Municipal urban rat management policies and programming in seven cities in the United States of America

ABSTRACT

While literature indicates that municipal rat management approaches are often unsuccessful, a lack of research comparing strategies makes the breadth of opportunities and challenges associated with different approaches uncertain. Here, we explored the municipal rat management policies and programs in seven cities in the United States of America. Rat policies were attained by collecting rat management-related municipal codes in each city. Information on rat programs was obtained through interviewing program stakeholders. Analysis followed a qualitative framework method to identify and describe themes associated with the structure and function of management approaches. Municipal codes served as a foundation for municipalities by outlining when, where, how, and by whom rat problems should be addressed. Programs employed the primary people responsible for performing on-the-ground management and they acted as a municipal “brain,” organizing the city’s strategy. We identify opportunities and barriers for other municipalities to consider in the design of their own rat management strategies.

KEYWORDS:

• Cities
• state and local governments
• urban health

Introduction

Rat (Rattus spp.) infestations are common in cities around the world and are associated with a constellation of negative consequences (Colvin & Jackson, 1999). Rats are the source of several pathogens responsible for morbidity and mortality in people (Pépin et al., 2016) and companion animals (Meeyam et al., 2006). Sharing living spaces with rats can affect mental health, resulting in anxiety, avoidance behaviors, and negative self-perceptions (Byers et al., 2019; German & Latkin, 2016). Rats impact local economies by damaging property and infrastructure and by contaminating and consuming foodstuffs (Almeida et al., 2013; Garba et al., 2014). Given that rat infestations and rat-human interactions may intensify in association with increased urbanization and densification (Himsworth et al., 2013), it is important that cities implement effective and efficient approaches to prevent, monitor, and eliminate their negative impacts (henceforth collectively referred to as management).

Although many municipalities have enacted citywide management initiatives, previous literature has indicated that many of these approaches have not been able to demonstrate a sustainable reduction in the number of rats (Lee et al., 2022). While the reasons for these reported failures are unclear, authors have suggested that this may be due to a lack of resources (Kaukeinen, 1994; Wirth & Brown, 2015), a lack of interest or prioritization by relevant stakeholders (Colvin & Jackson, 1999; Davis, 1952), an inability to account for the complexity of rat management (Davis & Jackson, 1981; Meyer, 1999), and difficulties in changing residents’ behaviors contributing to rats (Fall & Jackson, 1998; Lambropoulos et al., 1999).

The full scope of strengths, barriers, and opportunities associated with different city-scale strategies remains uncertain because of limited research describing, examining, evaluating, and comparing different municipal rat management approaches. In this study, we describe and explore the structure and function of the municipal rat management programs and policies in seven cities in the United States of America (USA). We synthesize this information to identify the potential strengths, barriers, and opportunities that exist in citywide rat management with a view toward informing future development and/or refinement of municipal rat management approaches.

Materials and methods

Municipalities

Seven municipalities in the USA that had ongoing, municipally-run, rat management programs were included in this study. Six of these cities were identified by a subject-area expert (author RMC) as representing a diversity of rat management approaches. The seventh city volunteered to participate prior to the start of this study. All except one city had a sea or lakeport and they ranged in population size from approximately 60,000 to more than 8 million. Cities were numbered to preserve stakeholder and program anonymity. Data on each municipal rat management strategy were collected from two main sources: (1) municipal code related to rat management; and (2) interviews and site visits with stakeholders in municipal rat management programs.

Municipal code

Municipal codes are the collection of all legislation that local governments enact, and they contain the specific legal tools (i.e., bylaws) that municipalities use to achieve their policy goals (Cook et al., 2016). We collected codes from the online databases: American Legal Publishing Corporation (Cincinnati, Ohio); Municode (Tallahassee, Florida); and LexisNexis (New York, New York). Each municipal code was searched using the keywords rat, rats, rodent, and rodents, which were combined using the boolean operator “OR.” For clarity, the term rat will be used to refer to both rats and rodents in general, unless otherwise specified. Codes were included if they were written with an intent to facilitate rat management such that codes related to rat-proofing garbage bins were included, but general garbage regulations that could impact rats, but were not written specifically about them, were excluded. We also included violation and enforcement sections associated with each rat management code—these sections contained the details of how and when the municipality could act in the case of noncompliance with bylaws (i.e., tickets, fines, orders to attend court). Codes were initially downloaded in May 2019 and checked for updates in October 2019. Stakeholders (see, section 2.3) were also asked which codes their rat programs used, and any codes not initially identified using the search strategy (e.g., public health codes that were distinct from the municipal codes) were included.

