Today – Sunday 31st July 2016 – is the annual World Ranger Day. This occasion has been marked since 2007 to honour rangers that have died in the line of duty (not so applicable to us in Britain, but well worth remembering). It is also a day to celebrate the work that rangers do ‘to protect the world’s natural and cultural treasures’; a category in which I think both Trelissick and the North Helford can most definitely be included.
To coincide with this occasion, it seems like a good time to offer an update on what we have been up to at Trelissick over the last few weeks and to exhibit some of the wildlife we have spotted (which is seemingly an abundance of stripey things).
Mulching trees in the Trelissick parkland:
Over the last few winters, the majority of our forestry work was carried out on the Iron Age fort at Roundwood, clearing beech and holly to encourage the growth and regeneration of our sessile oaks and heathland. The fact that this area has been designated a Scheduled Ancient Monument means we must do everything within our power to discourage fires that could potentially cause severe damage to our archaeology. To this end, instead of the usual habitat piles we leave in our wake, at Roundwood we make all the ‘brushwood’ – as we call the more spindly branches of the tree – into wood-chip and remove it from the site. This woodchip is then left to ‘mature’ for a year so the microbial activity that makes it so valuable can get started in earnest.
During the first week of July, the rangers and volunteers have been busy re-distributing this wood chip as mulch for the ancient trees in the Trelissick parkland. This practice is an especially important part of our tree management and has a number of benefits:
– In the park, the soil is only about six inches deep and mulching helps to build up the soil depth, retaining nutrients and water around the tree roots.
– Mulch insulates the soil and helps to provide a buffer against fluctuations in temperature.
– Using mulch helps prevent soil compaction which can occur as a result of our use of grazing animals.
These wondrous trees have been with us, in some cases, for several hundred years and deserve all the care and attention we can give them. Long may they go on!
Rolling bracken at Roundwood:
Later in the month, we carried out our annual bracken rolling at Roundwood Fort. The purpose of this ‘rolling’ is to suppress the bracken growth and unlike cutting, the ancient and rusty (yet trusty) bracken basher bruises the bracken stems in several places, greatly reducing its vigour and impeding its ability to re-grow.
Bracken itself is an incredibly invasive plant that we must keep under control because the horizontal roots – known as rhizomes – can be ever so detrimental to the Iron-Age archaeology that is just beneath the ground.
Now, if you go for a stroll down to Roundwood, you will know why great swathes of the bracken have apparently gone to sleep!
Jackson, the heavy horse steps up:
Many of our regular visitors will have met Jimbo, the magnificent heavy horse that has helped us tremendously with the extraction of our timber over the years. Time however, eventually takes it’s toll on all of us and Jimbo is a bit too old these days to be hauling heavy lengths of wood out of the undergrowth and so Jackson, his younger apprentice has taken up the task.
A working horse is not such a common sight in this modern, mechanized age but, for us at Trelissick, it is actually an incredibly effective and efficient way of extracting timber from the more inaccessible areas of the woodland with the lowest possible disturbance to ground flora and wildlife. Jackson is also a lovely, unexpected sight to see for our visitors as they enjoy the woodland walks.
Hornets and their counterfeit critters:
It’s summer, so it stands to reason that we would see a lot of insects out and about on the estate, but this month our attention has been taken by those creatures which boast that infamous warning of yellow and black stripes – either that, or they are proud to be in Cornwall….
Anyway, out in the severe world of insects, if you want to survive it pays to look like something that is big, scary and dangerous. It probably means that a lot of other insects aren’t going to take a chance on going anywhere near you so the colours of a hornet are a fairly good disguise to wear! Let’s take a look at the fascinating life cycle of the Eurasian hornet and then we will give a brief overview of some clever critters we have seen that are riding on the coat tails of its ferocious reputation.
Eurasian hornet (Vespa crabro):
Eurasian hornets (Vespa crabro) are a fairly common sight at Trelissick as they build their nests in tree stumps and our numerous woodpiles from May until September. Hornets are beautiful, impressive creatures that are actually very docile and completely undeserving of their fearsome reputation – a hornet is rather busy at the best of times and not actively interested in humans or our food. Furthermore, it will not actually sting unless physically attacked!
