OWL: CHARACTERISTICS, FEEDING, REPRODUCTION, HABITAT - BIOLOGY - 2024

The owl is a bird of prey belonging to the Strigidae family . Its main feature is the feather disk that borders each of its eyes. These are large and forward facing. Its sense of sight is highly developed, allowing it to hunt its prey at night.

For his victims, he also uses his hearing acuity. The morphology of its ears allows it to identify, with high precision, the orientation and distance where the source of any sound is located.

Royal Owl. Source: pixabay.com

In relation to his body, he is rounded and always maintains an upright posture. Their limbs are strong and covered with feathers. It has sharp claws, with which it not only firmly holds the animal it hunts, but also uses them to tear its flesh.

Another aspect that identifies the owl is its silent flight. This is achieved thanks to a series of body adaptations, within which are its feathers. These are soft and have fringes on the main flight feathers.

The preferred habitat of owls is the forests, although they can also live in thickets and in areas near the coast. They are distributed worldwide, with the exception of Antarctica.

Evolution

Bubo africanus. Pilansberg_095.jpg: Joonas Lyytinen, Käyttäjä: Joonaslderivative work: MPF

The first fossils of owls belong to the prehistoric period of the Paleocene. However, in the Eocene there was a radiation of highly relevant species and families. With regard to the Strigidae family, its appearance is somewhat uncertain.

Some fossilized samples that were attributed to this clade, belonged to the Tytonidae. The first evidence of these species appears in Europe and North America, during the Lower Miocene, between 22 and 24 million years ago. After this event, these owls were probably able to displace the Tytonidae.

The oldest preserved fossil is the Ogygoptynx wetmorei, found in Colorado, where it lived 58 million years ago. This suggests the existence of radiation from these birds 50 million years ago.

In addition, their characteristics indicate that the ancestors of the current owls were larger than the current species.

Linnaeus placed the Falconiformes and the Strigiformes in the same group, due to their carnivorous diet and their common characteristics. This classification lasted for about 130 years, until investigations revealed different information.

Currently, taxonomists maintain the existence of a close relationship between owls and Caprimulgiformes. This is supported by data from DNA-DNA hybridization.

The owl in popular culture

Bubo scandiacus. Diego Delso

The owl is associated, in some parts of the lot, with misfortune and death, probably because it is a night owl and because of the deep screech it uses as a call.

However, they are also related to prosperity and wisdom. This may be because, in Greek mythology, the goddess Athena, teacher of wisdom, was always accompanied by an owl.

The ancient Egyptians used, in hieroglyphics, a representation of this bird for the sound of the letter "m". Within Native American culture, they are often associated with witchcraft and evil.

In Mesoamerica, the Mayans and the Aztecs, considered the owl to be a symbol of destruction and death. In this sense, the Aztec god representing death, Mictlantecuhtli, was frequently symbolized with this animal.

Within the richness of Japanese culture, it is seen as a symbol of the positive and the negative, depending on the species. Thus, barn owls are perceived as demonic elements and eagle owls as messengers of the gods.

In Indian civilization, the white owl is associated with prosperity, since it is a companion of the goddess of wealth.

characteristics

Bubo sumatranus, Malaysia. laloq3

Owls have a large head with large eyes. Around each one they have a circle of feathers, known as a facial disk. There is a hypothesis that it contributes to the channeling of sound to your ears.

In relation to the beak, it is robust and short, with a hook-shaped upper jaw. Its wings are large, rounded and wide. Its legs are strong, with powerful claws.

Size

The Strigidae family is very extensive. It is divided into 26 genera with their own common characteristics, which define and differentiate them from the rest of the owls.

Among the smallest species are pygmy owls, which measure 13 centimeters and weigh around 50 grams. The wing span is 32 centimeters. Another example is the elf owl (Micrathene whitneyi), with a weight of 40 grams and a length between 13.5 and 15.5 centimeters.

Likewise, a group of these birds are very large. Such is the case of the Eurasian owl (Bubo bubo), which can weigh 4,200 grams and its body measures from 60 to 75 centimeters.

Also, the Verreaux's owl (Bubo lacteus), with an approximate length of 76 centimeters, a weight of 4 kilograms and a wingspan of 2 meters.

