Motmots (Momotidae)

(Momotidae)

Class: Aves

Order: Coraciiformes

Suborder: Alcedines

Family: Momotidae

Thumbnail description
Spectacular birds that range in size from starling to pigeon. Characterized by green and blue hues, a black mask, and a long racquettipped tail in most species

Size
6–19 in (16–47 cm); 0.9–6.2 oz (25–175 g)

Number of genera, species
6 genera; 9 species

Habitat
Predominantly tropical forest and woodland

Conservation status
Vulnerable: 1 species

Distribution
Northeastern Mexico to northern Argentina

Evolution and systematics

Motmots (Momotidae) are a striking group. An Oligocene (30–40 million years ago) fossil (Protornis) from Switzerland suggests that ancestors of contemporary motmots were from the Old World; climatic events and competition probably led to their absence. A fossil was found in Florida from the late Miocene (25–30 million years ago), before North and South America were joined by the Panamanian land bridge. More recent Pleistocene (20,000 years ago) fossils were found in South America, in several fossil quarries in Minas Gerais, Brazil. Climatic changes probably restricted motmots to Central America, and they later dispersed into South America (where little radiation occurred) about 2.5 million years ago during the late Pliocene. These events suggest that motmots are the only avian family with a center of origin and diversity in middle America.

Motmots are closely related to bee eaters (Meropidae), Kingfishers (Alcedinidae), and todies (Todidae), with closest kinship to todies. In fact, the tody motmot (Hylomanes momotula) is considered the most primitive family member, and perhaps links the motmot and tody families. Shared characteristics of motmots, bee eaters, kingfishers, and todies include a unique middle-ear ossicle, aspects of limb musculature, DNA, bright plumage, little or no dimorphism between sexes, predation by sallying (short flights from a perch to seize prey and return to the perch), and earth-excavated nest burrows. All four families are Coraciiformes, which likely radiated in the Eocene, and include rollers, hoopoes, and hornbills.

There are six genera with nine species. The turquoise-browed motmot (Eumomota superciliosa) represented by a single species, is more closely related to members of the genera Electron and Baryphthengus, each represented by two species, and the genus Momotus, represented by three species. These include the broad-billed motmot (Electron platyrhynchum), keel-billed motmot (E. carinatum), rufous motmot (Baryphthengus martii), rufous-capped motmot (B. ruficapillus), russet-crowned motmot (Momotus mexicanus), blue-crowned motmot (M. motmota), and highland motmot (M. aequatorialis). The rufous-capped motmot, though superficially similar to other species, lacks a racquet-tipped tail, as do some populations of broad-billed and rufous motmots. This suggests relatively recent divergence in these closely related genera. Supporting this hypothesis, while conducting playback experiments between motmots occurring together in Amazonian Peru, field ornithologist D. F. Lane discovered that rufous, blue-crowned, and broad-billed motmots seemed to respond territorially to each other's voices.

Physical characteristics

Motmots resemble kingfishers and have similar habits, although they are not found near water. They range from 6 to 20 in (16–50 cm), and 0.9–7.4 oz (25–210 g). The bill curves downward at the tip and in most species has serrated edges along the tomia (cutting edges of the bill). The tongue is relatively long. The tarsus is short and the middle toe is almost completely joined to the inner toe; there is only one rear toe. The wings are short and rounded. Plumage is soft blue or reddish brown; some species have blue or emerald stripes at the side of the head. A group of black feathers at chin and throat is characteristic of all motmots.

The tail is spatulate. The central pair of feathers is elongated, and barbs near the tail fall off readily, leaving part of the shaft of these feathers bare and resembling a thin wire. This barren area gives way to an oval disk at the feather tip where the barbs are retained, forming the spatulate-shaped racquet tip. The tody motmot is the smallest family member, characterized by more drab coloration and a shorter tail with no racquet tip. The blue-throated motmot (Aspatha gularis) also lacks a racquet-tipped tail.

These birds exhibit jerky tail twitching when disturbed. Male and female are similar in all species.

Distribution

Motmots are restricted to the neotropics, distributed from northeastern Mexico through most of tropical South America as far as northern Argentina. Although most species are lowland forms, there are two exceptions: the blue-throated motmot ranges 4,900–10,000 ft (1,500–3,100 m) in middle America, and the highland motmot ranges 4,100–7,200 ft (1,250–2,200 m) in the South American Andes.

The country harboring the highest diversity of motmots is Honduras, with seven species; Mexico, Guatemala, and Nicaragua each contain six species. In contrast, countries forming the Guiana shield (Venezuela, the Guianas, and Suriname) harbor a single species, the blue-crowned motmot.

About half the motmots are regionally restricted (four to middle America, one to the Andes). The species with widest distribution is perhaps the blue-crowned motmot, which ranges from Mexico through Argentina. The most range-restricted species is perhaps the blue-throated motmot, restricted to the central highlands of middle America.

Habitat

Most species are found in tropical or montane rainforest. Riverine gallery forest may be inhabited by blue-crowned, russet-crowned, and turquoise-browed motmots. Blue-crowned motmots will inhabit flooded forest, and blue-throated motmots will live in highland pine-oak forest. Several motmot species are found in secondary forests, often visually inconspicuous and widely distributed. Most motmots inhabit the midstory or understory of forest or woodland.

Behavior

Motmots appear solitary, but seem to maintain pair bonds during and between years.

Many motmots have a subtle or soft "hooting" call, but there are exceptions. The call of the tody motmot has a ring to it, and the call of the broad-billed motmot is a louder, resonant "honk".

Motmots are not very active and often go undetected. The tail often pendulates, sometimes jerkily. They are inactive at night, active during twilight at dawn and dusk. Calling is most active during early morning light.

