Explore the wildlife on a walk around Bat Willow Hurst Country Park in Bishop's Stortford
Jono Forgham covers your fortnightly look at nature around Bishop's Stortford...
Sometimes I plan a wander and then, for one reason or another, these plans change as they evolve. Last week was such an occasion as I had planned to start at Bat Willow Hurst Country Park, head along Rye Street into town and return along the River Stort to Grange Paddocks. However, after three hours I was still at the country park and had seen and heard plenty for a whole article.
I arrived in good temperatures and headed to one of the three overflow ponds, built to take away water from the new estate as well as from the Manuden road. Presently, two hold water with the most southerly being good for dragonflies and damselflies. The reason they prefer this site is that there is plenty of vegetation on the banks and these sedges and willows are used for the nymph insect to crawl out of the water to a height of 30cm or so, whereupon they emerge from the dried skin as an adult dragonfly. They will stay on the bush for an hour or so to pump up their wings and then let them dry before flying off to organise a territory and mate. For a few weeks they remain immature insects and will often head off into trees or long grass until they fully mature and show their adult colouration.
On one willow I found the excuvia (empty case) of a recently-emerged dragonfly, a hole just behind the head showing where it had squeezed out from. Over the water and on the sedges were a good selection of damselflies – common blue, azure, large red and blue-tailed. The common blues were noted egg laying where the male holds onto the female's head as she dips her abdomen into the water, laying a few eggs with each dip. The reason for the male holding on is he can lift her clear if a predator comes along and also this ensures she does not breed with another male. Further along, a pair were noted in the wheel position, the usual manner for mating. Others rested upon floating weeds.
Over the water were a few black-tailed skimmer dragonflies and four-spot chasers. The latter has a helpful habit of returning to the same roost site, usually the top of a dry stick or twig. This made photography a little easier as I just waited for the colourful insect to return, affording some reasonable shots.
I headed off to check the long grasses nearby and it wasn't long before I encountered an immature black-tailed skimmer resting, showing the bright yellow abdomen with dark stripes down the side, indicating immature.
Overhead, a common buzzard eased its way towards Stansted while a reed bunting called from the top of a sycamore, its familiar chip, chip, chip call followed by a short trill. A pied wagtail called unseen as I set off in search of other insects. A male orange-tip butterfly breezed by me as I tried unsuccessfully to get macro shots of one of the many small heath butterflies, the most abundant species.
Large and small whites were also present as were a few common blue butterflies, all of which evaded capture. I then came across webs on just about every spindle tree near the path. Inside these webs were masses of light yellow caterpillars, showing a row of black spots. These are the caterpillars of the spindle ermine micro moth (Yponomeuta cagnagella). Other flying moths included the macros silver Y, treble bar and the black and red cinnabar moth. Near a stand of nettles I also encountered another micro, Cydia pomonella. On a warm night soon it looks to be worth running a few moth traps here after dark. Be interesting to see what has already colonised this relatively new habitat.
Jays and magpies squabbled in the oaks whilst several blackcaps warbled from deep inside dense vegetation, as is their want. I then changed lenses from the large zoom to my macro and, as always happens, a good bird photo opportunity arises. Today, a Kestrel hovered, dropped to the ground and flew off with what looked like a field vole. However, my attention was now on the flowers, of which there are many species. The buttercups were in glorious yellow and on these, feeding on the pollen, were several Oedemera nobilis, the swollen-thighed beetle. Photo here is of a female that doesn't have such swollen thighs.
Next stop was at a patch where germander speedwell, forget-me-not and scarlet pimpernel were all in flower. Several bee species here and even more as I came across a small stand of white clover. The dog roses were in superb bloom and worth checking for more insects, but just another selection of Oedemera nobilis, all females. Nearby, a greenbottle was sunning itself and afforded good photo opportunities. This was a male as the eyes were close together. In many fly species, including hoverflies, the female's eyes are apart.
The temperature had now risen considerably so I headed back to the best pond to see if the dragon and damselflies had increased in number. Several four-spot chasers were now patrolling their territory. This usually is about 30 metres of pond edge and they will very quickly chase off any other males that encroach. A female four-spot was egg laying near the edge and the damselflies motored around, attaching themselves to twigs and sedge like mini airships. A few metres away from the pond the immature, or teneral as they are known, sheltered in the grasses, their wings whirring like a helicopter. These youngsters are often a very pale colour and can be difficult to identify to species until they get their adult colours.
On the other side of the pond were a good bloom of yellow irises on to which several azure damsels were clutching. A sudden breeze picked up and all activity stopped immediately. On the surface of the water were plenty of back swimmers and a few water boatmen, whirligig beetles and pond skaters.
I then thought another circular wander around would be good and it wasn't long before I spotted a bee orchid in the longer grass. My first of the year. I noticed that some grass cutting had recently taken place. It was pleasing to observe that just the first metre had been mowed, the rest left for the insects and mammals which is the way it should be.
Personally, I think there is too much mowing around the town. At a time when councils are struggling to balance the books post-pandemic, it seems an unnecessary expense to strim roundabouts and the verges along main roads. If these offer no hindrance to sight lines then leaving them is fine. In early spring, dandelions offer emerging bees nectar, so it seems crazy to strim them as often happens on the A120 roundabout near Tesco. I did note recently that the grass verge here has been cut back, but, good to see, only a metre-wide swathe along the road to the bypass roundabout. Grass verges make up a large proportion of wildflower habitats in England and, unless growth of grasses and plants causes an issue with sight lines, I see no reason for them to be cut to resemble a croquet lawn.
Our other splendid country park at St Michael's Mead is now looked after by the well-run Friends of Southern Country Park. These volunteers carry out maintenance, coppicing and general tidying duties on a regular basis throughout the year. It would be good to see a similar set up for Bat Willow Hurst as, in the next five years, it will be in need of some management. It has the potential to be a really important local habitat, especially for Odonata (dragonflies and damselflies) as there are not too many sites locally that offer the range of these species in such a small, concentrated area. It would be a valuable exercise to begin monitoring all species that are present here and begin to look at habitat improvement to attract new species by adding certain plants and grasses.
Certainly in high summer it is also a great place for good numbers of butterflies and, last Monday, it offered enough for me to be enthusiastic about searching for things for over three hours and I could have easily stayed longer had I the time. Parking is available a couple of hundred metres along the Manuden road and it is well worth a visit.