Summarized Project Description
This project is divided into three analytical parts (subprojects): 1. An investigation of conservational aspects concerning anthropogenic influences on the survival of hedgehogs. 2. A description of the health and survival status of hedgehogs. 3. An evaluation of the conservation initiatives developed by e.g. Hedgehog Street.
1. Driver awareness and factors affecting the probability of hedgehog-vehicle collisions.
Previous studies have described how road and roadside characteristics may affect the position of road-killed animals (e.g. Smith-Patten and Patten 2008). However, it appears no studies have focused on the distribution of animals killed on roads in urban areas, and thus exploring the influence of e.g. street lights, parked cars, pedestrian footpaths, road markings/signs on their survivability. Describing these aspects may provide us with knowledge of so-called hot spots for hedgehog-vehicle collisions, enabling local authorities to carry out targeted actions to avoid or reduce the number of hedgehog-vehicle collisions. This study will supplement the previous work on hedgehogs and traffic in urban areas e.g. by Dowding et. al (2007), describing the nocturnal ranging behaviour of urban hedgehogs. Through the study of 16 hedgehogs in 2 suburban areas, Rondinini and Doncaster (2002) found an overall significant tendency for both sexes alike to avoid crossing roads, with avoidance increasing in proportion to road width. Huijser (1999) discussed how local hedgehog populations of lower densities in urban areas may have disappeared due to road density and traffic intensity. Huijser (2000) described the effect of anthropogenic landscapes on hedgehogs as having a negative impact on population levels through e.g. traffic, drowning, disturbances of nests, poisons and injuries caused by dogs, but a mostly beneficial impact on species levels, due to the fact that the species has much higher densities in the anthropogenic landscapes with abundant edge habitats than in other habitats. However, Huijser (2000) also stated that it is important to monitor whether hedgehogs continue to do well in urban habitats, as parks and gardens tend to become smaller and more isolated and the hedgehogs may face new unnatural causes of death in this habitat type. In a study by Huijser and Bergers (2000) it was suggested that roads and traffic are likely to reduce hedgehog density by about 30%, which may affect the survival probability of local populations. Based on these studies there is no doubt that hedgehog-vehicle collisions have a large impact on the population. Huijser, Bergers and Ter Braak (1999) described how the location of hedgehog traffic victims is not random. 20 roads in the Netherlands were monitored in the study from 1995- 97. They concluded that the hedgehogs were more often killed in traffic in forested and suburban areas rather than agricultural areas, marshes and open sand dunes. Certain roadside characteristics were also described in the analysis. However, there is still a need for a comprehensive study on the influence of roadside characteristics, speed limits and landscape features in urban areas, on the hedgehog-vehicle collisions. If the results show that it is possible to point out certain “high risk zones”, the knowledge gained from this study will prove useful for the highways agencies and the local authorities, planning initiatives (e.g. signs, reduced speed limits, fences, fauna passages) to avoid wildlife-vehicle collisions.
Furthermore, a practical approach to a study of driver awareness in order to investigate if specific locations of hedgehogs on roads increase the probability of road-kill accidents, is long overdue (Litvaitis and Tash 2008). The hypothesis of this study is that there are certain angles from where drivers cannot see hedgehogs crossing the road. The method will be to place hedgehog dummies in different positions on the road of a driving center, monitoring whether test drivers of all ages (18+) are capable of spotting and avoiding the dummies, by placing cameras inside and outside the cars. We will also test the drivers’ reactions towards moving hedgehog dummies crossing the road, because we hypothesize that there is a higher tendency for drivers to swerve to avoid an animal, if the animal is in motion. We do not have any data from Denmark presenting the amounts of hedgehog avoidance manoeuvres taking place on the Danish roads each year. However, data from Australia and the US reveals that around 40% of the serious crashes where passengers die or are hospitalized, involved a vehicle manoeuvring to avoid hitting an animal (Attewel and Glace 2000; Conn et al. 2004). The road safety is reduced whenever a wildlife-vehicle collision takes place or is even avoided through swerving, due to the risk of hitting an oncoming car, a cyclist, a pedestrian or even a roadside tree or fence. Whenever the manoeuvring of a car to avoid hitting a hedgehog does not cause an accident, the episode is not reported anywhere. But every time a driver attempts to avoid a crossing hedgehog, the road safety is temporarily reduced, lasting until the drivers recover from the chock of having almost run over an animal.
In the 90’s a study claimed that 50.000-80.000 hedgehogs were killed in traffic each year in Denmark (Hansen 1982). It is fair to assume that at least the same number of hedgehogs has been avoided on the Danish roads every year, with the risk of causing an accident every single time. Hence, this subproject has a highly practical use not only to save a fraction of the hedgehogs that are killed in traffic, but also to increase road safety for the different types of road users, by investigating if there are certain “hot spots” for hedgehog-vehicle collisions in the urban areas, in order for the authorities to improve the actions to avoid road crossing hedgehogs, and understanding how driver awareness influences the risk of running over a hedgehog.
