Normal service resumed

I'm back from Papua New Guinea. Somewhat later than anticipated but more of that in a future post.

Since my return I have been busy tying up loose ends with the Wood Warbler project. My thanks to the friends who kept an eye on the last two nests; the Magician fledged successfully but Double Back was predated by a Tawny Owl.

It is great to see that there's been a good influx of Clouded Yellows in the last few weeks. It is a species that I rarely see so it is always a thrill to come across them.

Last weekend was the Rutland Bird Fair. I always take some live moths up to generate interest in our stand. This year I ran a moth trap at Queen Elizabeth Country Park near Petersfield for a few hours on the evening before I drove up. I mainly hope for attractive species to take to Rutland but this year the best species I caught was a rather drab one; Olive Crescent. This is a UK Biodiversity Action Plan Priority Species which was known from just a couple of sites in Essex and a few sites on the Kent / East Sussex borders. However there have been a few records from east Hampshire this year so perhaps it is colonising new ground.

The stars of our stand this year though were both donated; a Small Elephant Hawk-moth caterpillar

and three Privet Hawk-moth caterpillars which were brought, together with a potted privet plant by a chap from Wales.

 On Monday evening I went to check out a Swallow roost with a view to doing some ringing there the following evening. Amongst the good numbers of Swallows was an apparent albino which stuck out like a sore thumb, evening in the fading light. I didn't think that I had a cat-in-hell's chance of catching it but on Tuesday evening I caught 65 Swallows and 8 Sand Martins including.......

Clearly it is leucistic rather than albino but it is a stunning bird whatever label you put on it. 

Time to fly

A trip to Sandwich on Wednesday produced some quality species, as would be expected. My highlight was a species of pyralid moth that I have never seen before; Nyctegretis lineana.

Other Sandwich specialities such as Bright Wave and Thiodia citrana were seen in numbers but it appears that Rest Harrow moth has finished. It was nice to see the scarce pyralid Sitochroa palealis as well and it helpfully posed for its photo.

I didn't have time to look at many plants (and the Lizard Orchids had pretty much finished flowering) but the Marsh Helleborines were looking good.

On the Wood Warbler front, Fallen Cedar nest has fledged successfully (this female has achieved the almost unique feat of rearing two broods this year), Double Back had five one-day old chicks and The Magician still had eggs. Over to Gilbert's colleagues to monitor these last nests now as Gilbert is off on his holidays. Please look back at the blog on 9th August when hopefully there will be some spectacular photo's.......

A clean bill of health for the Horse Chestnut Leaf-miner?

I have recently been sent a copy of a paper by researchers from Forest Research (part of the Forestry Commission as was) on the impacts of the Horse Chestnut Leaf-miner Cameraria ohridella and the bleeding canker disease on Horse Chestnut trees (Straw, N.A. & Williams, D.T. in Agricultural and Forest Entomology (2013), DOI: 10.1111/afe.12020).

The forestry mafia have had it in for this moth ever since it arrived in Britain (as they do for virtually any new insect that turns up if it feeds on a tree or shrub). There was all sorts of nonsense written, even that it would destroy the game of conkers in this country! Strangely, no mention was ever made of the fact that Horse Chestnut is not native and is of virtually no commercial value. Unfortunately, many other people and organisations jumped on the bandwagon and I well remember Surrey Wildlife Trust printing a Forestry Commission press release in its magazine (presented as editorial) that told everyone how awful C. ohridella was and what steps everyone should take to try to get rid of it.

Presumably all this anti- activity was stimulated by the discoloration that the moth causes to Horse Chestnut leaves.

My opinion has, unsurprisingly, always differed from the mainstream. To me, the evidence that it had arrived in Britain by other than natural means was tenuous and circumstantial in the extreme. It is an attractive moth and provided a substantial food source for insectivorous species on a tree that was previously virtually sterile.

