget capture has decreased in the last 30 years from a nontarget capture rate of 19.1% in FY88 (USDA 

1997, Appendix P, pp. 23-27) to 6.5% annual average between FY11 and FY15 in the 6 states (AZ, CO, NM, 

OK, TX, and UT) analyzed; the number of nontargets killed versus released was about the same at 91% and 

87% for the same time periods, respectively. Cable devices are passive or power-activated methods that offer 

a comparatively low risk to human health and the environment. Risks to human safety primarily occur to WS 

employees and may include minor injuries. Risks of nontarget capture occur when using cable devices. Cable 

devices are set in locations where the likelihood of capturing nontarget animals is minimized. Risks associated 

with cable devices are greatest for nontarget animals that frequent the areas where the devices are placed and 

travel along the paths of the target species. Nontarget risks are minimized by modifying the snare or cable 

restraint, such as by adjusting the size of the loop, adjusting the height of the loop above the ground, and 

adjusting the pan tension of power-activated devices. Proper loop size and placement can minimize risks to 

nontarget. The use of breakaway devices and stops allow animals larger than the target species to escape the

device. Hazards to nontarget animals associated with the use of cable devices range from minor injuries to 

potential death. Cable devices are only used by employees experienced in targeting and capturing specific 

animals, which further minimize risks to nontarget animals. However, risks of nontarget capture occur from 

the use of cable devices despite these efforts. APHIS WS will continue to support and conduct research and 

education that supports more humane and effective capture methods, and will implement these methods, 

where appropriate, to further reduce risk to target and nontarget animals.

6 LITERATURE CITED

Association of Fish and Wildlife Agencies (AFWA). 2009. Modern snares for capturing mammals: Definitions, mechanical 

attributes and use considerations. AFWA, Furbearer Conservation Technical Work Group. 24 pp.

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Phillips, R. L. 1996. Evaluation of 3 types of snares for capturing coyotes. Wildl. Soc. Bull. 24:107–110.

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23-27. Revision. USDA-APHIS-WS, Operational Support Staff, 6505 Belcrest Rd., Room 820 Federal Bldg., 

Hyattsville, MD 20782. 337 pp. 

United States Department of Agriculture (USDA). 2017. National Environmental Policy Act. USDA-APHIS-WS. @ 

https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/programs/nepa. Accessed 5/15/2017.

Wildlife Services (WS). 2017. Predator damage management in Colorado. Environmental Assessment, Finding of No 

Significant Impact, and Record of Decision. 1/19/2017. USDA-APHIS-WS, 12345 West Alameda Pkwy., Suite 210, 

Lakewood, CO 80228. 334 pp.
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7 PREPARERS

7.1 APHIS WS Methods Risk Assessment Committee

Writers for “Use of Cable Restraints in Wildlife Damage Management Risk Assessment”:

Primary Writer: Thomas Hall 

Position: USDA-WS, Operational Support Staff, Staff Wildlife Biologist, Fort Collins, CO

Education: BS Biology (Natural History) and BA Psychology – Fort Lewis College; MS Wildlife Ecology – Oklahoma State 

University

Experience: Special expertise in wildlife biology, identification, ecology, and damage management. Thirtyfour years of 

service in APHIS Wildlife Services including operations and research in CO for research and OR, GU, CA, OK, and 

NV for operations conducting a wide variety of programs including bird damage research and management, 

livestock protection (predators and birds), invasive species management, wildlife hazard management at airports, 

property and natural resource protection including waterfowl, brown tree snake, feral swine, rodent, and beaver 

damage management and including aerial operations in OR, OK, and NV. Expert in preparing environmental 

documents for WS programs to comply with the National Environmental Policy Act and the Endangered Species 

Act. For snares specifically, have used and supervised their use.

Writer: Ryan Wimberly 

Position: USDA-WS, Operational Support Staff, Staff Wildlife Biologist, Madison, TN

Education: BS Wildlife Management and Ecology – Northwest Missouri State University

Experience: Special expertise in wildlife biology, ecology, and damage management. Sixteen years of service with APHIS 

Wildlife Services, including operations and research, conducting a wide variety of programs, including bird damage 

research and management, livestock protection, invasive species management, wildlife hazard management at 

airports, property, and natural resource protection. Expert in preparing environmental documents for WS programs 

to comply with the National Environmental Policy Act and the Endangered Species Act.