Interviews and site visits

Interviews and associated methodology are described in detail in Lee et al. (2021). Briefly, author MJL traveled to each city and spoke with stakeholders in each municipality’s rat management program via either in-depth individual, dual, or group (three to five people) interviews. The purpose of these interviews was to elicit descriptions of the municipal rat management programs from the perspective of these stakeholders. Their opinions on best practices in municipal rat management are described elsewhere (Lee et al., 2021). Stakeholders included directors and managers of the rat management programs under study, additional stakeholders identified by those managers and directors, and pest management professionals (PMPs) recruited at a metropolitan pest management conference. The number of interviewees varied by city. In City 1, we interviewed one municipal stakeholder from the mayor’s office, and the remaining participants were private PMPs, while in City 4 we interviewed three program leaders (director, assistant commissioner of the health department, design consultant). In the remaining five cities (City 2, City 3, City 5, City 6, and City 7), we interviewed nearly every program employee and multiple collaborators (i.e., public health veterinarians, private PMPs, a food program director, a professor). Sessions were semi-structured using a prepared interview guide and were conversational and open ended.

At the discretion of stakeholders, interviews were paired with site visits (n = 13) in which MJL accompanied stakeholders to sites throughout the city with ongoing or resolved municipal rat issues. Interviews during site visits were conducted while driving or walking throughout the site. While in City 1 there were no site visits, in all other cities one to five site visits occurred. Following site visits and interviews, we synthesized a holistic view of the components that were commonly part of municipal rat management programs. Where one of these key components of a program was not discussed or shared during a municipal site visit, we sought to gather this information through targeted searches of program websites.

All sessions were audio recorded and transcribed verbatim using the Otter.ai algorithm (Los Altos, California, USA) or by hand. All transcripts were reviewed by listening along with the audio-recording and resolving transcription errors and providing context.

Analysis

Municipal code content was analyzed using the framework method (Gale et al., 2013). Specifically, we developed a set of a priori themes (e.g., code content, structure, purpose) based on policy evaluation guidelines (Centers for Disease Control and Prevention, 2013) meant to describe the structure and content of the rat management codes. Themes were agreed upon by all authors and were then used for descriptive qualitative coding (MJL). During this process, code content relating to each theme was summarized in a spreadsheet (i.e., themes as columns, municipal codes as rows). The entire qualitative codification process was cyclic and iterative, such that as new information emerged, a priori themes were refined, emergent themes were added, and municipal codes were re-assessed using the updated framework. Qualitative themes are shown in Figure 1.

Figure 1. Coding structure used for the qualitative analysis. A priori and emergent (shown in red and italics) qualitative themes were used to define the overarching themes that the results section was organized into.

Interview transcripts were analyzed following a similar framework method, detailed in (Lee et al., 2021). However, where Lee et al. 2021 described the opinions and recommendations of stakeholders regarding rat management, this analysis focused on describing the structure and function of the municipal programs as reported by those stakeholders (i.e., what data did programs collect, what were the responsibilities and objectives of the programs).

Results

Municipal codes regarding rat management

Code structure

Municipal laws were organized into chapters (e.g., environmental protection, building requirements, businesses), which were further divided into sections made up of one or more codes (e.g., property use code, plumbing code). Each of these codes, in turn, was comprised of definitions, bylaws, and enforcement provisions.

Code jurisdictional scope

All municipalities had codes focused on specific property types or scenarios. For example, in City 1, there was a bylaw that prohibited the presence of rats in laundry facilities. Others had codes what were more broadly applicable. For instance, City 4 contained a bylaw that prohibited the presence of rats and conditions “conducive” to their presence in multiple property types including “commercial, private or public building[s] or structure[s], including all rooms within the property … areas surrounding the structure. It shall also include all vacant lots, parks, streets, and vehicles.”

Codes were written for specific municipal department(s); they applied only to the issues within the purview of that department and were only enforceable by that department. For example, in City 3 there was a rat management code containing approximately ten detailed rat management bylaws for all businesses in the city that was only enforceable by the health department. However, some codes increased their scope by specifically authorizing up to three departments to apply its’ contents (i.e., redundant city agency codes).

Code focus and aims

Rat management as outlined by the codes pertained to either the rats themselves (i.e., presence) or to the conditions which promote their presence (i.e., food, water, and harborage [FWAH]). Rat presence associated codes prohibited them within certain spaces and mandated their removal when present. For example, City 7 contained a bylaw rendering it unlawful for the “owner or occupant” of any property type to fail to remediate rats when present. FWAH-associated codes aimed to prevent the occurrence of, or remediate, the various environmental factors that contribute to infestations. Common FWAH bylaws mandated the use of rat-proof or -resistant refuse containers, rat-proofing requirements for buildings, and the prohibition of vegetation overgrowth (i.e., harborage) in yards.

