A little bit on grassland management

DSC_0846If you have been to either Farlington Marshes or Southmoor nature reserves you will have noticed that last month our furry lawnmowers appeared. Cattle are now used extensively in conservation to graze sites to achieve the specific goals that are needed. In most cases this is to maintain grassland/heathland in a perpetual state of suspended animation.

This is essentially what most conservation management is. You halt succession at a designated point that achieves certain goals for that site. This may be a flower rich grassland, grazing to stop woodland from establishing. It may be even earlier in the successional history, maintaining lichen rich heaths, early pioneering stages of habitats. It could also be for specific species, mixed height heathland for nightjars and woodlark for instance.

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The ins and outs and rights and wrongs of this type of management and the persuasion towards a more ‘natural’ management scenario is a topic for another post. This one really is for looking at how we graze our sites and why we do it.

From Spring until late Autumn, Farlington Marshes and Southmoor are grazed. The numbers are built up steadily until a peak in June/July when there can be as many as 200 on the main marsh. The overall aim is to get the grass nice and short for winter when the brent geese arrive and need somewhere to graze. Their short bills are perfect for tearing at grass up to 5cm. That’s why you see them on sports pitches so much.

You can’t however just shove 200 cattle on at the end for a few months, there are other aspects to look at, mainly our breeding birds. Lapwing, redshank, meadow pipit and skylark all use the main marsh areas to breed in. They need to have a mixture of short and long grass to feed and nest in. Too long and the young chicks won’t be able to find food easily. Too short and the nests will be easily found by predators. This means that a low number of cattle through their breeding season should provide a mosaic of sward heights, (or if you want to be fancy, structural heterogeneity).

If you overstock it, you run the risk of the nests being trampled. A rather good study looking at skylarks found that a density one cow every 3 ha has minimal effects on breeding success. This needs to be balanced out with the weather conditions. If you get a really hot spring with frequent rain, the grass will shoot up and you will need some more cattle to obtain the correct height and vice versa for a cold, dry one.

In a way Farlington is more like farming than many of my other sites. The overall picture is more about grassland structure rather than floral diversity, though the grazing method produces some excellent diversity on top of it being quite an interesting grassland anyway (coastal grazing marsh and transitional salt marsh). Other sites such as Swanwick Lakes and Hookheath nature reserves are grazed very differently. Cattle come on in July for a few months, leaving around October. This has a much better effect on plants as they have mostly gone to seed by this point and then you are removing the main bulk of the vegetation slowly. This benefits invertebrates by not being as sudden as cutting by machine. It also means that there are more flowering plants throughout the summer for invertebrates to take advantage of, hence why both of these sites are so good for butterflies.

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Grazing isn’t the be all and end all though. Last year for instance I supplementary cut two meadows at Swanwick as I felt that the cattle had not eaten enough and over the years a thatch had developed. This is a layer of tougher grasses that stop other plants from growing up. I therefore had it cut and the cuttings removed. This will hopefully allow more flowering plants, especially annuals, to grow this year. Hopefully the effect of the cutting will not have detrimentally affected the invertebrate population. You do however need to balance out the effect of cutting with the benefit of having more flowering plants, as the more of these you have the more inverts you will ultimately support.

So you’ve looked at your site, thought about what you want from it, decided on the stocking density (the number of cows you need to do the job) and the length of time and time of year. Great, shove them on and let them do their stuff. It doesn’t however stop here. You get plants in all swards that become dominant and these tend to be the ones that are unpalatable or super tough. Creeping Thistle is a big problem at Farlington and has a hold on a big section of the main marsh. This has to managed separately to the grazing by cutting it with machinery before it sets seed, preferably a couple of times. Hookheath has a lot of hemlock water dropwort which is a bit of a brute on wet pasture. This is managed in the same way, cut back after the cattle have done their bit.

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So, grassland management is a complicated beast as no grassland is the same, all have different facets to the sites that cause things to grow differently and a slight stray from the optimum management can have long lasting negative effects. If you churn up the ground in winter, for instance, you can ruin the soil structure which affects the sward for years to come. Managing the cows themselves can be an absolute nightmare – they escape, get ill, get stuck, give birth when you least expect it. That all said Hampshire has some amazing, hugely rich and diverse grassland sites, with colleagues at the Wildlife Trust doing excellent work on many of these (Winchester area and South Downs have some incredible grassland). So as we go into summer, get out there and take a look.

A big thank you has to go out to all our volunteer wardens and lookers, across the whole Trust who keep an eye on our cattle whilst we have them. We couldn’t do it without them.

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A Helping Hand

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The lapwing have been nesting across the marsh, as have a number of other ground nesting species such as redshank, skylark and meadow pipits. They are very vulnerable at this time of year and so we do a few things to help give them a helping hand.