Between these extremes there are about 200 species, of various sizes. In general, males are usually smaller than females.

However, there are some exceptions: the male of the Athene cunicularia is slightly larger than the female. The same occurs with several species of Ninox.

Feathers

The plumage of owls is smooth, white, cream, gray, black, brown and gold. Between species, variations may exist, but all colorations are adapted to blend in with their native habitat.

The fact of being able to go unnoticed within the environment where they live is very important for all members of this family. Because they are fierce predators, they are feared and hunted by various birds. Even if they are dead, they can be mugged and attacked.

Specializations

In addition to this adaptation, the feathers have also evolved so that the owl has a silent flight. This favors the capture of prey at night. Most of the plumage does not have a smooth surface, but is covered with a fine down.

As for the primary and secondary feathers, they have a soft and poorly defined posterior border. The primary flight feathers have a serrated outer edge.

In almost all species, they can cover, to a greater or lesser degree, their feet and claws. Thus, they have extra protection on their limbs, against rodents.

It can also work as a thermal insulator, in the face of extremely low temperatures. The exception to this feature is the fishing owl, with its bare legs, which allow it to regularly soak them in the water without suffering problems.

Some members of the genus Glaucidium and the eagle owl have patches on the back of the head, similar to eyes. In this way, they probably try to intimidate and confuse their predators.

Eyes

The width of the front linking field of the Strigidae is 50 °. Although the position of the eyes appears frontal, there is a divergence of 55 °. Thus, the binocular region is narrow, much narrower than might be assumed, and is not maximized within the image.

However, the location of the eyes is associated with better depth perception, even if light is poor in the environment.

In the protection of these organs, three eyelids intervene. The upper one closes when the animal blinks and the lower one when it sleeps.

The nictitating membrane, or third eyelid, is a thin layer. This extends diagonally over the eye, from the inside to the outside. Its function is to moisten, clean and protect the ocular surface.

Ears

Hearing is one of the most developed senses in owls. Through it, an animal of this type can hear sounds emitted at very low volume, whose source is at a long distance.

In addition to this, they have the ability to locate exactly where the prey is. They can achieve this thanks to a rather unusual anatomical feature: their ears are placed asymmetrically on their head. Thus, it can pick up sound waves from different sources and directions.

In this way, one ear is located higher than the other. Also, one is positioned further forward. The small temporal differences in the reception of each ear of the auditory stimulus are interpreted by the brain, yielding very precise information about the location of the prey.

Likewise, to try to identify the direction and the distance in which the sound is, these birds usually move their heads in different directions. Because of this, they need a flexible neck, which allows you to turn your head up to 270 ° in different directions.

Taxonomy and classification

- Animal Kingdom.

- Subkingdom Bilateria.

–Filum Cordado.

- Subfilum Vertebrates.

- Tetrapoda superclass.

- Class Aves.

- Order Strigiformes.

Strigidae family

Subfamily Asioninae

Genres: Asio, Pseudoscops, Nesasio.

Subfamily Striginae

Genres: Bubo, Ketupa, Jubula, Lophostrix, Mascarenotus, Margarobyas, Megascops, Psiloscops, Otus, Ptilopsis, Pyrroglaux, Pulstrix, Strix, Scotopelia.

Subfamily Surniinae

Genres: Aegolius, Glaucidium, Athene, Micrathene, Heteroglaux, Surnia, Ninox, Sceloglaux, Xenoglaux, Uroglaux.

Feeding

Bubo nipalensis. Dinesh Kannambadi

The diet of owls is very varied and will depend on the habitat where they are. Some feed on small mammals, such as mice, rats, squirrels, bats, and rabbits.

They also consume various invertebrates, among which are crabs, spiders, snails, insects, and some earthworms. Likewise, they eat amphibians, reptiles and other birds, such as magpies, partridges, pigeons and corvids. Fishing owls hunt freshwater fish.

The eagle owl (Bubo bubo) is the largest bird of prey in Europe. It is a predator capable of capturing large prey, up to 10 kilograms. Some of these are the fawn, the fox and other large birds, such as the buzzard and the red kite.

In the winter time, their diet can change drastically. This is because their main prey hide in their burrows, from which they rarely emerge. Thus, this bird quickly modifies its diet, adapting it to the new climatic demands.

