Dave P Cowan

• PhD
• Lecturer at Newcastle University

Norway rats (Rattus norvegicus) are considered one of the most significant vertebrate pests globally, because of their impacts on human and animal health. There are legal and moral obligations to minimise the impacts of wildlife management on animal welfare, yet there are few data on the relative welfare impacts of rat trapping and baiting methods...

Populations of wild boar and feral pigs (Sus scrofa) are increasing in numbers and distribution worldwide, in parallel with their significant environmental and economic impact. Reliable methods to detect the presence of this species are needed for monitoring its natural range expansion and its occurrence in areas where animals have been deliberatel...

1. As human-wildlife conflicts increase worldwide, novel methods are required for mitigating these conflicts. Fertility control, based on immunocontraceptives, has emerged as an alternative option to lethal methods for managing wildlife. 2. Immunocontraceptives are vaccines that generate an immune response to key components of an animal's reproduct...

We describe the first use of fertility control to manage a free-living mammal population in Europe. An immunocontraceptive vaccine (GonaCon) was used to reduce female fertility in an invasive feral goat Capra hircus population. Adaptive management was implemented to assess the feasibility of fertility control and to allow prediction of the required...

GonaCon, a single-shot injectable immunocontraceptive vaccine targeting the gonadotropin-releasing hormone (GnRH), has been tested in key mammal species in the UK and shown to be a safe method to reduce population size in areas of high human wildlife conflict. Badgers exhibit an unusual reproductive physiology in that females may maintain fertilise...

Population trends for commensal rodents are the subject of interest and speculation but accurate data are rarely available. Here we report data from a 15-year systematic survey of rats and mice in English dwellings and present national-level estimates of prevalence for 1996–2010. We found evidence for peaks in prevalence of mice inside and rats aro...

Anticoagulant rodenticides (ARs) are considered inhumane, show increasingly limited efficacy due to acquired resistance, and carry environmental consequences associated with non-target species uptake. In a questionnaire study of 499 UK farms that all deployed chemical rodenticide we found a high mean reliance (79%), on second generation ARs with ju...

Background: Populations of wild boar and feral pigs are increasing worldwide, in parallel with their significant environmental and economic impact. Reliable methods of monitoring trends and estimating abundance are needed to measure the effects of interventions on population size. The main aims of this study, carried out in five English woodlands...

Background: Wild boar and feral pig numbers are growing worldwide and have substantial economic and environmental impacts. Bait-delivered pharmaceuticals such as disease vaccines, toxicants and contraceptives are advocated to mitigate these impacts. Effective campaigns based on these pharmaceuticals rely on optimising the target species' bait upta...

Rose-ringed parakeets have recently become established in cities across Europe including London, where they are now commonly seen in parks and gardens. Concerns regarding impacts on native birds as well as noise and damage to horticultural interests, have prompted increasing interest in management of populations to reduce numbers. However, parakeet...

Wild boar and feral pigs (Sus scrofa) are increasing worldwide and baiting campaigns to deliver vaccines and toxicants are often undertaken to control their populations or the diseases they transmit. In these campaigns, it is important to assess bait uptake by the target species. We investigated the use of the systemic marker Rhodamine B (RB) to de...

Increasing urbanisation and growth of many wild animal populations can result in a greater frequency of human-wildlife conflicts. However, traditional lethal methods of wildlife control are becoming less favoured than non-lethal approaches, particularly when problems involve charismatic species in urban areas. Eurasian badgers (Meles meles) excavat...

Brief description of each study site Brief description of each study site.

Descriptions of case studies on licensed attempts to exclude badgers from urban setts

WHILE surveys of wild red ( Sciurus vulgaris ) and grey ( Sciurus carolinensis ) squirrels have revealed squirrelpox virus (SQPV) infections in both species (Atkin and others 2010), to date it has been unclear whether maternal transfer of SQPV to juveniles takes place. The observed presence of SQPV antibody in grey squirrel juveniles before leaving...

The grey squirrel (Sciurus carolinensis) is considered a reservoir host of squirrelpox virus (SQPV) which poses a substantial epizootic threat to the native red squirrel (Sciurus vulgaris) in the United Kingdom (UK). Here we evaluate the potential contribution of ectoparasite vectored transmission of SQPV to the epidemiology of the disease. This in...

The purpose of this study was to compare haematology and biochemistry data for captive and free-ranging wild boar in the UK and to evaluate whether significant differences were present between these two boar populations. The samples from the captive wild boar comprised 18 adult females housed in three interconnected outdoor paddocks, whilst the sam...

