20 March was celebrated as World Sparrow Day. The first edition of this day was celebrated in 2010 in different parts of the world. Historically, house sparrows (Passer domesticus) have cohabited with humans, while also playing the role of an indicator species for assessing ecological quality. Sparrows survive mostly on grains, insects, fruit buds and flower nectar. Insects present in herbs and shrubs also form an important food source and help in sustaining sparrow populations. Their nesting sites are often in close proximity to human habitation. Preferred nesting sites include roof overhangs, holes, or even masonry or rock (Khera et al. 2009).
The house sparrow has traditionally been associated with human habitation and was believed to be one of those species that persists even in the face of increasing urbanization. However, as indicated by several population surveys and reports, this has not been the case. Shaw et.al (2007) describes the areas of north-western Europe where the decline in house sparrow has been abrupt. While an aggregated 47 percent decrease in sparrow population has been recorded in England, the species has achieved near extinction status in Glasgow and Germany. In fact, the decline has been so drastic that the sparrow is on the red list of species that are of special conservation importance in the UK. In India, an ornithological survey conducted by the Indian Council of Agricultural Research (ICAR) has estimated an 80 percent drop in sparrow population in Andhra Pradesh and a 20 percent drop in the states of Kerala, Gujarat and Rajasthan (Kumar et al, 2018). The problem of declining sparrow population is further exacerbated in the coastal regions of these states. Similarly, ‘Common Bird Monitoring of India’ – a Citizen Science Program of the Nature Forever Society – an NGO – indicated the same pattern.
Population status reports indicating declining sparrow populations have been maintained and resounded in several journals (e.g. Journal of Endangered Biodiversity & Species), newspaper and magazine articles (e.g. Outlook India, Down to Earth, The Hindu, DNA Web Magazine, India Together Web Magazine), local and international NGOs (e.g. WWF-India, Hirval Foundation, Bombay Natural History Society), and accounts of ornithologists and other groups of concerned citizens who are involved in efforts for the conservation of house sparrows in India. State initiatives to recognize/emphasise dwindling sparrow population manifests in the declaration of house sparrow as the State Bird of Delhi in 2012.
According to Shaw et.al (2007), changes in socio-economic conditions in cities have played a role in affecting the population of house sparrows. They also state that, within cities, sparrows prefer the relatively socio-economic deprived areas over intensively built areas. In addition to preference based on the morphology of urban landscape, these birds are more suited to gardens which have rough grass and weedy patches, as this kind of vegetation is ideal for foraging.
Biotic factors that have affected their occurrence in urban spaces include competition from other avian species such as Common Myna (Acridotheres tristis), Rock Pigeon (Columba livia) and House Crow (Corvus splendens). These species have dominated spaces which were previously occupied by house sparrows, largely due to their greater adaptability to the changing nature of space and food availability in cities. For example, Rock Pigeons can feed their chicks with crop milk, whereas the chicks of house sparrows require a high-protein diet consisting of insects for their growth and survival. However, with the absence of herbs and shrubs in cities, the insect population has seen a decrease, consequently leading to less favourable conditions for the survival of the house sparrow (Khera et al. 2009). The vanishing of nesting spaces for sparrows in the time of rapid urbanization is also a formidable trigger for its decline in urban spaces.
Although it is hard to estimate the number of sparrows left in Delhi, experts agree that the house sparrow population has shifted from the urbanized areas to the forested areas and urban villages of Delhi. Within the city, parks and forests of the Delhi Ridge and other vegetation-rich areas like Lodhi Garden witness considerable sightings of house sparrows (Gandhiok, 2018). On a related note, a similar observation has been recorded in the Dheerpur Wetland Park of Delhi. Topographically, the park lies in the marsh and wetland areas of the Yamuna floodplain, which once extended from Azadpur to the present-day banks of the river. This 25.38 ha of land can be classified as a green space given that it bears attributes of a wetland. The sighting and recording of a significant number of house sparrows in the park find testimony in the monthly bird monitoring activity and other events like Campus Bird Count (2017-18). It is therefore pertinent to mention that while it is true that there has been inarguably a decrease or loss in the sparrow population in urbanized areas, not all urban spaces are deprived of house sparrow populations.
Species like house sparrow are in need of conservation as they play critical roles in ecology, maintaining stability in the natural food chain and food webs. Besides facilitating plant pollination by dispersal mechanism, sparrows help in pest control as at the fledgeling stage feed on small insect (commonly found in gardens) and on the larva of mosquitoes which breeds in the water stagnated around accessible areas of houses.
House sparrow counts are dipping in numbers susceptibly to loss of suitable habitat in urban areas. As mentioned above, green spaces in cities initiate bold difference in the pattern of regional-level sparrow population distribution. The importance of green spaces in urban areas has been discussed and emphasised in several studies of ecology and psychology from the point of view of sustainable aspects of nature in overtly urbanized/built-up regions, which has health and psychological implications and welfare benefits in society (Read more on Urban Green Spaces in previously published CUES blog post: https://cuesonline.org/2017/12/18/green-spaces-in-the-urban/).
- Kumar, A., Kanaujia, A., Kushwaha, S., & Kumar, A. (2018). Nopr.niscair.res.in. Retrieved 21 March 2018, from http://nopr.niscair.res.in/bitstream/123456789/31649/1/SR%2052%286%29%2014-19.pdf
- Khera, N., Das, A., Srivasatava, S., & Jain, S. (2010). Habitat-wise distribution of the House Sparrow (Passer domesticus) in Delhi, India. Urban ecosystems, 13(1), 147-154.
- Shaw, L. M., Chamberlain, D., & Evans, M. (2008). The House Sparrow Passer domesticus in urban areas: reviewing a possible link between post-decline distribution and human socioeconomic status. Journal of Ornithology, 149(3), 293-299.
- Gandhiok, J. (2018). Where have all the sparrows gone? Blame it on vanishing urban nesting spaces – Times of India. The Times of India. Retrieved 21 March 2018, from https://timesofindia.indiatimes.com/city/delhi/where-have-all-the-sparrows-gone-blame-it-on-vanishing-urban-nesting-spaces/articleshow/63372794.cms
- Anandan, G., Kumaresan, M., Thomas, A., Benickson, C., Devi, R., Geethu, M., . . . R, S. (2014). The House Sparrow is Homeless: A Small Attempt to Conservation. Journal of Nr UoJ Biodiversity & Endangered Species,2(2), 1000124th ser., 1-4. doi:10.4172/2332-2543.1000124