Editors/Contributors for “Use of Cable Restraints in Wildlife Damage Management Risk Assessment”:

Editor: Todd Felix

Position: USDA-APHIS-Wildlife Services (WS), Wildlife Biologist, Lakewood, CO

Education: MS Biology, Central Michigan University

Experience: Special expertise in wildlife biology, ecology, and damage management. Twenty-three years of work 

experience with WS and the National Wildlife Research Center in CO, HI, and MA. Experienced in a wide range of 

program activities including airport wildlife management, wildlife disease, and wildlife damage management to 

protect livestock, aquaculture, public safety, and natural resources.

Editor/Contributor: Michael Green 

Position: USDA-APHIS-Wildlife Services (WS), Environmental Coordinator, Fredrick, MD

Education: BS Wildlife and Fisheries Sciences, University of Tennessee

Experience: Special expertise in wildlife biology, ecology, and damage management. Eleven years of work experience 

with WS in MD and VA. Experienced in a wide range of program activities including nutria eradication, airport 

wildlife management, and wildlife damage management to protect livestock, aquaculture, public safety, and 

natural resources. Served as staff biologist in WS Headquarters for two years.

Editor/Contributor: Andrea Lemay 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis Services (ERAS), 

Biological Scientist, Raleigh, NC

Education: BS Plant and Soil Science (Biotechnology) - University of Massachusetts; MS Plant Pathology -North Carolina 

State University 
19

Experience: Twelve years of service in APHIS conducting risk analysis. Four years of experience in preparing 

environmental analyses in compliance with the National Environmental Policy Act.

Editor/Contributor: Fan Wang-Cahill 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis Services (ERAS), 

Environmental Health Specialist, Riverdale, MD

Education: B.S. Biology and M.S. Hydrobiology - Jinan University, Guangzhou, China; Ph.D. Botany (Ultrastructure/Cell 

Biology) – Miami University

Experience: Joined APHIS in 2012, preparing human health risk assessments and providing assistance on 

environmental compliance. Prior experience before joining APHIS includes 18 years environmental consulting 

experience specializing in human health risk assessments for environmental contaminants at Superfund, Resource 

Conservation and Recovery Act (RCRA), and state-regulated contaminated facilities.

Editor/Contributor: Jim Warren 

Position: USDA-APHIS-Policy and Program Development (PPD), Environmental and Risk Analysis Services (ERAS), 

Environmental Toxicologist, Little Rock, AR 

Education: B.S. Forest Ecology and M.S. Entomology – University of Missouri; Ph.D. Environmental Toxicology –

Clemson University

Experience: Seven years of experience working for APHIS preparing ecological risk assessments and providing 

assistance on environmental compliance. Prior experience before joining APHIS includes other government and 

private sector work regarding ecological risk assessments related to various environmental regulations.

Data Contributor: Joey Millison

Position: USDA-WS Information and Technology (IT), Junior Applications Developer

Education: Information and Technology coursework from various sources

Experience: Eleven years of experience in APHIS, WS Management Information System (MIS) Group. Retrieves WS field 

data from the MIS for writers, reviewers, and editors.

7.2 Internal Reviewers

USDA APHIS Wildlife Services

Reviewer: Michael Yeary

Position: USDA-APHIS-WS, State Director/Supervisory Wildlife Biologist, Lakewood, CO

Education: BS in Wildlife Ecology, Texas A&M University

Experience: Special expertise in wildlife damage management including applying and supervising M-44s and their use. 

Thirty-eight years of service in APHIS Wildlife Services in TX, KS, CO, and WS Regional Office with experience in a 

wide variety of programs (livestock, aquaculture, dairy, property, natural resources, and human health and safety 

protection) including predator, bird, beaver, feral swine, and rodent damage management activities.

7.3 Peer Reviewers 

The Office of Management and Budget requires agencies to have peer review guidelines for scientific 

documents. The APHIS guidelines were followed to have “The Use of Foothold Traps in Wildlife Damage 

Management Risk Assessment” peer reviewed. WS asked AFWA to have experts review the documents. AFWA 

selected reviewers from several state agencies with the appropriate types of expertise.
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7.3.1 Peer Reviewer Agencies Selected by the Association of Fish and Wildlife Agencies

Michigan Department of Natural Resources

California Department of Fish and Wildlife

Kansas Department of Wildlife, Parks & Tourism

North Dakota Game and Fish Department

7.3.2 Comments

Comments regarding concerns with the risk assessment and a response:

1. Comment: Snares and cable restraints are not the same and cannot be used interchangeably; use of these 

words should edited. 

Response: Terminology for cable devices was adjusted and clarified throughout the document.