I’ve had a few questions recently about some of the things that we have done so I thought a blog post may help answer some of these questions. The main one that has come across is to do with the spikes that we have put on many of the fence posts around the main marsh. These are to deter avian predators such as crows, buzzards and magpies from perching all day and scanning the site for vulnerable eggs or chicks.

There has been some very nice studies produced that show the effect of vantage points on nesting success in ground nesting birds such as lapwing. One study saw that lapwing would not nest within, on average,  50 metres of a potential perching point. Therefore to maximise the number of territories within a site you have to deter birds from perching on all the very convenient posts that we have placed for them with our fencing.

We have had to look at natural vantage positions as well. Hedgerows with standards and high points act in the same way, allowing predators to comfortably sit and observe. This in mind, we dropped the height on many of the hedgerows in strategic places around the main marsh. This will be a staged approach where we will do some each year so that there is still plenty of nesting opportunities for species like sedge warbler and whitethroats but within a few years we will have all the hedges at a manageable height. Most of the work that we have done, the hedges are still bulky enough to have birds nesting in any way.

The next step is with the cattle. I have put in 36 cows into the main marsh. This is a fine balance between having too many and increasing the chance of squashing a nest and having too few and the grass be too long for the chicks to feed. Lapwing chicks need areas of short vegetation to feed on, gleaning invertebrates off the surface.

It’s an important balance that needs to be struck. Do you dissuade all predators across the site? Do you leave a natural level? What is a natural level? What you have to bear in mind is that when natural levels of predators existed there was a much more natural coastline where sites shifted and changed each year with coastal erosion and drift. This means that there were many more places for these bird species to nest. Now there are very few and Farlington Marshes nature reserve represents an important site in the area. A bad year here has significant effects on numbers in the area.

Ringing in the Reedbeds

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An exquisite male Bearded Tit

On Sunday we started ringing in the reedbeds at  Farlington Marshes nature reserve. The aim is to concentrate on the bearded tits to try and get an idea as to how the population is faring. It turned out to be a reasonable start and we caught a good number of birds. The females all had brood patches which signifies breeding so things are looking good.

Bearded tits, actually called bearded parrotbills now (formally bearded reedlings) are one of Farlington’s iconic species. They draw in a lot of people as the site has a very good population, especially for its size. The only issue is that they are very difficult to see. Normally all you get is a fleeting view of them as they bounce over the top of the reed before quickly dropping down. This makes monitoring very difficult and really the only way that we have a chance of getting a population estimate is through ringing. This also helps us look at longevity of individuals and location within the reed bed itself. All very useful stuff which can help influence how we manage the site.

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A very handsome male Reed Bunting

It was a good session catching bearded tits, reed bunting, Cetti’s warbler and sedge warbler. The whole reed bed was alive with the chatter of segdes and there were even some reed warbler there. These will build up steadily as they migrate in and then disperse leaving the breeding population.

The lapwing have begun to settle down and there seems to be a good number of redshank on the marsh and in the hay field. Hopefully we will see a higher than average year for these this year but its still early days. The lapwing are in low numbers but this is the same across many sites at the moment so hopefully they are just late arriving.

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The very noisy Sedge Warbler

Sightings for week ending 12/03/2017

Its been a busy week down Farlington this week. Lots of Bearded Tits, a Marsh Harrier, Kingfisher, Barn Owl, tons of Curlew, Brent Geese and Shelduck and still a Short Eared Owl or two. There was a leucistic duck by the building Tuesday which I think was a Gadwall, despite being positioned next to a Pintail.

Today was particularly gloomy but there were 500+ Dunlin feeding on the mudflats west of the marsh with a few Black Tailed Godwits and Redshank mixed in. There was also one solitary Avocet roosting on the lake. I haven’t seen any Avocet around for a little while, despite the high numbers earlier in the year.

Spring really descended on Thursday. We were working in tshirts at Swanwick Lakes, basking in the warmth on the edge of the lakes. Whilst we were sat at lunch we had a Brimstone, Peacock, Comma and a Red Admiral pass by! These are the first butterflies that I have seen this year.

I think Saturday will be the better day this weekend and so will be a good opportunity to see the last of the waders and wildfowl. The numbers have certainly dropped significantly in the last couple of weeks and it will be sensible to keep an eye out for the first of the summer migrants. Reports of Wheatears and House/Sand Martins have been arriving across the country for a week or so now!

Sightings for week ending 29/01/2017

dsc_0509Nearly the end of the month! January has flown by in a flurry of Brent geese and waders! This week has been a good one too. I have spent some time down at Farlington and you may see our hedge laying work down by the building. I’m quite pleased with it, the volunteers have done an excellent job, especially as for many of them it was their first time laying.I also remembered to take my camera out with me for once as did our student from Sparsholt (thanks Gwyneth) hence the overload of images on this post.

