My highest ever total of field identified invertebrates was at Hoyle Farm, West Sussex in August

Posted by Graeme Lyons , Wednesday 9 August 2023 19:51

For the last few years, I have been keeping a daily total of all the invertebrates I have identified in the field (field dets) on any given day's surveying on a single site. Every day I do this and weirdly, I seem to be able to remember each day, within one or two species. So why bother? There is a very good reason; gamification. By constantly competing against  myself, I get better and better at identifying in the field. This serves a number of important functions:

1) I have to kill fewer invertebrates to identify them. They are very happy about this.

2) Which further saves me time in the winter at the microscope.

3) I become a more effective naturalist, by understanding what I am seeing in the field as I see it, which benefits my understanding of autecology. Identifying all specimens at home feels a very detached way to record to me.

4) It helps to push the boundaries of what is considered identifiable material, something that is particularly relevant with spider recording.

5) It allows me to frame how good the day's surveying has been based on the other totals I have been recording that year. Anything over 200 always feels like a good day and 250 is exceptional, for example.

6) It keeps my energy levels up and is fun!

This shot was taken by the owner of the site, Bianca Pitt. It's been great that Bianca was able to come out with me not just once but on every visit. So much so that I could see Bianca learning her plants over the summer but also, it's a great way to learn about habitat management, grazing, surveying etc etc and the two way flow of information makes it easier for me to write my report and tailor the recommendations. And I enjoyed having the company, as it's rare that someone is so keen to come out. I wish all my clients would do this at least once. So many people who work in land management find themselves too busy to spend time in the field, learning about wildlife and understanding the sites they are managing. How can this be right?

I digress, back to the field identifications! If I am not sure, I still take the specimen and 'ground truth' it back home, this being an important 'bridging' technique towards being comfortable at making a call in the field, however some species will never be field identifiable and you will always have to take them to ID them correctly. It's important to state that you can't fast-track this process; you can only confidently identify in the field after spending years identifying things at the microscope. You need to know exactly how and in what position to hold the invertebrate, where to point the hand lens and what to look for and do this efficiently. You also need to be able to hold identification guides, keys and spider genitalia images in your head. Again, something that comes from a great deal of repetition. It's peak entomology!

Late May/early June has always seemed like the time that I would get the biggest lists. Last year, I got two sites in the 270s in this time period, with the record for the total number after microscopic identifications being 355. Prior to this my record was at Ken Hill in 2019, again in May/June. So, I was not expecting to blow this out of the water in early August! Especially, as to the untrained eye, it might seem like a bad year for invertebrates; it really is not though. There is a LOT out there at the moment, with some very high species-counts to be made.

The site was Hoyle Farm in West Sussex. It has a number of features that make it perfect for a large day list:

1) It's in the West Weald. This part of Sussex is a fantastic landscape for invertebrates.

2) It's on the edge of the Green Sand, so has some magic soils and associated vegetation but this moves to heavier soils in places, adding to the diversity. There is some woodland with glades too, that is also very rich in invertebrate life.

3) It's a medium-sized site at c100 ha, that's compact and easy to get around, so I could spend six hours solid recording without lots of time moving between compartments.

4) The site is sympathetically managed. Chiefly, the grassland is not over or under-grazed and significant parts of the woodland have an open structure. The site has a great deal of nectar sources, bare ground, some old growth oak, plenty of shelter shelter and structural heterogeneity - perfect conditions for invertebrates.

