State of the Syrphs - 1-Apr-2024

Hello Syrphers!

It has been wet, hasn't it? Just a little bit. Ah well.

What to look out for...

April is lift-off month for hoverflies - check out which hoverflies are at their peak, and which are getting going in this month's 'What to look out for', which contains advice on getting identifiable pictures of the difficult 'black jobs' that form a significant part of the fauna at this time of year. (Bear in mind that species will appear earlier in the south and later in the north).

Keeping up with New Observations

Despite the weather, an awful lot of hoverflies have been uploaded (for March anyway)! This continues the trend of 2024 - so far well over three times as many hoverflies have been uploaded as in any previous year. Some of that is certain users uploading plenty of photos from previous years, but there has also been a significant increase in real time observations, easily more than twice as many as any previous year.

I don't expect that to continue - it is relatively easy to double or treble the small numbers at the start of the year. Nevertheless we have more than kept up with the influx and so the NeedsID pile continues to diminish. 87% of this month's new observations are RG already. Don't forget the handy URLs here which can help us keep up!

What would we need to do to keep up with observation numbers in April? One complicating factor is that this year much more of the City Nature Challenge (CNC) period is in April - so just comparing to last April (when all of the upload period fell in May) won't work. (Last time CNC was mostly in April - 2020 - there were more observations in April than May!) Last year there were nearly 2500 hoverfly uploads from April 1st to the end of the CNC. Based on the increase so far this year it doesn't seem inconceivable that there could be 2500-3000 in April this year. I worked out that on average an observation needs about 1.5 IDs additional IDs to reach RG (i.e. additional to the observer's ID), so that's up to 150 IDs per day on average between all identifiers to keep the pile the same size. In reality they will not be spread evenly - there will be a big surge in the week from Fri 26th. It will be interesting to see if April is the month the NeedsID pile starts to get bigger again...

Identifications

I suggested last month that we try to get the NeedsID pile below 8500 (half of what it peaked at last year). With a bit of a late activity over the weekend we have achieved that!

8 genera have increased (but not by much), with 30 unchanged and 33 down. The biggest fallers (with >50 obs to start with) are Pipiza (-85%), Neoascia (-76%), Eumerus (-66%), Xanthogramma (-65%), Syrphus (-56%), Melanostoma (-54%), Parhelophilus (-49%), Eupeodes (-43%), Epistrophe (-38%), Meliscaeva (-38%), Rhingia (-28%), Platycheirus (-26%), Chrysogaster (20%), Merodon (-20%), and Helophilus (-11%): Those are some serious numbers, so well done for your contributions. The neediest genera now (those with >100 observations) are Eristalis (1176), Platycheirus (1021), Cheilosia (595), Melanostoma (419), Eupeodes (364), Helophilus (198), Chrysotoxum (121), Xylota (113), and Syrphus (108). May I make a personal plea on behalf of Eristalis? It's my favourite genus, but I've already identified everything still needing ID in the UK so I can't do any more, and the numbers haven't moved much since new year. Anyone fancy having a go?

Another thing that is worth noting is that an increasing proportion of the NeedsID pile is not even ID'd to genus - currently 40%. This includes nearly 50% of Syrphini languishing at tribe. Identifying these is a great exercise for beginners because you don't have the pressure of making things research grade. The following rather messy pie chart shows you the whole NeedsID pile divided by genera. (Probably won't be readable on the app - but the big blue block is 'No Genus yet')

And here is how we did it. You can see just how many more IDs have been added over the winter compared to previous years, and it really is impressive :)

Annotations

It's also been a very successful month on the annotations front. Sex annotations over 95% for the first time.

Obscured locations

Unfortunately we had quite a high proportion of obscured locations this month. I wonder if more observation has taken place close to people's homes due to the relatively poor weather. Observations with obscured locations cannot be used by the Hoverfly Recording Scheme. An alternative that avoids this problem is 'Pinned Locations'.

Finally, Happy Easter to you all, and Happy Syrphing for April!

All data compiled on 31-Mar-2024

Posted on April 1, 2024 08:27 AM by matthewvosper