30 Days Wild – Day 28

A really blustery day spent at home, mainly in the garden. The conditions meant the moth trap had few visitors and photographing insects on waving flowers was a near impossibility.

The highlight was a male Cheilosia caerulescens, a hoverfly I first saw last year and which was only first found in the UK in 2006. It is one that probably came here in plants transported for the horticultural trade. The larvae mine the roots of house-leeks and were probably in the roots of imported plants. It was first found in Surrey and is now quite widespread in S. England.

Cheilosia caerulescens 4x3

Cheilosia caerulescens

Although this species may not do too much harm, unless you are an avid grower of house-leeks, it does illustrate how difficult it is to keep from inadvertently bringing species into the country. With increased travel and much more international trade the opportunities for stow-a-ways are many.

Introduced species can be a hot topic, with widely differing views about what controls there should be. My personal feeling is that wherever you stand on the rights or wrongs of controlling invasive species, bringing ever more in should be seen as a bad idea. Any newly arrived species is unlikely to be adapted to the environment and so most die out. If they don’t they will be competing with species already present, there are not generally lots of unused resources lying around, something will be using them and any arrivals will effectively be taking away resource from something else already using it. In the worst cases they thrive to the exclusion of lots of other species, especially if there is no local control by predators, parasites or disease to keep them in check as would be likely in the native range. The upshot of this is that we tend to gain widespread generalist species and lose localised specialist species, in short the species diversity is reduced and some of the variety that makes the world so interesting is lost. This is happening worldwide of course and the impact of introduced species is one of the greatest extinction threats to local wildlife faced across large areas of the world.

As I mentioned I spent most of the day in the garden and many of our garden plants are  a good fit for potentially invasive species. Most are not native to the UK and many not to Europe, but they are selected to be types that will grow here, and the ones we grow most often are the easiest to grow, which is to say they grow very well here. All characteristics that would make a successful invasive species. A lot don’t grow well from seed for one reason or another, but some will set viable seed and a good few will grow well from roots or rhizomes, which is why fly-tipping of garden waste can be sure a problem and  a major route out into the countryside for garden plants.

I have been refurbishing my pond over the lockdown period and it is beginning to look a lot better, with several plants coming into flower, including water forget-me-not and lesser water plantain.

water forget-me-not

water forget-me-not

lesser water plantain

lesser water plantain

30 Days Wild – Day 12 – The Power of a Flower

Tuesday at Blashford is volunteer day, or at least one of them, we also have a regular work party on a Thursday as well, today we were balsam pulling. The balsam in question is Himalayan balsam, a garden plant that escaped into the countryside and particularly likes growing along river and stream banks, “riparian habitats” as they are known. It is an extraordinary plant, growing to two or three metres tall in a matter of a few weeks,outgrowing all native plants that live in similar places. It also has explosive seed pods which can throw the seeds a metre or more when they pop. Being a non-native it has escaped its natural disease and insect controls and grows almost without check, which is why it has become a problem.

before

a disappointingly large stand of balsam

We have been removing this plant by pulling them up for many years now and have made good progress on the upper parts of the Dockens Water, where there are very few plants now. Clearly though, we failed to find quiet a few plants last year for there to be quite such a dense stand as this. Flooding carries the seed along and will also concentrate it where the seed gets deposited. We had a lot of plants to pull up, but we did pull them up and this is what it looked like a short while later.

after

after balsam pulling

What is very clear is that once the balsam is gone there is very little other vegetation, showing how it out competes other species.

Himalayan balsam has very nectar rich flowers, leading some to claim it is “Good for bees”, bees and other insects will take nectar from it, but I think the case for it being “good for bees” is very questionable. When it flowers it is very popular, but before this it shades out all the other flowering plants that would providing nectar, so across the season it probably provides no more than would be there anyway, it makes the habitat one of feast or famine cutting off food sources earlier in the season.

Flowers are immensely rich sources of food for lots of creatures, perhaps especially insects, but I have watch deer carefully picking off flowers and leaving the rest of the plant. The flower has the protein-rich pollen and the sugar-rich nectar, in short the stuff needed to make animals and keep them running. The flowers are not giving this largess, they are trying to get their pollen transferred to another flower to allow seed formation and make new plants. As the year progresses different flowers become the main attraction for lots of insects. Just now hemlock water dropwort is very attractive, but a new draw is appearing in the form of bramble flowers.

bramble flowers

bramble flowers

We easily notice the larger species such as butterflies, but look closer and you will see lots of tiny insects.

bramble flower with pollen beetles

A bramble flower with several small beetles

I think the beetles in the picture are pollen beetles, but I am not certain.

Closely related to brambles, the roses are at their peak now, the similarity in flower form between the bramble and this dog rose are clear even if the rose is the showier.

dog rose

dog rose

I was pleased to receive reports of four little ringed plover chicks seen today from Tern hide, the first proof of any hatching so far this year. It was also good to see the common tern arriving at the rafts on Ivy Lake carrying small fish to feed newly hatched chicks.

