Gargoyles can be divided into several groups, according to their shape: there are animal gargoyles, human shaped gargoyles, and hybrid gargoyles. For most gargoyles are grotesque, a further division into grotesque gargoyles and non-grotesque ones does not seem useful.

Animal gargoyles were depicted in varying degrees of fidelity to nature. Entire animals were likely to be posed as if holding by its claws onto the building They seem to stretch as if trying to throw their water as far as possible from the building. Motives were not only animals the stone mason knew by sight, but also exotic animals like for example lions and monkeys, and fantastic animals like the dragon. Their knowledge about those animals they received from the so called 'Bestiaries' like the 'Physiologus', or from travelling menageries.
Bestiaries were illustrated books of animal lore, which described the habits of animals, both fantastical and real, and gave them a moral meaning, equalizing their features and behaviour with a Christian way of live. The basis for those collections were laid (as in the case of the Physiologus) in the second and third centuries, in the twelfth and thirteenth century they had reached the highest state of popularity. The popularity of the Bestiaries coincided chronologically and geographically with that of the gargoyles. The symbolism given to animals in those Bestiaries were also attached to the gargoyle animals. So certain animals were used more frequently than others for having special positive or negative meanings. Dogs and lions were most frequently used.

Dogs were always known for the loyalty to their master, further they were usually watchdogs. In the Bestiaries they were described as being wise, and had high ability to reason. So they symbolized the priest who cares for his congregation and drives away the devil. But they were not only vehicles for positive meanings: they could also be intended - as well as the wolf - to frighten.
Lions and leonine beasts - "Kings of Beasts" and the most often depicted animals in medieval art - were in ancient times used as a symbol for Sumerian, Assyrian and Persian kings, later this tradition was continued in representing Christ, the king of the tribe of Judah. The lion was said to erase its tracks with its tail, which was either equated to Christ's ability to elude the devil or to the image of the Saviour living unrecognized on earth. Further the lioness gave birth to dead cubs, which were resurrected three days later by their father. When a lion was ill, the only certain cure for him was to kill and eat a monkey, which was a symbol of the evil forces. This was taken as a further symbol for the overcome of the evil by the good. It was also said never to close his eyes even if asleep, being an emblem of vigilance. So it was placed on tombs and beside the entryways to churches. Besides lion heads were used as door knockers. . But Vaux states that, if shown supporting the pillars of a door, the lion used to be evil, as well as if it was a holding a lamb or was a bicorporate lion of pagan or at least pre-Christian origin. In any case, the lion was predominantly associated with vigilant, valiant, regal, and powerful behaviour. This changed in the later Middle Ages, when the seven deadly sins were associated with animals - the lion became the symbol of pride.
Other animals with a symbolic meaning were the ram, equated to the priests leading their flock, further the fox �?an animal of deceit, cunning, craftiness, which sometimes also symbolized death. The goat was said to be omniscient, but male goats were also said to be chronically lustful. Monkeys were generally evil, or a symbol for the fall of mankind. Birds, with their aerial habitat a natural choice for gargoyles, have a unclear meaning, if there is one.
As it can be seen with the examples, animals (and other symbolic objects) had a complex meaning, which, in addition, changed over the centuries. For the explanation of their meaning it would be useful to date the gargoyles, but as shown above, this is difficult, if not impossible.

Human gargoyles are often bizarre and laughable. Their imperfect physical characteristics are probably connected with the medieval belief of physical ugliness and illness being caused by demons or evil. The public expression of feelings, as seen with many gargoyles, carried similar connotations. Benton suggests that their expressions may not have been intended to frighten, but that they are frightened by what they observe. Mouth pullers may refer to the sin of gluttony. They may also depict English traditions: competitions in face-pulling were common in northern England up to recent times. A protruding tongue may refer to Satan, who was often depicted sticking out his tongue. But it could as well refer to traitors, heretics, and blasphemers. It is also possible �?for it is a symbol of refusal �?that it should keep evil away.  If the water issues from an object (either a thing or an animal) held by the human shape, it could be related to Christian iconography, as for example Jonah and the whale, or Samson.  One of the most often depicted motives for human shape gargoyles is the Green Man.

