Spring is sprung ... and the frogs are hopping to it

EVERY year in Ireland we get a phoney spring, says Dick Warner

Tradition declares that spring starts on February 1, a more scientific approach by Met Éireann sets the starting date as March 1, but there’s not much happening in the countryside in early March.

There are exceptions. In milder places frogs come out of hibernation in February and even in the cold Midlands they’re usually active by early March. Although they’re cold-blooded animals they have metabolic adaptations to prevent them freezing solid at sub-zero temperatures. The substance involved is chemically very similar to the anti-freeze we put in our cars.

Most frogs hibernate on land, although they are capable of doing so under water because, as amphibians, they have two ways of breathing — with lungs when they’re on land and through their skins, using dissolved oxygen, when they’re in the water. This is very handy but one disadvantage of the amphibian lifestyle is that they can only breed in water. Breeding is the over-riding priority for a frog when it emerges from hibernation so they all start heading for water.

Normally they head for the pond or ditch they hatched in. However, there appear to be exceptions to this because a newly created pond will rapidly attract mating frogs. According to a long-running survey carried out by the Irish Peatland Conservation Council garden ponds nowadays make up about 50% of frog breeding waters which means they are extremely valuable for frog conservation.

They will travel several kilometres to get to their breeding site. The males normally arrive before the females and both sexes prefer travelling on warm damp nights. Sometimes the route crosses a road and large numbers of frogs get run over. At this time of year if you’re driving at night please keep an eye out for them.

When the males arrive at the water they get quite noisy. The common frog doesn’t have the voice power of a natterjack toad but it can produce quite a loud croak and they’re vocal year round, day and night. I didn’t realise this until I started listening carefully around my own garden pond and learned to recognise the quiet croaks they make outside the breeding season.

Eventually a male finds a female to mate with and the spawn is produced and fertilised in the water. It will hatch into infant tadpoles in 10 to 20 days, depending on water temperature. The females normally leave the water to forage on land immediately after spawning but the males often hang around hoping for another female to mate with. There is a very high infant mortality rate among tadpoles due to ponds freezing over or drying out and to predation by fish and other animals and birds.



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