The weather in Poland during the turn of March and April this year was unfavorable with frequent rains and strong winds, making it difficult to observe and record nature. However, after spending several nights near the habitats of the moor frog (Rana arvalis), I was fortunate enough to find good weather conditions and record an hour-long evolving soundscape of moor frogs mating at sunrise.

During this brief period, lasting only a few days, the male moor frogs turn a striking blue color due to the accumulation of lymph in their subcutaneous lymphatic sinuses. The moor frog’s mating call is also unmistakable – a series of gurgling and chuckling calls that sound like a bottle being opened underwater: “wuog…wuog…wuog”.

Despite the excitement of mating season, moor frogs are extremely alert and difficult to record. One careless movement or rustle can cause them to disappear quickly underwater. In such cases, it is best to remain calm and still in order to observe this fascinating species once again, as they will often return to their previously occupied positions.