The group was formed in September 2016, although the bonds of friendship stem back over 15 years, the IRA (Intervenção e Resgate Animal, in Portuguese) says.
Many of the animals they have rescued, dogs, cats and horses, were taken illegally after initial attempts for the owners to concede voluntarily proved futile.
The covert group, which wears masks and never gives their names, to remain anonymous, is aware that in cases it is breaking the law, according to an in-depth interview by newspaper Observador, but says it is a means to an end in instances where even the authorities struggle to intervene.
Last week they made headlines again after rescuing a mistreated dog that had been left exposed to the tempestuous elements in a Lisbon neighbourhood.
Its owners, two teenagers whose parents had recently been arrested, initially refused to let the group take the animal for rehabilitation and re-homing despite it being visibly neglected, but it was eventually taken by them to be groomed and checked over by a vet.
The group said it would be keeping an eye on the animal and on the two teens, who live in impoverished conditions.
“We receive complaints, we evaluate them, we enquire if the situation has already been reported to the competent authorities, and only then, if it has, do we assemble, plan and implement a rescue”, the founder of the IRA group told newspaper Correio da Manhã last week.