Natural Resources Wales is appealing for help after a spate of fires at a protected site near Flint.
Several fires at Halkyn Mountain have been tackled during April.
The fires are believed to have been set deliberately on common land between the villages of Pentre Halkyn and Brynford.
Wildlife is an important part of our environment, our heritage and our culture in Wales and anyone caught starting a fire on an SSSI without consent could be fined up to £20,000.
Anthony Randles, Natural Resources Wales, (NRW) Natural Resource Management Team Leader Wrexham and Flintshire said:
“Halkyn Mountain is one of many sites we look after across Wales, where people can enjoy the beauty of our natural environment right on their doorstep.
“And the area provides a home to a rich, diverse and valuable range of wildlife.
“Fires are particularly damaging in spring because they harm nesting birds and other wildlife that thrive there this time of the year, such as butterflies, newts and snakes.”
“Uncontrolled wild fires can cause temporary loss of habitat and wildlife, while repeated burning can also damage the land for agriculture as well as conservation.”
Kevin Jones, Business Education and Arson Reduction Team Manager at North Wales Fire and Rescue Service, said:
“It is extremely disheartening to find that such incidents have been ignited deliberately.
“Deliberate fires place tremendous pressure on resources, with our crews tied up for a considerable length of time trying to bring them under control - which in turn delays firefighters from attending life threatening incidents.
“The potential for serious damage to our environment, often in sensitive areas, by the impact of countryside fires is a serious concern.”
Halkyn Mountain is home to rare grasslands and heathlands where species such as the great crested newt and other amphibians, are protected by European law.
It has been designated as a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation (SAC), which NRW is responsible for protecting in Wales.
Anyone with information on such crimes is advised to anonymously call Crimestoppers on 0800 555111 or contact 101.