Owl butterfly
Encyclopedia
Butterflies in the genus Caligo are commonly called owl butterflies, after their huge eyespots, which resemble owls' eyes. They are found in the rainforest
s and secondary forest
s of Mexico
, Central
and South America
.
Owl butterflies are very large, 65–200 mm (2.6–7.9 ), and fly only a few metres at a time, so avian predators have little difficulty in following them to their settling place. However, the butterflies preferentially fly in dusk, when few avian predators are around.
The Latin name may possibly refer to their active periods. Caligo means darkness.
Some owl butterflies form leks in mating behavior.
. It is conceivable that the eye pattern is a generalized form of mimicry. It is known that many small animals hesitate to go near patterns resembling eyes with a light-colored iris
and a large pupil
, which matches the appearance of the eyes of many predators that hunt by sight. The main predators of Caligo are apparently small lizard
s such as Anolis
.
The role of eyespots as antipredator mechanisms has been discussed since the 19th century. Several hypotheses are suggested to explain their occurrence. In some butterflies, particularly Satyrinae
(such as the Gatekeeper Butterfly
and the Grayling
), it has been shown that ocelli serve as a decoy, diverting bird attack away from the vulnerable body, and towards the outer part of the hindwings or the forewing tip.
Research of Stevens et al. (2008), however, suggests that eye-spots are not a form of mimicry and do not deter predators because they look like eyes. Rather the conspicuous contrast in the patterns on the wings deter predators. In this study, however, the influence of surrounding forms, like the head region of a predator, was not tested. Also the question why animals evolved such complex imitations of other species is left.
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s and secondary forest
Secondary forest
A secondary forest is a forest or woodland area which has re-grown after a major disturbance such as fire, insect infestation, timber harvest or windthrow, until a long enough period has passed so that the effects of the disturbance are no longer evident...
s of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Owl butterflies are very large, 65–200 mm (2.6–7.9 ), and fly only a few metres at a time, so avian predators have little difficulty in following them to their settling place. However, the butterflies preferentially fly in dusk, when few avian predators are around.
The Latin name may possibly refer to their active periods. Caligo means darkness.
Some owl butterflies form leks in mating behavior.
Species
There are some 20 species in this genus, which can be divided into 6 groups that might constitute subgenera. Some species are of uncertain placement with regard to these groups, however:- C. eurilochus species-group
- Caligo bellerophon Stichel, 1903
- Caligo brasiliensisCaligo brasiliensisThe Brazilian Owl or Sulanus Owl is a butterfly of the Nymphalidae family. The species can be found in most of South America as various subspecies, including Brazil, Colombia, Venezuela and Ecuador...
- Caligo eurilochusCaligo eurilochusCaligo eurilochus is an owl butterfly Caligo eurilochus is an owl butterfly Caligo eurilochus is an owl butterfly (tribe Brassolini of nymphalid subfamily Morphinae, ranging from Mexico, through Central America, to the Amazon River basin in South America. The type locality is Suriname. Several...
– Forest Giant Owl - Caligo idomeneusCaligo idomeneusThe Idomeneus Giant Owl, Caligo idomeneus, is a butterfly of the Nymphalidae family. The species can be found in the Amazon rainforest and eastern Andes, from Venezuela to Ecuador, and south to the Mato Grosso in southern Brazil. The butterfly is named for Idomeneus, the leader of the Cretan army...
– Idomeneus Giant Owl - Caligo illioneusCaligo illioneusCaligo illioneus, common name Illioneus Giant Owl, is a owl butterfly belonging to the nymphalid family, Morphinae subfamily, tribe Brassolini.-Etymology:...
– Illioneus Giant Owl - Caligo memnonCaligo memnonThe Owl is a butterfly of the Nymphalidae family. It is also known as the Pale or Giant Owl Butterfly. The species can be found in the rainforests and secondary forests of Mexico down to the Amazon rainforest....
- Caligo prometheus
- Caligo suzanna (Deyrolle, 1872)
- Caligo telamonius (C. & R. Felder, 1862)
- Caligo teucer – Teucer Giant Owl
- C. arisbe species group:
- Caligo arisbe
- Caligo martiaCaligo martiaCaligo martia is a butterfly of the Nymphalidae family. The species can be found in Brazil.The larvae feed on Echinochloa crus-galli and Pennisetum purpureum....
