Rat Sightings Research Articles

Associations between Rat Infestations and Mental Health Vary by Gender, Race, and Income in Chicago.

Rats are an understudied stressor for people in urban environments around the world but the effects may not be distributed equally among residents. In this study, we examined associations between residential rat sightings and mental health in Chicago, where rat complaints are the highest of any American city. We examined how this relationship varied by frequency of rat sightings, race, ethnicity, income, home ownership, and gender and explored potential psychosocial pathways (e.g., feelings about the home) between rat sightings and mental distress. We conducted a randomized household survey along an income gradient in 2021 and asked about depressive symptoms in the past week (i.e., Center for Epidemiologic Studies Depression scale), frequency of rat sightings in/around the home, perceptions of rats, neighborhood conditions, and socio-demographic characteristics. We used logistic regression to assess relationships among these variables for our entire sample and for specific demographics using stratified models. Respondents (n = 589; 409 complete cases) who saw rats in/around the home daily/almost daily had 5.5 times higher odds of reporting high depressive symptoms relative to respondents who saw rats less frequently after accounting for socio-demographics and neighborhood conditions. This relationship was significant for men and respondents with lower incomes or race or ethnicity other than white. Our results show that rat infestations should be considered a threat to mental health among urban residents. Increased mental health support for residents living in rat-infested housing may improve public health in cities.

Social distancing measures differentially affected rats in North America and Tokyo.

Because rats are commensal organisms that depend on human activities for food, shifts in human behavior will have pronounced effects on local rat populations. In the spring of 2020, social distancing measures were implemented globally to curtail the spread of SARS-CoV-2. This presented a unique opportunity to obtain information regarding the immediate effects of shifts in human behavior on rat populations in a variety of countries. In response to increased sightings of rats in the USA that were reported in American media, we analyzed the changes in the number of public service calls in Tokyo, Japan. We found that the number of calls increased after the implementation of social distancing measures, suggesting that rat sightings had also increased in Tokyo. We then surveyed the changes in the business activities of pest management professionals in the USA, Canada, and Tokyo. We found that the activities were increased in 50 to 60% of the respondents from the USA and Canada. In contrast, 60 to 70% of the respondents from Tokyo answered that their activities were not changed. These results implied that, following the implementation of social distancing measures, rat infestations increased in North America, but not in Tokyo. The survey also suggested that roof rats were considered to be the predominant rodent species in Tokyo. This may account for the limited infestations in Tokyo because roof rats are more sedentary than brown rats. Taken together, our findings suggest that social distancing measures differentially affected rat populations in North America and Tokyo.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10340-021-01405-z.

\u201cI don\u2019t feel safe sitting in my own yard\u201d: Chicago resident experiences with urban rats during a COVID-19 stay-at-home order

BackgroundEncounters with rats in urban areas increase risk of human exposure to rat-associated zoonotic pathogens and act as a stressor associated with psychological distress. The frequency and nature of human-rat encounters may be altered by social distancing policies to mitigate the COVID-19 pandemic. For example, restaurant closures may reduce food availability for rats and promote rat activity in nearby residential areas, thus increasing public health risks during a period of public health crisis. In this study, we aimed to identify factors associated with increased perceived exposure to rats during a stay-at-home order, describe residents’ encounters with rats relevant to their health and well-being, and identify factors associated with increased use of rodent control.MethodsUrban residents in Chicago, a large city with growing concerns about rats and health disparities, completed an online questionnaire including fixed response and open-ended questions during the spring 2020 stay-at-home order. Analyses included ordinal multivariate regression, spatial analysis, and thematic analysis for open-ended responses.ResultsOverall, 21% of respondents (n = 835) reported an increase in rat sightings around their homes during the stay-at-home order and increased rat sightings was positively associated with proximity to restaurants, low-rise apartment buildings, and rat feces in the home (p ≤ 0.01). Many respondents described feeling unsafe using their patio or yard, and afraid of rats entering their home or spreading disease. Greater engagement with rodent control was associated with property ownership, information about rat control, and areas with lower incomes (p ≤ 0.01).ConclusionsMore frequent rat encounters may be an unanticipated public health concern during periods of social distancing, especially in restaurant-dense areas or in low-rise apartment buildings. Rat presence may also limit residents’ ability to enjoy nearby outdoor spaces, which otherwise might buffer stress experienced during a stay-at-home order. Proactive rat control may be needed to mitigate rat-associated health risks during future stay-at-home orders.

Short Communicaton:Increased Rat Sightings in Urban Slums During the COVID-19 Pandemic and the Risk for Rat-Borne Zoonoses.

Short Communicaton:Increased Rat Sightings in Urban Slums During the COVID-19 Pandemic and the Risk for Rat-Borne Zoonoses.

