Summer - Work on the NNR

A few snippets of how the last two months have been spent in the Lower Derwent Valley. 

Each year from the end of May, throughout June and into July week after week is spent pulling Marsh Ragwort from the meadows around the valley.

Marsh Ragwort is a plant of wet grassland, often occurring in un-improved wet hay meadows, along with more improved wet grassland. Marsh Ragwort is toxic to livestock due to the compounds it contains. However, grazing animals usually tend to avoid it but cattle have been known to graze the flowers, and sheep will eat the leaves when they first appear in a rosette form. The majority of the meadows in the valley are cut and baled for hay and so the Ragwort needs to be removed before the farmers can cut the meadows, it is thought that once dried and mixed in with the other plants it becomes more difficult for the animals to avoid.

So each year we have to ‘pull’ all the land owned by NE which is c500ha and requires a lot of time and effort! So many thanks to the staff and volunteers who have tirelessly worked over the last few weeks filling countless numbers of bin bags and skips!

Spraying and the complete removal is believed to be the only way forward by some. However Marsh Ragwort is a native and natural component of species-rich wet hay meadows, and unfortunately (at the moment) there isn’t a spray or other method of control that would selectively take out the Ragwort without it affecting the rest of the wildflowers. 

Since the ragwort 'season' finished we've moved on to sorting out all the paths around Bank Island and North Duffield Carrs, along with trimming back the vegetation from around the pools in anticipation of the waders and ducks returning as autumn approaches. By clearing the vegetation it make the pools more open and therefore more attractive for passage waders dropping in on autumn migration. It also stops species like willow from becoming established and shading out flowering plants such as Water Mint, Corn Mint and Purple Loosestrife which provide valuable nectar sources to many invertebrates.

Whilst busy strimming we've been seeing plenty of Emerald Damselflies and Ruddy Darters resting on the Soft Rush, whilst the Brown Hawkers and Emperor Dragonflies have been out hunting across the water. 

Along with the usual team we've also had extra help during the last four weeks, with two students on placement, first off was fifteen your old school boy Adam who spent an enjoyable two weeks here on his work experience placement. His time was spent between a variety of tasks such as helping us pull Marsh Ragwort from the meadows and Himalayan Balsam at Thornton Ellers, a sheep round-up on Skipwith Common, checking the Barn Owl nest boxes and then on his last day helping us catch and ring the broods of Mute Swans at North Duffield, Wheldrake Ings and the Pocklington Canal – made easier by his superb canoeing skills! Sam then joined us for the last two weeks, and was a big help with strimming the paths and clearing large areas of Himalayan Balsam. It's been a real pleasure having them both on board for the last few weeks, we now wish them well in their final year at school and hope to see them both again in the valley soon!

Since ringing the last of the first broods of Barn Owl chicks in June, things have largely been quiet on the ringing front, mainly due to the amount of work and lack of time to do it in. However after a morning pulling several members of the ragwort team were rewarded with close views of this male Sparrowhawk which had flown into one of our duck traps that had been left un-set, meaning it could fly in and out as it pleased, but we were swift enough to close the door on arrival. Not many Sparrowhawks are ringed in the Lower Derwent Valley each year so it was pleasing to see this small male at close range. With their bright yellow/orange eye, piercing looking bill, long legs and needle-sharp talons they look like they mean business! Sparrowhawk’s are adept hunters of passerines and with their relatively short rounded wings and long tail they are adapted for nimble manoeuvring through woodlands and trees, where they will prey on flocks of mixed tits and finches. 

Sparrowhawks breed in woodlands but are a regular visitor to towns and cities and often appear in gardens – where they will hunt their prey by skimming hedges, rooftops and gliding low over the ground before swooping through with lightning speed and ambushing an unsuspecting individual. Sparrowhawks usually tend to stay out of sight until they are ready to strike, one of the first signs that one may be in the vicinity is that of the alarm calls of small birds – who are alerting others nearby to the danger.

As with most birds of prey the females are a lot bigger, so we were able to sex this bird by looking at the size. The grey/blue colouring on the back is typical of an adult of at least two years, although it could be an older bird – especially with such a bright eye. This year’s Sparrowhawks are just beginning to fledge – they breed later than most other birds to coincide the hatching of their eggs with the fledging of small passerines – meaning an abundant food supply!

After a day pulling Ragwort, some of the team decided to stay late into the evening and ring in the reed bed on Wheldrake. A total of 61 birds were caught, including Sedge and Reed Warblers, Reed Buntings and 40 Swallows that had come into roost. However a highlight came in the form of this beauty – a juvenile Water Rail. 

Water Rails have had a good breeding season on Wheldrake Ings with five calling males regularly heard (they are seldom seen so recording the singing males is the best way of estimating the population). We know at least one pair bred raising two young as the chicks have been seen in front of Swantail Hide. Interestingly an adult female was also caught and ringed when pushing our corale trap for ducklings last month - she had a brood patch and had presumably also bred. These are first two Water Rails to be ringed in the valley for a few years, bringing the number ringed on site to 49.

Mute Swans appear to have had a better year than those of late, with seven pairs nesting across the Lower Derwent Valley. However, brood sizes have been mixed ranging from two broods of two and the largest of nine. This year three broods have been caught in the LDV, with broods of two on Wheldrake and North Duffield and a brood of five on the Pocklington Canal. Several new adults have also been caught with each one fitted (and the cygnets) with one of our red and white darvics.