Evaluation of the Humaneness of Rodent Capture Using Glue Traps, Prepared for the Canadian Association of Humane Trapping, 31 July 2013 Author: Nicole Fenwick, M.Sc.

Evaluation of the Humaneness of Rodent Capture Using Glue Traps

Prepared for the Canadian Association of Humane Trapping, 31 July 2013

Author: Nicole Fenwick, M.Sc.

Contact: nfenwick@shaw.ca

Summary

Glue traps are used for rodent pest control, particularly when chemical control methods (e.g. rodenticides) are undesirable, but their humaneness is questioned. Few scientific studies report on the effects that glue trapping has on rodents due to the ethical concerns of conducting harmful animal research. However, these findings show that rodents struggle to escape and become fully entangled in the glue, with feet, body and head eventually becoming stuck. Other data shows that a large proportion of glue-trapped rodents remain alive for at least 24 hours after capture. In evaluations of vertebrate pest control, methods that are considered the most humane generally cause the least amount and shortest duration of pain and distress. Therefore, the available evidence overwhelmingly demonstrates that the use of glue traps for rodent pest control does not meet established standards for either humane restraint or humane killing.

Introduction

Control of rodents (mice and rats) is an important part of minimizing health hazards for humans and protecting food supplies. Currently, a legal method of rodent control in Canada is to capture and remove them using a trapping device generally known as a “glue trap”. Various names are used to identify these devices including: glue trap, glue board, sticky board, sticky trap and others. For the purposes of this report, the term “glue traps” will be used unless otherwise stated. Glue traps typically consist of a flat, rigid base, such as a cardboard board or a plastic tray, coated on one side with a strongly adhesive glue (e.g. Frantz & Padula 1983). Sometimes they are used with a cover, creating a tunnel over the trap, or used with a bait to attract rodents. They are placed along areas of high rodent traffic (runways) so that when a rodent runs across the trap it is caught, unable to disentangle from the glue. They are used particularly when the use of chemical control methods (e.g. rodenticides) are undesirable, such as in interior food storage and preparation areas. Glue traps are widely available for purchase and used by both pest control professionals and private homeowners. However, their use is controversial for reasons related to animal welfare (e.g. Littin & Mellor 2005; Meerburg et al. 2008; Yeates 2010).

The term ‘animal’ welfare generally refers to the well-being of an animal. Within the academic discipline of animal welfare science it is further defined, and refers to whether an animal is physically and psychologically healthy; leads a reasonably natural life (for the species); and enjoys life without significant suffering (Fraser 2008). In this way, ‘animal welfare’ has been described as an “evaluative concept” that is not “merely descriptive but, rather, incorporate[s] notions of good and bad, better and worse” similar to the concept of food safety (Fraser 2008 p.273). To assess animal welfare outcomes and the humaneness of using glue traps for rodent pest control, an evidence-based review was carried out and the findings interpreted from the perspective of animal welfare science.

Evaluating the humaneness of vertebrate pest control methods

In evaluations of vertebrate pest control, methods that are considered the most humane generally cause the least amount and shortest duration of pain and distress (e.g. Mason & Littin 2003). Given the ethical concerns of conducting harmful research on animals, there is only a small amount of peer-reviewed experimental evidence that specifically evaluates the humaneness of pest control methods. Therefore, when these reviews are carried out, authors extrapolate from other mammalian data (including human) and use evidence collected from the field of laboratory animal science and/or evaluations of trap mechanical performance.

For example, to assess the welfare outcomes of fumigating rabbit warrens with the poisonous gas chloropicrin, data from sensory irritation and systematic toxicity studies from a variety of mammals, along with a review of symptoms and pathology prior to death were used (Marks 2009). The killing efficacy of spring traps was extrapolated from an experiment to assess the clamping force and impact momentum of the traps (Baker et al. 2012). Various non-rodent mammal killing and restraining traps were reviewed for their effect on target animals, and included consideration of physiological and physical outcomes such as injuries caused, time to death and trap reliability (Iossa et al. 2007). Species-specific biological and physiological details of the mole, such as thermoregulatory, hydration and social needs, were used to evaluate the humaneness of mole tube traps for live-trapping and relocation of moles in residential gardens (Baker & Macdonald 2012).

