Acridotheres tristis

Geographic Range

Common mynas are native to south Asia. Their natural breeding range is from Afghanistan through India and Sri Lanka to Bangladesh. They have been introduced to many tropical areas of the world except for South America. Common mynas are a resident species in India, although occasional east-west movements have been reported.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • introduced introduced
• oriental oriental
  • native native
• ethiopian ethiopian
  • introduced introduced
• australian australian
  • introduced introduced
• oceanic islands oceanic islands
  • introduced introduced

Habitat

Common mynas occupy a wide range of habitats in warm areas with access to water. In their native range, common mynas inhabit open agricultural areas such as farmlands as well as cities. They are often found on the outskirts of towns and also outlying homesteads in desert or forest. They tend to avoid dense vegetation. They are most common in dry woodlands and partly open forests. On the Hawaiian islands, they have been reported from elevations of sea level to 3000 meters. Common mynas prefer to roost in isolated stands of tall trees with dense canopies.

• Habitat Regions
• temperate temperate
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• forest forest
• scrub forest scrub forest

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

Common mynas range in body length from 23 to 26 cm, weigh anywhere from 82 to 143 grams, and have a wingspan of 120 to 142 mm. The female and the male are monomorphic for the most part – the male is only slightly larger, with a greater body mass and wingspan. Common mynas have yellow bills, legs, and eye skin. They are dark brown with a black head. They have white undertail coverts, tail tips, patches at the base of their primaries, and wing linings that are distinctive in flight. Juveniles have more brownish heads than adults. Common mynas are often confused with noisy miners ( Manorina melanocephala ). In contrast to common mynas, noisy miners are slightly larger and mostly grey.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike
• male larger

Reproduction

Common mynas are monogamous and territorial. In Hawaii pairs stay together year round. In other areas common mynas pair up during early spring and before establishment of territories. During the breeding season, normally from October to March, there is usually considerable competition for nesting sites. Occasionally, violent battles may occur between pairs over a single nesting site. The courtship display of the male is characterized by head bowing and bobbing, with fluffed plumage, accompanied by calls.

• Mating System
• monogamous monogamous

Common mynas reach sexual maturity around 1 year of age. Females lay four to five eggs in a clutch. The incubation period is 13 to 18 days, during which both parents incubate the eggs. The nestlings may leave the nest at around twenty-two days or longer, but may still not be able to fly for another seven days or so. Depending on their geographic location, common mynas have been reported to breed anywhere from 1 to 3 times a season. In their native range, common mynas begin nesting in March and breeding lasts through September. Even after nestlings leave the nest parents may continue to feed and protect these juveniles until 1.5 months after they hatch.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Both parents play an equal part in building and defending nesting territory. Both parents incubate the eggs, with the female incubating the most. The female incubates alone at night, and the male incubates only a little during the day. When the young are hatched they are altricial and blind. Both parents feed the hatchlings for nearly 3 weeks, during the fledging period, and even continue to feed and protect them for up to 3 weeks after they leave the nest. Parents carry food to their chicks mostly in their beaks because they don’t have crops. The young are stimulated to beg when parents give a rich, honky trill while approaching the nest with food. After the young are independent, they sometimes continue to forage with their parents and the parents continue to protect them from predators. Juveniles form small flocks when they become independent. Some young begin to form pairs when they are nine months old, but rarely attempt to breed in their first year.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• post-independence association with parents

Lifespan/Longevity

Little is known about the lifespan of common mynas. Reports suggest an average life expectancy for both sexes of 4 years. Lack of food or resources is the biggest limiting factor in the survival of common mynas. Other factors that contribute to mortality rates are poor selection of nest sites and unfavorable weather.

Behavior

Common mynas are social, with juveniles forming small flocks after they leave their parents. Adults forage in loose flocks of 5 or 6, composed of single birds, pairs, and family groups. Outside of the breeding season they roost in large groups that can vary from tens to thousands. Communal roosting is helpful for defense against predators and also for food distribution. During the breeding season, common mynas can be aggressive and violent while competing with other pairs over nesting sites. Common mynas are described as tame, gregarious, and bold, and engage in allopreening within mated pairs. When foraging, these mynas hop sideways and saunter along the ground and on branches. Common mynas have also been observed participating in anting with fire ants.

• Key Behaviors
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social

Home Range

The home range of common mynas consists of several regularly used day sites rather than a single contiguous area. Total home ranges average around 0.25 km2. The territory around nests is strongly defended, although sometimes nests are found in large colonies. Average territory size in India is 117.04 m2.