Rat and/or pest management was either the primary or secondary focus of each code. For pest management sections that were a part of this review, rats were included in the definition of a pest. Five cities had codes that were focused primarily on rat/pest management, such that all bylaws within them were integrated to specify a comprehensive management plan. These codes tended to encompass a greater breadth of jurisdictions (i.e., all buildings in the city) as well as multiple aspects of management (i.e., rat-proofing, infestation remediation, FWAH prohibitions). For instance, City 1 had a rat management focused code comprised of nine bylaws, each stipulating a different aspect of rat management pertaining to prevention, elimination, or monitoring. This included but was not limited to: a requirement that all buildings in the city be rat-proof; rat prevention regulations for anyone in the city who was composting; and mandating rat extermination prior to and during any construction and demolition. Codes with pest/rat management as the primary focus sometimes authorized multiple departments to check for compliance with its contents. For example, both the department of buildings and the department of streets and sanitation had the authority to enforce City 1’s rat management focused code.

All cities had codes from multiple departments in which rats were a secondary focus. In these codes, rat-related content was focused on specific prohibitions (i.e., rats must be eliminated from certain spaces or scenarios) and were nested in codes that otherwise had nothing to do with rats. For example, City 7 had a code outlining responsibilities of milk operation plants (i.e., pasteurization mandates, milk processing equipment prohibited for any other use) and within this code was a single bylaw that mandated the facility “use any means necessary to eliminate … rodents.” Codes in which rats were the secondary purpose were generally limited to a single department.

Monitoring and enforcement provisions

To ensure widescale resident compliance with bylaws, codes included provisions which detailed monitoring and enforcement. Monitoring for compliance involved only in-person inspections. As an example, a City 1 bylaw specified that prior to all construction and demolition, a PMP was required to inspect the premises for rats and remove them when found.

When inspections revealed noncompliance, bylaws were enforced using disincentives. For example, codes outlined a combination of notices and orders to comply and fines, property liens, and other penalties. Specifically, the notices and orders informed a resident of their bylaw violation and ordered them to comply (i.e., exterminate rats, remove FWAH) or else face the specified penalty. Because bylaws associated with businesses, construction, demolition, and sanitary facilities often required a permit for operations to occur, violations of rat regulations were enforceable via permit suspension/revocation and/or stop work orders. There were also bylaws that required ongoing management activities for certain types of commercial premises (i.e., food establishments, multi-tenant residences). This included requiring those businesses to regularly (or in response to a bylaw violation) employ PMPs.

Code specificity and clarity

Codes varied with regard to the specificity of their content in, but not limited to, three important areas. First, cities varied in the specificity of their definitions of when an infestation became a problem requiring action. For some cities, rats were considered problematic whenever they were “present” or when they became an “imminent health hazard.” Using a more specific definition, City 4 outlined a rat problem as “one or more live rodents, or rodent droppings, burrows, runways, tracks, rub marks, or gnaw marks; in interior or exterior.” Second, descriptions of “rat proofing” ranged from generalizations to specific requirements. For example, a City 7 code defined rat proofing as any “construction, maintenance, or repair of a building or premises which will prevent rodents from gaining entrance thereto, or from gaining access to food, water, or harborage.” In contrast, a City 3 code outlined precise rat-proofing regulations ranging from the prohibition of leaning fishing rods against structures to prevent rats from climbing them and finding harborage on the roof, to the specific allowable gap sizes under exterior doors. Finally, descriptions of whose responsibility it was to comply with management regulations were often left to the “owner or occupant” or the “person responsible for the property” or the “person responsible” for causing the problem.

The intended meaning of terminology was sometimes unclear and left open to interpretation because it was not defined. For example, the terms reasonable/effective/adequate measures to prevent/eliminate/control rats or FWAH, premise, property, place, abatement, proper precautions, eradication, and elimination were sometimes left without an associated definition, specific or otherwise.

Rat management programs

What did the programs look like?

So, total inspectors: 1, 2, 3, 4. (Stakeholder 1, City 7)

Municipal programs ranged from groups of two to over 100 people. Programs were located within a specific municipal department, although which department that was varied among cities and included the departments of health, sanitations, and pest control. Six programs were located within the municipal government, while the City 7 program was located in a shared municipal-county level public health department. Stakeholders felt that the programs were the primary group responsible for overseeing rat management within the city.

Program jurisdictional scope

our job is to protect residents of City 6 from rats … we can’t be the pest control people for businesses, because it’s a conflict of interest. So if and we only service complaints and address issues in the home for rats. (Stakeholder 2, City 6)

Each municipal program focused on specific property types or scenarios such that no single program was authorized to address any and all rat-related issues. For example, in some municipalities, programs only addressed areas where there was a public complaint about rats, while others only addressed city-owned properties and/or public spaces. The City 4 program had the greatest coverage, encompassing 10s of thousands of properties regularly. However, the program principally addressed rat-associated issues on private properties, and less frequently handled issues associated with municipal land and activities, such as parks, sewers, and sanitation procedures (i.e., trash pickup). However, in specific areas of the city (i.e., with historically high levels of complaints), the program was supported by a multi-departmental taskforce which attempted to share the responsibility of management among multiple departments by working with the accountable stakeholders to develop solutions within their jurisdictions (e.g., working with the sanitations department to increase the frequency of trash pick-up). Some programs also increased their scope beyond the municipality by collaborating with other stakeholders, such as academics and researchers. For example, City 3 collaborated on projects with researchers to understand pathogen and species presence and abundance across the city.

