Guwahati: There are estimated 4 lakh sparrows in the city which comes as good news as the world observes World Sparrow Day.
In a new paper, “How many sparrows are there in a city of a million people? Understanding the population of sympatric sparrows in the urban gradient of a tropical city in Southeast Asia”, authored by Anukul Nath, Hilloljyoti Singha, Minarul Haque, and Bibhuti P. Lahkar have estimated around four hundred thousand sparrows in Guwahati. The present study creates a baseline information for the sparrow population and habitat use in Guwahati City.
Around the globe, the urban wild animals have been declining including the successful urban bird species─ the sparrows. Recent years have witnessed a decline in the number of sparrows in many parts of the world.
Six species of sparrows have been reported from the Indian subcontinent. Out of them, House Sparrow and Eurasian Tree Sparrow are associated with man-made habitats and human activity.
Both House Sparrow and Eurasian Tree Sparrow share the same human habitats in many parts of North-East India. These species are closely related and ecologically similar.
“In India, limited studies have been carried out on the population status of sparrows, and there is no historical data to compare the population trend. However, in our recent study, we have estimated the sparrow population in Guwahati city around 400,000. Survey of sparrows was carried out in 572 locations of different urban settings,” Anukul Nath of Wildlife Institute of India told EastMojo.
The study found that the overall density of House Sparrow was higher (29.15 individuals per hectare) as compared to Tree Sparrow’s density (9.51 individuals per hectare) in different urban gradients. The density of sparrows significantly differed among different habitats. The density of House Sparrow varied significantly among different habitats compared to Tree Sparrow’s density except for a few habitat categories.
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Commercial area mix with residential buildings had a higher number of House Sparrow (44.17 per hectare) followed by commercial areas (35.34 per hectare), mixed of residential buildings with Assam type houses (28.57 per hectare), residential building areas (24.88 per hectare), commercial-Assam type (24.51 per hectare) and Assam type houses (17.52 per hectare).
On the other hand, Tree Sparrow density was highest in residential building mixed with Assam-type houses (14.82 per hectare) followed by commercial-Assam type (14.62 per hectare), residential buildings (9.57 per hectare), mixed of commercial-residential type (9.08 per hectare), commercial (4.99 per hectare) and Assam type (3.72 per hectare).
“We found that sparrows were largely associated with complex urban structures, and the density of sparrows significantly differed between species amongst the habitat. House Sparrow density was three-fold of Tree Sparrow, and the occurrence of both the species was highest at mid-level of urbanization,” Hilloljyoti Singha of Bodoland University told EastMojo.
Singha said Tree sparrow had low density compared to House Sparrow in areas where urbanization peaked. House Sparrows occupied commercial areas and a combination of commercial-residential sectors, while Tree sparrows significantly preferred human habitation dominated by residential houses.
The study says in general, multi-family residential areas in Guwahati comprised more of tree cover and lawn area, which would help in suitable placing for nests (mostly in the roof of Assam type houses), and green cover provides foraging opportunities to sparrows. House Sparrow density in commercial areas is primarily associated with the crowded open marketplaces where the food (grains, scrap from hotels/restaurants) resource is available in enormous extents.
The study says, however, the highly commercial areas with heavy traffic zones may have had a slight impact on the aggregation of House Sparrow. House Sparrows preferred crowded places compared to Tree Sparrows, and both the species avoided city outskirts.
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Anukul Nath says studies carried out in cities are necessary for detecting the changes of certain species, and may provide information on the processes operating behind observed patterns. “Our results support the idea that population density of urban avifauna are influenced by factors operating at a different urban structure associated with socioeconomic driven land use pattern,” he says.
“Therefore, integrative management of urban areas that pays attention to patch scale and large-scale processes is likely to be the most judicious approach for implementing policies addressing the conservation of avifauna in cities,” he added.
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