Fear of hornets seems to be born out of a lack of understanding. Many people view them as giant wasps and flee in terror when, in actual fact, the behaviour of a hornet is markedly different from its smaller relative. In an attempt to fight the corner of these remarkable (not-so) mini-beasts we would like to give a little information on what hornets are actually up to when we see them buzzing loudly about our woodland.
A hornet colony will not last over the winter and is survived only by a fertilised female known as a queen at the end of each season. It falls on her to survive the winter and, come spring, seek out a suitable and sheltered location for a new nest (such as a hollow tree trunk). She will build the nest herself by constructing as many as fifty small chambers out of chewed tree bark and arranging them in layers. She will then lay an egg in each chamber, nursing and feeding each larvae until they mature into the first generation of workers and a new colony is born….
These workers (all female) will take over the queen’s prior duties so she can concentrate on the important business of egg laying. Tirelessly, they continue the expansion and arrangement of the nest but their primary function is the procuring of food, and for that reason are most likely the hornets you will see out and about. Workers seek out other insects which they attack and subdue before removing any nutrient poor parts such as wings, head and legs; bringing back the protein-rich thorax (where the flight muscles are located) to the nest and feeding it to the new larvae that have been laid by the queen.
During hot weather, workers will even collect water and distribute it over the outside of the nest to keep the interior cool for the larvae within. At its peak, a successful colony can have as many as 700 workers.
It is during this time that the queen starts producing reproductive individuals. Eggs that have been fertilised will hatch into females (or gynes as they are known) and unfertilised eggs into males (or drones). The adult males do not take part in looking after the nest, finding food or taking care of larvae.
When autumn comes around, the males and females leave the nest to mate during what are known as ‘nuptial flights’. Males will die soon after mating, along with all the workers and any queens that didn’t manage to find a mate – only the fertilised queen will survive through the winter to begin the cycle again.
Ecologically, hornets provide an important – and beneficial – function by preying on many insects that are regarded as pests. A hornet will only catch live insects, including those that only fly at night, but particularly goes after flies. This is one of the distinct differences between hornets and wasps – wasps are drawn to human food and food waste which makes aggressive contact with us far more likely whereas hornets tend to stick entirely to live insects.
Giant Wood wasp (Urocerus gigas):
Several giant wood wasps, otherwise known as a horntail, have been spotted this summer at Trelissick. More commonly found near coniferous woodland, these enormous sawflies are often mistaken for hornets and can prompt episodes of high-pitched screaming and running away. They might look fearsome but the mighty ‘sting’ that is visible on the abdomen is actually an ovipositor used for laying eggs deep into softwood timber such as larch and, more specifically at Trelissick, silver fir. The larvae live in the wood of pine trees, where they spend up to five years developing.
Wasp spider (Argiope bruennichi):
This very large and colourful spider, with its distinctive ‘wasp striped’ abdomen was spotted in the field that houses our Community Orchard at Tregew – I was about to step on it with my big boot as it happens….
The wasp spider is actually a fairly recent arrival in the UK (first recorded in 1922), originating from Europe and slowly increasing its distribution to cover the south of England. Part of the orb web family of spiders, this unmistakable critter will craft its web on heathland or grassland. As is often the case in the insect world, the males get a bit of a raw deal and are considerably smaller and less attractive than the females. Even mating is a perilous task for the beleaguered boys who loiter at the edge of her web and wait until exactly the right moment, when the female has just moulted into a sexually mature form, and then dash out to take advantage of her whilst her jaws are still too soft to cause him damage. Many males do however get it slightly wrong and end up getting eaten….
Hornet longhorn (Leptura aurulenta)
The last creature that masquerades as a hornet was spotted by ranger, Charlie Watt whilst he was out working on the estate. This beetle is nationally scarce and now extremely localized to the South-West, particularly Devon and Cornwall – how apt that it wears our Cornish colours!
The soft larvae of this longhorn develop over several years in the totems of dead trees, stumps and cordwood. They particularly favour oak, beech and chestnut. When ready, they emerge as adults in July and August to visit the flowers of elder, angelica, bramble, broom and scabious, flying with a loud, almost mechanical hum.
Thanks for reading and enjoy the rest of the summer!
– National Trust ranger team, Trelissick and North Helford