GREAT CRESTED NEWTS
HABITAT SUITABILITY INDEX (HSI)
The habitat suitability index or HSI is used to assess waterbodies which could support great crested newts. The HSI is the first port of call when assessing a development site for the presence of newts. Ponds are essential for great crested newts to breed and support the population however only a short time of the year is spent in ponds.
The newts live within suitable foraging habitat and hibernacula such as woodland, hedgerows, grassland and brash/log/rubble piles. Great crested newts forage up to 500 metres from the breeding ponds. Any ponds identified within 250 metres of a development site will require a HSI assessment to ascertain whether the ponds are likely to support great crested newts.
The HSI assessment takes into consideration ten different environmental factors which may affect a newt’s likeliness to use a pond and was created by Oldman et al. (2000, 2008).
eDNA is a relatively new survey method which can be undertaken between March and June. This particular preliminary survey method can save costs and time caused by further survey work through faster confirmation of likely absence of great crested newts from waterbodies on your site. This may therefore allow for faster progress on planning applications.
The survey involves collecting a total of 20 water samples from a waterbody, which are sent to a specialist lab for DNA analysis via a courier. Results from the survey can take between two to three weeks dependent on the time of year.
The analysis will identify if great crested newt DNA is present / absent and will help inform whether further survey work (see below) is required.
The HSI and the eDNA surveys will provide information regarding the presence / likely absence of great crested newts. However, to inform the planning authority and Natural England on the newt population size further surveys may be required.
If newts are present in waterbodies within 250 metres of the development site then a series of either four (where great crested newts are not present on site) or six surveys (where great crested newts are present on site) will be undertaken. These surveys may include bottle trapping, torch counts, sweep netting and egg searches. A total of three survey methodologies must be undertaken between mid-March and mid-June, should great crested newts be present three of the six surveys must be undertaken between mid-April and mid-May.
The survey methodologies are as follows:
Bottle trapping – A series of half-inverted bottles designed to humanely trap any newts are assembled in the waterbody at night and checked early the following morning. To ensure newt welfare, these surveys are conducted in accordance with the Great Crested Newt Mitigation Guidelines (English Nature, 2001).
Torch counts – Approximately one hour after dusk the waterbodies will be methodically searched for great crested newts with a high-power torch.
Egg search – The emergent vegetation within the ponds and vegetation around the pond perimeter is carefully hand-checked to identify any newt eggs. Great crested newt eggs are usually found between folded vegetation.
Sweep netting – Where other survey methodologies are not possible, sweep netting of the waterbody may be used. A fine net is swept within areas of emergent vegetation or along the pond bed potentially capture any juvenile newts, otherwise known as 'efts'.