Field observations on the disturbance of grey seals in North Wales
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.
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS110019
- Metadata Language
- English
- Lineage
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The natural pattern of grey seal emergence from and return to the sea at Henllwyn, Ynys Enlli/Bardsey was recorded at intervals of 15 minutes through the tide cycle, in order to understand 'natural' behaviour. Incidental notes were made describing seal behaviour and its apparent relationship to disturbance and relaxation. A count of seals in the sea adjacent to the haul-out sites was made at the same time. Simultaneously, instances of human activity at or near the site were recorded at the same interval. The time of arrival and the duration of time stayed at moorings in the bay by boats were recorded. Records were made of wind direction, wind speed and sea state, in order to discover to what extent they might influence site choice around the bay. At Henllwyn events from which gross disturbance resulted were recorded at the time they happened. Some of these events were filmed using a camcorder.
- Dataset Reference Date (Publication)
- 2005-05-31
Temporal Extent
- Begin date
- 2003-07-27
- End date
- 2003-08-04
- Topic category
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- Biota
Extent
Extent
- Geographic Extent
- Caernarvonshire (49)
))
Vertical Extent
- Medin Extent Keyword
- littoral
Distribution
- Format Type and Description
-
-
Documents
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)
- Specification
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Report with footage from Mini DV Video Cassette
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Documents
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)
Quality
Data quality
- Quality Scope
- Dataset
- Conformity
- Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services
- Explanation
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This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Degree
- false
- Lineage
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The natural pattern of grey seal emergence from and return to the sea at Henllwyn, Ynys Enlli/Bardsey was recorded at intervals of 15 minutes through the tide cycle, in order to understand 'natural' behaviour. Incidental notes were made describing seal behaviour and its apparent relationship to disturbance and relaxation. A count of seals in the sea adjacent to the haul-out sites was made at the same time. Simultaneously, instances of human activity at or near the site were recorded at the same interval. The time of arrival and the duration of time stayed at moorings in the bay by boats were recorded. Records were made of wind direction, wind speed and sea state, in order to discover to what extent they might influence site choice around the bay. At Henllwyn events from which gross disturbance resulted were recorded at the time they happened. Some of these events were filmed using a camcorder.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
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NRW Thesaurus
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- disturbance
- grey seals
- marine and freshwater inventory
- halichoerus grypus
- Type
- Theme
Citation
- Date (Publication)
- 2026-08-27
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2024-06-19
Spatial Reference System
Content
Content Information
NRW Profile
Custom Elements
- NRW Related Title
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Field observations on the disturbance of grey seals in North Wales 2003
Constraints
Constraints
Limitations on Public Access and Use
- Restriction type
- Other restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
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There are no access restrictions to this data. NRW may release, publish or disseminate it freely.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
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© CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose.
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313130303139 XML
- Metadata Language
- English
- Resource type
- Dataset
- Metadata Date
- 2026-09-28T11:46:37.13Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0