By Alaine Camfield
Diversity
Pigeons and doves are in the order Columbiformes and family Columbidae. There are five subfamilies within Columbidae, 42 genera and 308 species. They are easily recognizable and have a world-wide distribution (although they are not found in Antarctica). They live in almost all types of terrestrial habitats from desert to dense forest and large urban areas. Pigeons and doves are stocky birds that range from 15 to 75 cm long. Many of the seed-eating columbids are buff, grey and brown colors, while the fruit-eaters are often more brightly colored. Many have ornamentation and iridescent feathers on the neck, breast, back, wings and face. They range from solitary to extremely social; the now extinct passenger pigeons (Ectopistes migratorius) are reported to have occurred in flocks of up to two million birds that were so dense that they blocked out the sun. (Baptista, Trail, and Horblit, 1992; Dickinson, 2003; Lack, 2003; Wells and Wells, 2001)
Geographic Range
Pigeons and doves are a cosmopolitan family (although they are not found in Antarctica or the high arctic). The highest diversity of columbids occurs in South America, Australasia and the Pacific Islands. Some species (for example, Rock Doves (Columba livia)) have been introduced throughout much of their range. (Baptista, Trail, and Horblit, 1992; Frith, 1982; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Habitat
Columbids are found in almost all terrestrial habitats from temperate areas to the tropics including: lowland rainforest, highland forest, tropical deciduous forest, riparian forest, boreal forest, savanna, desert, cliff, chaparral, coral atolls, mangroves, swamp forest, woodland edge, agricultural areas, suburban and urban areas. The highest diversity of pigeons and doves occurs in tropical rainforests. They can be found from sea level to 5000 m and their excellent flying abilities have allowed them to colonize oceanic islands. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Systematic and Taxonomic History
Pigeons and doves are in the order Columbiformes and family Columbidae. There are five subfamilies within Columbidae: Columbinae (typical pigeons), Otidiphabinae (pheasant pigeons), Gourinae (crowned pigeons), Didunculinae (tooth-billed pigeons) and Treroninae (fruit doves). There are 42 genera and 308 species within Columbidae.
There is disagreement as to which groups are most closely related to pigeons and doves. It has been suggested that columbids are closely related to gamebirds, buttonquails, parrots, shorebirds and sandgrouse (sandgrouse are sometimes included in the order Columbiformes). Dodos are now extinct, but were closely related to pigeons. Some researchers actually grouped dodos in the family Columbidae, while others placed them in the family Raphidae within Columbiformes. Recent DNA evidence suggests that there are no extant relatives of pigeons and doves and that they should be the only family in Columbiformes.
Characteristics that distinguish pigeons and doves include: “palate schizognathous; pelvic muscle formula A(B)XY+; internal caeca small or absent; syrinx with asymmetrical extrinsic muscles; schiorhinal, impervious nares, with a fleshy cere over the slit-like nostrils; two carotids; hallux incumbent; flexor tendons type 1; tarsi covered laterally and behind with hexagonal scales; thick plumage, feathers set loosely in skin; diastatxic; 11 primaries; 12-20 retrices; airshaft small or absent; caeca small, not functional; well-developed bi-lobed crop; produce ‘pigeon milk’ from crop lining for feeding young; oil gland naked or absent; nidicolous young hatched blind and without true down; drink by sucking or pumping (from Sibley and Ahlquist 1990, pg.421).” (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Payne, 2003; Sibley and Ahlquist, 1990; Wells and Wells, 2001)
- palate schizognathous
- pelvic muscle formula A(B)XY+
- internal caeca small or absent
- syrinx with asymmetrical extrinsic muscles
- schiorhinal, impervious nares, with a fleshy cere over the slit-like nostrils
- two carotids
- hallux incumbent
- flexor tendons type 1
- tarsi covered laterally and behind with hexagonal scales
- thick plumage, feathers set loosely in skin
- diastatxic
- 11 primaries
- 12-20 retrices
- airshaft small or absent
- caeca small, not functional
- well-developed bi-lobed crop; produce ‘pigeon milk’ from crop lining for feeding young
- oil gland naked or absent
- nidicolous young hatched blind and without true down
- drink by sucking or pumping
Physical Description
Pigeons and doves are stocky birds that range from 15 to 75 cm long and weigh from 30 to over 2000 g. The smaller species within Columbidae are often called doves and the larger species pigeons, but these names do not necessarily reflect true differences and are often used interchangeably. Columbids have small heads and short beaks and legs. Their flight muscles may make up to 44 percent of the bird’s body weight and allow them to have excellent flying capabilities and maneuverability. Wing-shape is often a good indicator of the species’ migratory behavior. They have soft skin at the base of their bills and a ring of bare skin around their eyes that can be red, blue, yellow or white. Columbids have a bilobed crop that produces “crop-milk” (or "pigeon milk") that they feed their young.