Who’s in the hood? Assessing a novel rodent deterrent at pest fencing in New Zealand

ABSTRACT Fenced ecosanctuaries may reduce predator presence at reserves by incorporating deterrents into pest management programmes. We quantified rodent visits to the steel hood of ecosanctuary fencing and illuminated our experimental sites to assess whether light could deter ship rats (Rattus rattus) and house mice (Mus musculus). Additionally, we assessed how mice used fencing in the presence and absence of ship rats by utilising two types of fence sections: one accessible to mice alone (along fencing within an ecosanctuary) and one accessible to mice and rats (at perimeter fence sites opposite pasture or forest habitat). We monitored sites using cameras and tracking cards within the fence hood and at tunnels at the fence base. Along the internal fence, mice were never observed within the hood but marked 40% of tunnels at the fence base. Along the perimeter fence, mice made four visits to the hood and marked 28% of tunnels at the fence base. Rats travelled exclusively within the fence hood (n = 42). Light did not reduce rat sightings but adjacent habitat affected their presence (forest > pasture; p ≤ 0.01). Positioning future ecosanctuary fencing alongside pasture and maintaining open corridors opposite fences at current ecosanctuaries may reduce rat presence.

Trivariate non‐Gaussian copulas to analyze the spatial behavior of rat sightings

The brown rat lives with man in a wide variety of environmental contexts and adversely affects public health by transmission of diseases, bites, and allergies. Understanding behavioral and spatial correlation aspects of pest species can contribute to their effective management and control. Rat sightings can be described by spatial coordinates in a particular region of interest defining a spatial point pattern. In this paper, we investigate the spatial structure of rat sightings in the Latina district of Madrid (Spain) and its relation to a number of distance‐based covariates that relate to the proliferation of rats. Given a number of locations, biologically considered as attractor points, the spatial dependence is modeled by distance‐based covariates and angular orientations through copula functions. We build a particular spatial trivariate distribution using univariate margins coming from the covariate information and provide predictive distributions for such distances and angular orientations.

Temporal and Space-Use Changes by Rats in Response to Predation by Feral Cats in an Urban Ecosystem

Feral cats (Felis catus) are predators that cause widespread loss of native wildlife in urban ecosystems. Despite these risks, cats are commonly released as control agents for city rats (Rattus spp.). Cats can influence their prey directly by killing or indirectly through changes to feeding or space-use. However, cats prefer defenseless prey, and there are no data suggesting that cats influence large (>300g) urban rats. We used a pre-existing radiofrequency identification assay (microchipped rats and field cameras) and ethograms to assess the impact of cats, including temporal and space use patterns, on an active rat colony. From Dec 27, 2017 through May 28, 2018 we captured 306 videos of pre-identified cats and/or rats that shared the same space. There were three instances of predation and 20 stalking events. Logistic regression showed the likelihood of a rat being seen on a particular day is associated with the number of cats seen on the same day (OR=0.1, p<0.001) or previous day (OR=0.15, p<0.001). Space-use was also impacted. For every additional cat sighting, a rat is 1.19 times more likely to move in the direction of shelter. Our findings of low levels of predation support why ecologists believe the risks to native wildlife outweighs any benefits of releasing cats. Even though rats were less likely to be seen, they simply shifted their movements and remained present in the system. Our findings that cat presence led to fewer rat sightings may explain the common perception of their value as rat-predators despite the associated risks.

Non-linear spatial modeling of rat sightings in relation to urban multi-source foci.

The brown rat has been living with humans in a wide variety of environmental contexts; it adversely affects public health by transmission of pathogens that can cause human diseases and allergies. Understanding behavioral aspects and environmental factors of pest species can contribute to their effective management and control. This aim of this study was to investigate the spatial distribution of rats in Latina district of Madrid (Spain), and its relationship with several potential multi-source foci. A focus is any particular social and environmental urban scenario that favors the clustering and proliferation of rats. We have developed a statistical framework to provide valid information on the spatial distribution and behavior of the rats around identified potential foci that favor the concentration of rats in urban environments. We extended the standard Poisson regression model by the inclusion of a multiplicative non-linear function of the distance, an unstructured random effect, and a spatial random effect to account for the spatial structure of socio-demographic and environmental covariates were also considered in the model to control for potential confusion. We found evidence of an association between the spatial distribution of rats aggregated by census tracts and distance to foci, and this association was controlled by the covariates considered in this study.

Modelling count data based on weakly dependent spatial covariates using a copula approach: application to rat sightings

Not all environmental processes are observed in a way that allows a straight forward easy modelling. Nevertheless, insights can also be gained by exploring weakly dependent covariates paying attention to details of the distribution. Using the concept of copulas, it is possible to explore the dependence of a multivariate distribution without the distortion of the marginal distribution functions acting on typical correlation measures. Furthermore, copulas turn the attention to the dependence across the entire range of the multivariate distribution and do not only summarise it in a single correlation measure. In our application, we study counts of rat sightings in the city of Madrid. The brown rat lives with mankind and adversely affects public health by transmission of diseases, bites and allergies. Better understanding behavioural and spatial correlation aspects of this species can contribute to its effective management and control. We explore weakly to moderately correlated covariates based on distances to broken sewers, feeding grounds and markets as well as population density. The use of copulas is motivated by the different dependence structures of the four covariates and the asymmetries therein. In order to deal with the discrete zero-inflated counts, we present a new approach that assigns conditional random ranks to discrete data. This way, we mimic an underlying continuous variable easing the vine copula estimation, but do not destroy the dependence as in a uniform randomisation. We show that a 5-dimensional vine copula model is able to capture the dependence in our application.

