Not only has our pond a mass of frog spawn, but we have had adult frogs too. Not surprising as you can’t get the former without the latter. But we don’t usually see the adults, and we have witnessed them mating too. That’s a lengthy process, with the male on top of the female for as long as 24 hours. She at last lays her mass of eggs and he scatters his sperm over them.
The frogs are the common frog, Rana temporaria. I have seen them about the garden in previous years, hidden away in heaps of leaves, but not seen adult frogs in the pond before. There have been at least six here this year, though at the time of writing they have left.
How many adults return to the pond in any year is down to chance. If we have 1000 tadpoles emerging from the spawn, roughly 50 or less, over three months, will become frogs. The rest will die, culled by predators (dragonfly larvae, newts or birds) or disease. A few will not complete the metamorphosis to frogs. A vital gene doesn’t kick in, holding them as permanent juveniles.
The few that leave the pond have a chancy time of it, what with birds, cats and strimmers, along with drought and disease. They have a better chance of returning to the pond if they don’t go far. Those that leave the garden are unlikely to get back or find another pond, what with pavements, fences, roads to cross as well as predators and mowers.
Between the pond and the back stage, there’s a large heap, made up of leaves, twigs and rotting wood, a perfect shelter for frogs. They need it as it takes them two to three years to mature. When they leave the pond, they are tiny, their body less than a centimetre in length. When they return, their bodies are the size of a billiard ball.
With so many hazards, just a few make it back to breed. In some years, none at all. This year though is a bumper year with six or more returning. The pond will be awash with tadpoles in a few weeks.
Frogs are amphibians, which means they are vertebrates that live on land but lay eggs in water. They have lungs and must come to the surface to breathe. We have another amphibian in the pond, the common newt. And more of them this year too. They don’t have spawn but lay single eggs, so you are unlikely to spot any. The adults are quite a bit smaller than frogs, much less visible, so it’s difficult to estimate how many we have. They too leave the pond as small newts. Mature newts return but leave after mating.
Last Sunday, we had a mass planting in the beds at Earlham bridge. The plants had come to the garden a few days earlier. On Sunday morning, we wheelbarrowed them along Earlham Grove to the bridge site. We planted sage, rosemary, periwinkle, lavender, thyme and quite a few others. It is an unsupervised site, so we hope that most of our plants will survive without being trampled on or stolen.