The method was my standard farm 'bioblitz' method for recording on farms. Split the site into six roughly similar blocks and spend an hour in each. I record as many invertebrates, plants, birds, mammals etc as I can. I was pretty surprised therefore, that this methodology (and not just an invertebrate survey) would be the one to beat my record and it wasn't until I finished the first hour that I thought I stood a good chance of beating that record. I was on 101 species and had recorded the sandiest, most open compartment first. In this 101, I think I had had about 10 species with conservation status. So, I decided to go for the record. Five hours later, I was on 298 field identifications. I fast-tracked the microscope work, adding a further 69 species. This ended up being 367 species in all (with a whopping 32 of these having conservation status). A total of 789 records were made on the day. Rewarding but exhausting work

This is an amazing site. I can honestly say it's the nicest acid-grassland I have seen in Sussex and some of the best I have seen anywhere away from the coast or the Brecks. It has some amazing plants that I could write a blog about alone (including several I have not seen in Sussex before), including; Hoary Cinquefoil, Mossy Stonecrop, Smooth Cat's-ear, Knotted Clover, Subterranean Clover, Common Cudweed, Corn Spurrey and more Common Stork's-bill (below in May) than I have seen before! The first bird I heard as I got out of the car on my first visit was a Woodlark.

So here are some of the goodies from 2rd August (I have included a full species list of the 367 species found on the day below). One of my all time favourites, the Hornet Beetle Leptura aurulenta, a Nationally Scarce longhorn beetle and THE beetle that got me into beetles, after I went looking for it in 2009 at Ebernoe on a hunch, and found it! Fourteen years later, I have seen 1653 species of beetle in the UK.

Beating this Lichen Running-spider Philodromus margaritatus  from Ash was a real surprise! After Graffham Common and Lavington Common, this is only the 3rd known site for this charismatic spider in Sussex. Nationally Rare, Near Threatened and Section 41.

And I had a trio of lifers too.

The hopper Aguriahana stellulata, which I have long coveted.

The Nationally scarce a weevil that feeds on Dark Mullein, Cionus nigritarsis, was a long overdue lifer too.

And a striking cranefly swept from the woods (with yellow wings and legs) turned out to be the Nationally notable Tipula livida. Here is the female's paraphernalia under the microscope. 

Other highlights included Woodland Grasshopper (Nationally Scarce).

And Attactagenus plumbeus, a Nb weevil I see on acid-grassland occasionally.

This was taken earlier in the year, but the much smaller spiderlings of Alopecosa cuneata are still field identifiable now and are much more widespread. Another benefit to learning the early stages of species.

Probably the rarest thing though was a species I had new to Sussex at the neighbouring farm in 2020 (c500 m away from this record). The pRDB1 Scythris potentillella (no photo I am afraid). Scythris are small micro moths that I encounter (possibly more than any moth-er in Sussex does) by using my suction sampler, which is a great way to record this whole genus - almost all of which are classed as scarce or rarer. This one feeds on Sheep's Sorrel. Targeting Sheep's Sorrel for Dalman's Leatherbug is therefore the way to find this rare moth (as on both occasions, that's what I was looking for). I also found the Nationally Rare rhopalid bug Rhoaplus rufus.

I run the day's data through Pantheon (the Biological Record Centre's online database for analysing lists of invertebrates) and the SQI (a measure of site quality based on the proportion and weighting of the rarities present) came out at 137, this is really high for one of my surveys (my average is 123.9). The true SQI is likely to drop a little when the the three dates are combined but this was a really interesting exercise. A total of 32 species for the day (at least 50 for the whole survey) is quite remarkable. My average for all surveys (ranging from three to six days - not just one visit!) is 34.5 species with status. Showing this has both quantity and quality. Here is the sward in August, full of nectar and rare invertebrates.

We discussed habitat management at length and it's great that many of the changes required to make this site even better are tweaks rather than radical changes in direction. This is an important, low nutrient, low pH site, with an invertebrate assemblage closer to a nature reserve than a farm and I am glad it's in safe hands. I can't wait to go back in a few years and see how it has changed! Now, here is the entire species list, starting with the field identifications. Species with status highlight in bold and conservation statuses in brackets are thought to be out of date. NS = Nationally Scarce, NR = Nationally Rare, Nb = Nationally scarce b, Na = Nationally scarce a, NT = Near Threatened, S.41 = Section 41, Nn = Nationally notable, etc.

And then a further 69 species identified at the microscope, which I fast-tracked so I could write this blog.

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