The latest research looked at what impact C. ohridella has had on Horse Chestnut trees. The abstract starts by stating that 'The leaf miner Cameraria ohridella and bleeding canker disease (BCD) are invasive organisms causing severe damage to horse-chestnut trees in Europe' [my emphasis]. So no change to forestry propaganda there then. But then the results: 'C. ohridella damaged up to 75% of the total leaf area [of Horse Chestnut] but it had no influence on stem radial growth or general tree condition' [my emphasis again]. Further, it stated 'Trees with higher rates of leaf miner damage generally had a lower incidence of BCD and there was no evidence that C. ohridella either facilitated the spread of the disease or accentuated its impact'.

I find it rather difficult to reconcile the actual results with the initial abstract statement and would suggest that independent peer reviewers should have requested changes.

Will these results, which in effect give a clean bill of health to the Horse Chestnut Leaf-miner, put a stop to all the negative comment about the moth? Probably not, but at least the facts are now known.

That end of season feeling

On Sunday I ringed the chicks at Fallen Cedar nest, which were thankfully still ok. The remainder of the day was spent checking round all the places where I have seen or heard a Wood Warbler in the last couple of weeks. Given the date, I would expect any remaining nests to have young and therefore the adults to be fairly conspicuous. The fact that I didn't find a single Wood Warbler anywhere suggested that it really is the end of the season. Even birds that I know had a mate could easily have been predated, given the widespread losses of nests that I'd already found.

I had to rethink this towards the end of the day when I checked on Double Back nest which still had five eggs. I then went to look at the male from Goshawk wood nest, who certainly had a mate the previous weekend. Sure enough she was there and alarming at me, while he alarmed some distance away. After some difficulty I found the nest and she has 4 eggs. If there are two nests still with eggs, you can bet that there are others but it is unlikely that I will be able to find them now. I was mulling over whether to call this nest 'the married couple' (as they were spending all their time a long way apart) or the Magician (as the female was adept at vanishing right in front of you) but have plumped for the latter as it turned out that the male was alarming at a Buzzard and hence already occupied when I arrived.

This evening I checked on Nursie nest and it has lost the last remaining chick. This time the camera worked.

Another bloody Badger. I was thinking that I hoped no-one sent me another one of the 'please sign the anti- badger cull petitions' and what do I get on Facebook? When I first showed that predation was having a significant effect on Wood Warbler productivity and that it might be the cause of the decline in this species, the response was 'What predator has increased enough to be making a difference to Wood Warbler populations?' Well the nest camera results from myself and the RSPB are showing that there are three primary predators; Jay, Buzzard and Badger. The population trend for Jays is stable whilst that for Buzzard is rapidly increasing (although it is hard to determine what the changes have been within areas occupied by Wood Warblers). There is no national monitoring of mammal population trends as there is for birds but some work has been done on Badgers and surveys in the mid-1980's and mid-1990's showed a 24% increase in the number of Badger social groups and a 43% increase in the total number of all types of sett.

What does this tell us? I certainly wouldn't claim that an increase in Badgers or Buzzards is responsible for the decline in Wood Warblers but, evidence is now emerging of a possible mechanism by which predation may be changing and having a negative impact. A great deal more data will be needed and there are plenty of people and organisations that will oppose any suggestion that predators are doing harm but the advantage of my position is that no-one funds me so no-one can take away my funding if they don't like my results!

Another one bites the dust

Checked on most of the remaining Wood Warbler nests this evening. Espanol nest had been predated, no surprise there but the predator was.

This is the first Sparrowhawk predation I've recorded on camera and in fact is the first Sparrowhawk I've seen in my study area in three summers fieldwork. Other surprising things were that it spent nearly quarter of an hour at the nest and the adult Wood Warblers returned to the nest for 15 hours after the predation, with the female even sitting in the nest brooding a non-existent brood.

Swamp bank nest should have fledged by now and the signs were good until I looked at the camera images. The young were clearly capable of leaving the nest yesterday and on many occasions all of them were outside the best begging for food from the parents.

They really should have gone.

Hopefully at least the others got away. The Jay was back at just after 5.15 this morning to check if there were any young still there.

Nursie is still looking after their one remaining chick and Fallen Cedar nest is ok, with 8 day old chicks now.

