Learn about the bird pests that damage crops and its control.
1. House Crow, Corvus Splendens Vieillot (Passeriformes: Corvidae):
The house-crow is distributed throughout the plains of the Indian Sub-continent, Sri Lanka and Myanmar. From the tip of the beak to the end of the tail, it is about 45 cm in length. It is to be distinguished from another allied species, the jungle-crow, Corvus macrorhynchos Wagler, which is more abundant in the mountains.
The jungle-crow is larger and is glossy jet black with a heavy bill. The house-crow is grey and has black and grey wings with a black area on the throat and the forehead. It is perhaps the commonest bird in India and abounds in the vicinity of towns and villages, living in close association with man.
Habits:
The house-crow is a very intelligent and cunning bird, and is usually not afraid of women and children. It is a constant nuisance in the houses and is always on the look-out for stealing tit-bits. Crows have the habit of community roosting in selected trees in the outskirts of towns and villages to which they are seen flying in large numbers every evening.
A crow’s nest is in the form of a platform made of twigs with a cup-like depression in the centre. The twigs are intermixed with iron wires, threads or other fibres and the depression is lined with coir fibre, etc. It is 3 metres or more above the ground and sometimes there are several nests in a tree. The nesting season is from April to June and 4-5 eggs are laid at a time. The eggs are pale blue green and are streaked with brown.
They are incubated and the feeding of the young ones is shared by both sexes. The shrewd or cunning koel (Eudynamys scolopacea) is often seen hanging around the nests of crows in which she lays her own eggs and throws out of the nest an equal number of crow eggs. The young ones of the koel are brought up by the naive crows as their own. Thus, the koel acts as a biological parasite on the latter.
The house-crow is an omnivorous bird and may feed on dead rats, carrion, kitchen scraps, locusts, termites, the eggs of other birds and the ripening grains of maize and fruits. At times, damage to the ripening crop of maize can be very serious. The crows are particularly attracted to maize when it is exposed on the cob. They are often seen in flocks in maize and other fields.
Control:
(i) The crows have a great sense of communal alarm and, if one of them is killed, the whole group creates a tremendous noise; therefore, a dead crow hanging on the top of a pole can effectively be used as a scare-crow.
(ii) Destroy eggs and nests during June-August.
(iii) The maize cobs on plants can be protected by wrapping one or two of the nearby leaves around them.
(iv) A large wire-gauze case, 2 × 1 × 1 metres, having on one side a converging entrance, can be used as a trap for crows if some attractive food is kept inside. As soon as two or three are caught, they should be removed through a side-window, otherwise they will deter the others from getting into the trap, and
(v) A piece of chapatti dipped in 0.3 per cent methyl parathion placed on top of a roof is good bait.
2. Weaver Bird, Ploceus Philippinus (Linnaeus) (Passeriformes: Ploceidae):
The common weaver-bird is distributed throughout India, Pakistan, Myanmar and Sri Lanka. It is the size of the house-sparrow and its colour resembles the female sparrow when it is not in the breeding season. It is dark-streaked, fulvous brown above and plain white fulvous below.
Habits:
The male builds a number of intricately and compactly woven nests which are retort- shaped with a long vertical entrance tube. The nests are made of paddy leaves and grasses and are seen in clusters hanging from ber (Zizyphus spp.) or other medium-sized trees near ponds or water holes. Mud is used for plastering the egg-chamber on the inside. By completing these nests, the male attracts a number of females who then incubate their respective clutches of 2-4 pure-white eggs. Breeding takes place from May to September.
The birds are active during the paddy season because this crop provides food as well as nesting material. In paddy areas, they roost in very large numbers as governed by their seasonal local migration. They can cause quite heavy damage particularly to the early-ripening crop.
Control:
The periodic collection and destruction of nests would lead to reduction in their population.
3. House Sparrow, Passer Domesticus (Linnaeus) (Passeriformes: Ploceidae):
The house-sparrow has always followed human civilization and is practically world-wide, the races from the temperate regions being somewhat larger. In India, it is equally common on the plains and the mountains up to 2,150 metres. The female is ash to greyish brown above and fulvous ash-white below. The male is 15 cm long, darker above, with blackish streaks on the wings and a black patch on the throat and breast. It has prominent white cheeks.
Habits:
This is the most familiar bird in cities and villages alike. Its constant chirping, tsi, tsi, tsi or cheer, cheer, cheer is too well known to us all. It breeds practically all year round and makes nests in the holes in walls or ceilings of houses by using straw, rubbish and feathers. The eggs are greenish white, blotched with brown. Three to five eggs are incubated at a time and several successive broods may be raised.