During this season, Strigidae usually store their prey for several days. To thaw them, these birds "incubate" them, heating them before eating.

Food diversity

The trophic specialization of this bird is the product of its evolutionary history and its ecology. There is a close feeding relationship between owl morphology, ethological and ecological aspects.

Thus, the feathers, legs and hooked shape of their beaks are linked to their foraging and habitat conditions. In this way, large predators, such as the eagle owl, capture larger prey than those of smaller size.

Also, those that hunt while flying tend to hunt over more mobile prey than those that use the stealth stalking technique.

In this order of ideas, within this group of nocturnal birds of prey there are taxa that have specialized in the predation of vertebrate animals. Examples of this are Asio flammeus and Tyto alba, which base their diet almost exclusively on rodents.

Others, like some species of Megascops, prefer invertebrates. However, the vast majority adapt to the seasonal diet. Thus, the feeding of a species could be more related to the availability of prey than to the specific predilection for any of these.

For example, in A. flammeus, due to the scarcity of rodents in their natural habitat, it incorporates insects and birds into the daily diet.

Feeding methods

Although some owls hunt during the day, the vast majority of species are nocturnal. These raptors are adapted to hunt in low light conditions. For this they use their sharp vision and the excellent sense of hearing they have.

In addition, the characteristics of their plumage make them have a silent flight, which allows them to stalk the animal without it noticing. Among the adaptations to allow this is the rigid crest of feathers that they have along the entire front edge of the wing.

Likewise, the velvety material found on the wings also plays a role in this regard. On the outside of this they have a flexible strip.

Strigidae are very patient hunters, being able to remain immobile for a long time on a branch, observing every movement of their prey. When the right moment comes, they fly in absolute silence, and the capture occurs in fractions of a second.

Another hunting technique is known as active search. In this, the owl stealthily flies large areas of land in search of its prey. You can catch it by diving vertiginously on it or while it is in flight.

Digestion

With the force of its claws it manages to immobilize its prey, which often offers no resistance. Then he moves it to another area to consume it. Sometimes it can transfer it quickly to the peak, devouring it quickly.

They tend to swallow all of their food at once. When the prey is very large, they use their beak and claws to tear it into smaller pieces. As they do not have a crop, unlike other birds, everything they eat goes directly to the stomach, where it is digested.

Strigidae, like some birds, after about 10 hours have elapsed after eating, regurgitate the pellets. These contain those elements that they could not digest, such as bones, skin and feathers.

Reproduction

Bubo coromandus. JMGarg

The owl reaches its sexual development when they are between 1 and 3 years old. However, some small species can reproduce at one year of age.

From that moment, both the male and the female are fertile, since they have the sexual, physical and anatomical maturity to reproduce. However, if basic survival conditions are not guaranteed, the owl could delay mating for a while.

The vast majority of owls in the Strigidae family are monogamous. Many couples have strong bonds between them, such that they could last together for several seasons, even for life. Such is the case with the Ural owl (Strix uralensis) and several small owls.

However, in the case of abundance in food, some species, such as the boreal owl (Aegolius funereus), usually form two pairs simultaneously.

Others may get together during one breeding season and look for a new mate during the following season. In conclusion, the mating behavior could depend on the characteristics of the species, population fluctuations and the availability of food.

Mating

The reproductive period may vary according to the regions and geographical latitude of each species. For those who live in cold areas, heat begins with the arrival of winter, a date that coincides with the time when the young disperse. In warmer areas, Strigidae zeal in early spring, when the temperature is much more favorable.

Courtship

Courtship is a very important stage in the mating process. In this, the male performs very varied behaviors, among which are the calls. These could be carried out for a month, in order to attract the females to their territory, in which the male generally stays most of the time.

You could also do it to renew the bond with a previous partner who is within the group. After he achieves his goal, the male often offers food to the female, thus demonstrating his suitability as a food provider for her and her young.

You could also show her the nests that are within the area. Once they have formed a couple, they both vocalize, as if singing a duet. This is one of the main characteristics of courtship in owls.

Another of the behaviors of the mating ritual are aerial displays, in which the male rises and strikes the body with his wings, trying to impress the female. Also, the pair could fly and turn over the territory.