Although these studies evaluated quite different methods of pest control using varying types of data, similar criteria were used to assess humaneness. These criteria included: time to unconscious and/or death; amount and severity of symptoms/injuries prior to death; amount of distress caused; reliability of the method; and the appearance and behaviour of target animals. In addition, unintended effects of the pest control method were also examined (such as impact on non-target animals).

Humaneness of a trapping method can also be evaluated by comparing the effect on animals with established standards for animal use. The humane standards for the use of animals in science has been proposed by several authors as a way to evaluate the humaneness of pest control methods (Meerburg et al. 2008; Yeates 2010). Others have suggested referring to the standards developed for trapping fur-bearing mammals (International Union for Conservation of Nature 1990; International Organization for Standardization 1999a, 1999b; Talling & Inglis 2009). These criteria and evidence-gathering methods provide a framework for the examination of the humaneness of using glue traps in rodent pest control. Although this was examined briefly by Mason & Littin (2003), their analysis relied partially on anecdotal reports. Therefore, the present review aims to build on Mason & Littin’s (2003) critique by the inclusion of additional peer-reviewed information and comparison with established humane standards.

Experimental studies involving glue trap capture of rodents

A literature search was carried out to identify peer-reviewed, scientific studies with relevance to the use of glue traps. Searches were conducted in Agricola, Google Scholar, PubMed and Web of Knowledge using the following search terms or combination of terms: ‘rodent’, ‘glue traps’, ‘glue boards’ ‘glueboards’, ‘sticky boards’, ‘sticky traps’ ‘rodent humane trapping’, ‘rodent traps’, ‘rodent pest control’ and ‘animal welfare’. In addition, a citation search was conducted for each article involving the experimental use of glue traps for rodent capture. Details of relevant, accessible studies reporting use of glue traps are given in Table 1.

Table 1: Experimental studies that involve use of glue traps to capture rodents

Study	Study Purpose	Rodent Species	Glue Trap Type	Ambient Temperature	Trap Placement
Advani (1992)	Efficacy of glue traps to “clean out” mice populations; efficacy of anti-coagulants for population maintenance	Mouse (Mus musculus)(wild)	not reported	not reported	Urban: New York City, United States (US) apartment buildings, indoors
Cavia et al. (2012)	Evaluation of methods to estimate rodent abundance in urban environments	Rat (Rattus norvegicus)(wild)	Cardboard boards, baited with peanut butter	not reported	Urban: Buenos Aires, Argentina coastal area, outdoors
Corrigan (1998)	Efficacy of glue traps for capture of mice	Mouse (Mus domesticus)(wild)	Cardboard boards and plastic trays	18 – 30°C	Rural: Indiana US, livestock buildings, indoors
Frantz & Padula (1983)	Laboratory evaluation of efficacy of glue traps for capturing mice	Albino house mouse (Mus musculus)(laboratory-bred)	Plastic trays	23 – 33°C	Urban: New York, US, laboratory animal facility mouse room, indoors
Kim et al. (2007)	Rodent-borne disease surveillance	Rat (Rattus norvegicus)(wild)	Boards	-2 – 25°C	Urban: Seoul, South Korea, military base, indoors
Tripathi et al. (1994)	Comparison of glue trap efficacy with live traps andbehaviour of trapped rodents	Rat (Rattus rattus); Mouse (Mus musculus)(wild)	Cardboard boards	not reported	Rural: India, residential premises and poultry farms, and laboratory facility, indoors

Physical effects of glue trap capture

Few scientific studies report on the physical effects that glue trapping has on rodents. Of these, just two studies include detailed observations of which body parts are caught and what injuries are sustained (Frantz & Padula 1983; Tripathi et al. 1994). Frantz and Padula (1983) conducted two separate experiments to evaluate the “holding ability” of two brands of glue traps. In the first, mice were deliberately placed on the glue traps by the experimenters (“no-choice”) and in the second, mice were exposed to the trap in their home environment but were not placed on the traps by experimenters (“choice”). Similarly, in their study comparing glue trap efficacy to live traps, Tripathi et al. (1994) carried out a laboratory experiment (with deliberate placement of rats onto the glue trap) and a field experiment. However, physical and behavioural observations were only made for the laboratory experiment. A summary of the physical observations of capture are provided in Table 2.