The sparrow is omnivorous and feeds on insects, fruit-buds, flower nectar, kitchen scraps and grains of all sorts. The non-breeding birds roost in large groups in leafy medium-sized trees. They visit the ripening fields, particularly those of wheat in the spring season and cause much damage both by feeding and by causing the grains to shed.
Control:
(i) Destroy eggs and nests during April-May and September-October.
(ii) Bajra (Pennisetum typhoides) seeds soaked in 0.3 per cent methyl parathion emulsion and dried, are placed in small cups and hung from the rafters or branches of trees. The poison bait is expected to be more effective in that season when no ripe grain crop is available in the fields.
(iii) Spraying the wheat crop when ears are in the milk stage with Thiurum (TMTD) 0.6 per cent, repels the sparrows and protects the crop.
(iv) In China, people were encouraged to catch and eat sparrows and thus the effort was successful in eliminating the pest.
4. Common Myna, Acridotheres Tristis (Linnaeus) (Passeriformes: Saturnidae):
The common myna is distributed throughout the Indian Sub-continent up to 2,750 metres and is also found is Myanmar and Sri Lanka. It is about 22 cm in length, being larger than the bulbul (Pycnonotus cafer) and smaller than the pigeon. It is a dark-brown bird, with a bright yellow bill, legs and patches around the eyes. As it flies, large white patches become visible on the wings. The birds live in pairs or in groups and are common near human habitations or in the countryside.
Habits:
The bird is known for its sharp chattering calls which are quite annoying to the ear. It breeds from April to August, raising two broods in succession. The nests are built in tree-hollows and holes in walls or ceilings. During the nesting season, the birds are seen collecting twigs, roots, rubbish and paper or tin foils from cigarette boxes. Four or five glossy blue eggs are incubated at a time and both sexes participate in raising the young ones.
The birds are omnivorous and feed on insects, earthworms, grasshoppers, fruits and kitchen scraps. They are pests and nuisance around houses and pick up all sorts of grains from the threshing-floors or from the fields. They are seen in ripening maize and wheat fields feeding on grains and their flocks are found alongside those of crows and parakeets.
Control:
(i) Destroying the nests goes a long way in checking their multiplication.
(ii) Since it is a clean bird, its shooting as a game should be encouraged in the field.
(iii) They can be killed by feeding them on chapatti soaked in 0.3 per cent methyl parathion emulsion.
5. Green Bee Eeater, Merops Orientalis Latham (Croaciformes: Meropidae):
This bird, the size of the house-sparrow, is found throughout the Indian Sub-continent, Myanmar and Sri Lanka. It is grass green, tinged with reddish brown on head and neck. It has a slender, long; slightly curved bill and the central pair of tail feathers have blunt extremities.
It is distinguished from the larger allied species, the chestnut-headed bee-eater, Merops leschenciulti Vieillot, which has a bright chestnut head and anterior back, without the long tail feathers. The blue tailed bee-eater, Merops philippinus Linnaeus, is larger with the crown, throat and breast a deep chestnut and a blue tail.
Habits:
The common green bee-eater, like the other species, is a resident or a local migrant. lt inhabits open country and is found near gardens and woodlands. It is often seen sitting on electric or telephone wires snapping at honeybees and other wild bees, flies and wasps. In the evening, it roosts in large numbers in its favourite leafy trees.
It makes a horizontal or oblique tunnel-like nest in the side of earth cuttings, sides of hillocks in the Shiwaliks or in uneven sandy ground. The eggs are pure white, roundish oval and 4-7 of them are placed in the widened egg-chamber. Both sexes participate in excavating nests and feeding the young.
This bird is extremely destructive to domesticated honeybees and is the cause of the failure of beekeeping in certain areas. In the plains their numbers become numerous in April-May and again in August-September.
Control:
(i) Locating the burrows and destroying the eggs may give some relief.
(ii) They should not be allowed to sit on trees and wires near apiaries and should be killed or chased away with air-guns.
6. Rose-Ringed Parakeet, Psittacula Krameri (Scopoii) (Psittaciformes: Psittacidae):
The rose-ringed parakeet, commonly known as tota, is one of the commonest birds in India, Pakistan and Myanmar, and is distributed from the Himalayan foothills right up to Sri Lanka in the south. In the hills of southern India.it has been recorded up to 1500 metres. It is slightly larger than the common myna, is grass-green and possesses a typical short massive and hooked red bill.