Nesting

Strigidae do not build their nests. They usually nest in the ground, in shallow crevices, or between plant roots. In addition, they can also do it in caves or in tree cavities, either natural or those made by woodpeckers.

Others lay their eggs underground, as is the case with the Burrowing Owl (Athene cunicularia). Thus, they use the burrows that have been used by rabbits. The largest species take the nests of other birds, among which are hawks and crows.

Generally, the pair choose the same nesting place, to which they return each year. To make the nest more comfortable, they usually use their own regurgitated pellets.

Incubation

The eggs are round and white. The number of eggs the female can lay varies between species. However, the average is 2 to 4, and may be higher if the feeding conditions are abundant.

Some fishing owls lay an egg, while others, such as the burrowing owl (Athene cunicularia), may lay up to 10 eggs.

The time interval between the laying of each egg is between one and two days, and can go up to four. When this happens, the young are born with significant differences.

The female begins to incubate from when she lays the first egg. This process could last from 22 to 32 days, in the case of larger species. During this time they rarely leave the nest, since the male is in charge of feeding.

The babies

When the chicks hatch, their bodies are covered with short, brown feathers. The male continues to carry food to the nest, where the mother regurgitates it and places it directly on the beak of each young. They do this until they are three weeks old.

Once that time has elapsed, they already feed themselves, with the food that the male brings them. When they are 6 weeks old, they fly out of the nest to explore their surroundings. Short flights begin to be carried out in week 8 or 9, being in week 14 when they completely abandon the nest.

Habitat and distribution

Bubo capensis. s9-4pr

Owls are distributed throughout the world, except Antarctica. They are birds that easily adapt to various ecosystems, provided that they have the basic conditions in terms of climate and food, among others.

These animals belong to the group of birds that rarely make an annual migration. Some may move, when the temperature drops, to warmer places. However, the vast majority remain in the place where they were born, as long as there are no alterations in their environment.

Location of some species

The snowy owl (Nyctea scandiaca) inhabits the northern tundra. During the breeding season and in the summer it prefers the treetops. Other species, such as the snowy owl, are found in both the Old and New World.

The genus Otus is the largest of the Strigidae family, with a total of 63 species. One aspect that characterizes them is that around 30 of them live on islands, small or large. Thus, the Otus rutilus is found throughout the Madagascar region.

The Otus nudipes inhabits the Virgin Islands and Puerto Rico, being abundant on Culebra Island; and it is believed extinct on the island of Vieques. The Bubo virginianus, known as the Great Horned Owl, has a wide variety of habitats, ranging from Alaska to Argentina.

Another species widespread worldwide is the Eurasian owl, which lives in the Old World, in territories ranging from Norway and Spain to eastern China, northern Japan and Russia.

The group of fishing owls is located in Southeast Asia and Africa. The Blakiston owl is one of those that inhabits the most northern area, southeast of Siberia, the island of Sakhalin, Manchuria and the island of Kuril.

Members of the genus Strix, called wood owls, are evenly distributed throughout the world, preferring forested regions.

The genus Ninox lives in Australia, New Zealand and throughout Southeast Asia. However, there are two exceptions: Ninox scutulata, which lives from Japan and Siberia to India, and Ninox superciliaris, which lives only in Madagascar.

Habitat

Owls live in almost all habitats except high altitude ones and treeless deserts like the Sahara. However, the highest concentration of Strigidae, almost 80%, occurs in lowland forests, compared to high-altitude tropical forests.

However, there are species, among which are the Bubo ascalaphus, that live in xerophilic regions. These have a golden plumage, which allows them to perfectly camouflage themselves in the desert where they reside.

Similarly, the coloration of Hume's owl (Strix butleri) also contributes to its being unnoticed in the arid habitat in which it develops.

Fishing owls, belonging to the Scotopelia and Ketupa and Scotopelia genera, are distributed along rivers, lakes or swamps, where they can hunt the fish that make up their diet.

Description of some habitats

Glaucidium passerinum and Glaucidium californicum prefer the edges of deciduous or coniferous forests. The species that live further south, such as Glaucidium perlatum, are located in scrublands and coastal areas.

One of the Strigidae with an open habitat is the Burrowing Owl. It lives in North America and in South America, in the desert grasslands and arid plains of these regions.

