I have had several inquiries from people who have encountered snakes in the Algarve. The cat or dog has brought one into the house, or one has been discovered in a shed or the garden and they are worried as to the danger. Generally, although there are some venomous snakes here in the Algarve, they are not dangerous to humans, because either their poison fangs are at the back of the mouth or they cannot open their mouths wide enough for them to be effective against anything much larger than a lizard, frog or mouse. The venom is also not considered particularly virulent and one would have to be extremely stupid in trying to handle the snake to get bitten at all.
Most snakes run for cover at the sound or vibration of something large approaching.
Snakes are quite variable in colouring, and some young ones, as these may have been, are more strongly patterned. According to my book there are 8 species of snake in the Algarve. Grows to nearly 2m. Heavy brow ridges. Juveniles may have irregular light markings, but can have more regular pattern around head.