The earlier pictures were taken on my wee compact Canon ixus 970IS, which involved sneaking up on the butterflies. This can be very frustrating when they fly off, but very rewarding when they don't!

Since 2012 I have been using a Panasonic Lumix FZ150, which allows me to zoom in to the butterflies from a couple of metres away.



Monday, 26 March 2018

More Graphs!


In my previous post I compared last year's butterfly records with the average for the previous five years.

I then realised that back in 2001 I had a job as a seasonal countryside ranger at John Muir Country Park, here in East Lothian. I used to keep a record of the butterflies I saw each day and I also walked a transect. So, I thought that it would be interesting to compare my 2001 records with the last five years.


I know it is not very scientific to compare the results of one person from one site with those of several people from all of East Lothian, but nonetheless I have noticed some interesting results.

These first few graphs don't show anything too remarkable ...







... as I expected saw fewer butterflies than the current 20 or so recorders, although I was outside all day five days a week. However, what I notice is that my records from 2001 appear to be about two weeks later than the average over the last five years. John Muir Country Park is coastal and well known for its sunny weather, so if anything I would expect butterflies to appear there earlier than much of the rest of East Lothian.

Could this possibly be a sign of climate change?


The Green-veined White seems to be a remarkably consistent butterfly. Year on year its numbers don't appear to change much.


And I was interested to see how few Large Whites I saw. They certainly seem to be more common these last couple of years than I remember them being in the past.


The Red Admiral has certainly become more common over the last few years. It now appears to be able to survive the winter here, but in 2001 I didn't see any until the end of June.


And I had the impression that there are fewer Small Coppers around these days than there used to be. My records from 2001 appear to confirm this.


The Small Heath intrigued me when I worked at John Muir Country Park. They appeared to have a very much shorter season there than elsewhere in East Lothian where I was surprised to see them several weeks after they had finished at John Muir Country Park. Checking the more recent records, from 2010 Small Heaths appear to have a much longer season. It makes me wonder if they used to have one generation a year, but now can manage two.


The Small Tortoiseshell used to be a very common butterfly, which has declined quite seriously in numbers over the last few years. It is amazing to see how many more there were in 2001.


In contrast it appears that the Small White is more common these day than it was back then.



I also notice that back in 2001 I didn't record any Commas, Small Skippers, Speckled Woods or Wall Browns, as they hadn't arrived here then. In 2001 I didn't record any Painted Ladies, either, although I do remember seeing several in 2000. So, 2001 was obviously not a year when they arrived here in large numbers.


I was wondering if my mind was playing tricks on me, but my recollections appear to be backed up by the figures. What we can't be clear about is the cause of these changes. It is easy to jump on the climate change bandwagon, but it might just be the cause.


I promise, there will be no more posts containing graphs this year!!

8 comments:

  1. Lovely photos.
    It is interesting to note what we find on our world.
    I know the critters in my woods change. When there are fox there are few hares and so on.

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    1. Thank you Tammie Lee. Yes, it is amazing how different things can impact on how many creatures we see. It is great to see how they can bounce back and I hope they are able to continue to do so.

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  2. I enjoy the graphs. I would love to eventually make a study and apply graphs to wildflowers that have recurred in urban environments within a period of a year. It may sound like a huge endeavor, but I can scale it down by sampling "'within a x miles radius". What you've done is exciting, and I have learned a lot.

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    1. Hi Maria, I find it very interesting to see how things have apparently changed in such a short time. I am sure there must be many more people around the world noticing similar changes. I hope that all of this information will be useful for people studying climate change and phenology.

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  3. Hi Nick, we were taught how to do Species Index in Ecology class, however i can't seem to do that with reliability for butterflies. Most of them fly from one area to another area and i don't know if the one i saw earlier is the same as what i see later! That is more difficult for the very tiny blues because they are also agile and fly maybe to the next group of their nectar plants several meters away!
    hahaha

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    1. Hi Andrea, For the transects it is easy as we just walk at a steady pace in one direction and only count butterflies that are settled, or that fly into an imaginary cube in front of us, but we don't count any butterflies that come from behind us. For the other casual records it is a lot more difficult. I always say to people that it is better to under-estimate than to count a butterfly twice. As I often stop to photograph the butterflies I try to be careful not to over-count. Sometimes I will estimate the size of a colony before I start taking pictures. I can imagine it will be a lot more difficult in the Philippines where the butterflies will be so much more active. I think the most important thing is to be consistent in the way we record our butterflies year on year, so that we are able to compare years.

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  4. WOW, you really did a considerable job getting all this data on so many species, and the results are very interesting
    Congrats Nick, not sure I would have your patience!!!

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    1. Thanks Noushka. It took a long time, but I find the results interesting.

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