Mediterranean tree frogs
Each month I like to keep my articles topical to the time of year. However, unless you have been in hibernation, you may have noticed that it hasn’t been favourable weather for wildlife photography recently. One night in a break from the rain, I was outside pondering over this month’s article when I heard what sounded like the local frogs holding a rain party.
The arrival of the wet weather has started the frog and toad breeding season. Here in the northern hills of the Algarve we have many varieties of frogs and toads calling during the spring evenings. From the noisy Iberian water frog, easily identified by a yellow stripe down the middle of its back, to the Midwife toad, bringing the hills alive with their strange electronic-type beeping.
Above all, nothing is more special than the noise of the Mediterranean tree frog. Their call carries long distances, even more so from inside a disused irrigation water tank on old farmland, which acts as a natural amplifier. The tank is the perfect breeding ground as it has shallow still water, plentiful bugs and grasses that grow through the cracks in the floor for camouflage.
Each night at dusk the tree frogs emerge from their daytime hiding spot, climb the concrete walls with their sticky feet and dive 1.5 metres into the water. Whilst taking position in the long grass, they inflate their golden coloured vocal sacks in the throat and make a piercing call. This call is to attract a female to lay her eggs so the male can fertilise them. The female will lay up to 1,000 eggs in small clumps. After fertilization, the tadpoles, which are only 5-8mm in length, hatch after approximately 10 days. Metamorphosis starts to occur around three months later.
As their name suggests, these frogs live amongst the trees, bushes and long grass. They can survive through the long dry summers and reside throughout both European and African Mediterranean regions but also here in the Iberian Peninsula. Their lifespan is around 15 years.
The frog grows to around 6.5cm long with the females being slightly larger than the males and, due to lack of a vocal sack, the females have a white throat. They are very similar to the smaller European tree frog, which is also found but less common in the Algarve. Not only is the call different, but the main giveaway is that the dark flank stripe only runs to the front legs on the Mediterranean tree frog whereas it continues down the side of the European tree frog, hence why it is sometimes known as the Stripeless tree frog. There has been evidence of cross breeding between the two species, however, the offspring appear to be sterile. As you would imagine, they are great climbers and have special adhesive discs on their feet that stick to many surfaces.
If you want to hear the chorus of these small green creatures, look for an area that has shallow, still fresh water during springtime and just after sunset you may hear them. I have recently published a male calling which can be viewed on my website along with more photographs.
By Craig Rogers
Craig Rogers is a wildlife and nature photographer from Wales, now living in the Algarve and offering photography workshops. More information, photographs and blog can be found on his website at www.craigrogers.photography
Photos: Craig Rogers