Table 2: Summary of post-glue trap capture physical observations of rodents

Reported Observation	Frantz & Padula (1983) (no-choice; 40 mice)	Frantz & Padula (1983) (choice; 19 mice)	Tripathi et al. (1994) (laboratory; 4 rats)
Feet caught/entangled	ü	ü	ü
Trunk of body caught	ü	ü	ü
Face/head caught	ü	ü	ü
Defecation	ü	not reported	ü
Urination	ü	not reported	ü
Eye damage/pathology	ü	not reported	not reported
Mouth glued shut	ü	not reported	ü
Raw skin	ü	not reported	not reported

All three experiments found that rodents become fully entangled in the glue, with feet, body and head eventually becoming stuck. They also report that the animals’ mouths became glued shut as a result of trying to chew themselves free from the trap. Two of the experiments observed the animals repeatedly defecating and urinating while one reported that the animals had eye damage and, where fur was torn away, raw skin patches.

The methods used had some limitations. Tripathi et al. (1994) did not provide a rationale for procedures or describe them in sufficient detail. For example, it was not explained why trapped rodents, freed for further observations, were then placed in cages with different types of flooring. Frantz and Padula (1983) used laboratory-bred mice for their study and carried out experiments at daytime temperatures. How this information may translate to wild mice, typically caught at cooler nighttime temperatures, is unknown. They also reported that some captured rodents had “broken” their legs while struggling to free themselves from the trap, however it is not clear how this injury was determined as necropsies were not conducted. The scientifically acceptable method of injury assessment, in particular for internal injuries, requires examination by veterinary pathologists (e.g. Iossa et al. 2007; Talling & Inglis 2009). Therefore, this review only considers the physical effects that can be observed without specialist training. Despite limitations, these experimental observations are consistent with technical information supplied by the pest control industry and anecdotal reports of use. For example, an agricultural college extension document reports that “[m]ice become entangled in the glue when they run over the boards…dying of suffocation” (Potter 1994).

Proportion of rodents found alive after capture in glue traps

Several studies using glue traps also reported on whether captured rodents were found dead or alive (summarized in Table 3).

Table 3: Summary of rodents found alive after capture in glue traps

Study	Rodent Type	Number Captured	Number found alive on glue trap			% alive after 24 hours
			3 hours	5 hours	24 hours
Cavia et al. (2012)	Rat	2	–	–	0	0
Frantz & Padula (1983) (no choice)	Mouse	40	38	38	35	85
Frantz & Padula (1983) (choice)	Mouse	19	–	–	16	84
Tripathi et al. (1994) (laboratory)	Rat	4	4	4	0	0
Kim et al. (2007)	Rat	1,750	–	–	yes	–

Some of this information is incomplete, for example Kim et al. (2007) did not report the number found alive, just that live captured animals were found 24 hours after placement and “euthanized in accordance with standard laboratory practices” (p.760). In addition, in some studies the exact time of capture was not known and traps were monitored only once every 24 hours, meaning the length of time rodents were held on the trap could vary considerably. Although animals may be captured at any time during the 24 hours period, Tripathi et al. (1994) observed the capture of rodents within 10 to 15 minutes of placement in areas with a high rodent population (p.144). However, the data clearly shows that a proportion of glue-trapped rodents remain alive for at least 24 hours after capture. In one experiment, carried out by Frantz & Padula (1983), 85% of the animals placed on glue traps (“no-choice”) were alive after 24 hours. In their second experiment, 84% of mice captured were found alive at 24 hours after trap placement (“choice”). These findings correspond with information provided in pest control technical reports, which find it necessary to suggest methods for killing rodents found alive on glue traps (Timm 1994a, 1994b).

Behavioural effects of capture

Just two studies include behavioural observations of rodents captured by glue traps (Table 4) (Frantz & Padula 1983; Tripathi et al. 1994). Some of the observations were made after trapped animals were freed by the experimenters and placed in cages with food and water sources. The animals were observed struggling to escape the traps and audibly vocalizing. Frantz & Padula (1983) wrote that “most animals struggled vigorously” when placed on the glue trap and mice “stretched, twisted, and pulled on body parts caught in the glue; some mice bit and chewed on strands of adhesive or on their hair embedded in the adhesive” (p.218). Tripathi et al. (1994) described rats as “exhausted” from struggling to escape (p.144). In addition, they observed rats trying to drink water, and being unable to do so as their mouths were glued shut (Tripathi et al. 1994).