My moth trap highlight today was a lobster moth caught at home, not a species I see very often and I still have to find the extraordinary caterpillar which is the source of the moth’s name.

lobster moth

lobster moth

To refer back to my earlier comments about the food value of flowers, I noticed the mullein moth caterpillar in my garden has eaten most of the flowers off the figwort plant, it has eaten all the best bits first!

mullein moth on figwort

mullein moth on figwort

What’s in My Meadow Today?

I know it is not a plant that belongs in a meadow in southern England, but I like bloody crane’s-bill, so I have it in the meadow, where it grows and seeds quite well.

bloody cranesbill

bloody crane’s-bill flower

Something else that does not really belong are the anthills, this is not because ants are not native here, but you do not usually get anthills in meadows. This is because a meadow is really a field that is grown to produce a crop of grass, so the act of cutting the field would knock down the anthills before they became large. I cut the grass around the anthills taking care to leave them to get bigger year by year as I rather like them. This maybe because I spent many years working at Farlington Marshes where the masses of anthills are a significant feature of the reserve.

anthill

One of the anthills being extended by the ants.

 

30 Days Wild – Day 4 – In Training

Not a very Wild Day today as I was mostly inside receiving First Aid training, important but not very wildlife-filled. On the plus side the training was taking place at Testwood Lakes, so at lunchtime I got out for a short walk around the area nearest the Centre. They have a fine education pond and it had several dragonflies racing about over it, I saw emperor, four-spotted chaser and black-tailed skimmer. On the emergent stems around the edge there were lots of damselfly exuvia, the case that is left when the larva leaves the water to transform into the flying adult. Unlike butterflies and moths this is done without a pupal stage, the aquatic larva walks from the water, the larval skin splits and the adult emerges, this is known as “incomplete metamorphosis”. Other insects that use a similar route are grasshoppers and true bugs. I could not get a picture of a damselfly exuvia but I did find an emperor one close enough to photograph.

emperor exuvia

emperor dragonfly exuvia

The pond is planted up with a good range of native water plants and marginals, we have many very attractive species to choose from. This makes the trade in invasive pond plants all the harder to defend, we do not need them to achieve an attractive pond and dealing with them when the get out into the countryside is very costly. One of my favourite native marginal species is the flowering rush and Testwood has several on full bloom now.

flowering rush

flowering rush

I was first introduced to this species when working at Titchfield Haven many moons ago in a time before digital cameras and mobile phones, hard to imagine such a time now I know!

What’s in My Meadow Today?

It was rather breezy and cloudy when I got home but as quick look in the meadow and I found a resting male common blue, it was waving about alarmingly in the wind but this shot is more or less in focus.

common blue

common blue at rest

Training continues tomorrow, so I doubt I will see much wildlife, but at least everyone should be a little bit safer on the volunteer tasks.

I am lucky as usually I get to spend a lot of my time out in the open and in wildlife rich places, today I had to grab what few minutes I could, but luckily there is, or should be, at least some wildlife somewhere to make every day just little bit wilder.

Brilliant Volunteers

As I have noted many times on this blog, Blashford Lakes would not be anything like as good a site without the invaluable input from our great volunteer team. Our volunteers help out with a range of tasks and do some projects in their entirety.

Over the last week we have had volunteer educators helping with school groups river dipping in the rain, reptile and butterfly surveyors, office administration and our Tuesday and Thursday working parties.

The rarest habitat at Blashford Lakes is the Lichen Heath, perhaps because of its industrial origin it is not actually designated, but it is home to many nationally rare species which form an assemblage which needs looking after.

lichens

Lichen Heath close-up

The importance of the area rests on it having very low nutrients, but over time nutrients fall from the sky and collect in the upper layers of the soil as mosses, lichens and small plants die. The obvious conclusion is that it will slowly disappear and turn into nutrient poor acid grassland. So how to keep some areas to true Lichen Heath? The answer is probably to strip off the surface layer and get down to the bare sandy surface and let it colonise once more. This seems very drastic and it feels wrong to be stripping off what is still a diverse sward with lots of interesting species. We started doing this in a small way on Tuesday, doing six small trial plots which we can monitor, if it looks a good technique we can extend it more widely in the years to come.

Lichen heath before

Lichen heath before surface stripping

Lichen heath after

Lichen heath after surface stripping

We chose sites where there were small bramble or birch trees that needed removing anyway and piled up the material on the northern side of the scraped area to provide some variation in the surface topography and potentially warm nesting sites for the many species of bees, ants, wasps etc. that call the heath home.

