Harlequin Ladybirds

[thunder]

Originally Posted by Lords and Ladies

I have what may be a stupid question and I never did like statistics much. When people interpret these recordings to see how populations are changing, how do they account for the changing popularity of sending data in?

The careful interpreters account for it with great difficulty.

Other interpreters choose interpretations that don't depend on popularity of sending data in.

Less careful ones ignore the problem and hope nobody notices (or haven't realised there is a problem).

You raise a good point, and many hours have been spent in trying to find a solution.

henrya

[Lords and Ladies]

Originally Posted by thunder

The careful interpreters account for it with great difficulty.

Other interpreters choose interpretations that don't depend on popularity of sending data in.

Less careful ones ignore the problem and hope nobody notices (or haven't realised there is a problem).

You raise a good point, and many hours have been spent in trying to find a solution.

henrya

Cheers henrya. The more I think about it, the more I see how difficult it really is. Best of luck to those involved in doing these things, whether it's insects or anything else.

My, entirely anecdotal, experience is that there's been something of a surge in interest in wildlife in the UK over the last few years. The number of new members here every day might suggest the same. There's increasingly more easily available information for the general public these days and easier ways to get public feedback.

Fifteen or twenty years ago, I don't know how I would have reported ladybirds. It could have been done I'm sure but I'd have had to find the right people, phone around and send things by post. It's a million times easier today and anyone can do it without too much effort. It must be near impossible to untwine these gradual changes from the gradual changes of insect populations, or whatever it might be.

I hope there's better minds than mine on these things .

[Paul mabbott]

Originally Posted by thunder

The under-recording of common species is a huge problem. At one point, in a database I used to manage, there were more records of Otters than there were of House Mice!
henrya

The same when Clive Herbert took over the London mammal records - pipistrelles were more numerous than grey squirrels ....

[Paul mabbott]

No, it's a good question.
Optimally you would get the same people making observations on a weekly basis, year after year .... Life is seldom like that ... if only because people move or die and because new people join in ...
It is essential to make allowance for the numbers of people and the amount of work that they put in. As you note recorder effort will seriously bias the results. That's not too much of a problem if you have lots of recorders since the variations tend to cancel each other out.
There are even more complicating factors - for instance N>S variation, altitude and other geographical factors (the outer London suburbs are an antirely different habitat from inner, urban London so results are not directly comparable ...).
So yes, good scientists will be aware of this from the outset and will not make wild "general" claims - although it's sometimes difficult to stop the media from doing over-enthusiastic write-ups!

Originally Posted by Lords and Ladies

I have what may be a stupid question and I never did like statistics much. When people interpret these recordings to see how populations are changing, how do they account for the changing popularity of sending data in?

I've been thinking of surveying my garden and sending that in, as my chilean potato vine (Solanum crispum) has lots and lots of ladybirds on it. Mainly two-spot but a couple of others (perhaps different forms of 2-spot, my ladybird IDing isn't very good ).

[Lords and Ladies]

Thanks Paul. It's very interesting to hear more about how these things are done in practice. The more explanation the better really as it does close the gap between the half-xexexexexe naturalist like myself and the people who, hopefully!, know what they're doing .

Having slept on it, I can see that the recordings are raw information that can always be returned to and re-evaluated if necessary so long as they exist. I'll have a good go at counting and reporting the ladybirds I have.

Thanks for your help.

[Paul mabbott]

Exactly so - if you don't have the raw data, however imperfect, you have nothing!
Even when the records are intermittent, they can still be useful for distribution (where are certain species found, are they moving over the years?), phenology (when do they become active, does time of activity affect survival?), behaviour (there are still a lot of unknowns, things to be discovered about ladybirds, not to mention all the other insects), predation (what do they eat, what eats them?) &c &c .... the value is endless!

Originally Posted by Lords and Ladies

Thanks Paul. It's very interesting to hear more about how these things are done in practice. The more explanation the better really as it does close the gap between the half-xexexexexe naturalist like myself and the people who, hopefully!, know what they're doing .

Having slept on it, I can see that the recordings are raw information that can always be returned to and re-evaluated if necessary so long as they exist. I'll have a good go at counting and reporting the ladybirds I have.

Thanks for your help.

[Paul mabbott]

This follows Ashe's query but applies to anyone. I don't have much time to spend on the computer in the summer so if I miss your ladybird queries and nobody else gives you a satisfactory diagnosis then why not send your photo to the national survey?
Harlequin Ladybird Survey - Recording sightings
Peter Brown will be happy to receive all pictures and pass them on to Mike Majerus if there are problems.

[Paul mabbott]

To keep you all up-t0-date ............
There's a fairly up-to-date summary by Mike Majerus in an on-line Powerpoint presentation, including possible biological controls:
http://tinyurl.com/2795rx
There's also an article by Peter Brown in the July BBC Wildlife magazine.

[mrs fish]

Loads of good info there Paul

Just sent this to the survey

[Paul mabbott]

Quite a few then
I suppose that I should give one warning about possible misidentification of larvae (actually, I think I did some while back, but maybe worth repeating?); the larvae of the sister species Harmonia quadripunctata, cream-streaked ladybird are very much like the 'harlequin's' and so, too an extent is that of the eyed ladybird, Anatis ocellata - so anyone finding the odd one or two larvae without adults, especially on pine and other coniferous trees should give serious thought before destroying a perfectly harmless ladybird!

Originally Posted by mrs fish

Loads of good info there Paul
Just sent this to the survey