The male has a black and rose-pink collar, whereas the female is plain. It is distinct from the Alexandrine or the larger Indian parakeet (rai-tota), Psittacula eupatria (Linnaeus), which is larger, somewhat the size of a pigeon and has a more powerful voice. In addition, the male of rai-tota has a conspicuous maroon patch on each shoulder and also has a rose pink and black- collar.
The female of this species is also grass-green but is devoid of the collar. There is yet another species, the blossom- headed parakeet (tuiatota), Psittacula cyanocephala (Linnaeus) which is the size of the common myna and is an inhabitant of the more wooded country and is also found in the Himalayas up to 1,850 metres.
The head is bluish at the crown and red below and the male has a small maroon patch on each shoulder. The female does not have the shoulder patches and its head is greyer with a bright yellow collar round the neck. This parakeet is a swift flier and it easily flies in between the trees.
Habit:
The rose-ringed and the large Indian parakeets are found living together in lightly wooded country on top of leafy trees, near orchards or cultivated areas and they are common in towns and villages alike. Quite often, they form large flocks and roost near the source of food which is primarily the ripening fruits, maize and other grains. They make much noise and chatter and the sharp screams (keeak, keeak, keeak) of the rose-ringed parakeet are quite characteristic.
Both the parakeets can be caged and they learn to repeat a few words or perform various circus tricks. Their nests consist of natural or dug-out hollows in trees and they may also utilize the holes in walls or rocks for this purpose. The nests are at moderate heights and there may be 4-6 pure-white rounded eggs in one clutch. Both male and female share the domestic duties of incubation and feeding during the breeding season which is December to April.
The parakeets are among the most wasteful and destructive birds. They gnaw at and cut into bits all sorts of near-ripe fruits such as guava, ber, mango, plums, peaches, etc. The ground underneath the fruit-trees is sometimes literally covered with dropped fruits and refuse. The birds are equally destructive to ripening cobs of maize and jowar (Sorghum vulgare) ears, and are often seen carrying and flying with ears of wheat. In the maize field, they are seen in large flocks and cause tremendous damage to the crop.
Control:
(i) The control measures include the location of nests and the destruction of eggs or the fumigation of holes with aluminium phosphide at the rate of 0.5 g tablet per hole, so as to kill the young ones,
(ii) Orchard owners often throw stones with gulel (slingshot) or try to frighten them with crackers or make noise with empty kerosene tins, with some success,
(iii) Killing them with shot-guns is very effective but expensive, and
(iv) The parakeets do not accept poison baits. They can be repelled from maize and sunflower fields using malathion 5 per cent dust on cobs, sunflower heads, especially on outer rows in maize.
7. Blue Rock Pigeon, Columba Livia Gmelin (Columbiformes: Columbidae):
The blue rock pigeon is about 32 cm long, widely distributed in Eurasia, and in India it has been recorded up to 4,000 metres in the Himalayas. It is the most familiar bird near churches, temples, historical buildings with minarets, power-houses, railway station, grain warehouses, etc. It is slightly grey with a glistening metallic green, purple and magenta sheen on the neck and upper breast. There are two dark bars on the wings and a band across the end of the tail.
Habits:
In the wild state, it abounds in mountain cliffs or old and crumbling battlements, outlying cultivations, but in the semi-domesticated state as a commensal of man, it has learnt to live in towns and even in noisy cities. It breeds practically throughout the year and makes nests by collecting a few sticks and lines them with rags and feathers.
The nests are located in the holes on cliffs, rafters and ceilings of the houses, particularly those uninhabited. The projections outside ventilators or sunbreakers in modern houses are commonly utilized by them for building nests and raising their broods. There are generally two white elliptical eggs in a clutch and both sexes share domestic duties.
Pigeons generally roost together in large numbers and visit, in huge flocks, the ripening grain fields, threshing-floors, etc., where they feed. They use up quite large quantities of wheat, bajra (Pennisetum typhoides), sorghum, maize, etc. Individually or in small groups, they are always around to pick up grains from here and there. In large buildings, they are a nuisance as they cause noise and make the floors and walls dirty with their droppings. In powerhouses, they are a special hazard. While sitting around on wires and insulations they cause short circuits and power failures.
Control:
(i) The meat of the rock pigeon as well as that of the dove is quite tasty and, therefore, they can be killed as game.
(ii) The strategic places in power-houses should be protected by installing chicken wire-netting around the weak spots.
(iii) Destroy eggs and nests during March-June and September-October.
(iv) They can also be killed by feeding on poisoned bajra grains (see under ‘House-sparrow’).