Where have all the frogs gone?

[Andy-H]

We have a reasonably sized semi-natural pond. It’s fed by a small spring stream and we excavated it to make it larger some 25+ years ago.

Every year, around mid-February, it is alive with frogs mating and one end of it fills with frogspawn. We can hear the croaking through teh night from our bedroom 🙂

This year, not a single frog has made it to the pond (yet) – is anyone else noticing the same? are frogs late this year?

[Paul-R]

don’t see too many around here normallybut I did see one a couple of weeks ago in our field border

[Andy-H]

They finally turned up and produced vast amounts of spawn.

I am wondering if they delayed spawning because of the heavy rain causing flood conditions. I haven’t heard it mentioned before, but it could be a strategy to prevent spawn being washed away to less suitable areas.

[Tammy-S]

Glad they came back, Andy. Think you might find this interesting, copied from a post I put on the MWT Facebook last year:

Used to have frogs in your pond, but now they have gone? Perhaps they’ve been replaced by newts? There is a good reason for this and it’s nothing you’ve done wrong; rather it is all down to the breeding ecology of the frog. With thanks to Peter Hill, Connecting the Dragons Project Officer at Amphibian & Reptile Conservation, here is the explanation:

“A topic that I notice is often brought up here among the members is that of frogs being present in garden ponds during the first few years of the pond’s creation, but newts displacing frogs over time. This is a typical scenario, and one that I have significant experience of over the years in different situations, so I thought people may find an explanation useful. To start with, the common frog has a very different ecology to that of newts. Overall, frogs prefer to spawn in shallow, temporary water bodies. Often, ditches, and flooded grasslands, flooded pasture and even flooded golf courses are utilised. So why do frogs spawn in a ditch or puddle that may potentially dry out rather than an established pond? Well, shallow water bodies are ideal as the shallow water warms quickly, boosting the growth of algae and the tadpoles themselves. By the time the tadpoles are hatching, in a shallow sun-lit pool or ditch, the spawn will have a coating of algae present on which to graze. By the time the tadpoles have eaten the algae-covered spawn mat, they are the free swimming animals that we are all familiar with and can feed in the more widely understood manner. As well as being shallow, temporary water bodies that dry out at the end of the summer have significantly less predators present (aquatic inverts and their larvae, newts etc) so herein lies the answer. The highly mobile frog is usually the first amphibian to arrive at and utilise a new garden pond, as it will look and feel a lot like a temporary water body. Newts generally take a while longer to arrive, and slowly but surely increase in number. As garden ponds develop, they become more suited to newts (a dense under-water jungle loaded with potential newt prey of all forms) and as most garden ponds are comparatively small, the newt population can eventually reach an incredibly high density. As a child, I would regularly visit a model village that had numerous small ponds throughout its design, serving as model rivers, boating lakes and harbours. The population of smooth newts within the network of small water bodies at the model village was of epic proportions. One casual sweep of the net would result in 10-15 newts squirming in the net. Contrary to popular belief, frogs are not entirely faithful to natal ponds and can make the choice to abandon garden ponds at which newts have reached high density. They simply go elsewhere. If you find yourself in a situation of a pond full of newts and hardly any frogs, consider creating a shallow sun-lit extra “puddle” or two elsewhere. Manage the vegetation in a pretty severe manner at the end of each active season, removing most of the vegetation which can be destined for the compost heap. You could even drain it completely at the end of the summer, or let the water evaporate, and then let the rains fill it again in the spring. This will keep your frog “puddle” in a condition that is highly suited to frogs, and less so for newts, and the newts can continue to proliferate in the main vegetated and established pond. You will of course experience newts raiding the frog puddle if it becomes more newt-friendly, but ongoing management, a very different regime for the two very different water bodies, can keep the amphibian assemblage in your garden more diverse that way. I hope this helps, and good luck.”

[Helen Anderton]

Hi Tammy,
I found the article you’ve posted here about frog behaviour very interesting and useful. It does explain what happened in our last pond, where newts totally took over. On the subject of “frog-puddles”, would a large marginal shelf in a much larger pond work just as well or does it need to be a completely separate puddle for the frogs? As we are going to fit out a new pond this year it would be good to think about this and see if we can incorporate good structure somewhere right from the off. Many thanks.

[Author]

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