Programs had both reactive and proactive components

We respond to all complaints within 10 days. So, that was that sort of the traditional model with pest control. Then we started doing what we call the indexing … going through all the properties in that neighborhood. (Stakeholder 3, City 4)

All programs were focused on managing the presence of rats and FWAH and they did so mainly in response to complaints (i.e., reactively). Response to complaints was similar among programs and consisted of sending an inspector to verify the infestation and initiate management. However, the approach to prioritizing complaints varied by program. In some cities, complaints were managed in the order they were received, while other municipalities triaged calls to address the most severe (i.e., numerous rats observed or rats inside a building) and urgent issues first (i.e., those involving the elderly or small children). City 7 was unique in first sending a letter requesting that the property alleviate the specific rat/FWAH issues noted in the complaint and only sent an inspector after a follow-up discussion with the complainer indicated that the problem remained unresolved.

While each program was reactive to complaints, they all also had proactive components (i.e., finding and addressing rat issues before they are reported to the city). The nature of and resources allocated to reactive and proactive components varied by city, and one municipality (City 4) had a primarily proactive program. Their large team (>100) regularly inspected exteriors of all properties in entire regions defined as rat reservoirs (see, section 3.2e), scoring each property using a survey to enumerate signs of rat presence and FWAH. When properties exceeded a threshold score on the survey, they issued an enforceable order for the residents to fix the conditions found. Other programs performed sporadic inspections of specific areas within the city in which they walked the extent of entire neighborhoods, treated issues that were found (i.e., FWAH issues, rat signs), spoke with residents, handed out pamphlets, and enacted code enforcement. These “blitzes” were typically only done when programs had extra time and resources and were either performed by the rat program alone or through collaborative approaches with other departments (i.e., departments of health, housing, property maintenance). In collaborative approaches, rat program staff walked the neighborhood with members of other departments, each looking for rat or non-rat related issues within their own jurisdictions (i.e., housing looked for housing issues, sanitations looked for garbage problems). Overall, programs employed a variety of different proactive strategies to meet the rat management needs within their municipalities. For more proactive program components see supplementary appendix 1.

Program methods of managing rats

Rat management programs used a number of methods to address rat infestations that could be grouped into three categories: (1) code enforcement, (2) education of their citizenry, and (3) other initiatives to prevent and/or eliminate infestations.

Code enforcement

We give an abatement notice, like I said, first. And then if they don’t fix that problem within 30 days, under the new regulations, we would fine at that point. (Stakeholder 4, City 5)

While five programs had the authority to enforce rat-related code (as described in section 3.1), City 2 and City 3 had little to no authority over rat management bylaws. Among programs with enforcement power, they either had the authority to enforce one or two bylaws, such as high weeds and excessive garbage, or they could enforce all bylaws within rat management specific codes. Further, these programs varied in their culture of applying disincentives. For example, while City 7 worked with residents to address regulations before issuing disincentives (sometimes for years), City 4 took a firmer approach, issuing tickets regularly and soon after noncompliance (i.e., days to weeks). When programs had no enforcement power, bylaws related to rat management were enforceable by other non-rat specific departments and programs. For example, in City 3, rat management bylaws related to businesses were enforced by the health department as a part of their overall business specific health inspections.

Education of their citizenry

We also have flyers that [employee name] distributes to the individuals that have the rats and then we have block level flyers that we send that we deliver to that block. So educating people because again, we can’t necessarily always just go traipsing on private property. (Stakeholder 5, City 2)

The goal of education was to enable citizens to manage rats on their own properties by teaching them how to prevent, recognize, and address rat issues. Common methods included pamphlets, door hangers, websites, town newsletters, information booths at events, and community presentations. In all cities, the most prevalent method was face-to-face or follow-up phone conversations during/after a visit to address a complaint by a resident (or in the case of City 4, during/after a regular inspection). The most structured initiatives were “rat academies” in which rat experts were invited to teach courses that communicated the nuances of how to recognize a rat problem and address it. These academies were tailored to the public, PMPs, and even municipal employees from various departments (including city council) and were offered either once or multiple times annually. Education efforts were described as unidirectional, with experts providing information to students. While all programs utilized education strategies, investment into these activities varied and they tended to be haphazard, opportunistic, or initiated only when there was excess time and money.

