Trout in the winter in Hertfordshire's Panshanger Park

Winter time can sometimes feel like a long stretch of radio silence on the wildlife side of things.

Thankfully, the last couple of weeks the daylight is getting noticeably longer, with birds starting to rehearse their springtime songs, and investigate potential nesting sites, and snowdrops peeking through the leaf litter. 

And even though for much of the wildlife the past few months have been a quiet time, it has been a busy time for some of our aquatic wildlife at Panshanger.

Winter is a time for spawning fish in the river, with the native brown trout preparing the gravel to their liking to lay their eggs in. They do this by fanning their tails to create small hollows in the gravel.

These prepared sections are called redds, which the fish use as a nest for their eggs on the river bed.

Gravel Trout redd on the Mimram. (Image: Rob Mungovan)

The conditions need to be just right for them to successfully hatch; a river bed of fairly small loose gravel of between 10-40mm, no silt and a good flow of oxygen rich water are all factors that improve their chances of success. 

Over the past couple of years some really positive habitat improvement works have been going on along sections of the River Mimram spearheaded by the Wild Trout Trust.

This has been to improve the river conditions to create good spawning conditions for the trout, which also benefits the other wildlife in and around the river.

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The naturalistic felling of trees, hinging into the water either across the river between the banks, or pinned alongside one bank, can help to diversify the flow.

The more constricted sections increase the flow rate, scouring the bed, removing the silt and creating good sites for the trout redds.

Slower flow sections are good for young fish nursery areas. Other key fish species in the river, such as grayling, also benefit from these variations in flow rate.

The slower flow can also encourage aquatic vegetation, such as sedge, to grow which provides food and shelter for water voles.

The hinged trees on the bank sides have proven to be good stop off points for passing otters. Their spraint, or sometimes signs of their dinner (quite often crayfish remains) are evidence of this.

If you’d like to learn more about the nature, history and geology of Panshanger Park take a look at our upcoming events at panshangerpark.co.uk.  

Panshanger Park is 1,000 acres of countryside situated between Welwyn Garden City and Hertford. Herts and Middlesex Wildlife Trust is working with the park's owners, Tarmac, to manage the park for both people and wildlife.

•  Jo Whitaker is the Panshanger Park People and Wildlife Officer.
• She works for Herts and Middlesex Wildlife Trust and her role is funded by Tarmac.

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