Bats

In the Nightshade Chronicles series book two, The White Assassin, the rats of the Catacombs allied with an ancient colony of bats in order to thwart Billycan's plans of overrunning Nightshade City with an army of savage swamp rats. The rats of Nightshade City were able to fly with the bats by holding onto their legs. The bats in the Nightshade Chronicles were microbats.

About Bats
''The microbats constitute the suborder Microchiroptera within the order Chiroptera (bats). They are most often referred to by their scientific name. Other English names are "insectivorous bats", "echolocating bats", "small bats", or "true bats". All these names are somewhat inaccurate, because not all microbats feed on insects, and some of them are larger than small megabats.''

The distinctions between microbats and megabats are:

'' Most microbats feed on insects. Some of the larger species hunt birds, lizards, frogs, smaller bats or even fish. The three species of microbats that feed on the blood of large mammals or birds (vampire bats) exist in the Americas south of the United States. Microbats are 4 to 16 cm long. Leaf-nosed microbat species are not all known to be fruit and nectar-eating. Three species of leaf-nosed bats follow the bloom of columnar cacti in northwest Mexico and Southwest United States northward in the spring and then the blooming agaves southward in the fall. Yet other leaf-nosed bats, such as Vampyrum spectrum  of South America, hunt a variety of prey such as lizards and birds. The horseshoe bats of Europe, though, have an incredibly intricate leaf-nose for echolocation and feed primarily on insects. Finally, the California leaf-nosed bat of North America is yet another insectivore to have this trait, as its name indicates.The term "leaf-nose," despite common fallacy, applies to a great variety of microbats and does in no way dictate the variety of diet a species with this trait prefers. ''
 * Microbats use echolocation, whereas megabats do not typically. (The Egyptian fruitWhite-assassininterior.jpg bat Rousettusegyptiacus is an exception, but does not use the larynx echolocation method of microbats, instead giving scientists the theory that it clicks using its nasal passages and back of its tongue.)
 * Microbats lack the claw at the second finger of the forelimb. This finger appears thinner and almost bonded by tissue with the third finger for extraWhite-assassininterior-3.jpg support during flight.
 * Megabats always lack a tail, whereas this trait only occurs in certain species of microbats.
 * The ears of microbats possess a tragus (thought to be crucial in echolocation) and are respectively larger than megabat ears, whereas megabat ears areWhite-assassininterior-2.jpg comparatively small and lack a tragus.
 * Megabat eyes are quite large, whereas microbat eyes are comparatively smaller.