Communication and Perception

Common mynas communicate vocally with other mynas and other bird species. They have a wide variety of alarm calls, that can warn other bird species as well. During the day, pairs resting in the shade also utter songs while half-bowing and bristling their feathers. When under duress, common mynas utter high-pitched screams. Parents sometimes utter a specific trill when approaching their nest with food, which signals the nestlings to begin begging. In captivity, common mynas are able to imitate human speech. Both females and males sing, but males sing more frequently. Common mynas also participate in loud dawn and dusk choruses.

• Communication Channels
• visual visual
• acoustic acoustic

• Other Communication Modes
• choruses choruses

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Common mynas are omnivorous and feed on almost anything. Their primary diet consists of fruit, grain, grubs, and insects. They prey on eggs and young of other birds, such as akepas ( Loxops coccineus ). They sometimes even wade in shallow waters to catch fish. Common mynas feed mostly on the ground. In residential areas they eat anything from garbage to kitchen scraps. Common mynas eat small mammals, such as mice, as well as lizards and small snakes. They also eat spiders, earthworms, and crabs. Common mynas eat mostly grains and fruit, but also feed on flower nectar and petals.

• Primary Diet
• omnivore omnivore

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• fish
• eggs
• carrion carrion
• insects
• terrestrial non-insect arthropods
• terrestrial worms
• aquatic or marine worms
• aquatic crustaceans

• Plant Foods
• seeds, grains, and nuts
• fruit
• nectar
• flowers

Predation

Common nest predators of common mynas are house crows ( Corvus splendens ) and house cats ( Felis silvestris ). Javan mongooses ( Herpestes javanicus ) raid nests to take nestlings and eggs. Humans ( Homo sapiens ) in some of the Pacific Islands also eat common mynas. Common mynas roost together for predator defense and often mob predators in flocks. They warn each other through alarm calls.

Ecosystem Roles

Common mynas are important pollination or seed-dispersal agents for many plants and trees. On the Hawaiian Islands they disperse the seeds of Lantana camara . They also help control cutworms ( Spodoptera mauritia ) on the Hawaiian Islands. Common mynas also act as hosts for various parasites such as nematodes, tapeworms, trematode flukes, arthropods, and bird mites. In areas where they have been introduced they negatively impact native bird and seabird species by preying on eggs and nestlings.

• Ecosystem Impact
• disperses seeds
• pollinates

Economic Importance for Humans: Positive

Common mynas may be helpful in reducing insect populations in agricultural areas. On the Hawaiian Islands, they help control populations of cutworms ( Spodoptera mauritia ). Common mynas also pollinate and disperse the seeds of economically important trees. Common mynas are often sold as pets for their intelligence and ability to mimic human speech. In 1883, common mynas were introduced into the cane fields of Australia to combat insect pests such as plague locusts and cane beetles.

• Positive Impacts
• pet trade pet trade
• pollinates crops
• controls pest population

Economic Importance for Humans: Negative

Common mynas are able to establish themselves in almost any habitat and, as a result, have become an invasive species in some areas outside of their native range. They are considered a pest because they eat grain or fruit from agricultural crops, such as fig trees. They are also seen as a nuisance for their noise and droppings in the vicinity of human habitation.

• Negative Impacts
• crop pest
• household pest

Conservation Status

Common mynas remain common throughout much of their range.

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Tiffany Lin (author), Stanford University, Terry Root (editor, instructor), Stanford University.

References

Invasive Species Specialist Group, 2006. "Global Invasive Species Database" (On-line). Ecology of Acridotheres tristis. Accessed May 22, 2007 at http://www.issg.org/database/species/ecology.asp?si=108&fr=1&sts .

Kannan, R., D. James. 2001. "The Birds of North America Online: Common Myna" (On-line). Accessed May 29, 2007 at http://bna.birds.cornell.edu/BNA/account/Common_Myna/ .

Rousset, P., D. Thorns. 2007. "Europe Solidaire Sans Frontieres" (On-line). The avifauna of the Parc des Beaumonts : list of species identified. Accessed May 22, 2007 at http://www.europe-solidaire.org/spip.php?article5884 .

2002. National Geographic Field Guide to the Birds of North America, 4th ed. . Des Moines, IA: National Geographic.

Net Industries. 2007. "Birds Scientific Reference: Vol. 5" (On-line). COMMON MYNA (Acridotheres tristis): SPECIES ACCOUNTS. Accessed May 22, 2007 at http://animals.jrank.org/pages/1392/Starlings-Mynas-Sturnidae-COMMON-MYNA-Acridotheres-tristis-SPECIES-ACCOUNTS.html .

Australian Museum. 2003. "Factsheets: Common Myna" (On-line). Factsheets: Common Myna. Accessed May 29, 2007 at http://www.amonline.net.au/factSheets/common_myna.htm .