The star of the show, in my opinion, this week has been the Marsh Harrrier which has been cruising over the reed bed for a few days now. It is quite obliging and regularly pirouettes mid air whist quartering.  No less impressive have been the Bearded Tits which have been seen a lot up by the building and the feeder, even in the thick fog at the start of the week. I filled the feeder on Thursday so hopefully this may draw them in this weekend.

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Marsh Harrier

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Black Tailed Godwit and Teal – Gwyneth Mitchell

The usual high numbers of Black Tailed Godwits, Redshank, Avocet and Dunlin have been in the lake at high tide and Widgeon, Teal, Pintail and Lapwing have been in good numbers across the site. Three Short Eared Owls are still around, using the Point Field and the Main Marsh.

I am please to say that the Brent Goose numbers have rocketed in the last week and where we were only getting a few hundred, well over a thousand are now using the fields, especially the hay meadow. This is much more in line with what we would expect. I was surveying this morning, looking out to Farlington from Broadmarsh. Hundreds of geese were along the foreshore and between the islands and they steadily moved into the marsh at high tide.

The Robins are, to be completely honest, getting to ridiculous numbers in the bushes at the moment. Whilst cutting scrub on Thursday there must have been 20 over the four patches we were clearing. There were also a few Stonechats coming over to see what we were unearthing. One of our wardens thought that they saw a Black Redstart so worth keeping your eyes peeled, it’s a great little bird.

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Stonechat inspecting our handiwork

Southmoor was also very good today. 40 Red-Breasted Merganser were off the point, mingling with Gadwall and Widgeon. There was also a Greenshank sitting on the end of the stream.

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Greenshank

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Marsh Harrier

The Swanwick feeders have been as busy as usual with Nuthatch, Bullfinches and Marsh Tit.

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A beautiful pair of Bullfinches – Gwyneth Mitchell

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A handsome Marsh Tit – Gwyneth Mitchell

Nails, Rings and a Dagger

We were back at Farlington again today to continue work on the boardwalk, the aim being to complete the job started on Friday. Today’s volunteers were the Beechcroft team and they so nearly got it done, it was only a shortage of nails that stopped them just two boards short! Whilst they were working on the boardwalk I continued topping the fields and mowing the edges of the bramble clumps in the Bushes. Before I started the bramble cutting I went to check if the ringers had caught any waders on the roost along the Stream, I would not have wanted to flush the birds by charging about in the tractor. Luckily they had already caught and very successfully, catching 12 teal, 17 greenshank and 60 redshank. The waders were colour-ringed, this allows field sightings to be made and if the combination is seen well the individual bird can be identified. This allows the movements of an individual to be tracked and also such data as survival and longevity to be studied. All this is important as we still know rather little about many of the waders that visit us, although we do know that populations of most species are falling. Obviously we would like to be able to take action to help them but to do this with affair chance of success we need to know much more about where the problems are.

colour ringed redshank

colour ringed redshank

As I spent most of the day in the tractor cab I saw rather little wildlife, a small group of sand martin along the Stream and a few yellow wagtail with the cattle in the Hayfield were about the highlights. However as I got back to the Building at lunchtime I found a caterpillar on the hedge and very smart it was too, a part grown grey dagger larva.

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grey dagger caterpillar

They have a most extraordinary “spire” on one of the segments towards the head, it looks a bit like a thorn, but it fleshy, rather than the more usual tuffs of hair that many caterpillars have.

Of Emperors and Admirals

I was in the office for a good part of the day today, not generally my favourite place to be on a sunny day, but at least today it was cooler inside. However I had to go out first thing to deal with a snapped branch at Swanwick and meet up with Emma and the volunteers. Although it was rather hot for working it was brilliant for butterflies as it has been for the last few days. As though to confirm this Emma reported seeing a male purple emperor by Centre Lake at Swanwick on Saturday, a species I have not seen for many years.

I did get out in the afternoon and on my way over to check the cattle at Farlington I stopped off at Hookheath Meadows, which were alive with butterflies, including several white admiral and silver-washed fritillary, both looking immaculate having just emerged. The heat meant that they were all very active and evaded all attempts at getting pictures.

On to Farlington and the hunt for the cattle, I know it does not sound too much of a task to count cattle in a field, but it can be surprisingly difficult. They crowd together so it is hard to work out where one starts and another ends and they sit down on undulating ground in long grass adding to the problems and that is just in open fields, add in bushes and it gets almost impossible at times. Anyway I managed to find most of them with the aid of a telescope!

In the process I had to go onto the seawall at the viewpoint so I also counted the waders on the Lake at high tide these included 3 dunlin in fine summer plumage, 263 redshank, 249 oystercatcher and 80 black-tailed godwit, including many in fine red summer plumage, just back from Iceland.