2. The health and survival status of hedgehogs.
Over-winter survival of hedgehogs. This field study will be a continuation of a research project I am currently conducting on behalf of the British Hedgehog Preservation Society. Adult and juvenile hedgehogs will be radio-/GPS-tagged, micro chipped, and monitored for a year, starting from September. Measurements of weight development, home ranges, hibernation date/place, nest shifts during hibernation, time of awakening and mating success will be provided. The findings of this study will be compared to the work of Jensen (2004) and Kristiansson (1990). Thermographic cameras will be used during the hibernation in order to monitor survival in the hibernaculas and as a means of monitoring the survival of independent juveniles in the nest, without disturbing the mother. In order to improve the conservation initiatives directed at hedgehogs, it is necessary to monitor their survival challenges and causes of death. This part will furthermore offer a description of how climate change affects hibernating mammals; an area of study for which the hedgehog is an ideal model because the species’ behavioural ecology is affected by changes in climate. My current research has already provided solid indications of certain effects of climate change on the behaviour of hedgehogs.
A parasitological survey of live-trapped hedgehogs and a description of the dental conditions of hedgehogs. Hedgehogs deriving from the field study will be checked for ectoparasites using a standardized examination method, as an extension of the work by Reeve and Huijser (1999) and Gaglio et al. (2010), focusing on living, non-rehabilitated individuals.
Deceased hedgehogs collected in the road-kill survey and during the field work will be autopsied, age determined (Morris 1971 and Haigh et al. 2014) and receive a dental evaluation by a veterinary odontologist. These are subjects that have previously been neglected scientifically. The findings will describe the age distribution and health status of the collected road kills, providing us with a relevant insight of the population composition and their general health.
During my years of fieldwork and hedgehog rehabilitation, I have discovered that a large amount of the hedgehogs I have handled, have very poor teeth, causing them to lose weight and rely completely on supplementary feeding with softened cat food. The dental evaluations will contribute to our understanding of the hedgehog’s dental conditions. There are hypotheses amongst the veterinary odontologists stating that inbreeding and ingestion of unnatural food items may cause increased findings of dental problems in e.g. cats (pers. comm. Hanne Kortegaard). Lund et al. (1998) found a higher frequency of feline dental resorptive lesions in indoor cats, not having access to their natural food items such as rodents. These hypotheses are also interesting to the study of hedgehogs, because their food items may have changed e.g. due to the control of slugs and insects in residential gardens and they may have become more inbred due to the fragmentation of the Danish landscape.
Population genetics of hedgehogs. Genomic approaches have been suggested as a promising tool for conservation practice as scaling up to genome-wide data can improve traditional conservation genetic inferences and provide qualitatively novel insights (Schafer et al. 2015). The use of genomic approaches has not yet been implemented in hedgehog research. The goal of the population genetics focus is to present results from DNA analyses of hedgehogs in fragmented landscapes and comparing DNA between hedgehogs in Jutland, Funen and Sealand, comparing the DNA of the different isolated populations. One of the goals is to answer the question whether fragmented landscapes are causing inbreeding in hedgehog populations. We will also determine the diet compositions of hedgehogs in different habitats through genetic analyses of faeces.
3. An evaluation of the current conservation initiatives aimed at hedgehogs.
Factors affecting the use of gardens by urban hedgehogs. Hedgehog Street (People’s Trust for Endangered Species and British Hedgehog Preservation Society), the Danish Animal Welfare Society (Dyrenes Beskyttelse), Pindsvinevennerne and Pindsvin SOS in Denmark encourage people to make their gardens more hedgehog friendly through different initiatives. One recommendation is to make a hole in the fence to increase garden connectivity for hedgehogs, another is to establish hedgehog homes such as log piles, compost heaps or custom-made hedgehog houses. A study on the hedgehog activity before, under and after such garden improvements, by setting up wildlife cameras or footprint tunnels (Huijser and Bergers 2000), would evaluate the effects of these different conservation initiatives. A questionnaire survey among gardens owners would illuminate factors contributing to the enhanced presence of hedgehogs in gardens, e.g. the use of custom-made hedgehog houses. This study is based on citizen science, where local volunteers (in this case garden owners) help carry out the research.
Post-release survival of rehabilitated orphans. I will measure the post release survival of rehabilitated orphans and wild, juvenile hedgehogs (Rasmussen 2013) by including them in the over-winter survival study. This analysis will be a comparison between the survival of those individuals having received their mother’s milk (immunization) and attention, and those raised on milk replacers for kittens or dogs by wildlife rehabilitators. In a study on the immunization of juvenile hedgehogs by Morris (1961), it was evident that the juveniles were dependent on receiving their mother’s milk during the entire phase of dependency, because the immunization against Salmonella spp. proved to be a gradual process. Other mammals species, e.g. horses acquire immunity only via the colostrum fed during the first 48 hours of life (Brambell 1970). Therefore, rehabilitated juvenile hedgehogs, having been raised on milk replacers, may lack immunity against common diseases.
This study will supplement the work done on adult rehabilitated individuals by Molony et al. (2006) and juveniles by Morris et al. (1993+1994) and Rasmussen (2013). This study serves as an evaluation of the conservation work done at the numerous wildlife rehabilitation centres. Does it pay to rehabilitate juvenile hedgehogs?