Table 4: Summary of behavioural observations of glue-trapped rodents

Observation	Frantz & Padula (1983) (no-choice)	Tripathi et al. (1994) (laboratory)
Struggling (escape behaviour)	ü	ü
Vocalization (audible)	ü	ü
Unable to drink	not reported	ü

Field evaluations of glue trap efficacy as a rodent control method

Some of the glue trap studies carried out field experiments to evaluate the effectiveness of this rodent control method but their findings were mixed (Table 5). Two studies concluded that glue traps were effective for the capture of mice (Advani 1992; Tripathi et al. 1994) and one found them to be ineffective (Corrigan 1998). Advani (1992) found glue traps useful for “initial clean out of high densities of mice population” (p.210) and Tripathi et al. (1994) found that they were effective for rats and mice.

Corrigan (1998) compared the efficacy of glue traps and against other trap types, finding that snap traps and curiosity traps had higher capture rates than glue traps. The relative ineffectiveness of glue traps in Corrigan’s (1998) study was attributed to mice’s ability “to determine and avoid the danger of sticky surfaces” (p.272) using facial vibrissae (whiskers) to explore the area in front of them, and to trap contamination by dirt, dust and moisture. Cavia et al. (2012) found glue traps ineffective at trapping rats in an outdoor location and similarly attributed it to humidity and dust contamination. The effect of contamination has also been reported in the technical literature and anecdotally (e.g. Fitzwater 1982; Timm 1994a).

Table 5: Field studies of the efficacy of rodent capture with glue traps

Study	Rural/Urban	Indoor/ Outdoor	Effective for rats	Effective for mice
Advani (1992)	Urban	Indoors	–	yes
Cavia et al. (2012)	Urban	Outdoors	no	–
Corrigan (1998)	Rural	Indoors	–	no
Tripathi et al. (1994)	Rural	Indoors	yes	yes

Unintended effects of rodent glue traps: human health and non-target species

The presence of rodents has long been associated with negative impacts on human health (e.g. Advani 1992; Kim et al. 2007; Phipatanakul et al. 2012). This has necessitated the need to control rodent populations and remove them from human settlements. However, some evidence suggests that use of glue traps can contribute to human health hazards associated with rodents, or reduce the effectiveness of attempts to minimize them. Deficiencies in trap management and timely disposal of dead rodents can result in contamination from rodent urine, feces and decomposing carcasses. This can cause, for example, impacts to humans with asthma and rodent allergies (Phipatanakul et al. 2012), blowfly infestations (Beckendorf et al. 2002) and illness from hantavirus (Health Canada 2013). Due to the health hazards of coming into direct contact with wild rodents, it is difficult to humanely kill those still alive and caught in a glue trap. Pest control professionals advise that “Traps and glue boards should be checked daily and dead mice disposed of in plastic bags. Gloves should be worn when handling mouse carcasses” (Potter 1994; Health Canada 2013). However, for the general public there appears to be a lack of widely accessible information about safe handling procedures and humane methods for killing trapped live rodents.

The use of glue traps to capture rodents can also have unintended harmful effects on non-target species. For example, raptors attempting to eat the captured rats or mice may themselves become entangled in the glue. A Spanish study of raptor admissions to wildlife rehabilitation centres for years 1998-2007 found that 4.7% of admissions were due to glue traps (Rodriguez et al. 2010). The glue traps caused plumage damage, resulting in the birds being unable to fly. Glue traps also have the capacity to trap reptiles, and are used in some studies of herpetology to capture lizards and snakes for scientific study (Ribeiro-Junior et al. 2006). Glue traps were effective at holding the lizards, as researchers reported having to use vegetable oil to release them. Various studies have reported glue trap capture mortality rates for lizards ranging from 11% to 48% (as summarized in Ribeiro-Junior et al. 2006)(Glor et al. 2000; Ribeiro-Junior et al. 2006; Vargas et al. 2000). In one study, the principal cause of mortality for glue trapped lizards was “ant predation” and these authors recommended that traps be checked more frequently to avoid this (Ribeiro-Junior et al. 2006).