Some short-distance migration patterns are probable. For example, turquoise-browed motmots are often absent from breeding grounds for most of February, but return in March. Such seasonal movements are likely associated with changes in habitat association, but the family is mostly nonmigratory.

Feeding ecology and diet

Motmots are omnivorous, taking invertebrates, small animals, and fruits. Invertebrates include beetles, butterflies (Morphos) and caterpillars, dragonflies, mantises, cicadas, spiders, centipedes, millipedes, scorpions, snails, earthworms, and crabs. Small animals include anole and gecko lizards, small snakes, frogs, small fish, an occasional nestling bird, and, in one recorded case, a blue-crowned motmot took a mouse. Fruits include those of palms, heliconia (Heliconia), nutmegs (Compsoneura, Virola), incense (Bursera), figs (Ficus), and other fruits. Frugivory (fruit consumption) seems to increase with size. For example, Remsen and colleagues found broad-billed motmots to be largely insectivorous, but rufous and blue-crowned motmots were more frugivorous. There are no records of the smallest species, the tody motmot, taking fruit.

Different motmot species obtain their prey in different ways, although patterns overlap. Smaller species appear to sally more as sit-and-wait strategists; larger species often perform long, broadcasting flights while continuously searching for prey. Smaller species also seem to catch more prey on the wing than larger species. Prey too large to swallow whole are often seized with the bill and clubbed against a perch. Pellets may be regurgitated. Several motmot species are "antfollowing" birds that take insects turned up by long trains of army ants.

Smaller seeds of consumed fruits are passed through and dispersed; larger seeds are regurgitated on the spot. Species such as rufous motmots are important dispersers of the nutmeg Virola surinamensis, accounting for approximately 17% of dispersed fruits. Seed dispersal helps regenerate tropical forests.

Reproductive biology

Vocal duetting between male and female occurs to some degree and may serve to strengthen the monogamous pair bond during non-breeding season and maintain the territory. Nests are typically built solitarily, but there are exceptions involving colonial nesting that ranges from a few nests to more than 100 in species such as the turquoise-browed motmot.

Motmots nest in an underground chamber dug by both sexes. They take turns loosening the soil and kicking dirt out toward the opening. The chamber may be up to 16 ft (5 m) long in larger species. Eggs remain on bare soil, but hard insect parts regurgitated by incubating parents may be added underneath.

Eggs are rounded, shiny, and white. The clutch typically ranges from three to five eggs. In middle America, eggs are typically laid every other day between March and June; April and May are peak laying months. Typically a single clutch is laid each season, but if a clutch is lost replacement clutches are laid after 10–21 days. Both sexes incubate eggs during long shifts, perhaps changing duties once in 24 hours. Incubation is 17–22 days, depending on the species.

Chicks hatch blind, featherless, and dependent on parents. Skutch provides information on development from studying broad-billed motmots: partly feathered at 11 days, eyes begin opening at 12 days, soft calls at 13 days, taking food at burrow entrance at 15 days, and leave nest at 25 days. Young blue-throated motmots have soft down that appears soon after hatching. Both sexes care for the brood and feed the chicks lepidopterans and other insects, vertebrate innards, and protein-rich fruits. Young generally leave the nest at 24–32 days, though one record has a blue-crowned motmot leaving the nest at 38 days.

Conservation status

Of the nine species, only the keel-billed motmot is considered Vulnerable. The main threat is a rapid rate of habitat destruction.

Significance to humans

Indigenous tribes may use motmot tail feathers or wings in ornamentation. Folklore of the Brazilian Pareci Tribe of Mato Grosso attributes gaps without barbs along the tail of the rufous motmot to carrying fire embers. Motmots were well known in the Mayan culture.

Species accounts

Resources

Bird Life International. Threatened Birds of the World. Barcelona: Lynx Edicions, 2000. del Hoyo, J., A. Elliot, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 6, Mousebirds to Hornbills. Barcelona: Lynx Edicions, 2001.

Feduccia, A. R. The Origin and Evolution of Birds. New Haven: Yale University Press, 1999.

Forshaw, Joseph M., and W. T. Cooper. Kingfishers and Related Birds. Vol. 3, Todidae, Momotidae, Meropidae. Sydney: Lansdowne Editions, 1987.

Sick, Helmut. Birds in Brazil: A Natural History. New Jersey: Princeton University Press, 1993.

Stiles, F. G., and A. F. Skutch. A Guide to the Birds of Costa Rica. London: Christopher Helm, 1989.

Stotz, D. F., et al. Neotropical Birds: Ecology and Conservation. Chicago: University of Chicago Press, 1996.

Becker, J. J. "A Fossil Motmot (Momotidae) from Late Miocene of Florida." Condor 88 (1986): 478–482.

Delgado-V., Carlos A., and D. M. Brooks. "Aberrant Vertebrate Prey taken by Neotropical Birds." Cotinga (2002) (in press).

Olson, S. L. "Oligocene Fossils Bearing on the Relationships of the Todidae and Momotidae (Aves: Coraciiformes)." Smithsonian Contributions to Paleobiology. 27 (1976): 111–119.

Orejuela, J. E. "Comparative Biology of Turquoise Browed and Blue Crowned Motmots in the Yucatan Peninsula, Mexico." Living Bird 16 (1977): 193–208.

Remsen, J. V. et al. "The Diets of Neotropical Trogons, Motmots, Barbets, and Toucans." Condor 95 (1993): 178–192.

Neotropical Bird Club. c/o The Lodge, Sandy, Bedfordshire SG19 2DL United Kingdom. E-mail: secretary@neotropicalbirdclub.org

[Article by: Daniel M. Brooks, PhD]