Decline of nocturnal birds of prey: Barn owl

Rahul Ashem *

Barn owl is one of the common cosmopolitan nocturnal birds of prey. Changes in vegetative structure, small mammal abundance and other ritualistic activities led to the decline of Barn owl populations. In Manipur, most of the owl species are believed to be a sign of ill omen.

Nocturnal birds of prey play an important role in the ecological cycle of life. They are carnivores, with beaks and claws adapted to tear flesh from their prey. Majority of the crepuscular birds are considered as biological indicators because of their versatile habit of nature. In the present era, the changes in land use pattern, urbanization and infrastructural development faces serious threat to such bird of prey.

Clearing of forests, habitat loss and fragmentation are other multiple issues on the decline of nocturnal habitats. Recently, a family of barn owl was fluttering unsteadily in Moirang kampu area near Chingkhei ching, a range of Nongmaiching hills in Imphal east district. The hill 'Nongmaiching' known as healthy and pristine forests since Puyanic time is now being degraded due to the fragmentation of foraging habitat.

The result of degradation led to the disturbance of ecosystem services and other wildlife habitat in the surrounding Puyanic hills. The opening of vegetative structure changes the rodent population and threatening the survival of barn owl populations by eliminating their food source in the area. It also affects the nesting sites which in turn reduces the reproductive output and adult survival in the long term.

Furthermore, the scenario of climate change as well as the effects of changes in farming practices on the barn owl populations. Therefore, it is the right time to understand the role of land use patterns in determining the distribution of nocturnal birds in order to conserve the species at the landscape or regional scale. Different species of birds has different capacitive dispersal abilities but the key success is to give all species the best possible chances of survival.

Barn owls are widely distributed in open habitat and low light medium to suit the ecological role as hunters of small mammals. They mostly hunt on rats, insects, frogs and occasionally on birds. Generally, 'Barn owl' possibly gets the name by making nest especially in barn areas surrounded by meadows, grasslands, fields or even buildings.

Sometimes, the species, Tyto alba are commonly known as Ghost owl' because of its white face features and underbelly feathers which is visually visible while flying. The Barn owl is protected Schedule IV species under the Wildlife protection act, 1972. It is listed under Appendix II of CITES. The barn owl is included in IUCN as least concern although hunting and trading is totally prohibited.

The special appearance of barn owl makes the species included in different species and probably the most specialized of all owls family. Unfortunately, the barn owl is susceptible to extinction, partly because of natural evolutionary selection and partly because of human interference. Conversely, most of the owl's species are threatened by other activities of humans.

Mythlogically, the barn owl is honored as the carrier of goddess Lakshmi, the deity of wealth. The same bird is feared as the ill symbol in several literary texts. However, at the same time, the barn owl is illegally trafficked for their body parts that are falsely considered to have medicinal and occult healing properties. They are the major victims of environmental contaminants as they occupy a wide range of tropic levels in different food chains.

Scientifically, it is said that the barn owl plays an important part in the ecological cycle of life. They scavenge and dispose of carrion, control rodent populations, and eat various pests that are harmful to crops. They also provide benefits to humans by killing large numbers of small rodents which might otherwise eat crops in the field or in grain storage.

As recorded, a typical family of barn owl consumes about 1000 rodents during the 10 week portion of the year when the young ones are in the nest. They are medium sized bird with long legs that sparsely feathered down to their grey toes. Barn owl is the only species of owls family to nest in buildings and around human settlements.

Survival status of barn owls is dependent upon the conservation of landscape and grass covered in the surrounding environment. Most importantly, land use pattern plays a key role in the existence of nocturnal birds of prey. Over the time, there are significant changes in bird migration, shifting of ranges and abundances due to the modification of landscape and habitat fragmentation.

Large areas of the forest are being diverted for developmental projects, displacing wildlife and local communities living in the fringes. As a result of altering land use pattern, many of the wild species including the nocturnal birds of prey have become vulnerable in the State. Such disruption of ecosystem services reduces the bird populations and even leads to local extinction.

For example, an oriental scops owl (Otus sunia) was captured and killed in Purul Atongba in Senapati District because of the lack of ecological importance of owls. Scops owl is a common dweller bird in forests and other well wooded areas. Urbanization and infrastructural development in the Imphal valley also causes serious threat to such nocturnal birds.

Urban development is likely to increases the exposure of wild species to a range of contaminants. The urban associated predators alter the composition of the rodent community in areas adjacent to urban development. Similarly, the introduction of mobile tower, amount of residential and commercial land area within the home range reduces population density of nocturnal bird of prey.

Logically, it is said that the presence of mobile tower has possible chances of affecting the bird's diversity in the surrounding environment. The result is that the surface area of a bird is relatively larger than their weight in comparison to human body. They absorb more radiation (power= power density* area) since fluid content is small due to less weight, it gets heated up very fast and also the magnetic field disturbs their navigational skills.

Apart from bees, birds and animals, electromagnetic radiation emanating from mobile tower also affect vegetables, crops and plants in the vicinity. Studies show definitive clues that mobile tower wave even choke seeds, inhibit germination and root growth, thereby affecting the overall growth of agricultural crops and plants.

In fact, the disappearance of barn owl appears to be linked to a complex set of factors including climatic changes, fragmentation and loss of specialized habitat. Therefore, it is the right time to start awareness drive and more scientific to highlight the usefulness of owls in controlling rat population and to educate people about the false nature of superstitious beliefs.