Evaluation of glue trap humaneness

Severity of injuries and distress

It is well-established in the scientific literature that rodents experience both pain and distress (Baumans et al. 1994; Kohn et al. 2007; Committee on Recognition and Alleviation of Distress in Laboratory Animals 2008). This literature review has shown that rodents captured and restrained in glue traps are restrained in a way that causes physical injury. They also exhibit behaviours associated with acute distress and fear, such as struggling and vocalization (Baumans et al. 1994; Brown et al. 2006; Kohn et al. 2007). In one study, the remains of trapped rodents were found eaten (Cavia et al. 2012), suggesting that the live-caught animals likely experienced acute fear from predation. In addition, in most of the reviewed studies, many trapped rodents were found alive after 24 hours and therefore likely experienced their injuries and distress for a prolonged length of time.

The severity of injuries and distress experienced by rodents caught in glue traps was compared with established standards for humane use of rodents in science. In Canada, the Canadian Council on Animal Care (CCAC)’s Categories of Invasiveness for Wildlife Studies are used to assess the level of pain and distress of animal use in wildlife research. The animal outcomes of using glue traps place it into Category of Invasiveness “E”, the most severe category, because it exposes trapped animals to “environmental deprivation that has the potential to seriously jeopardize an animal’s well-being” and it is a “capture method with a high potential of causing severe injury that could result in severe chronic pain” (CCAC 2003 p.63).

The Agreement on International Humane Trapping Standards (AIHTS) states that humane evaluation of restraint traps includes consideration of the states of “psychological distress (i.e. fear), physiological distress (i.e. a high level of stress), pain, and physical injury” and acknowledged the interrelation of these states (Talling & Inglis 2009 p.160). To classify a restraining device as humane, released, uninjured animals must be able to return to their normal patterns of behaviour. Therefore the AIHTS concluded: “type of physical injury caused by a restraining trap was therefore chosen as the best indicator of the welfare of animals caught in that trap” (p.161). Assessment against these criteria determines that glue traps are inhumane, as trapped rodents experience a high degree of fear and physical injury and, when released, cannot resume normal behaviour. This assessment is in agreement with the Canadian Veterinary Medical Association (CVMA)’s pest control position statement that describes the use of “sticky boards” (glue traps) to capture rodents as an inhumane method (CVMA 2003).

Time to death

Time to death is another commonly used indicator of humaneness. The finding of live animals after 24 hours raises two additional animal welfare concerns: what is an acceptable time to death; and what methods are used to kill live-captured animals (since glue trapped rodents cannot be freed from the glue and relocated). The AIHTS describes the ideal kill trap as “one that kills without the captured animal experiencing any pain or suffering” (Talling & Inglis 2009 p.60) and this includes the animal experiencing irreversible unconsciousness within 60 seconds. Marks (2009) noted that the characteristics of a humane pest control killing method are “broadly similar to those described for methods of humane animal euthanasia” (p.349). The CCAC euthanasia guideline (CCAC 2010) for animals used in science (all vertebrates and cephalopods) similarly requires killing methods to be “as distress free and painless as possible” (p.7) and result in rapid loss of consciousness. The CVMA similarly states that animal death should be “quick and cause the least possible pain and distress” and states that this euthanasia position also applies to pest control methods (CVMA 2006). The American Veterinary Medical Association (AVMA) also states that glue traps are an unacceptable form of killing animals (AVMA 2013).

Appropriate killing methods for live-captured rodents remains a concern, particularly when glue traps are used by members of the public. Pest control technical information suggests using carbon dioxide to asphyxiate rodents or a “stick to kill them with sharp blows to the base of the skull” (Timm 1994a, 1994b). In a laboratory setting, cervical dislocation is often used (CCAC 2010), however all these methods require specialized equipment and/or training to carry out humanely. It is unclear what methods of killing members of the public use when they have captured a live rodent, and whether they are able to perform the killing humanely.

