In general the bird fauna of towns tends to have a lower species richness and divesity than nearby forest, but the biomass and density are higher, and there are a very few dominant species. In addition, the major guild shifts from the bark and canopy insect eaters to ground feeders. These changes are not surprising since relatively few urban trees exceed 10 m in height, and they are often widely dispersed between large areas of grass or hedges. The total number of individual birds and bird species is low in urban centres. Part of the reason is the predatory habits of young children with catapults, but ecological reasons include the lack of fruit suitable for birds and the few insects able to utilizzze the 'foreign' trees, leading to less food being available for insectivorous or partially-insectivorous birds.
The eurasian tree sparrow has spread widely in Indonesia. It is native of Eurpe, Russia and China, an probably first arrived in Indonesia aboard ships in the 16TH and 17TH centuries. The most frequent feeding preference is for insects accounting for 24 of the 39 species above. Some of these eat insects as a major part of their diet, while others eat insects as an important component of their diets when a higher protein intake is required such as during moulting or breeding or when they are feeding young. Insects are more abundant on trees with finely-divided leaves such as Samanea, Casuarina, Delonix, Parkia and Albazia, probably because of the greater number pf potensial resting places. Insect-rich microhabitats are also created by the growth of epiphytes, creepers and climbers on the trees.
The proprtion of nectarivorous birds is very small, but they are attractive to urban dwellers because of their bright colurs and their pleasing songs. In addition, the flowers from which they suck nectar are generally large and showy to attract these birds (as well as butterflies) to heights at which they can be easily seen, lants such as Hibiscus rosasinensis, Ixora and Calliandra can be planted.
Birds need not only food, but also places and materials for nesting. Two of the most favoured nesting materials are the fluffy seeds from Ceiba pentandra and long grass. Certain swiflets also use the dead leaves of Casuarina. Thus, these plants must be available in any area where birds are being encoraged to live. Hole-nesting birds can also be encouraged by leaving dead boughs in place, but only where human life is not endangered. In summary the best way to attract birds to urban areas is to provide areas of heterogenerous vegetation-tall aand short trees, shrubs and undergrowth, including long grass-and protecting from catapults.