The mother of all spiders and a snake in the grass

Whenever you spend time in the field with another naturalist you inevitably learn things and see new species. When you spend time with an excellent entomologist who specialises in groups that are different from your own areas of expertise, you learn loads and see lots of new species, even in a poor summer at a not particularly exciting site. So a recent day out produced 22 new species for me and I even started to take an interest in spiders. It helps when they are as impressive as this one.

This is Thomisus onustus, a nationally scarce heathland species, with its bumble bee prey. There will no doubt be additional new species to come when all retained specimens have been identified.

Last night I had the pleasure of moth trapping on National Trust owned sand dunes on the west Sussex coast. The specialised habitat ensured that a number of interesting species were seen, including two that were new to me; Channel Islands Pug (a recent colonist that feeds on Tamarisk) and Shore Wainscot (a Marram specialist). Neither are particularly rare but the joy of not having chased round twitching moths (as seems to be the trend these days) is that I can still come across new species by chance.

Shore Wainscot

There was little evidence of immigration apart from a few Diamond-back Moths and a number of Red-necked Footman which seem to be turning up all over the place at the moment.

The real joy of the evening however was the effort made by the warden to facilitate our trapping and the interest that she and her volunteers showed in what we caught. This blog on occasion has criticised both wardens generally and the National Trust specifically and I have no doubt that such criticism will be made in future so it is a pleasure to give credit where it is due. Thank you Lisa and team, if only there were more like you.

The last remaining Wood Warblers are having a tough time. Nursie has lost four of her 5 eggs and the remaining egg was missing part of its shell on Monday evening. It looked more like damage than natural hatching and I feared the chick was dead until I saw it move slightly. I very gently removed the remainder of the egg shell but didn't really expect the chick to survive, not least because the predator that had the other eggs may return. It was pleasing therefore to see that the chick was ok and being fed normally on Tuesday. The camera did not reveal which predator was involved.

Whitemoor nest has been lost as predicted. Once again the predator is a Badger but what is interesting is the time on the pictures below.

There is a Badger with it's snout right in the nest. Nest predated? No, the actual predation takes place below.

So, more than three days later. Did it not realise the nest was there on 6th? Did it realise but leave the food for another night?

Porky nest has also bitten the dust, this time to a new predator for this year.

So it is clearly a snake and I think this photo shows dark chevrons on the back, making it an Adder. Other pictures show quite a small snake which would also fit with Adder. We had an Adder predation last year but that was a nest quite close to the edge of a wood and this was some distance from open habitat. Adders clearly operate far deeper into woodland than I had realised.

No sting in this tale

A couple of years ago I noticed that the Hampshire moth atlas said there was only one site for Hornet Moth in the county so I went off to find new sites. On the very first poplars I looked at there were a number of emergence holes plus a few exuviae and an empty cocoon but no moth. Needless to say, I've never found any other sites since.

Having never seen the actual moth, and hearing that they were seen emerging elsewhere yesterday, I thought I'd do a slight diversion on my way to Surrey today and have a look. I had a pheromone lure but when I arrived I thought I'd have a look for exuviae first. Whilst examining the second tree, I almost trod on ....

Buzzing with the unexpected success I headed off to the Surrey recorders meeting at Sheeplees. Unfortunately it was a bit chaotic and I saw very little, the highlight being Yellow Bird's-nest.

After lunch I was meeting Sophie who has recently contacted me about learning to ring birds. She hasn't ringed anything yet so the plan was to look for Reed Warbler nests (nice job in this weather) and put up a net to catch a few adult birds at the same time. The first couple of reed beds produced only three nests and they each had four eggs. This is far fewer than normal, perhaps Reed Warblers are having a bad year. The first two net visits had also produced nothing.

Normally when a trainee starts ringing they are given Blue Tits but Sophie's first bird came in the next reed bed. Something that had left the nest but was unable to fly and just flopped through the reeds towards her when I tried to grab it. Sophie was able to catch it so her first bird was

We must have found close on 50 Reed Warbler nests at this site over the last three years and this is the first Cuckoo we've had. She might as well give up ringing now, it won't get much better than this. She did get her obligatory Blue Tit later, plus a few Long-tailed Tits and a Garden Warbler.