London HogWatch identifies hedgehog populations in Greater London to promote conservation strategies for their protection, connection and expansion.
What do we do?
London HogWatch was established in 2016 to identify the locations of the main hedgehog populations in Greater London. By increasing our understanding of hedgehog abundance and distributions, we can better inform future conservation management strategies and help halt the decline of hedgehog populations in London.
So far, HogWatch has conducted major surveys of some of the most important green spaces supporting hedgehog populations, in addition to exploring new locations where there was deficient information on hedgehog presence and absence. More specifically, we have identified substantial hedgehog ‘hotspots’ - in northeast London including in the Highgate and Hampstead area, and others in the southwest Barnes and Twickenham area, in addition to several smaller populations across North and South London.
Hedgehogs have recently been classified as ‘Vulnerable to extinction’ in the UK as their numbers are estimated to have declined by 46% in the last 13 years. Multiple factors may be interacting to produce this effect, including habitat loss and fragmentation, use of pesticides and agricultural chemicals, road traffic, and potentially the increasing badger population.
Historically, hedgehogs have been an integral element of both urban and rural biodiversity in the UK but have declined dramatically in recent years. Evidence suggests that this decline has been particularly severe in rural areas, highlighting the significance of urban hedgehog populations for conserving this species. Hedgehogs occur in several areas across Greater London but our current understanding of these remaining populations is poor. For us to take effective conservation measures a greater knowledge of their distribution and population sizes in London is required.
How do we do it?
Between April and October, we carry out systematic camera trapping surveys across Greater London in a range of different habitats, including parks, gardens, and private green spaces. This allows us to collect data on the presence and absence of hedgehog populations. Camera trapping also means we can monitor the occurrence of other London wildlife populations that might impact hedgehogs, such as red foxes and badgers. Our analyses of the data enable us to address knowledge gaps about the occurrence, size, and connectivity of hedgehog populations. With this information, we can detect where habitats have become fragmented, for example we have identified roads as a major threat for London’s hedgehogs preventing them from accessing otherwise suitable habitats.
London HogWatch’s ability to conduct surveys is only achievable with the kind support of our funders and collaborators. We work with a variety of groups including councils, local environmental groups, charities, and companies. We are particularly grateful for the support of the British Hedgehog Preservation Society, HogWatch's core funder, without whom this work would not be possible.
HogWatch continues to expand every year and has currently carried out surveys in a third of all London Boroughs and put out over 3,000 camera traps across London. The map below shows in green all the London Boroughs we have conducted surveys in to date, however the scope of our work continues to expand into new areas.
Our work across various London Boroughs, would not be possible without the help of numerous volunteers from community groups, residents, and societies. HogWatch is constantly undertaking camera trap surveys that involve large numbers of volunteers. Volunteers help us set up cameras in London’s parks and green spaces, and take cameras home to conduct their own garden survey to monitor potential hedgehog activity. These garden surveys are an important addition to our data as gardens can act as important refuges for hedgehogs in highly urbanised areas.
Citizen Science: Our work combines citizen science data obtained from various external charities such as, NBN, GIGL, PTES. We have used this information to better understand hedgehog habitat use across the capital which can be found here. We have also recently conducted our own historical knowledge survey to understand the recent present and past distributions of hedgehogs in the Hampstead and Kentish Town area.
School’s education: The iconic status of hedgehogs along with the conservation technology that underpins this work, provides an ideal platform for supporting schools’ education activities, and throughout the programme, we have made several schools visits (both in primary and secondary schools) and supported works experience placements for secondary school children.
Rewild London project
As part of the Mayor of London’s Rewild Fund, London HogWatch is conducting surveys in various Sites of Interest for Nature Conservation (SINCs) and other green spaces within the North Camden area. Working with a range of community partners, our surveys will assess the current distributions of hedgehogs and other important wildlife species to help target areas that act as critical corridors of movement between these areas and inform future local conservation efforts.
Regents Park is marked as an important hedgehog habitat as it contains the last breeding population in central London. A 2018 report by HogWatch identified Hampstead Heath as one of the largest and most important hedgehog populations in Greater London. Additionally, smaller hedgehog populations in sites between these two larger populations, such as Kentish Town City Farm, have been found but knowledge of other sites is very limited. This project aims to fill the knowledge gap on the extent of hedgehog distributions between Hampstead Heath and Regent’s Park. It will combine camera-trap surveys, and historical knowledge surveys to provide up-to-date information.
HogWatch has been working in the Barnes area for the past few years in collaboration with Friends of Barnes Common, Barnes Hedgehogs, and Richmond council. The area was first identified as a hedgehog hotspot in 2018 when a survey on Barnes common revealed high hedgehog activity. Since then, many other areas in Barnes have been surveyed and revealed a large hedgehog distribution in the area. Unfortunately, our analysis has shown a decline in abundance and distribution over the five-year monitoring period, especially on Barnes Common. Reasons for this decline are unknown but we continue to monitor the area and support local conservation strategies. Our results suggest that gardens are acting as important refuges for hedgehogs here and Barnes Hedgehogs continues the important work of putting holes in fences to create hedgehog highways to help conserve this population.
HogWatch started surveying Chiswick in 2021 in collaboration with WildChiswick. This revealed a strong hedgehog population in Chiswick House and Gardens which extended across the Grove Park and Strand on the Green area of Chiswick. Promoting the results from the surveys in the local area meant people became more aware of hedgehogs and their needs. WildChiswick was able to start a hedgehog highway campaign by putting holes in garden fences and directing these efforts to where it was most beneficial to the hedgehog population. Once local residents knew hedgehogs were in the area WildChiswick has been able to do successful outreach activities, talking to people about how to make their gardens more hedgehog friendly, including speaking in school assemblies. When people know there are hedgehogs in their area, they are more willing to take action.
HogWatch has been working with Kingston Council to investigate their hedgehog population. In 2021 a survey in the Surbiton area was conducted which found only a few sightings suggesting the population here is small and in need of conservation action. The results also helped identify an adjacent area for further study in 2022. This survey revealed how important garden habitat is for hedgehogs here. HogWatch continues to work with Kingston council to monitor their hedgehog population and to promote conservation action in the area.
Amazingly the 2022 Kingston survey detected a pine marten, the first record in London for over a century. Highlighting the importance of biodiversity monitoring and how useful camera traps can be for picking up rare or elusive species.
Other Urban Biodiversity Monitoring
Camera traps provide a wealth of information not only on hedgehogs but on many other mammal and birds species. This makes them ideal for general biodiversity monitoring and HogWatch has been involved in projects which are aiming to learn more about the dynamics of urban biodiversity.
South London Partnership, Internet of Things
Funded by Internet of Things, London HogWatch has been working in collaboration with Richmond council using cellular cameras to gather real time data on the fauna of Richmond to inform its strategy of nature recovery. This data will be combined with other data to inform an approach that considers site connectivity, climate change resilience, and the priority actions for habitats and species. Data gathered will also be used in the future to monitor the success of planned conservation actions, for example, HogWatch has recently surveyed Crane park Island for water voles prior to the planned reinforcement of the population.
The habitats around railway lines in cities potentially provide important sites for a wide range of plants, and insects and potentially are important corridors for a range of mammal species including hedgehogs. In 2022, London HogWatch and Instant Wild, both ZSL programmes, started a partnership with Network Rail, in south London to better understand the use of these areas by hedgehogs and other species. Thus far we have seen evidence of the use of these sites by a range of species including hedgehogs, badgers, and foxes. We hope to extend this work further in 2023.
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