Take a nature walk along the River Stort Navigation to Pishiobury Park in Sawbridgeworth

Nature Notes columnist Jono Forgham covers your fortnightly look at nature around Bishop’s Stortford

A week last Monday dawned warm and clear, perfect for a Nature Notes wander, so I set off to Sawbridgeworth and parked in Sheering Mill Lane, not far from the lock gates.

I picked up the towpath heading north towards The Maltings as I fancied a cup of coffee and a sausage sandwich from the splendid Shed café near the antique dealers. All very good and I was soon back outside on the towpath, retracing my steps.

As soon as I accessed the path it was apparent there were plenty of dragonflies on the wing. These were almost all male migrant hawkers. I waited a while for one to land near enough for a photo and it wasn’t long before one obliged. Whilst I was waiting I noted a dock bug (Coreus marginatus) resting atop some leaves, so two reasonable snaps to set me on my way.

I wandered on, noting flotillas of mallards, several moorhens and a trio of Canada geese by the lock gates. Several folk were feeding these with bird seed. Another dragonfly whizzed by - a common darter that carried on in a southerly direction. The dragonflies will now be noticeable until there is a change in the weather. Once we get the first cold nights and days they will soon disappear, but the forecast doesn’t look too bad for the next few weeks, so they should still be seen into October.

I crossed the lane by Lock Cottage and noted a variety of vegetation that had climbed up the wire fencing here. Bittersweet flowers have now finished and there were strings of their bright red berries. This plant is also known as wood nightshade, a relative of deadly nightshade as well as the potato. Other species here were hops and black bryony, the latter also displaying long ribbons of red berries.

I searched the hop leaves for signs of a relatively rare moth species, Cosmopterix zieglerella. This tiny micromoth, 4mm in length, spends its larval time in the leaves of hops and eats its way around the leaf, displaying a very distinctive white pattern. After a few minutes searching, I had found another species of leaf mine (Lyonetia clerkella), but not the rarer species I was after. In the many years I have searched for this moth I have only found it twice. Once on the towpath near Spellbrook and once in Little Hallingbury. Both of these are records for Essex so would be good if I could track it down in Herts.

Large shoals of small fish darted in the shallows, more mallards came to inquire if I had any food, magpies and jays argued in willow trees and a Cetti’s warbler burst into its explosive call from the far bank.

Soon I came to paths that led into Pishiobury Park, but I was aiming for the osier beds in the far south-eastern quarter of the park so continued along the towpath. A sign near a footbridge over the Stort signals the entrance to this area. Spaniels hurled themselves into the Stort backwater as I wandered along the raised boardwalk. A nuthatch called from the canopy of (mainly) alders whilst a moorhen stood on floating leaves, watching the river flow.

After a few hundred yards there is a well-placed bench overlooking the meandering backwater. More moorhens called and a common buzzard mewed overhead, but the hoped-for kingfisher didn’t put in an appearance. I enjoyed just sitting here for 20 minutes or so before pressing on and, soon after, emerging into the green space that is the majority of the park. Not too much to find in these open grasslands, so I picked up another path leading into a wooded area that eventually deposited me back on the towpath. Several very old and impressive oaks in this area and clear signs of good woodland management.

Indian balsam was an ever-present plant here, but, pleasingly, not noted in huge numbers as this invasive species can easily take over and create a minor monoculture. I stopped to help myself to blackberries that were just coming to their best. Nearby, some bramble was coming into flower, the recent warm snap having tricked the plant into flowering for a second time.

Soon I re-emerged onto the towpath. A metal handrail for a footbridge held a pair of mating emerald damselflies that departed as I steadied the camera. A small black and yellow bug flew by, landing on the upper surface of a leaf and out of sight. However, this could still be identified as a capsid bug, Liocoris tripustulatus.

I waited to see if the damselflies would return before moving on to check a good stand of flowering ivy. In high summer, nettle patches are my go-to plants for insects, but as autumn approaches I have much more success checking ivy. Here, a host of insects: Vespa vulgaris (common wasp), Colletes hederae (ivy bee), harlequin ladybird and a small, dark hoverfly species with bright red eyes, Melanostoma scalare. The latter two posed reasonably for some snaps. The harlequin ladybird is an invasive species, first recorded in the UK on the beach at Dungeness in 2004 before spreading very rapidly as far north as Yorkshire.

I began checking the numerous spiders’ webs. In one, a fly species had been trapped and rolled in silk for a future feed whilst in the centre of another web, a Metellina segmentata spider was busy repairing damage.

Before long I was back at Sheering Mill Lane so went off to check the extensive reedbed adjacent to the small layby I had parked in earlier. Another Cetti’s warbler and a pair of swallows swooped low, hawking for insects on their southerly migration. By now the temperature was in the low 20s, not usual for the last week in September.

I headed home to process the photos and check the garden moth trap. Recently there has been a large movement of moths from the continent and when I checked the garden trap on my return I was not disappointed. A stunning clifden nonpareil with a wingspan of 12cm was roosting on the side of the trap as it was too large to enter, whilst actually inside were a migratory delicate and an L-album wainscot.

Up until the last three to five years all three of these moths have been considered to be immigrants, but there is now a general belief that they may be breeding in Hertfordshire. However, so far no actual proof that they are as caterpillars and pupae have yet to be discovered. A deep brown dart macro moth was also present, a new species for the year and my 462nd moth species for 2023.

Soon my attention will turn to checking autumnal leaves for small leaf-mining moth species. I shall be concentrating this effort in Stocking Wood. If anyone would like to join me in this search, please drop your contact details into the Indie office and I shall be in touch. The search will be very easy to do and no experience or knowledge is required. It is, however, a great way of getting to know tree species by leaf identification. All are welcome.

Finally, I am planning an Indie bird walk around the lagoons at Stansted Airport, usually the best place around here for migratory birds. Again, do drop details into the office if you would like me to forward further details. It will probably be a Saturday morning later in October and last a couple of hours. Be great to have some readers come along.

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