European tree frog

Profile

European tree frogs are small frogs living, of course, in Europe, but also in western Asia. Most frogs are hard to distinguish from other species, but this frog is actually quite easy to recognize. The overall green color of this frog doesn’t do much to make it unique, but its brown stripe does. These frogs have stripes running from their nostrils down the sides of their body. As you can see in the picture, their eyes are right in the middle of this path.

The normal color for the frog’s back is green, but this can range from pale green to a very dark green. Earlier in the year, when the weather is cooler, they will normally be a darker color to help them absorb the heat from the sun better. They may have a few other brown or yellow markings on their back, head, and legs. The underside of this frog ranges from off-white to brownish-yellow.

One more thing to notice about this frog is its horizontal pupils. Unlike most animals, different frogs have different pupil shapes. Some have slits, while most have ovals. These can be either horizontal or vertical. They can also have circular pupils, but the European tree frog has horizontal ovular pupils.

Another weird fact about this frog is that it was named “Frog of the Year 2008” by the German Society for Herpetology and Terrarium Science.

Size

These tree frogs are not very large, even smaller than what is probably the most famous tree frog: the red-eyed tree frog. The adults range from 1.25 to 2 inches (3-5 cm) in length with the females being slightly larger than the males. I couldn’t find their weight anywhere, but it can’t be a lot with that small of a frog.

Diet and hunting

Given that this animal is a frog, you can probably guess its favorite food. If not, it’s insects. But evidently European tree frogs prefer a bit more of a challenge than most frogs as it frequently eats flying insects.

For me, it’s hard enough to swat a fly in mid air, much less catch one in my mouth. Not that I’ve ever tried to do that. European tree frogs, however, are skilled at this challenging way of hunting. They use their powerful legs to propel themselves through the air at the insect, either while it’s on the ground or even in mid-air! Other prey includes snails and spiders.

Habitat and range

European tree frogs live mostly in Europe, as you can see in the map below, but they also inhabit a little bit of western Asia. At one point this species had been introduced to the United Kingdom, but they are now thought to be extinct there. This isn’t a big deal since this is not their native range.

These frogs prefer to live in wooded areas – after all, they are tree frogs – that are near water. This is just a preference, and European tree frogs don’t seem to be too picky about this. They have been seen in gardens, meadows, parks, large cities, and even dry areas! One place these frogs do avoid is dark, dense forests.

Status, threats, and conservation

The European tree frog is classified as ‘Least Concern’ on the IUCN Redlist, but their population level is decreasing. In some places, this frog is collected for the pet trade. Other places habitat loss and pollution of their breeding pools take a toll on the population.

Most likely there are some natural predators for this frog, such as birds, raccoons, cats, snakes, etc., but my sources didn’t mention these.

In Sweden, a conservation program increased the population from 2,000 to 50,000 over the course of 28 years.

Reproduction and young

These frogs hibernate from September to early May, but it may be as short as December to February depending on the temperatures. Mating season is usually April and May, but it may extend from March through July. During this time, the frogs will gather around small bodies of water, usually ponds.

The males will call to the females in a sound that resembles a high-pitched duck quack. Choirs of these males can be heard over half a mile (1 km) away! When a female finds a suitable male, she will lay her eggs in the water in clumps of about 100 as the male fertilizes them. She may lay anywhere from 200 to 2,000 eggs!

About a week later, the eggs hatch, and the tadpoles are easy prey for fish and water insects. Over the next 40 to 60 days, they will metamorphose into the adults. The speed of their change depends on the temperature of the water, with warmer water bringing faster results.

After this time, the juvenile European tree frogs will spend a few days or weeks around the water before venturing up into the trees. They are thought to be able to live up to 15 years in the wild.

 

Sources:

Photo credits:

  • European tree frog – Marek Szczepanek
  • European tree frog range – Public Domain
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