Columbids can be divided in to seed-eating and fruit-eating species. Many of the seed-eating columbids are buff, grey and brown colors while the fruit-eaters are often more brightly colored. Typical pigeons (subfamily Columbinae) are usually grey, brown and/or pink. Fruit-eating pigeons (subfamily Treroninae) are more colorful with oranges and greens. Crowned pigeons (subfamily Gourinae) are grey with pink or chestnut underparts and a white wing patch. Tooth-billed pigeons (subfamily Didunculinae) are chestnut colored on the back and wings and dark green elsewhere. Many doves and pigeons have ornamentation (such as crests and colorful eye rings) and iridescent feathers on the neck, breast, back, wings and face. They range from sexually monomorphic to sexually dimorphic, and molt annually after breeding. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Reproduction
Pigeons and doves are monogamous, and many have the same mate from year to year. They have numerous displays that are performed either on the ground or in the air. For example, while on the ground, males of some species squat, lift their tail, lower their head, twitch their wings and scratch the ground with their feet while calling. Some species have aerial displays that usually involve wing claps (most forest and ground living species do not have aerial displays). Aerial displays are used in courtship and to indicate territory boundaries. During a pre-copulation display, a male inflates his crop, bows, spreads his tail feathers, pirouettes and calls. This display varies among species, and birds with ornaments and colorful plumage usually show them off during the display. Some species of pigeons and doves also engage in courtship feeding and/or mate guarding. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Mating systems:
Breeding is triggered by food availability and photoperiod and can be seasonal or year-round, depending on the species. Some columbids breed colonially, some solitarily. The males bring nest material to the females who build the nest. The nest is a platform or shallow cup of twigs and stems built on a crevice, cliff, tree or the ground. Columbids will re-use nests and will build nests on top of abandoned bird nests. Nest building usually lasts two to four days and nest sites are defended.
Clutch size is usually one to two eggs (occasionally three). Frugivorous species usually have only one egg; fruit is low in protein so the birds can not raise more than one chick. The eggs are white or buff colored and unmarked. Both males and females incubate, but females usually spend more time incubating than males. Species that live in the desert wet their stomach feathers before incubating to help cool the eggs by evaporation. Incubation lasts 11 to 30 days, and hatching can be either synchronous or asynchronous. Chicks are altricial and are fed by both parents. Chicks fledge in 10 to 36 days (earlier if disturbed) and may continue to receive food from their parents for 30 to 40 days.
Breeding pairs can have up to five broods in one breeding season. Their short breeding cycle allows pigeons and doves to have more broods to compensate for their small brood sizes and relatively high rates of predation. Fledglings grow their adult plumage a few months after fledging and reach sexual maturity in 6 to 12 months. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Both males and females incubate, but females usually spend more time incubating than males. Species that live in the desert wet their stomach feathers before incubating to help cool the eggs by evaporation. Incubation lasts 11 to 30 days. Chicks are altricial and are fed by both parents. The chicks are usually fed crop-milk for three to four days and are then fed seeds and fruit, however, some continue to be fed crop-milk even after they have fledged. Crop-milk is made in the crop of the adult birds and is 75 to 77 percent water, 11 to 13 percent protein, 5 to 7 percent fat and 1.2 to 1.8 percent minerals and amino acids. Nestling pigeons and doves grow rapidly because of the crop-milk. Chicks fledge in 10 to 36 days (earlier if disturbed) and may continue to receive food from their parents for 30 to 40 days. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Lifespan/Longevity
The oldest recorded columbid is a mourning dove (Zenaida macroura) that lived 19 years and 4 months. Adult annual survival has been estimated to be 40 to 65 percent. (Wells and Wells, 2001)
Behavior
Pigeons and doves can be solitary to very social and can be found in flocks of several thousand. A flock of the now extinct passenger pigeons (Ectopistes migratorius) seen in 1740 was 3 to 4 miles long and 1 mile wide, it was so dense that it blocked out the sun. Dominance hierarchies occur in flocks. Many species roost communally at night (pigeons and doves are diurnal) and some are colonial breeders. To stay warm, Inca doves (Columbina inca) form groups of up to 12 and stand on each other’s backs. They shift positions so that each bird takes a turn on the outside.
Species in hot areas rest during the hottest part of the day. In cold weather, pigeons and doves fluff up their feathers to conserve their body heat. If they are hot, they raise their feathers even more so that the tips do not touch (a behavior called piloerection); this allows heat to escape and helps the bird cool down. Columbids spend a lot of time preening and bathing in the sun, water, dust and rain.