Other methods of rat management

I’d say 99% of what we do is baiting burrows for rats. (Stakeholder 6, City 6)

All programs were engaged heavily in extermination activities, primarily through the application of rodenticide baits (and occasionally traps, carbon dioxide, and/or tracking powders) to outdoor areas. City 6 estimated that 99% of their program was focused on baiting. Baits were placed in bait boxes or directly in rat burrows. Less frequently, rodenticide was placed in sewers and only City 6 regularly enacted control activities on the interior of structures on private properties (i.e., in homes). These extermination methods were primarily undertaken by the program itself and were occasionally contracted out to PMPs. For example, the City 5 program enacted all its own extermination work in public spaces; however, the municipality hired PMPs to conduct extermination on government property. At the time of these interviews, City 5 was investing in alternative technologies such as rat contraception.

Relatively fewer resources were devoted to modifying the urban environment to prevent or eliminate infestations through minimizing FWAH. Most programs only enacted environmental management themselves (e.g., cleaning out a vacant property, removing junk accumulated on a lawn) in severe cases, where there was repeat noncompliance with a code, to assist other municipal departments, or in specific scenarios. For example, the City 4 program had a team devoted to cleaning out vacant properties that harbored rat infestations. City 6 was the only program that did environmental modification regularly. Their team employed a full-time “rat proofer” whose job it was to help residents rat proof their properties subsequent to a complaint (e.g., such as cementing rat entry points into residents’ homes and teaching them how to prevent future infestations). However, the majority of environmental modification that was attempted by programs was done indirectly through teaching residents, on a case-by-case basis, how to alleviate their own problems and/or through bylaw enforcement.

Program data collection and use

A lot of the data that I’ve seen is also just like, here’s where the volume of 311 calls is coming from. (Stakeholder 7, City 1)

All programs collected and used at least one of three types of data including: (1) survey results from inspections verifying the presence of rats and FWAH; (2) rat complaints; and (3) other geospatial data (e.g., the locations of parks, sewers). City 4 electronically collected and stored inspection survey data on the presence of rats/FWAH. Their program then used this data to directly inform action by: (1) defining when, where, and which disincentives to issue (e.g., a notice of violation for the presence of FWAH or ARS) or actions to take (i.e. increased garbage pickup frequency in a target area), and (2) to inform the multi-department taskforce where and what actions of other departments were needed. In contrast, City 2 imported the results of rat-related inspections made by other departments (i.e., property maintenance issues, building violations, garbage problems) into their own database in which they looked for correlations between increased violations (i.e., garbage infractions) and rat complaints. When an association was found, they worked with the responsible department to target those areas and alleviate the causes of the heightened violations (e.g., increased bylaw enforcement). Second, all cities collected and electronically stored information on the number, date, and location of rat complaints overtime. Complaints were primarily used to inform when and where to deploy inspectors to the field to verify and address rats. However, cities 4 and 6 used historically higher levels of complaints to define areas as “rat reservoirs” or “problem sites” respectively, that required increased management resources (e.g., devoting an employee’s full time to alleviating the issue in a problem site). Third, three cities collected some form of geospatial data regarding rat infestations. For instance, City 7 had a sewer baiting program (Table S1) in which they were working to systematically map rat activity (bait consumption) in sewers across the city. As a part of that project, they linked rat data to features of the sewer (e.g., location, age, construction type) to eventually predict and target sewers with a higher likelihood of infestation. Similarly, City 2 and City 4 geocoded their rat distribution information (inspections or complaints respectively) and linked it to municipal land use data (i.e., property types, green space, infrastructure). They then used this information to focus management efforts in areas with a higher number of risk factors.

Program evaluation

We don’t really have a good way to determine it [program success]. People ask that question all the time. I’m like, I don’t know. Does it mean cases are getting resolved? Successfully? … Does it mean people, the public doesn’t report to us? I don’t know. So for me internally, it’s really are we resolving cases. (Stakeholder 1, City 7)

Only City 4 had a clear and actionable objective that was linked with a definition of overall success. City 4’s program aimed to drive the number of infested properties below a proportion threshold that changed overtime as they learned what was practical and what wasn’t (i.e., an initial threshold of 5% of properties was changed to 8% when experience indicated that the lower threshold was infeasible). Their evaluation consisted of monitoring the number of infested properties over time and tracking progress toward their pre-defined threshold.

The other six programs had informal methods of self-assessment. The most common was monitoring the number of rat complaints over time. However, these programs could not identify a clear definition of success, though they generally looked for a temporally stable number of complaints even though they recognized that the lack of change may not be an optimal measure. Beyond complaints, these six programs primarily relied on anecdotal and case-by-case evidence of success such as accounts of tough cases where they had achieved large reductions in rat populations. For example, in City 5, one stakeholder anecdotally evaluated the effectiveness of their municipal code that defined rat-proof garbage bins. This stakeholder explained that the bins approved by code were, in his/her experience often chewed through by rats, indicating that they were not actually rat proof. Similar situations regarding “rat-proof” garbage bins existed in several cities.