Mitigation of the animal welfare problems associated with glue traps

Some mitigation of the welfare problems associated with glue traps may be possible if animal distress can be minimized and if humane killing of live animals in glue traps is achievable. It may be possible to decrease the pain and distress experienced by captured rodents if traps are baited with sedative-containing bait (Mason & Littin 2003). However, the rodent would need to consume the bait prior to being trapped or its mouth becoming glued shut. The duration of distress for trapped animals may be minimized by frequent trap checking and placement at only indoor locations to minimize predation on trapped rodents.

Although there are precedents to show that wild animals benefit from pest control research (Hiltz & Roy n.d.; Warburton & O’Connor 2004), any future research using glue traps should proceed cautiously. Animal welfare science ethics would require that research only be conducted in an applied situation (i.e. when glue traps were to be used regardless of the proposed research) as it is not necessary to further prove the inhumanness of glue traps. In these controlled and supervised studies, it may be informative to record ultrasonic vocalizations as a way to measure rodent distress (Castelhano-Carlos & Baumans 2009). Social science research to determine how users of glue traps kill live rodents and how often they check traps would be useful. Most importantly, continued research into the development and evaluation of new, more humane methods of rodent pest control is needed. Mason and Litton (2003) suggest the following areas for study: chemical killing agents, repellent compounds and anti-fertility compounds.

What are the alternatives to glue traps?

Ethical use of pest control methods requires first considering whether it is necessary to control pests at all and second, whether it is necessary to kill them for control (Littin & Mellor 2005; Yeates 2010). The use of integrated pest management (IPM) strategies are also advocated. IPM rodent management consists of prevention (the exclusion of rodents and reducing the attractiveness of their habitat); monitoring (to assist in pest control decision-making); and control (killing) (Traweger et al. 2006; Meerburg et al. 2008). With this approach, the “goal is to change the carrying capacity of an environment for the pest species of concern” with killing as just one part of pest management (Traweger et al. 2006 p.123).

When it has been determined that rodents must be killed, sufficient evidence proves glue traps are not humane and may not be the most effective method of control (due to susceptibility to dust, humidity, temperature). In their comprehensive review of the humaneness of rodent pest control, Mason and Litton (2003) determined that the most humane currently available methods include: deterrence and proofing; well-designed snap traps; electrocution traps; cyanide gas; bait poison alpha-chloralose; and live-trapping followed by humane killing. Further, newer snap-traps are being developed with goal of meeting modern requirements for efficacy and animal welfare outcomes (Thomas et al. 2011).

Conclusion – the humaneness of glue traps

As discussed, just two laboratory studies on the effect of glue traps on rodents have been conducted. However, these experiments, combined with observations from field use of glue traps, provide overwhelming evidence that their use does not meet established standards for either humane restraint or humane killing. This review finds that the current use of glue traps is inhumane and agrees with similar findings reached by other reviewers (Mason & Littin 2003; Meerburg et al. 2008) and with positions taken by North American veterinary medicine professional associations (CVMA 2006; AVMA 2013).

Acknowledgments: Thank-you to Sara Dubois, Dr. Deborah McLennan and Don Mitton for providing information, advice and critical reviews of earlier versions of this report.

References

Advani, R. 1992. Field evaluation of three anticoagulant rodenticides against Mus musculus populations in apartmental buildings in New York City. In: Proceedings of the 15th Vertebrate Pest Conference, (Ed. by J. E. Borrecco & R. E. Marsh), pp. 208–211. Davis, California: University of California.

American Veterinary Medical Association (AVMA). 2013. AVMA Guidelines for the Euthanasia of Animals : 2013 Edition. Schaumburg IL: AVMA.

Baker, S. & Macdonald, D. 2012. Not so humane mole tube traps. Animal Welfare, 21, 613–615.

Baker, S., Ellwood, S., Tagarielli, V. L. & Macdonald, D. W. 2012. Mechanical performance of rat, mouse and mole spring traps, and possible implications for welfare performance. PloS One, 7, e39334.

Baumans, V., Brain, P. F., Brugere, H., Clausing, P., Jeneskog, T. & Perretta, G. 1994. Pain and distress in laboratory rodents and lagomorphs: Report of the Federation of European Laboratory Animal Science Associations (FELASA) Working Group on Pain and Distress accepted by the FELASA Board of Management November 1992. Laboratory Animals, 28, 97–112.

