My orange frog

Jane comments:

‘I have an orange frog in the pond – what sort is it?‘

The answer below is taken from the Natural England’s leaflet ‘Amphibians in your garden: your questions answered’.

CLICK THE PICTURE TO SEE A LARGER VERSION

Natural England is the main Government agency that is responisble for nature conservation in England.

Appropriately, for the first (official) day of spring

Hi Jeremy,

Just thought I would give you an update on our pond.

After burying about 30 frogs that had died [during the cold weather] I am overjoyed to report that at the moment there are probably about 50 young adult frogs having a whale of a time in the pond laying frog spawn, so hopefully all is not lost and it is a joy to see.

Carole

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FOOTNOTE: We will be publishing the results of the Big Pond Thaw survey on Monday or Tuesday this week. Jeremy

Is removing half the water in the pond, followed by a rainwater top-up, likely to be good for wildlife?

Joe asked in the comments what I thought about half-changing the water in a pond – something that’s pretty widely recommended.

Well….removing half the water and topping up with rain water should reduce pollutant levels, but whether it reduces them enough to make a difference might be another matter.

Nutrients, in particular, need to get down to a pretty low level to be ‘safe’ for wildlife: if the half dilution didn’t get down to that level the benefits might not be as much as you’d hope.

As so often, at the moment the problem is that no-one has carefully observed the effects on wildlife in ponds where this kind of water change has been done, so it’s hard to give anything other than a tentative answer.

And because a lot of nutrients can be locked up in sediments and plants (a re-released into the pond) there’s a good chance you’d need to combine water changing with regularly removing plant material and sediments to have a chance of success.

But to be honest, at the moment we’re all a bit in the dark about how effective a technique this would be.

But before yuo get to gloomy remember that, even if the pond does have some management problems it’s still going to have a lot of life in it – it’s just that it may not reach it’s full potential.

If you’re worried, one thing we can do is have a look at the pond conductivity – send us a sample and we can check whether watr changes might be a good idea or not.

It’s frog city out there

UPDATED: 9.0 am 21 March 2010. There are now another 17 clumps in other parts of the pond away from the main spawn patch.

It’s a common phenomenon for frog numbers to build up quickly in new ponds.

This has certainly happened in my ‘old’ pond, filled in April 2007.

In 2007 we were too late for the frog breeding season.

In 2008 we had 2 clumps of spawn.

In 2009 we had four – and a huge number of tadpoles which stripped the pond bare and turned the water green for a while.

This year the frogs have really gone for it.

The tape measure is pulled out to 1 metre

There’s a one metre wide patch of spawn which, using the graph below, is equivalent to about 50 clumps which means 50 female frogs (each female lays one clump of spawn).

And there are a few more clumps away from this main patch.

To work out how many spawn clumps you estimate the area of the spawn patch in square centimetres – a patch 1 m diameter is roughly 7500 square centimetres.

On the graph you read up from 7500 on the horizontal axis until you cross the middle line of the graph – and then read back to the vertical axis to estimate the number of clumps.

So that means we’re heading for somewhere between 50,000 and 100,000 tadpoles in the pond (there are usually 1000-2000 eggs in a clump).

Everyone loves ponds, and ponds certainly need all the love we can give them

We joined in with ‘Oxford Goes Wild’ today – and no surprise that we had a pretty constant crowd around the trays of pond animals we brought along. Everyone really loves the life in ponds.

And ponds – and watery wildlife generally – certainly need friends.

As we reported a couple of weeks ago, out in the countryside ponds are in a pretty terrible state: 80% in England and Wales are in ‘Poor’ or ‘Very poor’ condition.

If you would like to help, one of the best things you could do is join up as a Pond Conservation supporter here and help protect our threatended freshwater wildlife.

Water vole of old rubbish

Browsing the web today, I was reminded of what was the possibly worst example in 2009 of PR masquerading as a wildlife news story.

In November the BBC reported that a survey of the UKs canals had shown that 2009 had been a ‘bumper year’ for water voles. You might remember the story as it was quite widely reported, being covered in:

The Guardian

The Independent

The Telegraph

Countrylife

and

Mail Online

Good news apparently, and something that interested me. So I naturally looked at the source: the British Waterways Wetland Wildlife Survey.

Members of the public were invited to send in their sightings of wildlife on canals.

The public had done something similar in 2008 as well.

You can see the results here but as they don’t take up much space I’ve reproduced them in full below.

The results of the 2008 and 2009 British Waterways National Wildlife Survey

It was the remarks at the end of the piece on the BBC’s November 2009 article that caught my eye.

In 2009 the survey went web-based and there were ‘a lot more entries [in 2009] than in the previous years‘ according to a British Waterways spokesperson.

And the total number of records went up from ’6000-7000′ a year to ’42,000′.

It was at this point I began to smell a rat – well, more specifically a water rat.

In 2008 there were 43 records of water voles. In 2009 there were 89 sightings of water voles. This was what the BBC and other reported as a ‘bumper year’ for water voles.

But hold on a moment: the total number of observations increased by about 6 times – from somewhere between 6 and 7 thousand to 42,000, presumably because more people sent results in – not because wildlife suddenly increased 6 fold on the canals. (Nobody would seriously suggest that there had been a near 20 fold increase in mallard between the two years – take a look at the real data here collected by the British Trust for Ornithology which shows a long-term increase in breeding mallard with number fairly stable since 2000).

If you take that increase in recording effort roughly into account – by multiplying the 2008 count of water voles by six – you see that if you’d applied the 2009 amount of survey effort in 2008 there should have been around 250 water voles recorded.

