Birds and mammals damage to crops is significantly higher in fields closer to forest patches
Answers
Birds often causes severe damage to agricultural crops and several reasons with which incidence of damage seems to be increasing.
Nature of modern agriculture and its stress on mono culture and highly specialized crops and high cost of bringing crop to the harvesting stage when any bird damage normally happens are the factors involved.
Perfect estimation of the value of grain destroyed by birds is extremely difficult to get.
Many field surveys has been made but among them most convincing are those involving ducks and little grain in Canadian Prairie Provinces, California blackbirds and rice in Arkansas and blackbirds and corn in Ohio and other states.
Losses of grains in Canada has become very serious that major efforts had been made to check them.
Devices of different kinds to frighten birds and spreading grain near marshes to lure birds from unharvested grainfields are two ways that had been used.
Both are expensive and they aren't effective everytime.
Yes the given statement is true that birds sometime causes a lot of damage in the fields because they came out of the forest in search of food and grains are one source of food to them and the pickup the grains and thus they destroy the grains and become and suitable for used by the human.
In various parts of Canada and North America it has been observed that the fields and the paddy fields which lies near to the forest are more prone to attack by the crows. As a result they have to take measures to prevent this which is costly and maybe sometimes ineffective.