For more information about the structure, function, and interconnections among program components, see supplementary appendix 2.

Discussion

Municipal rat management strategies

In this study we explored the municipal rat programs and codes in place in seven cities across the USA. Municipal codes consisted of bylaws and regulations written with the intent of facilitating specific aspects of rat management including actions to prevent, monitor, and eliminate rats across each city. Programs were delivered by groups within each municipality dedicated to addressing rat issues on behalf of the local government.

Codes specified where, by whom, how, and when rat management must be enacted. Specifically, the codes outlined a municipality’s jurisdiction by delineating the property types or scenarios in which rat management was to be undertaken and who in the city (i.e., a specific municipal department or the public) was responsible for doing so. Codes also described how management should be enacted, usually through FWAH reduction, extermination, or some combination thereof. Further, codes provided enforcement tools to the municipality so that they could encourage adherence to specified management activities (e.g., fines for not removing FWAH on private property). Finally, codes outlined the thresholds at which rat management should be enacted by specifying the level of rats and/or FWAH (e.g., presence/absence) required to trigger action.

In each municipality, the programs were a primary group responsible for enacting on-the-ground rat management. To do so, programs either enforced the codes they were authorized to use, or they referred issues to the municipal department with the relevant jurisdiction. Programs also engaged in activities that extended beyond the confines of the code, including monitoring, proactive management, complaint response, and education initiatives. In combination, programs appeared to serve as the “brain” of the overall municipal approach, able to adapt and expand management, while the code served as a foundation, providing a baseline structure for action. For example, City 4’s rat program used their enforcement of the municipality’s rat management code to structure how and what data they collected on the distribution of rats, FWAH, and code violations. They regularly analyzed this code enforcement derived data to identify factors contributing to ongoing infestations. When they found issues in the jurisdiction of another municipal department, they convened with a multi-departmental task force and developed solutions to the ongoing infestation with the responsible department. In general, programs served as a primary point of experience and knowledge within each municipal government regarding how the municipality can and should manage rats across the city.

While this study described a complementary role of municipal code and programming for rat management in these seven cities, it was not possible to objectively determine the success of any one city with regard to rat management or to compare among cities, because of a lack of consistent and robust program evaluation. Most municipalities used either anecdotal or non-robust evaluation measures and indicators of success. For instance, although changes in rat complaints (i.e., their number and location) were sometimes used as a proximate indicator of success in reducing infestations, there was a lack of evidence in the literature (Margulis, 1977; Meyer, 2003) and low confidence among these stakeholders (Lee et al., 2021), that complaints accurately reflected what these cities were attempting to measure (i.e., a reduction in rats).

The lack of clear, robust, and accurate evaluation measures leaves municipal decision makers without evidence to support their choices. For municipal programs in general, this lack of informed decision making is associated with missed opportunities, poor allocation and wasting of resources, and can drive negative perceptions of government programs and policies (Seasons, 2002, 2003). In the context of rat management, a lack of evaluation likely contributes to missed opportunities because decision makers have little information on which rat management techniques and policies are the most cost-effective. This may contribute to why methods that have the least up-front costs (i.e., rodenticides) are often selected for rat management programs, even though there may be more cost-effective and sustainable alternatives such as modifying landscaping practices to minimize FWAH (Colvin et al., 1996; Meyer, 2003; Richards, 1988). In conjunction with missing opportunities, the impacts of poorly allocating or wasting resources are likely to be highly consequential for rat management, given that these programs and policies face existing issues of under-resourcing and low public interest (Brown & Laco, 2015; Colvin & Jackson, 1999; Kaukeinen, 1994). Future programs and policies may capitalize on the insights and opportunities of urban planning literature unrelated to rat management. For example, Seasons (2003) explored the implementation of evaluation strategies within several municipalities in Ontario, Canada. They highlighted key challenges to the effective implementation of ongoing monitoring and made several high-level suggestions for how municipalities can implement long-term evaluation strategies, such as, dedicating staff to evaluation programs, aligning key objectives and evaluation metrics, and triangulating success through a variety of simple to attain qualitative and quantitative indicators.