- Caligo oberthurii
- C. atreus species group:
- Caligo atreusCaligo atreusThe Yellow-Edged Giant-Owl is a butterfly of the Nymphalidae family. The species can be found from Mexico to Peru.The wingspan is 140-160 mm....
- Caligo uranus
- Caligo atreus
- C. oileus species-group
- Caligo oedipus
- Caligo oileus – Oileus Giant Owl
- Caligo placidianus – Placid Giant Owl
- Caligo zeuxippus
- "Caligo repugno" – Turquoise Giant Owl
- C. beltrao species-group
- Caligo beltraoCaligo beltraoThe Purple Owl is a butterfly of the Nymphalidae family. The species can be found in Brazil.The wingspan is about 120 mm.The larvae feed on Canna indica, Calathea zebrina, Musa spp. and Hedychium coronarium....
- Caligo beltrao
- incertae sedisIncertae sedis, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
- Caligo euphorbus – Euphorbus Giant Owl
- Caligo superbus
Functions of the wing pattern
The underwing pattern is highly crypticCrypsis
In ecology, crypsis is the ability of an organism to avoid observation or detection by other organisms. It may be either a predation strategy or an antipredator adaptation, and methods include camouflage, nocturnality, subterranean lifestyle, transparency, and mimicry...
. It is conceivable that the eye pattern is a generalized form of mimicry. It is known that many small animals hesitate to go near patterns resembling eyes with a light-colored iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
and a large pupil
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...
, which matches the appearance of the eyes of many predators that hunt by sight. The main predators of Caligo are apparently small lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s such as Anolis
Anolis
Anolis is a genus of lizards belonging to the family Polychrotidae. With nearly 400 species, Anolis represents the world's most species rich amniote genus. Several species of Anolis are occasionally ascribed to the genus Norops, but the validity of the Norops genus is not widely accepted...
.
According to the Batesian mimicryBatesian mimicryBatesian mimicry is a form of mimicry typified by a situation where a harmless species has evolved to imitate the warning signals of a harmful species directed at a common predator...
theory the pattern on the wings of Caligo resemble the head of a predator like a lizardLizardLizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
or an amphibianAmphibianAmphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
. It should deter predators while resting, feeding, mating or emerging from the pupaPupaA pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
.
The role of eyespots as antipredator mechanisms has been discussed since the 19th century. Several hypotheses are suggested to explain their occurrence. In some butterflies, particularly Satyrinae
Satyrinae
Satyrinae, the satyrines or satyrids, commonly known as the Browns, is a subfamily of the Nymphalidae . They were formerly considered a distinct family, Satyridae. This group contains nearly half of the known diversity of brush-footed butterflies...
(such as the Gatekeeper Butterfly
Gatekeeper Butterfly
The Gatekeeper sometimes called the Hedge Brown is a common butterfly in the United Kingdom. It is a member of the subfamily Satyrinae in the family Nymphalidae. A similar species is the Meadow Brown; the two species can be difficult to distinguish with closed wings since underwing markings are...
and the Grayling
Grayling (butterfly)
The Grayling is a species in the brush-footed butterfly family Nymphalidae. It sometimes occurs in coastal areas of northeast Scotland such as the Fowlsheugh Nature Reserve. It can also be found near the coast around England, such as Fire Beacon Hill...
), it has been shown that ocelli serve as a decoy, diverting bird attack away from the vulnerable body, and towards the outer part of the hindwings or the forewing tip.
Research of Stevens et al. (2008), however, suggests that eye-spots are not a form of mimicry and do not deter predators because they look like eyes. Rather the conspicuous contrast in the patterns on the wings deter predators. In this study, however, the influence of surrounding forms, like the head region of a predator, was not tested. Also the question why animals evolved such complex imitations of other species is left.
Further reading
- Garwood, K. M., Lehman, Carter, W., & Carter, G. (2007). Butterflies of Southern Amazonia. Mission, Texas: Neotropical Butterflies.
External links
- Pictures of an owl butterfly
- Micropanorama of an owl butterfly wing
- Taxonomy Browser Upperside and underside photographs.
- Pteron In Japanese but binomial names