Wilden Marsh And Great Crested Newts
Great Crested Newts, the UK’s most protected amphibian, are loved by many naturalists and rather less so by some property developers. Unfortunately, loss of ponds and their surrounding newt friendly habitats, as well as changes in farming practices, have set these wonderful animals on a path to steep decline, Fortunately, Wilden Marsh is a protected nature reserve and home to many great crested newts as well as a good selection of other amphibians. The marsh has a variety of amphibian friendly wet habitats, including wet grassland, many different shapes, sizes and depths of ponds, scrapes and puddles; here are a few images of some of these.
I recently removed a lot of brash left in the duckweed covered GCN pond following recent restoration work. A small coppice canopy that heavily shaded the main GCN pond at the north end of the swamp, close to Hoo Brook, has been removed, giving the whole area access to our glorious British sunshine. The water is nutrient rich: a result of many years rotting down willow leaves and branches from the coppice canopy. Approximately half the pond is colonised with reedmace and yellow flag iris. Some of the nutrient rich sediments at the north end of the pond should probably be removed, but I don’t want to do this until I have had chance to see how the pond reacts to a year of sunlight. I also need to be very careful about what we do around great crested newts and their habitats. There are hefty penalties for those who get it wrong.
Amphibians in general, and the great crested newt in particular, depend on ponds, scrapes and other suitable waterbodies for breeding, but they can spend the rest of their lives living on land around their breeding ponds. Newts are generally more active on warm, wet evenings or those following rain. They eat a range of invertebrates, such as earthworms, insects, spiders and slugs
The main factors affecting the general decline of great crested newts are:
- The deliberate filling in or destruction of ponds
- Pond loss through natural succession
- Introduction of fish
- Chemical pollution and nitrification of breeding sites
- Loss of terrestrial habitat
- Habitat fragmentation
- Habitat management which renders sites unsuitable for great crested newts
- Deterioration of ponds through neglect or misuse
A significant number of willow and alder trees growing in the Wilden Marsh swamp have been recently coppiced, pollarded and generally thinned out, opening half a dozen previously shaded small ponds to sunlight.
Great crested newts need both aquatic and terrestrial habitat. They prefer small to medium sized breeding ponds, Smaller ponds are likely to attract newts more successfully where they occur in clusters. Very small ponds, garden ponds, small bog ponds and larger lakes are usually not of interest to the newt. Breeding ponds should support aquatic vegetation for egg laying. Great crested newts prefer extensively vegetated ponds with submerged plant covering of about two thirds of the pond surface, and emergent/floating vegetation cover of one quarter to one half of a pond; in other words a well established, mid-succession pond. Ideally there should be open, less vegetated areas within the pond to allow adult males to display in clear view of females. Ponds that lack shade on the southern margin seem to be preferred.
A Breeding female will lay around 250 eggs per season, each egg is bonded to the underside of a submerged leaf on a marginal plant; the newt then bends and bonds the leaf over the egg to provide a protective envelope.
So, I’m not going to do anything further with the GCN pond this year, apart from skimming the duckweed from its surface (to make it less attractive to ducks who are already overnighting there) and monitoring it over the forthcoming breeding season. In the meantime, I will get some expert advice on the best ways of improving the pond and the immediate area surrounding it. Hopefully, any necessary improvement work can be carried out next winter.