In medieval times there was a high acceptance of seemingly impossible animals. So it is not surprising to find a lot of fantasy creatures on churches and cathedrals, most of them composed of different known beings reassembling their symbolic meanings. Many hybrid (composite) gargoyles belong to unknown species. They combine either parts of different animals or animals and humans.

Gargoyles combining several animals are also called chimeras. In Greek mythology a chimera is an imaginary creature that breathes fire, has a lion's head, a goat's body and a snakes tail (DCE), but the term is often used to name animal-animal mixtures. When being depicted in medieval times, they are generally viewed as sexual warnings, and warnings about the deception in physical appearances that comes with underestimating the devil. (Online Source 8) The origin of the meaning of these creatures can only be explained in some cases. Some may be the result of confusions with actual, but exotic animals, as for example the unicorn can be traced back to be a rhinoceros, as it is said in the Bestiaries, that in ancient Greece it was called so.

 Isidor of Sevilla (c. 570 - 636) writes in his "Ethymologiae", a summary of the ancient knowledge, that criminals, because their offences made them slaves to the demonic powers anyway, had to eat magic plants, which transformed them into the most different animals and hybrids. That could have been the basis for the medieval connotations to chimeras. Another explanation for human shaped hybrids (characterized by excessive hairiness or animal extremities) could be the medieval belief in "wildmen", wild people living in the woods. They were regarded as a degeneration of humans who had allowed the beast within to appear, or to be sinners in the sense of Isidor of Sevilla. As animals were considered to be lower forms of life, and those wildmen being very close to them, depictions of them could have been a warning to potential sinners. Chimeras could also be a symbol for physical and spiritual disorder, because the law of nature and therefore of God was mixed up. Sometimes "known" monstrous races were depicted, i. e. monsters of Ancient mythology, but it is not certain whether they were known to the medieval carvers as well, their similarity could also be pure chance.

Although the first gargoyles were made out of wood, the materials used for the later gargoyles were predominantly limestone and marble, but a few examples of metal gargoyles have survived. Lead gargoyles were more common after the fifteenth century. Brick was not used for gargoyles: Even brick buildings have stone gargoyles. No examples of terracotta gargoyles, sometimes used in medieval times, survive. In all probability they did not withstand the weather conditions and the rain for longer than a few decades.

Gargoyles were seldom carved when they were already in position. They usually were carved down on the ground, but �?maybe to avoid delay if the gargoyle had to be inserted at a specific point of construction, or it could be damaged while brought in position �?some had to be carved in place. The gargoyles were carved after a model of clay or plaster, much in the same way as it is done today. As well as grotesques inside and outside the church, they were richly painted and gilded. It seems that nearly as much money was spent on the gilding and painting as on its carving. In Victorian times, the last traces of the paint and the gilding were removed, when churches and cathedrals were restored in the sense of the Victorian Age.  So it is not sure today, which colours were used, but it seems likely that they were similar to those of other medieval art objects.

Credits:

Benton, Janetta Rebold (1997). Holy Terrors: Gargoyles on Medieval Buildings. New York: Abbeville Press.
Bindman, David (ed.) (1985). The Thames and Hudson Encyclopaedia of British Art. London: T & H.
Clifton-Taylor, Alec (1967). The Cathedrals of England. London: T & H.
Fitzgerald, Roger (1995). Buildings of Britain. London: Bloombury.
James, Simon (1998). Das Zeitalter der Kelten. Augsburg: Bechtermünz.
Mehling, Franz N. (1998). Knaurs Kulturführer in Farbe: Großbritannien und Irland. München: Knaur.
Piltz, Georg (1985). Streifzug durch die deutsche Baukunst. Berlin (DDR): Kinderbuchverlag.
Stone, Lawrence (1955). Sculpture in Britain. Middlesex: Penguin.
Toman, Rolf (1996). Die Kunst der Romanik: Architektur - Skulptur - Malerei. Köln.
Vaux, J. H. (1989). The Canterbury Monsters. Gillingham: Meresborough.