The Belgian Naturism Federation has come to the defence of its burgeoning membership after the Flemish wildlife agency blocked an application for a second nudist beach in the country on the grounds that bathers’ “subsidiary activities” would pose a threat to a rare bird.

Attempts to gain designated naturist status for a quiet spot near Westende, about 12 miles south of the popular seaside resort of Ostende, hit a snag after objections were raised that sexual activity in the dunes would scare off the locally treasured crested lark, or Galerida cristata.

The Flemish Agency for Nature and Woodland informed the region’s environment minister, Joke Schauvliege, that the lark, whose name derives from the feathers on its head that rise up during courtship, would be alarmed by the activity and would flee.

The dunes themselves were also likely to be damaged by such “subsidiary activities”, the agency said in its formal submission.

A subsequent suggestion that a fence could be established around the dunes where the birds breed was met with scepticism. Steve Vandenberghe, the local mayor in Bredene, where Belgium’s first and only nudist beach is located, told the Flemish daily newspaper Het Nieuwsblad that it would not offer much of a deterrence. “Barbed wire against nudists? Pff. As if a man without clothes cannot get over a barbed wire,” he said.

Koen Meulemans, the chair of the Belgian Naturism Federation, said members frowned on the behaviour of some people who called themselves naturists. “We too regret this behaviour, which has nothing to do with naturism,” he said. “These are not real naturists for us.”

Meulemans said the beach at Westende was perfect “as there is no building or sea dyke that looks out on to the beach”. The federation’s 8,200 paying members – up 600 on two years ago – needed a new beach because during the summer months “1,000 people face each other on a strip of 400 metres in Bredene,” he said.

“After a long period of declining figures, we are now clearly growing. But those 8,200 are only a fraction of the total number of naturists in our country. Not everyone joins one of our 17 clubs and departments. According to surveys, about half a million Belgians sometimes do nudist recreation: they go to nudist beaches, spend their holidays at a naturist campsite or regularly go to public saunas.”

He added of the growth in numbers: “The new members mainly come from the age group 30 to 40. Where the work pressure is often the greatest. Naturism is literally unbuttoning. Those who leave their clothes leave the mobile phone and the work behind them. And it fits perfectly with the great call to go back to nature.”

Reflecting such growth, the first Belgian naturist B&B has opened in Nieuwpoort. “We have room for two families,” said its proprietor, Ann Engelen. “Every room has its own dining room, so you are not sitting naked at the breakfast table with other families. But in the garden with swimming pool, sauna and jacuzzi, that is the intention.

“Some of our customers are people who take the first step towards naturism here. Often they are busy people who come to recharge their batteries for two days without clothes, an ideal tool against burnouts. They literally throw off their armour without being seen.”