Global increases in road networks have been matched by traffic flows and are implicated in declines of many sensitive species. Impacts on wildlife by linear development features such as roads include mortality due to vehicle collisions and secondary effects such as preventing traditional movements or severing links between populations. European leg...

As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present rev...

Context Fertility control is being promoted as a non-lethal means of managing wildlife populations. We recently evaluated a single-dose injectable immunocontraceptive vaccine (GonaCon™) on captive female wild boar for effectiveness and potential side effects; reproductive output was inhibited for 4–6 years, with no obvious detrimental effects on ph...

Impacts of overabundant ungulate populations on human activities and conservation include crop and forestry losses, collisions with vehicles, disease transmission, nuisance behaviour, damage to infrastructures, predation on livestock and native species, and reduction of biodiversity in plant and animal communities (e.g. Curtis et ai., 2002; Massei...

Background: The grey squirrel, Sciurus carolinensis Gmelin, is an invasive alien species introduced into Great Britain in the late nineteenth century and into Northern Italy during the early twentieth century. Grey squirrels have displaced the native European red squirrel, Sciurus vulgaris L., throughout much of Great Britain and have a significan...

Context Fertility control appears as a publicly acceptable alternative to lethal methods for limiting population growth in wildlife. Recently developed single-dose immunocontraceptive vaccines have induced infertility in several mammals. However, the potential side-effects and the long-term effectiveness of these contraceptives have been poorly inv...

Grey squirrels (Sciurus carolinensis) are an invasive species in Britain and Italy. They have replaced native red squirrels (Sciurus vulgaris) throughout most of Britain, and cause damage to trees. Currently, lethal control is used to manage grey squirrel populations in Britain, but nonlethal methods might be more acceptable to the public. One such...

Oral delivery of fertility control agents requires information on rates of bait consumption by the target species. In this study, the consumption of cereal bait by wild ricefield rats (Rattus argentiventer) was assessed under enclosure conditions using Rhodamine B (RB) as a bait marker in two baiting rounds. Total bait consumption increased during...

The grey squirrel is an invasive alien species introduced to Great Britain in the late 19th Century and to Northern Italy during the early 20th Century. As well as displacing the native European red squirrel, grey squirrels cause significant impact to trees and woodlands through bark-stripping activity, and are implicated in the decline of woodland...

ABSTRACT Bait-delivered pharmaceuticals, increasingly used to manage populations of wild boar (Sus scrofa) and feral pigs, may be ingested by nontarget species. Species-specificity could be achieved through a delivery system. We designed the BOSTM (Boar-Operated-System) as a device to deliver baits to wild pigs. The BOSTM consists of a metal pole o...

ABSTRACT  Chemical markers are increasingly used to investigate consumption of baits used to deliver vaccines, toxicants, and contraceptives. We evaluated whether ethyl-iophenoxic acid (Et-IPA) and propyl-iophenoxic acid (Pr-IPA) can be used as long-lasting systemic bait markers for wild boar (Sus scrofa). We presented captive wild boar with baits...

Rose-ringed parakeets (Psittacula krameri) have become widely established outside their native range through accidental or deliberate release. Potential economic impacts on agriculture, conservation concerns, and mixed public opinion regarding the species have highlighted the need to develop effective but humane management options. Fertility contro...

Context Rabies causes ~55 000 human deaths each year, primarily as a result of bites from dogs, which are the major rabies reservoir in the developing world. Current rabies control strategies include vaccination, culling and surgical sterilisation of dogs. However, recently developed immunocontraceptives could be used alongside vaccination to apply...

Context Animal movements recorded by radio-telemetry produce a series of spatio-temporal point-location estimates that sample an animal’s continuous track. However, uncertainty in the point locations themselves, and uncertainty of how the animal moved between locations, could be large enough to render data unsuitable for some purposes. Aims Our ob...

Growing public concerns about lethal methods to mitigate human–wildlife conflicts place increasing constraints on wildlife management options. Translocations, perceived as humane and non-lethal solutions, are increasingly advocated to resolve these conflicts. The present study summarises the literature on translocations of wild mammals, with partic...

�Context:� Rabies causes ~55 000 human deaths each year, primarily as a result of bites from dogs, which are the major rabies reservoir in the developing world. Current rabies control strategies include vaccination, culling and surgical sterilisation of dogs. However, recently developed immunocontraceptives could be used alongside vaccination to ap...