Rat sightings in New York City are associated with neighborhood sociodemographics, housing characteristics, and proximity to open public space.

Rats are ubiquitous in urban environments and, as established reservoirs for infectious pathogens, present a control priority for public health agencies. New York City (NYC) harbors one of the largest rat populations in the United States, but surprising little study has been undertaken to define rat ecology across varied features of this urban landscape. More importantly, factors that may contribute to increased encounters between rats and humans have rarely been explored. Using city-wide records of rat sightings reported to the NYC Department of Health and Mental Hygiene, this investigation sought to identify sociodemographic, housing, and physical landscape characteristics that are associated with increased rat sightings across NYC census tracts. A hierarchical Bayesian conditional autoregressive Poisson model was used to assess these associations while accounting for spatial heterogeneity in the variance. Closer proximity to both subway lines and recreational public spaces was associated with a higher concentration of rat sightings, as was a greater presence of older housing, vacant housing units, and low education among the population. Moreover, these aspects of the physical and social landscape accurately predicted rat sightings across the city. These findings have identified specific features of the NYC urban environment that may help to provide direct control targets for reducing human–rat encounters.

Modelling of the spatio-temporal distribution of rat sightings in an urban environment

The brown rat lives with man in a wide variety of environmental contexts and adversely affects public health by transmission of diseases, bites, and allergies. Understanding behavioural aspects of pest species can contribute to their effective management and control. We report an analysis of the spatio-temporal distribution of rat sightings, which are directly related to rat infestation, in a district of Madrid (Spain). We first consider an empirical analysis of the first-order for the first and second order properties of the spatio-temporal point process of rat sightings, in which we model the first-order intensity function as a product of two intensity functions, one spatial and the other temporal, and use the inhomogeneous spatio-temporal K-function to estimate second order properties. We then formulate a more mechanistic model in which the conditional intensity of the point process depends explicitly on its past history. We have found that the sightings show strong seasonal variation and are strongly influenced by environmental factors related to human behaviour. We have also identified spatio-temporal clustering and interaction over and above the separate temporal and spatial components of variation in risk, and have estimated the spatial scale on which the interaction operates.

Risk factors and spatial distribution of urban rat infestations

Urban rat infestations have multifactorial causes and may result in severe public health and environmental problems, as well as heavy economic losses. The identification of putative environmental determinants of urban rat infestations and the mapping of areas prone to experiencing such infestations (hot spots) are crucial for effectively addressing intervention efforts. We investigated the associations between a selection of environmental factors and the occurrence of rat infestations in the city of Madrid, Spain. This was done by modelling 10,956 citizen-reported rat sightings from 2002 to 2008 using generalized additive models, both at municipality (Madrid) and district (Latina) levels. Increased age and density of housing, and decreased distance to vegetated areas, markets and cat feeding stations were factors associated with an increased risk of rat infestations. Risk maps for rat infestations were also developed and recurrent hot spots of rat activity were identified. Although a better fit to the data was obtained in the model for the smaller scale and possibly more environmentally homogenous study area of Latina, modelling the spatial distribution of rat sightings was useful for identifying factors associated with an increased risk of urban rat infestations, as well as for identifying hot spots of rat activity, providing local authorities with a practical tool for effectively targeting intervention efforts to high-risk situations based on the local environmental contexts.

Temporal Distribution and Weather Correlates of Norway Rat (Rattus norvegicus) Infestations in the City of Madrid, Spain

Urban Norway rats are challenging pests, posing significant health and economic threats. Implementing ecologically based integrated rodent management (EBIRM) programmes relies primarily on the understanding of ecological relationships between rodents and their environments, with emphasis on the processes influencing rodent populations in the target ecosystem. We investigated the temporal distribution of urban Norway rat infestations in Madrid, Spain, and tested for the association of such infestations with temperature, relative humidity and precipitation by fitting a multivariate Poisson generalized linear model to a 3-year (2006-2008) daily time series of 4,689 Norway rat sightings. Norway rat infestations showed a marked seasonality, peaking in the summer. Most Norway rat sightings were reported on Mondays. Minimum temperature and relative humidity were positively associated with Norway rat infestation, whereas the association with precipitation was negative. The time series was adequately explained by the model. We identified previously unrecognized time periods that are more prone to Norway rat infestation than others and generated hypotheses about the association between weather, human outdoor activity, resource availability, rodent activity and population size. This provided local authorities engaged in preserving urban ecosystem health with basic research information to predict future rodent outbreaks and support the implementation of EBIRM programmes in urban areas.