|common frogs mating:erikpaterson|
It takes about three years for our common frogs to become sexually mature. You can generally tell the commonn male frogs from female frogs by size and the females in our pond are huge compared with their paramours, but apparently in some species, males and females are hard to tell apart and the male frogs make a special release call when another male makes a mistake.
Mostly eggs are fertilised outside the female's body.The female releases her eggs and the male releases his sperm at the same time. To make sure that the sperm reach the eggs, the male climbs onto the female's back and clasps his forelegs around her middle - plenty of that going on in the pond today!. Frogs can stay like this for hours or even days depending on how many eggs the female releases - sometimes as few as one but our common frogs can lay anything between 1000 to 4000 eggs at a time.
All frogs' eggs need moisture to develop, and most frogs abandon their eggs once they're fertilized. We're used to seeing the gloopy masses of the common frogspawn floating in ponds, but a few species carry their eggs in their vocal sacs or their abdomens. Others lay eggs in dry areas and keep the eggs moist with water or urine.
Depending on the weather the tadpoles will hatch out in anything from a week to 40 days and will feed on their spawn jelly for the first few days. After that they begin to eat algae. Spawn and tadpoles have many predators - fish, birds and grass snakes. On average, only 5 out of every 2000 eggs will survive to become adult frogs and I'm sure that heron knows where they are.... I'll be keeping my eyes open in April for tadpoles and also for toad spawn. We saw toads and newts last year - proof that the urban farm pond provides an important habitat for local amphibians!
Last week I went on a compost making course at Hackney City Farm. I went expecting to learn how to make compost - but I should have read the details a bit more carefully. Sheffield's Heeley Farm have won lotttery funding promoting compost making. Their plan is to train up 15 or so hubs of accredited compost trainers around England. If Sarah's application is successful we'll be able to run compost making courses at the farm. Any potential rotters out there?
If you're interested in joining us at the farm. Come along any Tuesday after 10.00 for a chat or email email@example.com
If you've got any thoughts on this or anything else to do with the urban farm just leave a comment in the box.