2. Comment: Too much discussion about irrelevant injuries to people.

Response: This was clarified in the document, and though seemingly irrelevant, the information illustrates the 

relative risk of cable devices to people as this is an overarching concern of the public and risks.

3. Comment: Inconsistent time periods – FY13-FY15 and FY11-FY15. 

Response: Data for OWCP claims was only available for FY13-FY15 – this has been clarified in document.

FY11-15 was the period used for all other analyses because take levels are best averaged over at least a fiveyear period to reflect all animal species taken.

4. Comment: Consider adding discussion of how cable restraint check times are important to reducing or 

preventing injury/death.

Response: This information has been included in the document.

5. Comment: In the first paragraph of the Introduction, an erroneous statement indicates a stop can be used to 

make a snare non-lethal. The primary components of the snare that make it non-lethal are the lock type and 

cable diameter. A significant external feature is presence of entanglement. Several statements in this document 

seem to display a misunderstanding of what it takes to live restrain with a snare (i.e. a cable restraint). As an 

aside, I believe use of stops as a mechanism of live restraint were tested and failed BMP standards.

Response: WS has used stops on neck snares to make them mostly nonlethal, but not commonly. They are 

mostly used to prevent neck snares from being lethal to nontarget species.

6. Comment: Use of terminology to describe snares is somewhat inconsistent. The document refers to “passive” 

and “power-activated” snares. The document reference “standard” and “mechanical” neck snares. Again, I 

would recommend adopting terminology from citation above.

Response: These were changed and made more consistent throughout the document.

7. Comment: Consider discussing how in-line springs on foot snares can reduce or prevent injury/death.

Response: This information has been included in the document.

8. Comment: Consider more illustrations of the methods, especially foot nooses.

Response: More pictures were included in the document. 

Commenters provided editorial suggestions and these were appreciated and corrected. They also gave 

comments on the risk assessment not requiring a response, including:
21

1. Comment: Nontarget injury and lethal take clearly are the biggest risks with the use of cable devices. Data 

summarized was sufficient to demonstrate devices are being used in an efficient and safe manner.

2. Comment: Assessment adequately addressed all components- providing appropriate details relative to the use 

and risks of a specific device as well as practices used to minimize risks associated with each tool.

3. Comment: Assumptions and uncertainties were identified and addressed adequately.

4. Comment: References were appropriate.

5. Comment: Data was sufficient in the risk assessment to assess effectiveness and safety in the risk assessment.

6. Comment: Authors admit to potential for animal injury but also lay out best management practices to reduce 

injury to non-target animals as well as humane treatment of target animals.

7. Comment: Basically I think the document pretty much covers everything I had in mind concerning techniques 

to humanely remove animals, reduce non-target capture rates, and BMPs in general. I liked seeing all the 

numbers documenting target vs non-target captures as well as success per trap nights and such. I don’t have 

anything more to add.
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Appendix 1. “Other Species” Included in Tables.

Table 1

NECK SNARES

Other predator = feral house cat*, swift fox, kit fox, mink, ringtail, hog-nosed skunk and western spotted skunks 

Other hoofed mammal = sika deer*, axis deer*, pronghorn, blackbuck*, feral cattle*, goat* and feral sheep*

Other rodent and rabbit = western gray squirrel, eastern gray squirrel, yellow-bellied marmot, hoary marmot, brown rat, 

mountain cottontail, desert cottontail and feral European rabbit*

Other raptor = turkey vulture, black vulture, red-tailed hawk, great horned owl and crested caracara

Other bird = glaucous-winged gull, Canada goose, American black duck, fork-tailed storm-petrel, ancient murrelet, wild 

turkey, gray francolin* and feral domestic chicken*

Other reptile = American alligator, southern painted turtle, black spiny-tailed iguana* and ball python*

POWER-ACTIVATED NECK SNARES

Other predator and hoofed mammal = domestic dog*, common gray fox and feral swine*

Table 2

FOOT CABLE RESTRAINTS

Other predator = feral house cat*, swift fox, kit fox, mink, ringtail, hog-nosed skunk and western spotted skunks. 

Other hoofed mammal = mule deer, white-tailed deer, Philippine deer*, feral cattle* and feral sheep*

All rodents = beaver and woodchuck

All bird = red-tailed hawk, herring gull, wild turkey and ring-necked pheasant

FOOT NOOSES

Other raptor = turkey vulture, black vulture, red-tailed hawk, great horned owl and crested caracara

Other bird = black skimmer, mew gull, northern flicker, yellow-headed blackbird, American crow, tree swallow and 

loggerhead shrike 

* Introduced