One notable characteristic of both the codes and programs was the relative dominance of reactive management (i.e., addressing rat infestations once they have already become a problem). For example, all seven cities responded to public complaints about rats, and in six of them, this consumed most of the programs’ resources. Although this focus on reacting to and ultimately aiming to reduce established rat infestations is consistent with previous descriptions of municipal rat management policy and programming (Al-Sanei, Zaghloul, Salit, Omar & Balba, 1984; Bragdon et al., 2012; Brown & Laco, 2015; Fernández et al., 2007; Lambropoulos et al., 1999), it conflicts with the recommendations of researchers and rat management experts who have advocated for systematic, proactive, and preventative interventions that act upon the determinants of rat infestations before they become problematic (Davis & Jackson, 1981; Drummond, 1970; Kaukeinen, 1994; Margulis, 1977; Meyer, 2003; Sherrard, 1943). Such an approach might consider how parks, sewers, and buildings can be designed and engineered to deter future infestations (Colvin, 2002; Colvin et al., 1990, 1996), instead of addressing them through bylaw enforcement and rodenticides once they are already a problem. The cities included in this sample did, however, develop several innovative proactive approaches to rat management such as neighborhood blitzes and sewer mapping (Table S1).

Despite recommendations for proactive rat management, municipal governments are, to some extent, obligated to directly respond to the concerns of their citizens (Lee et al., 2021; Steytler, 2005). As such, reactive elements of control may always be an integral component of programming. There are benefits of being responsive to residents, such as keeping a municipality’s objectives and decisions grounded in the needs and desires of its citizens (Liao, 2016). Therefore, to balance community response with the benefits of proactive measures (Lee et al., 2022), it may be prudent for cities to strategize how to best blend these approaches based on strategic goals and available resources.

Municipal rats in the context of the broader urban ecosystem

Given the multi-jurisdictional nature of municipal rat management described in these seven cities, one potential way to manage rats while addressing competing municipal priorities might be to integrate rat management in the context of the broader urban ecosystem (Lee et al., 2022). This approach de-centers rats and instead manages them as one part of an otherwise complex and constantly changing urban environment. This lens has been applied to other complex urban issues. For example, Kanta and Zechman (2014) deliberately viewed urban water management as one part of a larger complex system by mapping out the constituents of a water system driven by supply, demand, climate, and the behaviors’ of both consumers and policymakers. This approach allowed them to simulate a highly complex system and then to vary its components and the relationships between them to highlight the water management strategy most resilient to changes in the system. Such an approach may benefit rat management by first framing the problem as part of a complex urban system highlighting its’ many components, and the array of relationships between rats and different parts of the system (Nel et al., 2018).

Overall, this view of municipal rat management enables management approaches to engage with the larger problems in which rats exist, but that may have little to do with rats themselves. For example, when rats are found in association with vacant housing, thinking about rats as a part of the larger system highlights the need to consider and modify the reasons that vacant housing persists such as inadequate municipal housing policy. Although such an approach has never been applied to municipal rat management (Lee et al., 2022), it could be operationalized by using systems thinking tools, such as visually mapping the municipal rat management system (Carey et al., 2015) and considering which connections or components would have the greatest impact on the wider system if they were modified. However, because such an approach may engage with and manage a variety of different jurisdictional problems (i.e, vacant housing policy, landlord-renter agreements, park design and maintenance, etc.), future work is needed to understand how municipal rat management programs can be structured to address such a breadth of issues.

Limitations

This study included several limitations. First, this work was performed in seven nonrandomly selected cities within a single country, therefore it is unlikely to represent the full breadth of rat-related policy and programming found throughout the USA. While national and global applications may be limited, this study provides important baseline knowledge from which to begin exploring the strengths and weaknesses of current municipal approaches in the context of what is known about urban rat management. Second, this study only included interviews with stakeholders directly involved with the municipal rat management programs. In the future, it will be important to gain a better understanding of the desires and expectations of the public and other stakeholders, such as urban planners, regarding municipal rat management. Third, because program information was compiled from varied sources in each city (section 2.3), descriptions of city programs may differ depending on where the data were derived from. Due to this variation, opportunistic sampling of participants, and limited samples sizes (i.e. only seven cities and three to eight interviewees per city) we avoided making conclusions about how information may have varied depending upon the source as this could lead to erroneous inferences. Instead, we focused on qualitatively describing trends across programs and providing specific examples supporting or contrasting this trend where they were available. Future work building on this foundation to make more robust comparisons among cities or to evaluate relative effectiveness would benefit from implementing systematic data collection to ensure that information from each city is directly comparable.

Conclusions

This study demonstrates how municipal rat management code and programming have the potential to work in tandem to produce a municipality’s overall management strategy. However, the lack of shared definitions or measures of success at municipal scales makes it difficult to evaluate which practices or codes are the most effective and should be used. This study has revealed several possible ways to improve upon current strategies, including developing overarching and robust evaluation metrics and strategies and carefully considering how to balance reactive and proactive methods. Finally, as evidenced by this review, municipal rat management strategies vary across cities. This variability may be necessary given that cities and their services are shaped by their communities. As such, this study serves as a foundation for municipalities to consider when building and improving their own rat management approaches to meet the needs of their residents.