The rain this last week is what allowed us to work on the heath as it meant the lichens absorbed water and so could be walked on gently, in dry conditions they would just crumble to dust under foot, which is why we ask visitors not to walk on it. Even in wet conditions it is intolerant to trampling so we do as little as possible out there. So it was a treat whilst we were there to see some of the special species that grow on the heath including the two rare bird’s-foot trefoils.

hairy bird's foot

Hairy bird’s-foot trefoil

 

slender bird's foot

slender bird’s-foot trefoil

On Thursday the volunteers were back on the task of clearing Himalayan balsam and pink purslane from along the Dockens Water. These two invasive alien species can muscle out native species, but can be controlled by pulling them up to prevent seeding. After several years of doing this we have made great progress and balsam is now no more than occasional where once it was the dominant plant. Along the way when doing such tasks we come across other things of interest, one such find was a mating pair of lime hawk-moth.

lime hawk pair mating

Lime-hawk moth pair

Some discoveries though are less welcome and one such was an American skunk cabbage plant, the first I have ever heard of along the Dockens Water. This plant has been a big problem in wetland sites across the New Forest and the subject of an eradication program, so finding it here is a worry. I suspect that somewhere up stream someone has it planted around their pond and the seeds are escaping to grow in the wild.

skunk cabbage

skunk cabbage, a young plant without the huge leaves and yellow flower that attracts water-gardeners.

Our last chance find was made by Geoff, one of our most regular volunteers who photographed this crab spider which had ambushed a bee visiting a daisy flower.

spider

Crab spider with bumble-bee prey on ox-eye daisy.

I will endeavour to do a wildlife update for the week later, I know we have received a number of fabulous photographs from visitors.

 

Progress Against an Invader

Thursday at Blashford is volunteer day and we had a good turn out of fourteen for our first Himalayan balsam pull of the year. After many years of pulling this plant we have very significantly reduced the population and it is nowhere the dominant plant. The advantage of doing the first sweep early in the season is that we remove a significant number of plants but also get an idea of where the main problem areas are and so where to concentrate on our later visit. Pleasingly we found no more than a couple of hundred plants on about half the length of the stream, enough to suggest that there is still a seed source upstream  somewhere but not so many that it is having a serious impact on native wildlife.

The common terns are finally taking some interest in the rafts on Ivy Lake, although they are still not really taking control of any in numbers sufficient to deter the black-headed gulls. I tried putting out another raft during the afternoon in the hope that a new one might tempt them in. The gulls often just loaf around on the rafts, but have the annoying habit of bringing reeds and sticks and leaving them scattered  over the surface. I suspect they are mostly young adults, as the older birds started nesting a couple of weeks ago, a few may eventually build a proper nest, but in the meantime their practice efforts are putting off the terns.

Generally things were quite across the reserve, most of the birds are now nesting or getting ready to do so. Our visitor form North America, the Bonaparte’s gull is still to be seen, although it does not now attract more than the occasional admirer. I did manage to get a slightly better picture of it, which does show a couple of the differences from black-headed gull. You can see the slightly smaller size and overall thinner, more “pointed” look. Now that it is getting a summer plumage hood you can also see that this is blacker than that of black-headed gull, which is actually chocolate brown.

Bonaparte's gull

Bonaparte’s gull (right)

A very noticeable feature of the past week has been the huge increase in the numbers of damselflies around the reserve. Common blue and azure damselflies are now out in numbers, but the large red damselfly, typically the commonest spring species is very hard to find, perhaps due to the very poor April weather last year.

 

 

From Around the World to Blashford (unfortunately!)

It is the time of year when reserve officer’s thoughts turn to invasive plants, yes we can be a bit boring like that! Anyway after weeks of building tern rafts today the volunteers had a walk along the Dockens Water to look for Himalayan balsam. This plant used to dominate long stretches of the stream shading out other species but several years of pulling it up is showing real dividends, it is not gone, but for long stretches there is little or none to be found now. The seed are only viable for two or three years so pulling it up before it flowers for this time should have seen it gone, but a few always seem to hide away and get missed, so it never quiet disappears.

Although the balsam has got much rarer it is noticeable that we are seeing more of another invasive alien plant, the pink purslane, this time hailing from North America. Hopefully it will not become as much of a problem as the balsam, but we are pulling it up, just in case it has plans for a take over!

pink purslane

pink purslane

We came across a few other plants that do not belong, highlighting that garden plants are getting thrown out and establishing themselves all the time and, probably some of them will become invasive in time. One of the new ones today was star of Bethlehem, I doubt this will become a problem, but you never know and every garden escape is growing where a native plant could have been, so in a small way they all impact upon out native flora.

 

There should have been a picture of star of Bethlehem here , but it would not load!

Of course alien plants do not just impact upon other plants, they also reduce the native plants available for insects and other species to feed upon. Plants support lots of other wildlife, often specific to single species, native plants support a native fauna. By contrast alien plants tend to support a range of species that live in that plant’s native range and usually do not occur here. Some alien species will support some of our native fauna, but usually not much, which is why they do so well, there is not much eating them!

The warm sunshine today did bring out quite a few insect, I actually saw two species of dragonflies for the first time this year, which just shows how slow the season has been so far. The species were broad-bodied chaser and downy emerald. I did not get pictures of either of them though, but I did get one of a snail-killing fly,

snail killer

snail-killing fly

and a weevil.

weevil

weevil