I recently took part in a field trip to the “Grube 7”, an old limestone quarry in Haan-Gruiten. This was a very interesting field trip, whose report I will post next week. However, as a little sneak peak, I want to present you one of the most interesting species, we had found during the field trip.
This isn't a plant but an amphibian: Buffo calamita LAURENTI from the Bufonidae family. In English, this species is known as “Natterjack toad”. In German, we call it “Kreuzkröte” (cross toad).
B. calamtia is a small toad, which can reach length between 5 and 7 (sometimes to 8) centimeters. In contrast to other Amphibians, female toads aren't much larger than male toads. The head is wider than long and rounded. The eyes of B. calamita has a black, horizontal pupil, while the iris has a lemon-green color.
B. calamita - habitus
Unusual for a toad, the hind legs of B. calamita are very short. Because of that, the species is not able to make long jumps like other toads. It runs rather over the floor like a mouse.
B. calamita - front view
The back-color of the Natterjack toad is a brown to olive-green pattern on a light background. The typical toad warts have a reddish to red-brown color. However, the unique and most significant feature of B. calamita is the yellow (or white) stripe, which runs from the forehead to the base of the tail. Unlike other toads or frogs, the skin on the back is very dry and not mucous. The belly has a white color with some darker spots. Some male toads also have a dark-violet spot on their throat.
B. calamita - back view; you can see the yellow stripe
on the back
The vocal sac on the throat has a large volume. As a result, B. calamita can blow it wide and has a very loud voice despite its small size. This voice sound like a dry “arr arr arr” and is heard in a radius of nearly 2 kilometers (!).
2) Modus vivendi & reproduction
The Natterjack toad is a pioneer and prefers warm, open places with only loose vegetation. Such places are e. g. natural riversides or lake sides, where the flood prevents a denser vegetation. In such areas, the toad live outside the water, where it hunts insects, worms or snails.
B. calamita - face; you can see the pupil and the iris
It only goes into the water for mating. The male toad goes into a suitable stretch of water (like a puddle or a pound), where it starts to shout with its vocal sacs in order to attract female toads. After mating, the female toads lay a long spawning into the water, which contains nearly 4000 eggs.
Main breeding season is between April and May.
Shallow ponds like this are the ideal habitat for B. calamita
After about 4 days, the tadpoles hatch. These tadpoles live in large swarms in the warmer regions of the water. They have a black color and only need about four weeks to grow into a young toads. This is important, because their birth places can dry out very fast. On the other side, there are not many predators (like fishes or other Amphibians) in puddles and so, nearly all of the tadpoles survive.
There were also some tadpoles in the pond (red circles)
3) Habitat and Distribution
B. calamita is native to Western-Europe, Middle-Europe and parts of Easter Europe. It can only be found north the alps and not in Southern Europe or the Balkans. As I said it before, the species is a pioneer and can be found on wastelands with loose vegetation. These are salt marshes, riversides or brownfield lands which are seasonal flooded.
However, such places become rare in Middle Europe and as a result, the Natterjack Toad is threatened by loosing its breeding places and habitats. However, there are some man-made habitats for B. calamita, which are perfect alternative habitats. These are e. g. ruderal wastelands, former quarries or even former training areas of tanks (these heavy vehicles compress the soil and create ideal puddles for the toad without high vegetation).
Today, the Natterjack toad is protected strictly by law. Its new, artificial habitats (like the “Grube 7” are obtained by conservationists.
Please note: These animal was shown to me by qualified conservationists. It wasn't in danger and released after the presentation.