People visiting National Trust sites have dropped "unprecedented" amounts of litter during lockdown.
The charity said at Murlough Nature Reserve in Co Down alone, rangers and volunteers were collecting 40 bin bags full of rubbish a day between the end of May and the start of this month.
Wildfires were also reported at several trust sites, including on Black Mountain in Belfast, at Bloody Bridge in the Mournes and in the sand dunes at Murlough.
The charity urged visitors not to light barbecues or campfires because, despite recent rain, the record-breaking dry and hot spring had caused perfect conditions for wildfires to spread, particularly in heath, gorse and grassland habitats.
The trust said fires put vulnerable wildlife at risk, including ground nesting birds such as sky lark and meadow pipit on Black Mountain or Skernaghan Point at Islandmagee.
In scrubby and woodland areas, song thrushes, dunnocks and robins are among the birds at risk.
The Irish hare and common lizard, found in the longer grassland areas during this period, particularly on Divis and the Black Mountain, are also under threat.
Various invertebrates and caterpillars’ eggs and larvae including the rare Marsh Fritillary butterfly larvae that can be found in the dunes at Murlough are also vulnerable.
The trust also hit out at rising levels of litter. It urged people to keep their rubbish until they return home and not drop litter.
Craig Somerville, lead ranger for the trust in Belfast, said scores of bags of rubbish have been collected and staff have also had to deal with frequent fly tipping.
"In terms of staff time, across our Belfast sites, we are spending around 40 hours a week just picking up rubbish when we should be doing vital conservation work," he said.
Patrick Lynch, area ranger for the Mournes and Murlough National Nature Reserve, said: "At the beginning of June we collected an average of 15 bin bags of rubbish a day at Bloody Bridge, so that’s over 100 bags of rubbish a week that have to be lugged 750m down the Bloody Bridge valley.
"During the same period (29 May – 3 June) we collected about 40 bin bags of rubbish a day at Murlough Nature Reserve.
"We had an average of three staff members litter picking all day across those six days totalling 135 staff hours.
"As a conservation charity spending this type of resource simply picking up litter is unsustainable."
He said volunteers were also helping the trust to pick up litter and thanked them for their efforts.
