The end of my toading; for this year, anyway!
17th March 2012: Toads were still lingering in North Pond again this morning, although their numbers had thinned a little; quite a few of them are on the bottom … dead!
Grass snakes and hedgehogs seem to be immune to the effects of bufagin, and are the only animals prepared to eat toads. I expect to see a heron or two as I approach the pond in the early mornings, but I haven’t seen a single heron in North Pond since the toads arrived.
The reason so many toads descend on North Pond to mate every year, is that females return to the place they were born. Obviously, both sexes have to be present at the right time and be able to find each other, if mating is to be successfully. To this end, toads have developed complex behavioural patterns that make sure breeding goes to plan. Odours, pheromones, light, temperature and moisture all play a part in initiating the toad mating instinct. Their hearing becomes very sensitive to different pitches, which is important as atmospheric pressures affect the vibrations and volume of the already relatively quiet common male toad’s mating call. The toad’s tactile senses increase in sensitivity on the toes, underside of males, and the back of the females.
If a male toad grasps another male, or a female who has already mated or is not yet ready to mate, then a defensive posture will be adopted. On the other hand, if the two toads are compatible, the result will be the mating embrace or amplexus, during which the male will ward off others by kicking with its hind legs – at least that’s the theory. It doesn’t always work, because single females are sometimes encased in frenzied males intent on passing-on their genes. Fertilization is external, with the male fertilizing the eggs as they are laid. The male releases a single spermatophore about 5mm in length that is picked up by the female through her cloaca. Once fertilised the females lay their spawn in water. The many ova are attached to rocks or vegetation and laid in double gelatinous strings up to 4.6m (15 ft) in length. The tadpoles hatch after 10-21 days and are smaller and darker than those of frogs. The toadlets leave the water during the warm humid conditions of summer, completing their transformation into terrestrial toads in the autumn.
Toads are naturally shy, mostly nocturnal animals that live on land, hiding during the day in dark, damp places and becoming active at night in their search for insects, grubs, slugs, worms, and other invertebrates. Adults are completely carnivorous and respond only to moving prey. I think many of the marsh toads retreat from North Pond to the withy wood and the swamp after mating. I’ve seen toads in the withy wood at night-time, but they are extremely difficult to see amongst dead and decaying leaf mould.
This post ends my infatuation with toads; at least for this year.