So, far from being a bumper year, if anything the survey suggests that water voles might have declined. Of course, the truth is that the survey is so silly that it’s not really worth any attention at all.

The story, and the survey itself, is just a bit of nonsense – but it is a PR triumph.

Does it matter – well, probably not much. It’s just one flawed piece of work – a little floating thing in the otherwise fairly clean stream of information. Harmless you might say, except next time when you hear a more balanced story about the state of water vole populations, which one will you believe? I can’t help feeling that this kind of thing feeds the mistrust people have of statistics, and if we want to protect the world that does matter.

Safe to drink but (often) not good enough for your wildlife pond

UPDATED: See the comment from my Pond Conservation colleague Chris Monk which neatly shows how, especially in the north, it’s worth checking the quality of your tapwater.

This post is partly in response to Sue’s comment yesterday that she was regretting filling her new pond with Yorkshire Water’s best.

Well, sadly, it looks as though she was right to worry.

Taking Sue’s postcode I checked the quality of her drinking water.

This will work for most of the big Water Companies in England and I think in Wales. I haven’t checked whether the same information is on-line in Scotland and Northern Ireland where there are different arrangements for drinking water supply.

First I went to the company’s website – in this case Yorkshire Water.

Dragging yourself away from the irresistable offers for iPhones and emergency plumbing you choose the Water Quality tab.

Under that you’ll see a sub-heading called ‘Check your water quality’ and a link to ‘View Water Quality Report‘.

Click the link and up pops this page where you enter your postcode.

Enter your post-code and you get this page – a summary of what’s going on in your postal district.

It really is an excellent site!

At the bottom left of the screen you’ll see a link to the pdf copy of the Annual water quality report for your postal area.

This is based on detailed analysis of hundreds of laboratory samples of water from the tap in the relevant area.

It’s gobbledegook unless you know quite a lot about water chemistry – but there it is, in full detail.

There’s a map showing the area the report covers – in this case part of York and the surroundings.

And then a page of detailed results – covering everything from Arsenic to……I was hoping for something that begins with Z, but for some reason Zinc is not regarded as important in drinking water (it is a regularly present water pollutant – mostly from decaying car tyres – but presumably the levels are not dangerous for people).

It’s also worth noting that the water companies don’t usually measure phosphorus – the other very widespread pollutant in freshwater that is not actually harmful for people but has had a huge impact  on freshwaters.

Here’s one of the detailed pages.

Click to see this more clearly

On the second line down you can see the value for nitrate – in this case the average value (called the mean here) in the last but one column on the right is a fraction over 21 milligrammes of nitrate in each litre of water.

This is of course a tiny amount but its very large by natural standards – roughly ten times what you would expect naturally. In my pond, the value a couple of weeks ago was just over 1 milligramme of nitrate per litre of water – so 20 times lower.

So, sadly, Sue was right to regret putting tapwater in her pond.

In many parts of the United Kingdom our tapwater, though treated to a very high standard and safe to drink, is not really good enough for a wildlife pond.

This is mainly due to the very high levels of nutrients, particularly nitrogen, present in our drinking water supplies.

Add that to you pond and hey presto – instant pollution.

But it is worth checking because not everywhere will be as bad as this.

Quite a puzzler

From Pat (see the comments)

‘On the 16 March my small pond, 3ft by 2.5f, was smelling and dirty.

So I drained it and found 13 dead frogs and 1 barely alive. I refilled with fresh water.

On the 17 March the pond water was cloudy so I drained the thing again: this time 1 dead frog and 15 live ones. Quite a puzzler as I have lived here for 10 years and not seen anything like this.’

I think it’s time to call in Paul Daniels.

My frog spawn dates

I was so busy last week that I didn’t go in the garden at all.

So it was a nice surprise on Saturday morning to find my first frog spawn – and by the looks of it quite a lot more than last year with at least 12 clumps now.

This was a little later than last year and about the same time as 2008.

My dates for first seeing frog spawn over the last three years are:

2008: 17th March

2009: 4th March

2010: 13th March.

At the moment, this is still a common animal

Here is a common British animal.

It’s a common frog – Rana temporaria.

But sometimes people are inclined to believe it’s not common.

A good example of this is here – reporting the launch of an important study about animals and plants that have become extinct in England, a throwaway remark reported by the Guardian – that common frogs are no longer common  – also slipped into circulation (the exact quote given to the Guardian was ‘….some once prolific species are under threat, including the common toad, common frog, common skate and the corncrake. “They are not common any more,” said……’ – well, I’ll draw a veil over who said it).

Of course one small slip isn’t important – but then I noticed it was repeated here today by a commentator who is a little more widely read – George Monbiot.

Monbiot got it from an impeccable source: his own newspaper – the article this little remark originally slipped into was otherwise very good (and it was hardly the fault of the journalist – she was quoting….well….I drew a veil over that).

So for the common frog the facts are:

- from 2007 to 2009 surveyors taking part in the National Amphibian and Reptile Recording Scheme saw frogs in just over half of the ponds in the countryside.

- in 2009 Pond Conservation’s surveys of garden ponds suggested that Common Frogs are seen in practically all garden ponds and breed in around two-thirds of them.

There probably are fewer frogs than in the past but, at least for the time being, the Common Frog is still a common animal – there are probably millions of them. But a few more people now believe something that is at variance with the facts – even though this creature is probably hopping around in their gardens at this very minute.

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FOOTNOTE

Of course we can’t afford to be complacent, even about about common animals: many creatures once common – the common eel, the red squirrel, the native white-clawed crayfish, even house sparrows are declining or have all but disappeared. It’s entirely possible our still-common frog could go the same way.