Saturday, 29 August 2009

Frogging in Lincolnshire

NOTE: I'm not a biologist, so I might be talking rubbish in this post! You're welcome to correct me!

I was invited to go along to help catch Xenopus frogs not too long ago by Albert. I've long been interested in Xenopus frogs since Sherry kept them as pets. I guess this is a story, in a way, of how I got some. This post is also long overdue.

Xenopus are a type of amphibian.. some people call them frogs, some call them toads, I believe the reason for this is the fact that the terms "frog" and "toad" is a generalisation to what people identify certain kinds of amphibians to.. and xenopus shows characteristics of both if you were to get a checklist and check the boxes as you went. I shall avoid going into the what defines each.... They are from the sub-Saharan part of Africa, the particular species which is so widespread, and the ones we went to catch were xenopus laevis, or the african clawed toad/common platanna. There are other xenopus species out there, like Sherry's x. victorianus.

Unlike the native frogs/toads, xenopus spend almost all their lives in water, and are aquatic. They have been exported worldwide from Africa for the purposes of research, and until not-so-long-ago, pregnancy tests. From what I understand, they are considered a model organism, they exhibit behaviours and resemble the workings of other species, or something like that. By injecting the urine of a pregnant woman, the hormones would cause the xenopus to lay eggs and this was how one could use xenopus as a pregnancy test (goodness knows who discovered this...!). For these reasons, xenopus have become common around the world, and in addition to this, xenopus have become popular as pets (they are considerably easier to keep than other frogs/reptiles/amphibians and are quite hardy).

Fast forward to a few weeks ago, when I was up in Lincolnshire... we (a group of us) were there trapping frogs for a few days. The story is that a pet shop owner shut his shop some time ago, and wanted to give these frogs a chance so he set them free. We became aware of this particular feral populations (a number of feral populations exist worldwide, e.g. Chile, California, France and even one near Bridgend, UK) when the locals started catching xenopus in the nearby angling pond. The land they are on is an old slag heap site, where there are a number of water bodies. Much of the area we walked around felt like old wasteland which was overgrown - it probably was,... I'm guessing...!?

As usual, I'm no expert photographer, I just enjoy taking pictures to record the moment. That sort of thing... On the first day, we didn't get as much done as we'd like to, as we had the BBC filming. They're putting together a program on Invasive Species. In the pic below, Professor Richard Tinsley is being interviewed on the xenopus. This spot is one which xenopus were previously caught in, and we have decided to put out some traps to catch them. We've nicknamed this bit "Tadpole Nursery".

So during the daytime when we arrived in the area, we set out the traps. It's now night, we went to check them out to see if we'd have any luck. There was the odd one swimming around and a few tadpoles here and there. Here's a xenopus we caught with a net (rather than a trap).

This is one of the traps. It is simply a bucket with poles popped in the lid, and a funnel. The bucket is half-submerged, and baited with liver. The idea is that the xenopus can smell the bloodied water, and they will try and find their way in... so the funnel is for that, they can enter the bucket where the liver is, but not get out very easily. Since xenopus need to come up to the surface to breathe (I believe they have lungs?), it was important that the buckets were only half-submerged... you don't want to drown the little guys! If you look carefully, theres a little one there, trying to find out where the food is.

A selection of some fine specimens... that night.:

A bucket full of tadpoles:

The next day.... we've come back to check the traps. Let's bear in mind that xenopus feed at night, so that's why it was much easier to spot them in the water last night. Look at this catch... a HUGE female! (yeah, I want one... :P )

With the xenopus in the traps, we have to scout the various sites and collect them and bring them back to the car to take them back to the B&B where we will sort them out later. Tadpole Nursery was one of several sites (one of them is, affectionately, named Albert's Pond). This is what it looks like with the water fully trapped.

Our crew - Left to right... Sophie, Gemma, Albert, Me, Kirsten and Professor Richard Tinsley.

We're now back at the B&B that we stayed in during our time there. This is one of the BBC guys, he's a cameraman of sorts. I spoke to him about his kit, and he told me he's a local guy, and is not associated with the presenter (the interviewer in the first pic), who travels around and does various programs - his last one was about steam i believe, as in, steam trains , that sort of thing. So they do a lot, and get around a lot.

Here is Albert sorting out the xenopus into Male, Female and Juveniles. The females were the most important initally as we'd managed to find new "homes" for them, Dundee University wanted 60 plump females... unfortunately the males and juveniles were put to sleep (with anaesthetics) before an "order" came in for 20 various xenopus. Thankfully,Sophie took home 2 little xenopus, and I took home 4 and rehomed another 3 with Sherry's mum.

A few pictures of the village where we stayed. With the afternoon a little free, I ventured (but not very far at all....) into the village's high street.

The pub where we ate served up some enormous sized meals... the perfect dinner for the hard work! ... hey, even I struggled to get a desert down into me!

We're back to frogs now - another reason we were sent to remove these guys from the area was that xenopus is one of the species blamed for the spread of a chytrid fungus which can kill various species of frogs, but xenopus themselves are not affected. It was important that we swabbed the xenopus and native amphibians we saw - these swabs are then sent away to be tested for chytrid.

Whilst we were there, we managed to trap and catch a large number of xenopus - this is what a netful of them from a big binful of them looks like!

And this is what a trapping-bucketful of them looks like!

When frogs mate, they get into amplexus. The female lays eggs which the male then fertilises with his sperm. Xenopus have an unusual position, in which the male grabs the female by the "waist", rather than just under the arms (the wikipedia has a few pictures of other species of frogs). When we collected the xenopus from the traps around Grass Pond (the name of a pond we found xenopus in..), this frisky male attached himself to this female. What was impressive, was that by the time we carried the bucket (water swaying and everything, mind you!), put it on the car, drove back to the B&B and unloaded the buckets, the little guy was there still hanging on! We had to pull him apart unfortunately, but it was pretty amazing to see.

Well that's it - we removed some 120+ (no idea what the exact numbers are....) xenopus from there, I thoroughly enjoyed it, and it was really great to meet some other people to learn more about this species. Although not pictured (I forgot to take a pic!), Angela, our host at the B&B was the loveliest person ever, it felt almost, but only a little, uncomfortable settling into such a cosy surrounding and being treated like friends in a way. The rest of the crew have known her longer than I did so I rarely felt out of place... only in my experience (or lack of) did it show. Jim, the Natural England man, who came to meet us and learn more about the situation gave the group the go-ahead for funds to carry on with this work in removing xenopus from this area. He was an interesting guy to talk to, and was very knowledgeable about reptiles and amphibians (much like Albert :P ) With that, hopefully I get to go again at some point in the future, and see and learn more! What a change it was, from anything else I've done before.

1 comment:

James said...

Hi, just found this post whilst searching for information about introduced reptiles & amphibians. I was wondering if you managed, or think you managed, to remove the entire colony?

I was also wondering where exactly the site was, as I am trying to see all the native & introduced reptiles and amphibians this year, and African Clawed Frog is probably going to be one of the, if not the most, difficult to see.

Completely understand if you don't want to publicise the information online, so feel free to contact me at