When talking about langurs in episode 5 the narrator states that over the course of a month's shooting the monkeys become totally used to the (static) spy monkey.
But the whole premise of the series is that the animatronic models are so realistic that they blend in almost perfectly and thus provide previously unobtainable footage of the animals they are filming.
However, if they need a month to be accepted by the other animals then this is obviously not true and in fact (for the monkeys anyway) any inanimate object (rock, tree stump, etc.) could be used to hide a camera for the same effect. Thus there would be no need to design, build and film with such complicated and, presumably expensive, models.
But the whole premise of the series is that the animatronic models are so realistic that they blend in almost perfectly and thus provide previously unobtainable footage of the animals they are filming.
However, if they need a month to be accepted by the other animals then this is obviously not true and in fact (for the monkeys anyway) any inanimate object (rock, tree stump, etc.) could be used to hide a camera for the same effect. Thus there would be no need to design, build and film with such complicated and, presumably expensive, models.