Fen Management Handbook - Scottish Natural Heritage

Great Crested Newt
Great crested newts prefer a mosaic of rough grassland, scrub and woodland, so general fen
management techniques should ensure that suitable terrestrial habitat is maintained. Grazing
livestock, if present, should be excluded from ponds to prevent poaching and overgrazing of
emergent and marginal vegetation. Great crested newts are highly negatively correlated with the
presence of fish, so ponds should be maintained fish-free and new ponds located in areas not at risk
of fish colonisation during flood events.
Overhanging vegetation should be cut back periodically to prevent overshading. Aquatic vegetation
should be controlled on a 2-3 year rotation to prevent excessive growth – management should
aim to ensure that 50-75% of the pond surface is free of vegetation, especially around the shallow
pond edges where adult newts gather for courtship displays. Pond depth should be maintained at
between 1-2 m, with periodic dredging to remove accumulated sediments.
Sensitive periods
Works to ponds should be carried out outside of the main breeding season when newts and larvae
are most likely to be present. Operations such as vegetation removal, pond desilting and reprofiling
should therefore be carried out between October – February. Mowing grass and fen vegetation
should be carried out in hot conditions in summer, and vegetation should be cut to no less than
10cm high, with refuges of unmown vegetation left.
Adults hibernate on land between November- February (depending on temperatures), so work
involving ground disturbance in areas where great crested newts might be hibernating should be
avoided during this time.
Hibernation sites can be created relatively quickly and cheaply from part-buried rubble mounds
situated near to ponds in areas free from flood risk.
Smooth Newt and Palmate Newt
These species use a full range of water bodies and are frequent colonisers of new ponds. They will
tolerate the presence of fish to a certain degree but predation on larvae by fish is a significant factor,
and ponds should be maintained fish-free. Management actions described above for great crested
newt will also maintain ponds and habitat for smooth and palmate newts.
Fish
Recommended Management
In most cases fish will be conserved alongside other aquatic organisms by general management
measures designed to maintain unpolluted water and to retain essential habitat features that are
needed by fish. This includes maintaining natural river and stream profiles that favour invertebrates
for food and aquatic plants for food and cover from predators, as well as spawning sites and refuges
for fish fry.
Monitoring of fish stocks is recommended if fish are main prey for a priority species. Re-stocking
of fish should be considered, especially after pollution incidents, but care should be taken not to
introduce fish to ponds used by great crested newts for breeding.
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