Field observations on the disturbance of grey seals in North Wales dataset https://portal.medin.org.uk/portal/start.php?tpc=007_NRW_DS110019 Many studies quantify the impacts of non-lethal human disturbance on animal behaviour to which animals respond by deploying what are interpreted as anti-predator strategies. These strategies are recognised as diverting time and energy from behaviours that would have occurred in the absence of human influences. In this report, levels of disturbance to grey seals are measured and these take into account the variety of seal vigilance levels as the prelude to / trigger of gross disturbance. Gross disturbance here denotes the stampeding of a seal or seals into the sea, where they were assembled on land, or where seals 'crash dive' when already in the sea. The purposes of this data capture were to: - Record the haul-out patterns of grey seals at Henllwyn Bay on Ynys Enlli/Bardsey when subject to no disturbance caused by people, in order to show examples of normal behaviour. To record examples of disturbance caused by human activity on land, in the sea and in boats, at Henllwyn for comparison with 'normal' / undisturbed behaviour. - Describe variables in seal behaviour observed over several tide cycles. - Outline some aspects of survey design to best measure disturbance. - Outline some site-specific management measures designed to reduce the frequency of disturbance events while also respecting the desires of people to have good views of and insights into the behaviour of grey seals at haul-out sites. - Provide a short review of papers and reports on seal disturbance at haul-out sites on the shores of the northeast Atlantic. This will examine management measures that have been or are about to be deployed elsewhere and the ways that such measures are being, or will be, monitored. 20050531