Beckendorf, R., Klotz, S., Hinkle, N. & Bartholomew, W. 2002. Nasal myiasis in an intensive care unit linked to hospital-wide mouse infestation. Archives of Internal Medicine, 162, 638–40.

Brown, M., Carbone, L., Conlee, K. M., Dawkins, M. S., Duncan, I. J., Fraser, D., Griffin, G., Hampshire, V., Lambert, L., Mench, J., Morton, D., Richmond, J., Rollin, B. E., Rowan, A. N., Stephens, M. L. & Würbel, H. 2006. Report of the Working Group on Animal Distress in the Laboratory. Lab Animal, 35, 26–30.

Canadian Council on Animal Care (CCAC). 2003. CCAC guidelines on : the care and use of wildlife. Ottawa, ON. http://www.ccac.ca/Documents/Standards/Guidelines/Wildlife.pdf

Canadian Council on Animal Care (CCAC). 2010. CCAC guidelines on : euthanasia of animals used in science. Ottawa, ON. http://ccac.ca/Documents/Standards/Guidelines/Euthanasia.pdf

Canadian Veterinary Medical Association (CVMA). 2003. Pest Control – Position Statement. http://www.canadianveterinarians.net/DOCUMENTS/PEST-CONTROL

Canadian Veterinary Medical Association (CVMA). 2006. Euthanasia – Position Statement. http://canadianveterinarians.net/DOCUMENTS/EUTHANASIA

Castelhano-Carlos, M. J. & Baumans, V. 2009. The impact of light, noise, cage cleaning and in-house transport on welfare and stress of laboratory rats. Laboratory Animals, 43, 311–27.

Cavia, R., Cueto, G. R. & Suárez, O. V. 2012. Techniques to estimate abundance and monitoring rodent pests in urban environments. In: Integrated Pest Management and Pest Control – Current and Future Tactics, (Ed. by S. Soloneski), pp. 147–172. Rijeka, Croatia: InTech.

Committee on Recognition and Alleviation of Distress in Laboratory Animals. 2008. Recognition and Alleviation of Distress in Laboratory Animals. Washington, DC: National Academies Press.

Corrigan, R. M. 1998. The efficacy of glue traps against wild populations of house mice , Mus domesticus , Rutty. In: Proceedings of the 18th Vertebrate Pest Conference, Costa Mesa, California, (Ed. by R. O. Baker & A. C. Crabb), pp. 268–275. Davis, CA: University of California.

Fitzwater, W. D. 1982. Bird limes and rat glues — sticky situations. In: Proceedings of the Tenth Vertebrate Pest Conference, (Ed. by R. E. Marsh), pp. 17–20. Davis, CA: University of California.

Frantz, S. C. & Padula, C. M. 1983. A laboratory test method for evaluating the efficacy of glueboards for trapping house mice. In: Vertebrate Pest Control and Management Materials: Fourth Symposium, (Ed. by D. E. Kaukeinen), pp. 209–225. Philadelphia, PA: American Society for Testing and Materials.

Fraser, D. 2008. Understanding Animal Welfare : the Science in its Cultural Context. 1st edn. Chichester, UK: Wiley Blackwell.

Health Canada. 2013. Archived-Hantaviruses. http://www.hc-sc.gc.ca/fniah-spnia/promotion/public-publique/hantavirus-eng.php#a3

Hiltz, M. & Roy, L. D. (n.d.).Rating killing traps against trapping standards using computer simulations. http://www.fur.ca/files/Rating%20Killinng%20Traps%20against%20Humane%20Trapping%20Standards.pdf

International Organization for Standardization. 1999a. ISO 109990-5 Animal (mammal) traps – Part 5: Methods for testing restraining traps. Geneva, CH.

International Organization for Standardization. 1999b. ISO 10990-4 Animal (mammal) traps – Part 4: Methods for testing killing-trap systems used on land or underwater. Geneva, CH.

International Union for Conservation of Nature. 1990. Resolutions and Recommendations: 18th Session of the General Assembly of ICUN- The World Conservation Union. Perth, AU.

Iossa, G., Soulsbury, C. D. & Harris, S. 2007. Mammal trapping : a review of animal welfare standards of killing and restraining traps. Animal Welfare, 16, 335–352.