Rose-ringed parakeets Psittacula krameri (Scop.) have recently become established in several European countries, with potential for significant negative economic and ecological impacts. However, in northern Europe the potential for reproductive output is largely unknown. In 2005 the authors established a captive outdoor colony in north-east England...

Tracking and census baiting are two techniques that are commonly advocated for monitoring the size of mouse populations. However, currently these techniques are only able to provide an index of population size, rather than an assessment of absolute numbers. In this study the authors tested the reliability of both tracking (footprints left on tiles...

Targeting the host has been the most common approach to managing disease in wildlife. This has essentially involved some form of host population reduction, achieved through dispersing, culling, or controlling reproduction. Dispersion of animals from the site of a disease outbreak has mainly been employed for birds (Wobeser 2007) but has also been a...

Targeting the host has been the most common approach to managing disease in wildlife. This has essentially involved some form of host population reduction, achieved through dispersing, culling, or controlling reproduction.

The increasing incidence of reports of damage caused by Eurasian badgers (Meles meles) in UK urban environments requires the development of effective, humane, non-lethal solutions. Ultrasonic deterrents are widely available to the public and are sold as a humane solution to the presence of unwanted animals in urban gardens. The reported failure of...

Norway rat Rattus norvegicus populations are usually controlled with toxic baits, but this approach is increasingly recognized as having negative welfare and environmental impacts. An integrated strategy that relies less on rodenticides is therefore required. Here we investigate the possibility of using a resource‐based approach to rat population m...

Fertility control has the potential to be used as an attractive alternative to lethal methods for limiting population growth in overabundant species. This study tested the effectiveness and potential side effects of the single-dose gonadotrophin-releasing hormone (GnRH) vaccine GonaCon on the physiology and behaviour of two groups of captive female...

There are currently an estimated 40 million rabbits (Oryctolagus cuniculus) in Britain, causing £115 million of damage to the agricultural industry. It is estimated that £5 million are spent each year to manage rabbit populations. We report on a Decision Support System (DSS) to help landowners calculate the costs and benefits of managing the rabbit...

Several authors have suggested that edible plants could avoid herbivory by mimicking olfactory cues of toxic plants. However, very few studies have been carried out to test this hypothesis. The aims of the present study were to identify the volatiles of three clover species and to test whether a species lacking chemical defences, such as red clover...

Systemic application of sodium silicate can significantly enhance the levels of leaf silica in winter wheat (Triticum aestivum L. cv. Mercia), suggesting that this material could reduce the palatability of plants to vertebrate herbivores (e.g. rabbits, Oryctolagus cuniculus L.). A bioassay was developed using hydroponically grown wheat plants. Plan...

Baits are increasingly used in wildlife management to deliver orally administered vaccines and contraceptives. The efficacy and cost-effectiveness of vaccination or fertility-control campaigns can be substantially affected by bait uptake rates. This study assessed whether bait type and deployment strategy affected bait uptake by free-living badgers...

This study was carried out to assess whether Rhodamine B, ethyl-iophenoxic acid (EtIPA), and propyl-iophenoxic acid (PrIPA) can be used as long-lasting systemic bait markers for free-living badgers (Meles meles). Between June and November 2003, these chemicals were incorporated into bait distributed around badger setts. Serum, hair, and whiskers fr...

In summer 2001, visitors to a wildlife park in Norfolk, uk, became infected with verocytotoxin-producing Escherichia coli (vtec) O157, which was associated with wild rabbit faeces. The rabbits lived in an adjacent field together with E coli O157-positive cattle. A pilot study was therefore performed to investigate the factors affecting the associat...

For a conditioned taste aversion (CTA) agent to be successful in wildlife management applications, the compound must not be detectable by the animal. Levamisole is an effective CTA agent when administered by oral intubation, but it is readily detected by a number of species when mixed directly in food. This paper describes the development of an ion...

Chemicals that reduce food intake by stimulation of satiation receptors could offer a novel, nonlethal method of reducing feeding damage to crops or stored products by vertebrate pests. Such chemicals result in a deep-seated, physiological response whose effects on feeding are unlikely to wane through habituation. We describe a preliminary evaluati...

Vaccination and fertility control by means of oral baits may be potential tools for the management of bovine tuberculosis (TB) in populations of the Eurasian badger (Meles meles L.), but bait monopolisation may hamper the effectiveness of these methods. One potential method to reduce bait monopolisation is to induce learned aversion to bait. Learne...