Pigeons and doves are known for their navigation abilities and have been used by humans as messengers. Some species are sedentary, and others are migratory. Some are nomadic and move as their food supply changes, and some make altitudinal movements as seasons change. Some pigeons and doves fly up to 40 km each day from their roosting sites to their foraging sites. Many species have high nest-site fidelity and during breeding they are aggressive and defend small territories around their nests. (Baptista, Trail, and Horblit, 1992; Lack, 2003; Wells and Wells, 2001)
Communication and Perception
Pigeons and doves have a variety of songs and calls that they use to find mates, signal danger, and defend territories. Males have special vocalizations that are only used in courtship and advertising. Both males and females sing; most songs are flute-like cooing noises that differ in the length of each note and in the interval between notes. Some species sound like a whistle, and others sound more like a croak. Small columbid species have higher-pitched calls than larger species. They will sometimes call in duets. Some species make quiet purring sounds that function in mate-bonding. Adults will respond to song playbacks. Young birds have begging calls and the results of cross-fostering experiments show that songs are innate and are not learned from their parents.
Pigeons and doves have a variety of courtship displays (see Reproduction: Mating Systems). They also have threat displays in which they spread and raise their wings and spread their tail. If the display does not work to repel and intruder, they will “buffet” with their wings or peck at the intruder.
Columbids are excellent navigators and use both the magnetic field of the planet and the position of the sun to find their way. (Baptista, Trail, and Horblit, 1992; Lack, 2003; Wells and Wells, 2001)
Food Habits
Pigeons and doves can be seen feeding in flocks. They are primarily grainivorous and frugivorous, but occasionally they eat insects, snails, worms, lizards, leaves, buds and flowers. Seeds are picked up off the ground and eaten whole and fruits are plucked from trees. Grainivorous species have specialized gizzards, intestines and esophagi that help them eat and digest seeds. Grain is stored in their crops and ground by the grit in their gizzard. Grainivorous species need to drink a lot of water in order to digest seeds. Desert species get their water from succulent plants and have the ability to drink saline water. Columbids drink by submerging their beaks into the water and sucking the water up, they do not scoop water in their beaks and lift their heads to swallow like most birds.
Size differences among columbids often reflect dietary differences and allow for resource partitioning. Larger birds eat larger fruit than smaller birds and smaller birds can feed on thinner branches and reach fruit that the larger birds can not reach. (Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; Lack, 2003; Wells and Wells, 2001)
Predation
- snakes (Serpentes)
- falcons (Falconidae)
- birds of prey (Falconiformes)
Pigeons and doves often form feeding flocks, which allow for increased vigilance and reduce the chance that any one bird will be caught by a predator. They also use broken wing displays to draw predators from the nest. In response to high rates of nest predation, columbids have developed short incubation and nestling periods. Snakes (suborder Serpentes) are common nest predators and falcons (family Falconidae) and other birds of prey (order Falconiformes) feed on adults. (Baptista, Trail, and Horblit, 1992; Goodwin, 1983)
Ecosystem Roles
Pigeons and doves are important seed dispersers and are host to a number of feather parasites (including Columbicola columbae and Campanulotes bidentatus). In addition, they can carry human diseases. (Baptista, Trail, and Horblit, 1992; Lack, 2003)
Key ways these animals impact their ecosystem:
disperses seeds.
Economic Importance for Humans: Negative
Because they feed on cultivated grain, columbids are often thought of as crop pests. They are also pests in urban areas where they nest in man-made structures and their droppings can be a nuisance. They are also known to carry human disease. (Baptista, Trail, and Horblit, 1992; Lack, 2003)
Ways that these animals might be a problem for humans:
injures humans (carries human disease); crop pest; household pest.
Economic Importance for Humans: Positive
Pigeons and doves are often a part of folklore and literature, and havae been domesticated for food (both eggs and adults are eaten by people). Research involving columbids has lead to increased knowledge about the inheritance of morphological and behavioral traits, endocrinology, learning, evolution, orientation and navigation. Pigeon racing is also a common pass-time and racing pigeons can sell for as much as $350 000. Pigeons and doves were also used as messengers during war times and are sometimes kept as pets. (Baptista, Trail, and Horblit, 1992; Lack, 2003)
Conservation
Some species of pigeons and doves have expanded their ranges and increased their population sizes as a result of human activities (for example, 'rock doves Columba livia' and 'Eurasian collared doves Streptopelia decaocto'). Other species are less fortunate and their ranges and populations are shrinking as a result of habitat loss and fragmentation, hunting, introduced species, agriculture and pesticides. Columbids that live on islands are the most threatened. Habitat preservation is the best solution to dwindling numbers of some columbids, and captive breeding may be useful as a last resort.
The IUCN lists 109 species of columbids in various categories from ‘Extinct’ to ‘Near Threatened. CITES lists 26 members of Columbidae ranging from Appendix I to Appendix III. ("UNEP-WCMC Species Database: CITES-Listed Species", 2004; Baptista, Trail, and Horblit, 1992; Gibbs, Barnes, and Cox, 2001; IUCN, 2003; Lack, 2003; Wells and Wells, 2001)
Contributors
Alaine Camfield (author), Animal Diversity Web.
Kari Kirschbaum (editor), Animal Diversity Web Staff.
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