The reeds at the bottom of the valley at Sta Marija Estate in Mellieha were set on fire by a person who was seen pouring inflammable liquid and setting them alight.
Reader Mark Vella Bardon sent in the video above and said there was a similar fire in the same area on May 7.
Unlike today, the day had not been windy then and the flames subsided.
The damage today was 10-fold, he said.
The incident was condemned by Kaccaturi San Ubertu, which called on residents to be vigilant and report any cases of abuse.
The area, it said, supported a variety of flora and fauna and needed full protection.
It said it also received recent reports from residents who wanted to remain anonymous of poisoned collared doves.
This location, it said, had the largest local colony of these protected birds in Malta. These were apparently poisoned due to what some considered as their “monotonous call and endless excrement”.