Taking a stroll in the countryside and keeping an eye out for animals and plant life could help conservationists build up a picture of alien species invading our county.

Taking a stroll in the countryside and keeping an eye out for animals and plant life could help conservationists build up a picture of alien species invading our county.

Norfolk Wildlife Trust (NWT) is calling on nature detectives to help them compile a map of non-native flora and fauna which can harm other species and their habitats.

It is working with Norfolk Bio-diversity Partnership and Norfolk Biodiversity Information Service and is keen to hear about five main offenders and where they were seen.

These are Himalayan balsam, which grows in dense clumps up to 3m tall, with fragrant, purplish-pink slipper-shaped flowers held on long stalks, which appear in late summer and autumn; Japanese knotweed, which grows to a similar height, is like bamboo and has creamy white flowers from July to September, and giant hogweed, which lives up to its name by growing up to a staggering 6m and must not be handled as it contains toxic sap. It has hollow stems, which are green with reddish-purple blotches and many small white flowers which form an umbrella-shaped head up to 50cm across.

The wildlife survey will also record sightings of two mammals - the Muntjac deer, introduced to Woburn Park from China about 100 years ago, and the American mink, which bred from escaped animals imported for fur farms.

The Muntjac regularly visits gardens in urban areas, is just 45cm tall at the shoulder and has a dark V or diamond-shaped mark on its face. The American mink is about half the size of an otter with rich, glossy dark- brown or black fur with a pale patch on the chin and a ferret-like pointed face and a fluffy tail.

Wildlife and community officer Gemma Walker said: 'This is a very interesting survey and gives people the opportunity to actively get involved in nature conservation.

'We believe it is really important to understand the extent to which these non-native species have spread in the county, because they can do harm. For example: invasive plants shade out the native plants, and when they die back often leave bare ground which is vulnerable to erosion, especially on river banks. The American mink is a voracious predator of water voles. Plants such as Japanese knotweed can cause damage to buildings and hard structures.'

NWT's director Brendan Joyce said he was thrilled with how many people have taken part in NWT's surveys already and hoped many more will join in.

The Wildlife Invaders survey will run until the end of October and can be completed online at www.norfolk wildlifetrust/naturalconnections or via a survey card, available by calling 01603 598333.