Hello everyone,
Hope you've had some chance to enjoy nature this month, wherever you've been. It's been a great month. We seem to have had a bumper spring for iNat hoverflies, which seems to be improving the diversity of what is recorded compared to previous years.
Fantastically, we have passed 100 members this month. Thanks to everyone who has gotten stuck in and made it feel like a team effort to improve our hoverfly data for the benefit of the national recording scheme. If you are new, please be sure to read this key article about how to make your observations as useful as possible to the national recording schemes (because much of the advice there does not just apply to hoverflies).
I have tweaked the URLs in the Useful URLs post. The links for adding sex and life stage annotations now include Research Grade. Originally they didn't because it seemed more important to focus on observations that were yet to go through to HRS, rather than observations that had already gone through. But now that pile is basically done, and we only need to keep up with new observations as they come in, and deal with the old RG ones.
I have also added a new URL, "Pre-Mavericks", which allows you to find the observations where there is a disgreement that is potentially one ID from resolution (depending on which way it needs to go!). It deploys the Pre-maverick project by @jeanphilippeb, which you can also use for other taxa you are interested in.
Another record month for observations with just over 4000 posted (the previous record for May being 2854 last year). In terms of diversity, we have provisionally recorded 113 species, more than any previous month! Highlights include: Cheilosia lasiopa, Pocota personata, Brachyopa pilosa, Criorhina asilica, Dasysyrphus venustus s.s., Pipiza luteitarsis, and a smattering of P. austriaca
In June, more species are at their peak than any other month of the year, so have a good one! Here's what to look out for in June.
A history of the NeedsID Pile
We are approaching the point where we will have a whole year's worth of data from this project. One thing that's bugged me for a while is the inability to compare what we have acheived to previous years when there was no project. You cannot get from iNat how many observations needed ID at a point in the past. Anyhow, one very dull evening I had a crack at estimating the size of the NeedsID pile in times past. Starting from Jan 2018 (before which only 0.5% of observations were posted) I used the number of observations posted and IDs made each month, coupled with the average number of IDs that UK hoverflies have needed to reach Research Grade (which is 2.45 if you're interested!) to estimate the change in the NeedsID pile each month, eventually I reached the recent months for which we have real data and tuned the single unknown constant until they matched (gory details at the end). I think the graph below must be accurate enough to tell a true-ish story - maybe I'll be able to improve it once we have some real data from the upward curve. But see what you make of it, I definitely think we've made a difference!
Despite the record numbers of observations, the NeedsID pile has grown this month by only a few hundred. It looks like we have a really good chance of keeping it well below last year's peak. It's been especially cool to see members of this group stepping up and starting to try a few IDs for other people.
Here's the usual breakdown of the tribes, and the deep dive into Syrphini.
Only 7 genera have decreased, with 21 unchanged and 43 increased. It's nice to see though that the number stuck at higher levels has actually decreased by more than 5%. The biggest climbers (with >50 obs to start with) are, Chrysotoxum (+19%), Eupeodes (+18%), Helophilus (+16%), Rhingia (+16%), Xylota (+16%), Cheilosia (+15%), Melangyna (+15%), Meliscaeva (+13%), Platycheirus (+13%), and Sphaerophoria (+12%). Platycheirus is the runaway train here, leapfrogging Eristalis to become the neediest genus with nearly 1500 observations needing ID. Cheilosia is also rising much from a very high base. Just over 70% of observations posted in May are already Research Grade.
We have maintained a high level of annotation. Great job!
Obscured locations remain at about 4.5%. Observations with obscured coordinates cannot be used by the hoverfly recording scheme (and most other recording schemes). For an alternative way to address privacy, recommended by NBN, see here.
Right, that's all! Happy Syrphing for June!
All data compiled on 31st May
[Gory details
The average number of IDs per research grade observation was calculated as the total number of IDs made on RG observations posted before the end of 2023 divided by the total number of such observations. The time limit was intended to keep out more recent observations for which the numbers will still be changing more. Call it A. It turns out that for UK hoverflies A=2.45. (This includes the original poster's ID).
The number of observations needing ID at the start of 2018 was assumed to be as small as possible given the number of IDs and observations before that time, assuming that A=2.45 and all observations had an ID on upload (no unknowns). Any error from those assumptions shouldn't matter because all the numbers are so small at that point. Given these assumptions the maximum possible number of RG observations at the start of 2018 is [ IDs(Pre2018)-Obs(2018) ]/(A-1), where the subtractions account for the observers' initial IDs.
Therefore the starting point, NeedsID(Jan 2018) = Obs(Pre2018) - [ IDs(Pre2018)-Obs(2018) ]/(A-1).
Each month the NeedsID pile changes by Obs(Month) - K.[ IDs(Month)-Obs(Month) ]/(A-1) where K is a fudge factor multiplying the maximum possible number of RG observations from that month (0 < K < 1) to account for the fact that we don't in fact make the maximum possible number of RG observations per ID. This is the number that was scaled to match the true data from recent months. K=0.913, which suggests that on average we make just over 90% of the number of research grade observations possible with the number of IDs we use. This is assumed to have always been constant.
]
