Of the three species, the oriental magpie-robin is listed as “nationally vulnerable” on the Singapore Red Data Book, which means that it is locally threatened.

Mr Alan Owyong, former chairman of the Nature Society Singapore’s Bird Group, said: “This is a prized song bird in the pet bird trade and can be sold for hundreds of dollars if it sings well.”

The status of the other two bird species are listed as being of “least concern” in the Singapore Red Data Book, and are therefore not endangered.

However, according to Mr Ting Wai Kit, co-founder of the CITES Global Youth Network, poaching with glue poses a risk to all bird species, as it indiscriminately ensnares any bird which comes into contact with it. This includes endangered ones such as the straw-headed bulbul, which has its last stronghold in Singapore.

He also said that the three species implicated in these incidents are linked by a common thread.

“These birds play crucial roles in maintaining Singapore’s ecological balance by controlling insect populations, pollinating plants, and dispersing seeds.

“These species are susceptible to glue traps because their habitual perching, trusting nature and familiarity with human presence may reduce their wariness of altered environments and make them easy victims of this poaching method.”

Akin to poaching with traditional glue traps – where adhesives are applied onto a board or tray – this method of poaching leads to high mortality in trapped birds.

Mr Movin Nyanasengeran, vice-president of the Bird Society of Singapore, said: “Rescuing glue-trapped birds often requires the extensive removal of feathers that could impede the birds ability to thermoregulate or fend for itself in the wild.”

“It causes immense suffering and often leads to death from stress, injury, predation, starvation, dehydration or suffocation,” said Mr Ting.