Minimum number alive (MNA) is commonly used to assess population size with capture-mark-recapture data. However, MNA uses information from prior and subsequent capture sessions to assess the population at each point in a longitudinal study. Therefore, it is subject to negative bias that is greatest at the beginning and end of the study and least in...

In a previous pilot field trial on autumn-sown oilseed rape (Brassica napus L), a suspension concentrate formulation of the avian repellent cinnamamide, using Acronal 4D (50 g litre(-1)) as the sticker, was shown to reduce damage by woodpigeons (Columba palumbus L). However, the persistence of cinnamamide on rape leaves was poor. This paper describ...

Conditioned taste aversion (CTA) develops when an animal associates the taste of a particular food with illness and subsequently avoids consuming that food. We evaluated the potential of two compounds, levamisole hydrochloride and antimony potassium tartrate (APT) to induce CTA to meat in captive ferrets (Mustela furo). On conditioning day, one gro...

A rabbit-census method, based on systematic counts conducted at night or at dawn and dusk, was developed and validated in terms of estimating the total number of rabbits present in a given area. Initially, models were developed under semi-natural conditions to describe the relationships between the numbers of rabbits counted and population size. Co...

Conditioned Taste Aversion (CTA) develops when animals associate the taste of a particular food with illness and subsequently avoid consuming that food. We evaluated the potential of two chemicals, thiabendazole and levamisole hydrochloride, to induce CTA to meat in captive foxes (Vulpes vulpes). Foxes were presented for 45 min with thiabendazole o...

The need to control Norway rats in the United Kingdom has led to heavy reliance on rodenticides, particu- larly because alternative methods do not reduce rat numbers as quickly or as efficiently. However, such reliance has led to concerns that repeated use of rodenticides poses unacceptable risks to other animals as well as encouraging resis- tance...

Predation on eggs affects the population dynamics of many bird species throughout the world. We investigated whether Conditioned Taste Aversion (CTA) can be used to decrease predation on bird eggs by rats. Conditioned taste aversion occurs when an animal associates the taste of a particular food with illness and subsequently avoids consuming that f...

Conditioned taste aversion (CTA) occurs when animals associate the taste of a food with illness and subsequently avoid that food. CTA can be experimentally induced by adding an undetectable, illness-inducing chemical to food. The use of CTA has been suggested as a humane, non-lethal method for vertebrate pest control. The present study tested the a...

The presence of commensal rodents was assessed in the 1996 English House Condition Survey (EHCS). Logistic regression techniques were used to identify the key factors that might determine the susceptibility of dwellings to infestation. The overall percentages of dwellings that were infested, weighted to allow for the more intensive sampling used in...

Male mice produce scent marks by depositing urine throughout their territory. The scent marks contain a number of pheromones and contain major urinary proteins (MUPs). Up to 1 g of these MUPs may be produced everyday. It is therefore likely that scent marking is costly and as such will impact on male fitness. In order to investigate the costs of sc...

A conditioned taste aversion (CTA) is acquired through an association between the taste of a food and a feeling of illness experienced after ingestion. It can be induced deliberately by the addition of an undetectable illness-inducing chemical to food. Harnessing the CTA response could provide humane and effective means of controlling vertebrate pe...

The potential of Norway rats (Rattus norvegicus) to spread the parasite Cryptosporidium parvum was investigated by examining parasite prevalence in relation to the structure and movements of three permanent rat populations living on farmland in Warwickshire (UK) from October 1994 to March 1997. One population lived among a group of farm buildings h...

Populations of Norway rats (Rattus norvegicus) are usually controlled through the use of rodenticides. Chemical attractants can be used to complement rodenticide treatments by, for example, attracting rats to bait stations. Chemical repellents can provide a non-lethal alternative in applications where the aim is to prevent pest damage to crops, str...

The odors left by predators are biologically significant chemicals in that they may signal to prey that there is an increased risk of predation if they remain within the vicinity of the odor. We investigated the possible repellent effect of fox (Vulpes vulpes) fecal odor. We used rabbit (Oryctolagus cuniculus) fecal odor as a control which, by acti...

Chemical repellents may provide an effective and humane method of reducing bird damage to crops via modification of the feeding behavior of the target species. We observed behavior of free-living birds, in particular greenfinches (Carduelis chloris), blue tits (Parus caeruleus) and great tits (P major), feeding on peanuts contained in wire-mesh fee...

