The Otterwatch Project provides a means by which we can monitor otters that regularly pass through the Winchester City Mill. The system has been in place for over 10 years, and started when the Environment Agency installed the first cameras in the nineties. Since 2006, the CCTV cameras have been upgraded and altered many times, enabling the mill to share with its visitors the quite unusual relationship between this old building and the completely wild otters that make it part of their territory.

More recently, the project has benefited from a partnership between the National Trust, who own and run the city mill; the Environment Agency, who are responsible for the River Itchen, that flows through the mill; and the Hampshire and Isle of Wight Wildlife Trust, who protect the nature and wildlife around Winchester. Supplemented by some quite unique technology provided by IBM and the University of Exeter, the Otterwatch project has become capable of monitoring wildlife as it passes through the mill, and automatically identifying if the animals are otters. Once trained, this software will process footage of wildlife and detect if the subject of the film is an otter or something else (for example spider's web, duck, fog!). When an otters is detected, it will tweet a notification, alerting the mill's hundreds of followers of the visit.

The cameras are now positioned within the mill building overlooking the slip channel. This is the slower moving path of the river, that takes a smaller quantity of water than the mill race itself (which is where the water wheel is located). There is also a camera positioned at the end of the mill garden , watching a set of steps that have been installed to help the otters traverse the dam that restricts the flow of water into the slip channel.

The otters are shy, primarily nocturnal, creatures that are unlikely to be spotted by passers-by. Having said this, they have been spotted on occasions, so definitely worth looking down at the Itchen at dawn and dusk!

Prior to 2006, the cameras and technology that watched the slip channel, which is where the majority of otters are filmed, had become unmaintained and was not regularly monitored. The mill itself was also going through a major change, and demonstration milling was started in 2005, becoming more regular in 2006. In October 2006, one of the millers began to take an interest in the otter cameras, and picked up the task of checking the footage being collected, and identifying where this video included otters. Together with another volunteer, otter sightings began to be recorded in a more organised way, and this continued until January 2007.

The footage itself was now being regularly reviewed in order to pick out the sightings of otters from all of the other spurious video of spiders' webs, ducks, flying insects and even fog that the CCTV inevitably captured.

This site is not intended to be widely accessible. For more information about the National Trust, the City Mill and other related matters, please see the links below:

• Winchester City Mill National Trust Site - https://www.nationaltrust.org.uk/winchester-city-mill
• Follow us on Twitter - @WCMOtters
• National Trust
• About European Otters
• Hampshire and Isle of Wight Wildlife Trust
• Hampshire CC - River Itchen

This site is intended for use by volunteers and staff at the Winchester City Mill who manage the Otterwatch system. This system records footage of wild otters as they pass through the mill's buildings. It also will tweet a screen capture of the otter, when it is pretty sure that it is an otter it's seen!

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Otterwatch Documentation Wiki