The best known non-forest species is the snowy owl. To mate, they do so in various areas of the arctic tundra, in elevated regions or on rocks.

Behavior

Owls have solitary habits, less when they are in the reproductive stage. Some, like the Asio otus, gather in shelters during the winter, forming groups of up to 20 birds.

To socialize, they emit vocalizations. These can range from the growl, much like that of the pig, to the deep screech of the great owls. Such calls are often used to call young people, to intimidate intruders and to mark their territory.

They can be accompanied by various body postures. While emitting them, some owls lean forward slightly, thus revealing the white feathers on their necks, which look like a flash in the middle of the night.

Likewise, they move the strands found on the ears in different positions. An aggressive posture for Strigidae is when they spread their wings, raising them and turning them so that the back is facing forward. At the same time, they inflate the feathers on their body. All of this makes the owl's appearance look bigger.

When these displays are combined with the loud sound they can make from their beaks, they give this bird the appearance of a fierce threat, which many predators avoid.

Danger of extinction

Because most live in tropical regions or on islands, they are vulnerable to their habitat being destroyed. In 1994, BirdLife International noted that 11% of owl species are in danger of becoming extinct, while 7.4% are very close to this.

The main cause of population decline is forest fragmentation. Man has destroyed the natural habitat of owls, to build urban settlements and roads. Likewise, this has caused many rivers to dry up, disappearing with them the fish that are part of the diet of some species.

An example of the negative influence of man's actions on these birds is the Athene blewitti, which lives in India. In 1997 it was rediscovered, after 113 years since the last verified record of this species.

Six months after this, the cutting of the trees devastated their habitat, significantly reducing their chance of survival.

The Strigidae are threatened by persecution, poisoning and by illegal capture for commercialization. Also, because their flight is low and slow, many die while crossing the roads. This is the product of its collision with the vehicles that pass by.

Captivity (laws and care)

Care

accommodation

Within the first 30 days of birth, the baby can be in a small box. This is because in the early stages it moves little. The temperature must be controlled and a white paper towel, which does not have dyes, can be placed as a substrate.

After this time and until day 49, the chick should have enough space so that it can make some small jumps and spread its wings. Likewise, the area must allow the young man to hunt with the food that is supplied.

After day 50, the cage should allow him to exercise his first attempts at flight. It is recommended that the same box be placed in that place where it was previously, so that it sleeps in it.

To avoid stress to the bird, experts suggest avoiding eye contact with other animals or people. For this, the cage must be covered with canvas on the inside, leaving the roof uncovered, so that you can observe the environment. In this place, the young owl can remain until it is released.

Feeding

The ideal diet for owls should include small mammals and some birds. An important aspect to consider is that they have a quality certification, because if the food is contaminated it could cause serious damage to the young.

Ectoparasites

If the chicks have external parasites, they must be eliminated, because they can cause various conditions. The most common infectious agents in the nest are mites of the genus Dermanyssus. These could slow its growth, cause allergies and even death.

Imprint

To avoid imprinting, the young could be fed a puppet similar to the face of an adult owl. Food could also be entered in such a way that the chick does not see the breeder's face.

Release

The release process must consider that the bird is in perfect health, that it has been previously fed and that it is carried out in the early evening hours.

Protection laws

Strigidae are included in Appendix II of CITES. In this are those species that, although they are not in serious danger of extinction, could be if their commercialization is not regulated.

Within the controls, an export permit is necessary. Although within the CITES legal framework an authorization to import is not contemplated, some countries have strict legislation that imposes rigorous measures in this regard.

References

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2. Wikipedia (2019). Strigidae. Recovered from en.wikipedia.org.
3. Nicole Bouglouan (2019). Recovered from oiseaux-birds.com.
4. ITIS (2019). Strigidae. Recovered from itis.gov.
5. Grzimek's Student Animal Life Resource. (2019). Owls: Strigidae. Recovered from encyclopedia.com.
6. R.MartinD.Osorio (2008). Vision in Birds. The Senses: A Comprehensive Reference. Science Direct. Recovered from sciencedirect.com
7. British Trust for Ornithology (2019). Strigidae - Owls. Recovered from BTO.org.
8. Julia B. Ponder, Michelle M. Willette (2015). Strigiformes. Recovered from sciencedirect.com.