Kim, H.-C., Klein, T. A., Chong, S.-T., Collier, B. W., Yi, S. C., Song, K.-J., Baek, L.-J. & Song, J.-W. 2007. Seroepidemiological survey of rodents collected at a U.S. military installation, Yongsan Garrison, Seoul, Republic of Korea. Military Medicine, 172, 759–764.

Kohn, D., Martin, T., Foley, P., Morris, T., Swindle, M., Vogler, G. & Wixson, S. 2007. Guidelines for the assessment and management of pain in rodents and rabbits. Journal of the American Association for Laboratory Animal Science, 46, 97–108.

Littin, K. E. & Mellor, D. J. 2005. Strategic animal welfare issues: ethical and animal welfare issues arising from the killing of wildlife for disease control and environmental reasons. Revue scientifique et technique (International Office of Epizootics), 24, 767–82.

Marks, C. A. 2009. Fumigation of rabbit warrens with chloropicrin produces poor welfare outcomes – a review. Wildlife Research, 36, 342.

Mason, G. & Littin, K. E. 2003. The humaneness of rodent pest control. Animal Welfare, 12, 1–38.

Meerburg, B. G., Brom, F. W. A. & Kijlstra, A. 2008. The ethics of rodent control. Pest Management Science, 64, 1205–1211.

Phipatanakul, W., Matsui, E., Portnoy, J., Williams, B., Barnes, C., Kennedy, K., Bernstein, D., Blessing-Moore, J., Cox, L., Khan, D., Lang, D., Nicklas, R., Oppenheimer, J., Randolph, C., Schuller, D., Spector, S., Tilles, S., Wallace, D., Sublett, J., Bernstein, J., Grimes, C., Miller, J. & Seltzer, J. 2012. Environmental assessement and exposure reduction of rodents: a practice parameter. Annals of Allergy, Asthma and Immunology, 109, 375–387.

Potter, M. 1994. Control of Mice. Kentucky, US. Kentucky Cooperative Extension Service.

Ribeiro-Junior, M., Gardner, T. & Avila-Pires, T. 2006. The effectiveness of glue traps to sample lizards in a tropical rainforest. South American Journal of Herpetology, 1, 131–137.

Rodriguez, B., Rodriguez, A., Siverio, F. & Siverio, M. 2010. Causes of raptor admissions to a wildlife rehabilitation center in Tenerife (Canary Islands ). Journal of Raptor Research, 44, 30–39.

Talling, J. & Inglis, I. 2009. Improvements to trapping standards. 1–329. http://ec.europa.eu/environment/biodiversity/animal_welfare/hts/pdf/final_report.pdf

Thomas, B., Taylor, R., Dunlevy, P., Mouritsen, K. & Kemp, J. 2011. The Ka Mate reverse-bait snap trap – a promising new development. In: Island Invasives: Eradication and Management, (Ed. by C. Veitch, M. Clout, & D. Towns), pp. 233–238. Gland, CH: IUCN.

Timm, R. M. 1994a. House Mice. In: The Handbook: Prevention and Control of Wildlife Damage, pp. B31–B46. DigitalCommons@University of Nebraska-Lincoln.

Timm, R. M. 1994b. Norway Rats. In: The Handbook: Prevention and Control of Wildlife Damage, pp. B105–B120. DigitalCommons@University of Nebraska-Lincoln.

Traweger, D., Travnitzky, R., Moser, C., Walzer, C. & Bernatzky, G. 2006. Habitat preferences and distribution of the brown rat (Rattus norvegicus Berk.) in the city of Salzburg (Austria): implications for an urban rat management. Journal of Pest Science, 79, 113–125.

Tripathi, R. S., Mathur, M., Jain, A. P. & Patel N. 1994. Relative efficacy of glue and other traps for commensal rodent management. Annals of Arid Zone, 33, 143–145.

Warburton, B. & O’Connor, C. 2004. Research on vertebrate pesticides and traps: do wild animals benefit? Alternatives to laboratory animals : ATLA, 32 Suppl 1, 229–34.

Yeates, J. 2010. What can pest management learn from laboratory animal ethics? Pest Management Science, 66, 231–237.