The potential of cinnamamide, a non-lethal repellent, to induce a conditioned taste aversion in house mice (Mus domesticus) was investigated. Mice were presented with saccharin solution, then assigned to one of four groups, each of six individuals, receiving lithium chloride, cinnamamide or blank carrier by oral intubation. The fourth group were ha...

Woodpigeons Columba palumbus cause significant damage to oilseed rape Brassica napus. (Cruciferae) in Britain, especially between January and March. The potential of cinnamamide, a non-lethal chemical repellent, to protect growing oilseed rape from woodpigeon damage was assessed in 20×20 m plots laid out in a 9-ha field frequented by >500 woodpigeo...

Second-generation anticoagulant rodenticides were introduced to control Norway rats that had become resistant to first-generation compounds. Unfortunately, some rats have become resistant to these as well. The lack of alternative rodenticides with the same attributes of ease of use and relative safety is potentially a serious problem should resista...

To investigate whether behaviour within litters predicted later dominance status, male mice were observed whilst in their litters from three weeks old, and when paired with an unrelated male as an adult. We found that males that were dominant in their litter were not more likely to become dominant as an adult. The best predictor of adult dominance...

The systemic application of L-phenylalanine (PHE), a phenolic precursor, significantly increases the phenolic pool of oilseed rape (Brassica napus var. Bristol). In a two-choice test with captive feral pigeons (Columba livia), PHE-treated plants sustained significantly less damage than control plants. This was supported by the results of behavioral...

Cinnamamide, a non-lethal repellent, deters feeding by a wide range of avian species. We investigated the potential of cinnamamide as a repellent for house mice (Mus musculus) and wood mice (Apodemus sylvaticus), using a 3 day, ‘short-term no-choice test’. Both species were presented with cinnamamide-treated food at 0.8% w/w. After an initial sampl...

Groups of wild rats (Rattus norvegicus) were housed in large arenas and their foraging behaviour towards unfamiliar food, novel food and novel food containers was monitored using remote sensing equipment. Three main findings resulted from the study. There is a large individual variation in the responses to new foods and food containers placed in th...

Two non-lethal vertebrate feeding deterrents, cinnamamide and 3,5-dimethoxycinnamic acid, were tested as seed dressings for the protection of winter wheat against damage by the field slug, Deroceras reticulatum. Both compounds were active in deterring feeding in a two-choice test. Cinnamamide was the most effective repellent, significantly reducing...

Few effective repellents are currently available for the non-lethal management of vertebrate pests. This is perhaps not surprising considering the ad hoc nature of past applications which assumed that the target pest species would have the same attraction/aversion preferences as man. A more rational approach is to identify compounds that have real...

The palatability of 12 rodenticide baits, formulated to vary from poorly accepted to well accepted, was measured in laboratory choice tests against Wistar and wild-caught Norway rats. The baits, derived from six bait bases and two active ingredients, difenacoum and bromadiolone, were simultaneously tested in the field against 24 farm infestations (...

For the first time, it has been unequivocally shown that multiple-feed second-generation anticoagulant rodenticides were ineffective against a population of rats in N.W. Berkshire, UK because of an unusually high prevalence and high degree of resistance. Use of the non-anticoagulant rodenticide calciferol led to a substantial reduction in the popul...

There is a need for effective and environmentally sensitive methods of controlling vertebrate pest problems in agriculture and the urban environment. Nonlethal chemical repellents may meet this need where more traditional methods of control, such as scaring, shooting, and trapping, are either ineffectual or unacceptable. One such chemical repellent...

Resistance amongst rats to second-generation anticoagulants, notably difenacoum, has been recognised since the 1970s. Although initially considered to be of practical significance, doubts were subsequently expressed that the degree of resistance was sufficient to explain ineffective rodenticide treatments. Research published elsewhere demonstrated...

In a series of 3 experiments with different experimental paradigms, feeding patterns of laboratory rats (Rattus norvegicus) were monitored in 2-choice feeding tests after intubation with a sublethal dose of an anticoagulant rodenticide. We report for the first time that contrary to accepted wisdom, anticoagulants can induce taste aversions. Further...

In a series of 3 experiments with different experimental paradigms, feeding patterns of laboratory rats (Rattus norvegicus) were monitored in 2-choice feeding tests after intubation with a sublethal dose of an anticoagulant rodenticide. We report for the first time that contrary to accepted wisdom, anticoagulants can induce taste aversions. Further...