Data availability

Data is not publicly available: stakeholders only gave their consent for their interview transcripts to be accessible to members of the research team. Municipal policies are freely available online at the sources indicated in the text, but we cannot supply them here to maintain the confidentiality of participants.

Acknowledgments

We would like to acknowledge and thank all the participants of this study for taking the time to speak with the research team and for their role in co-creating the contents of this analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/07352166.2022.2091995

Additional information

Funding

This work was funded by the City of Vancouver’s 2018–2020 Street Cleaning Grant Program in support of their efforts to establish suitable rat management protocols for Vancouver.

Notes on contributors

Michael J. Lee

Michael Lee is a PhD candidate in the School of Population and Public Health in the University of British Columbia and an environmental epidemiologist at the British Columbia Centre for Disease Control. His PhD thesis is focused on understanding the current state of municipal rat management with a view towards providing recommendations for cities seeking to improve or implement their own strategies.

Kaylee A. Byers

Dr. Kaylee A. Byers (she/her) is the Deputy Director of the British Columbia node of the Canadian Wildlife Health Cooperative and a University Research Associate at Simon Fraser University working in the field of health communications. She completed a PhD in Interdisciplinary Studies at the University of British Columbia where she studied rat-associated health risks.

Susan M. Cox

Susan M. Cox is a Professor in the W Maurice Young Centre for Applied Ethics and the School of Population and Public Health at the University of British Columbia in Vancouver, Canada. She is sociologist and ethicist and is Director of the MSc and PhD programs in Population and Public Health. Her research employs arts-based and qualitative methods to understand and represent lived experiences of health and illness (such as dementia) and to identify and explore ethical challenges in innovative research methods. She has published widely on research ethics and arts-based inquiry and employs research-based theatre in her collaborative work addressing equity, diversity and inclusivity in graduate supervisory relationships.

Craig Stephen

Craig Stephen serves as the president of a new think tank dedicated to increasing the social contribution of animal health professionals and making a ‘future-ready’ animal health cohort able to contribute to global health threats shared by people, animals, and ecosystems as well as being a clinical professor both the School of Population and Public Health (University of British Columbia) and Ross University School of Veterinary Medicine. Craig’s research focus has been on the interface of the health of people, animal, and our shared environment and how we can both co-manage this interface for intergenerational and interspecies health equity. He adapts and applies population health methods across species to encourage the reciprocal care of our health and the health of the world around us. Recent work has focused on the adaptation of harm reduction and health promotion to animal and environmental health as well as in the creation of human capacity for leading change in the areas of One Health and Climate Change and Health.

David M. Patrick

Dr. David M. Patrick is an Infectious Diseases Specialist and Epidemiologist with a career interest in responding to emerging infectious diseases. His current focus is on the broad effort to contain the threat of antimicrobial resistance in Canada and around the World. He is particularly interested in understanding the drivers of antibiotic utilization in the community and intervening to reduce unnecessary use.

Robert Corrigan

Robert Corrigan has been active in the science of pest control for over 30 years starting as a pest control technician running a route in NYC for three years full time while saving for college. After graduate school, Bobby taught and conducted research on rodent control at Purdue University for 16 years. Dr. Corrigan has published over 175 technical papers and has authored or co-authored four textbooks including the 1) The Scientific Guide to Pest Management Operations; 2) A Professional’s Guide To Rodent Control and the Mallis Handbook of Pest Control. Bobby has appeared in Time Magazine; the New York Times, conducts interviews for PBS and NPR and has made multiple appearances for the Discovery Channel. The Mayor of New York City awarded Dr. Corrigan, The NYC Scientific Innovation Award for his work on City Rat Control. He was inducted into the Pest Control Hall of Fame in 2008. In 2016, Dr. Corrigan appeared in the mainstream Hollywood movie: Rats (Netflix); in the National Geographic magazine (April 2019) and in Australia’s Wildbear Entertainment multi-series production of: “How to Build A City” (2021). Bobby holds his Ph.D. degree in urban rodent pest management from Purdue.

Chelsea G. Himsworth

Dr. Chelsea G. Himsworth received her DVM from the Western College of Veterinary Medicine, before staying on to complete a Masters of Veterinary Science and Senior Residency in Anatomic Pathology with a Wildlife Health focus. She went on to achieve Diplomate status with the American College of Veterinary Pathologists before completing her PhD in the School of Population and Public Health, University of British Columbia. Currently, she is a Diagnostic Pathologist and the Leader for Veterinary Science and Diagnostics at the Animal Health Centre, BC Ministry of Agriculture. She is also the BC Regional Director for the Canadian Wildlife Health Cooperative and an Assistant Professor in the School of Population and Public Health, University of British Columbia. Dr. Himsworth’s research and practice is focused on the surveillance of infectious disease, particularly zoonotic disease (i.e., diseases transmitted from animals to people) and diseases involving free-ranging wildlife.