New report about the welfare of urban wild animals

We’ve just published a report about the welfare of wild animals in urban environments. Existing scientific information about the lives of urban animals is primarily analyzed for purposes such as understanding animal behavior and population ecology. Wild animal welfare is focused on studying the welfare of captive wild animals, and wild animal rehabilitation is concerned mainly with treating injury and disease. There is little in the scientific literature than analyzes data from the perspective of learning about the natural harms that animals living in the wild suffer and the factors that affect their wellbeing. Even less is known about how wild animals in urban animals are affected by their environment. Yet we can use much of the existing information to begin to form a picture of what the lives of some urban animals are like. By wild animals we mean those who do not live with humans and are not controlled by humans such as animals in zoos and circuses. Wild urban animals includes animals such as birds, bees, grasshoppers, mice, and lizards, to name a few.

We’ve produced a new report that evaluates the existing scientific literature and outlines what we can learn about population dynamics, behavior, and natural harms as they relate to animal welfare. It begins by considering population dynamics, behavior, and natural harms in urban environments. It then considers these factors in relation to the lives of five urban wild animals. The report was completed by Amber Ross. You can read the full report by clicking on the link below:

Investigating the welfare of wild animals in urban environments

You can also read the executive summary of the report here:

Introduction

The welfare of wild animals has so far received little attention in the scientific literature, particularly concerning wild animals living in urban environments. While there has been an increasing amount of research regarding urban wild animals over the last few decades, it has primarily been focused on the topics of animal behavior, conservation, landscape ecology, wild animal management, and population ecology. Few of these studies have considered the wellbeing of urban animals, but information from this research can be used to consider the ways in which urban wild animal welfare may be impacted.

Objectives and methodology

This review aims to gain a better understanding of what the lives of urban wild animals are like and the factors that may positively or negatively affect their welfare. This information can then be used to devise ways of improving overall welfare and reducing suffering in urban wild animals. We will also present ideas regarding future research that could inform the development of a new research field called urban welfare ecology.

We conducted a review of publications on urban wild animals from various fields to investigate how the welfare of these animals may be impacted. Definitions of the term “urban” vary within the existing field of urban ecology, and we have specified the types of urban areas and degrees of urbanization as they have been described in the literature. We consider the general term “urban” to refer to areas occupied by humans that have a relatively high cover of buildings and infrastructure, primarily cities, suburbs, and industrial areas.

Population dynamics

The characteristics of urban wild animal populations were examined to identify patterns and trends. We found that many wild mammals and birds have high survival rates, early and prolonged breeding seasons, high population densities with small territories, and reduced migration in urban environments. Factors that have likely contributed to these trends include high resource availability due to food subsidies, low rates of predation, warm climates from urban heat island effects, and the tendency of many urban animals to adopt more sedentary lifestyles and have slower life strategies.

Behavior

Increased intraspecific aggression has been observed in some urban animals, which may be due to high population densities and competition for better quality resources. Interspecific competition for resources may also increase among urban species with similar diets. Birds were found to be more social in urban areas, which may be advantageous as it helps individuals find new food sources, compete with other species, and detect threats. Some urban animals display low vigilance behavior, which is believed to be the result of low rates of predation and becoming accustomed to the presence of humans. However, the masking effect of urban noise can reduce the ability of some animals to detect a potential threat, and they may compensate for this by increasing their vigilance behavior.

Harms facing urban wild animals

The conditions of urban environments leave wild animals vulnerable to a number of different harms. Increased competitive behaviors in urban animals are likely to result in higher instances of injuries, mortalities, and weak body conditions in some individuals. High densities and increased contact between individuals can lead to high transmission rates of diseases and parasites in populations. Transmission rates can also be influenced by the nutritional quality of supplemental food and lighting patterns in urban environments. Survival rates are high in many urban animals, but this can result in more aging animals with the potential to develop cancer. While warm urban temperatures can be beneficial during colder months, urban heat island effects can intensify extreme heat events, increasing the risk of dehydration, mortalities, and poor welfare in wild animals.

Five animals commonly found in urban areas

To gain further insight on the factors affecting urban animal welfare, case studies were conducted on five wild animals that are commonly found in urban environments: Apodemus agrarius (striped field mouse), Passer domesticus (house sparrow), Columba livia (urban pigeon), Pteropus alecto (black flying fox), and Iguana iguana (green iguana). Although these case studies were limited by the amount of information available in the reviewed literature, we found that an individual animal’s welfare was influenced by many factors, including their life history, physiology, behavior, and susceptibility to particular harms.

Green iguanas, for example, have become increasingly abundant in urban areas of Florida. They are ectothermic reptiles who depend on environmental temperatures to regulate their body temperature. In cold temperatures, they may become lethargic and cold-stunned, and prolonged exposure to cold can result in death. There have been many reports of cold-stunned iguanas lying immobile or falling from trees in urban areas of Florida during periods of cold weather. There is a high risk of injuries and mortality when they fall, and they are extremely vulnerable to other harms while they are unable to move. If they recover from a cold-stunned state, they may still experience health problems, decreased fitness, and reduced territorially and breeding behaviors afterward, which can have long-term effects on the iguana populations.

Helping urban wild animals

We recommend that the wellbeing of wild animals should be taken into account when designing, constructing and managing urban areas. Providing resources such as artificial shelters can offer animals protection, and additional water sources can reduce cases of dehydration and mortality in extreme heat events. Vaccinating wild animals can reduce cases of disease, and contraception can reduce transmission rates by lowering the number of individuals in a population. Reducing the size of populations through contraception can also reduce suffering in populations where individuals experience poor welfare. Public awareness and education can improve the welfare of urban animals by encouraging people to assist animals in need of help, and generating long-term support for policies and organizations that aim to improve animal welfare.

Future studies

Many studies of urban animals have so far been limited by the number of species and types of areas being researched. Due to the heterogeneity of different urban areas, and the variation in responses of different animals to these environments, the findings of such studies many only be relevant in specific contexts. Future studies of urban animals would benefit from collaborating with different researchers to build datasets on multiple species in a range of different urban environments. These datasets can then be used to form theories and models related to urban animal welfare, and help develop plans and policies to reduce suffering of urban animals. Future studies in the developing the field of urban welfare ecology would aim to assess the welfare of individual animals, as well as the impact that their presence has on the wellbeing of other animals in the area. We could then evaluate how the presence of animals of a particular species contributes to more or less suffering, and use this information to develop effective ways to improve the overall welfare of all animals in urban environments.