The Future Problem of House Sparrows Regarding Nest Construction in Kolkata, India

It was revealed that the nests of House sparrow (Passer domesticus), in Kolkata, India, are mainly composed of different types of grasses of the plant family : Poaceae, during the study of some nest-building materials of House Sparrow, in the University laboratory and also at my home. It was also found that among the all types of Grasses, mainly Cyanodon dactylon (Local term : Durba Ghass) species was used (about 50% or more in different nests) by the House Sparrows to construct their nests. These grass elements have been collected by the House Sparrows to construct their nest as well as to sew the other elements of their nests. They collect those grass elements from the near grassland, playfields, unused lands of a house/home etc.

# 2

On the other hand, as we know that the human population is rapidly increasing and simultaneously the growth rate of the industrial belts, agricultural demands, overgrazing by domestic animals, urbanization procedures are also increasing very fast. These are causing the decreasement of grassfields for building factories, official houses and private houses, and to convert grassfields to agricultural and horticultural fields. It is well known that most of the agricultural and horticultural field are devoid of grasses where they are treated as unwanted plants.

# 3

Now I am going to link between the above mentioned two paragraphs (# 1 and # 2).

It is a big question that if the total biomass of all grass species is reduced for the reasons of human population growth and it's consequences then, from where the House sparrows will collect their nesting elements ? The increasing demand for land is increasing the probability of declination of the nest-building elements as the land use rate diminishes the number of grasses on the lands. It is generating a great threat to the reproductive success of this bird species (because House sparrow is chiefly dependant on grasses to prepare their nests) reducing the probablility of nesting as a part of their parental care in the Kolkata city and also in other cities over the whole world. Other wise this bird will be either compelled to collect nesting materials other than grass elements or they will be introduced in the red listed categories in near future showing the probablility of extinction. But if they choose other elements besides grasses for nest building, like 'throw away' materials of man, different unhygienic parts will be introduced into their nests and that will threat the hygiene of the young of this bird.

# 4

To overcome the above problems we should think about the importance of grasslands related to nesting of House Sparrows and other city birds. We should keep some grasslands free from the curse of urbanization to maintain the ecological balance of the environment.