Mousebirds are slender greyish or brown birds with soft, hairlike bodyfeathers. They are typically about 10 cm (3.9 in) in body length, with a long, thin tail a further 20–24 cm (7.9–9.4 in) in length, and weigh 45–55 g (1.6–1.9 oz).[5] They are arboreal and scurry through the leaves likerodents, in search of berries, fruit and buds. This habit, and their legs, gives rise to the group'sEnglish name. They are acrobatic, and can feed upside down. All species have strong claws and reversible outer toes (pamprodactyl feet). They also havecrests and stubby bills.
Mousebirds are gregarious, again reinforcing the analogy withmice, and are found in bands of about 20 in lightly wooded country. These birds build cup-shaped twig nests in trees, which are lined with grasses. Clutches of two to three eggs are typically laid.[6]
The mousebirds could be considered "living fossils" as the six species extant today are merely the survivors of a lineage that was massively more diverse in the earlyPaleogene andMiocene. There are comparatively abundant fossils of Coliiformes, but it has not been easy to assemble a robustphylogeny. The family is documented to exist from the EarlyPaleocene onwards; by at least the LateEocene, two families are known to have existed, the extantColiidae and the longer-billed prehistoricallyextinctSandcoleidae.[3]
The latter were previously a separate order,[7] but eventually it was realized that they had come to group ancestralCoraciiformes, the actual sandcoleids and forms likeNeanis together in aparaphyletic assemblage. Even though the sandcoleids are now assumed to be monophyletic following the removal of these taxa, many forms cannot be conclusively assigned to one family or the other.[8] The genusSelmes, for example, is probably a coliid, but only distantly related to the modern genera.[9]
Extinct Coliiformes occupied a wide range of ecologies.Sandcoleids in particular often preserve uncrushed seeds on their stomachs, while bearing talons similar to those of modernbirds of prey.[10]
^Cunningham-Van Someren, G.R. (1991). Forshaw, Joseph (ed.).Encyclopaedia of Animals: Birds. London: Merehurst Press. pp. 138–139.ISBN978-1-85391-186-6.
^Winkler, D. W., S. M. Billerman, and I.J. Lovette (2020). Mousebirds (Coliidae), version 1.0. In Birds of the World (S. M. Billerman, B. K. Keeney, P. G. Rodewald, and T. S. Schulenberg, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.https://doi.org/10.2173/bow.coliid1.01
^It has a peculiar footmorphology not found in any other bird, with very stubby toes. Thespecific nameabsurdipes ("absurd foot") refers to this. The genus name is ananagram of "Messel", where it was first found.
^Mayr, G. 2018. New data on the anatomy and palaeobiology of sandcoleid mousebirds (Aves, Coliiformes) from the early Eocene of Messel. Palaeobiodiversity and Palaeoenvironments 98: 639–651. doi: 10.1007/s12549-018-0328-1
