We have started conservation of House Sparrow in the year 2014 by installing around 10 nests and all of them were found occupied. It almost took around four to six months’ time for occupancy of all the nests from the date of installation. In the next year, we installed about 20 nests in the adjacent areas. These nest boxes were found to be utilized by the new generations. Among these nest boxes, one nest box left unoccupied even after six months, because of the entry of House Gecko (Hemidactylus frenatus
R.) Clearance and replacement of that nest box resulted in the occupancy of the next by the House Sparrow within a month.100% occupancy was observed in the year 2015 also and it also increased the demand for nest boxes. To fulfill that around 37 nests were installed in the adjacent new areas. By the end of the year 2016, 36 of them were occupied and utilized and among them, one nest box was utilized by Indian Robin (Saxicoloides fulicata
L.) for breeding. Only one nest out of 37 was not occupied because of the usage of that nest by squirrel for breeding.
As the new generations were brought up from those 66 installed nests, a competition aroused between old male sparrows and new generations for existing nests for breeding. Again 90 more nests were installed in the study area in the year 2017 and among them, 88 nests were occupied and used for breeding. Another 147 more nests were installed in the year 2018 and among these, 138 nests were occupied by the new generations. This indicates that by the end of the year 2017, the sparrow population has been increased to 138 couples. In the year 2019, 138 more nests were installed extending to the adjacent areas. We found that except five all of them were occupied by house sparrows. By the next year i.e.
, 2020, we have successfully installed 128 nests and among them, 124 nests were found to be occupied (Table 1). The occupancy rate of the nest box (within 30 days after installation) was increased from 15% to 39% in the past three years. Occupancy rate has been doubled in the next thirty days after installation (Fig 6, 7).
Table 1: Monthly analysis of occupancy of nest boxes by sparrows.
Fig 6: Graph showing the comparison of installed Vs occupied nest boxes (year wise).
Fig 7: Rate of occupancy of the nests day wise.
The current work on the design of a protective nest for House Sparrow is highly significant to sustain its population and we are almost involved in sparrow conservation from the past 7 years and are successful in raising the sparrow population. But our studies are limited to Jangareddigudem, an upland area in the West Godavari district of Andhra Pradesh with minimum crop food resources. The study area is famous for tobacco, chillies, oil palm and cashew nut cultivation. Initially we used different nest designs made of carton boxes and wooden boxes to provide artificial habitats that can be used as breeding grounds by House sparrows. The wooden boxes were found to be the best choice owing to their durability, longevity and ease of handling. Our first nest model made of wood contained less extended roof planks. That nest was disturbed randomly by the Indian Myna Acridotheres tristis
that too only during its breeding season. Another model made without the extension of roof planks, was also tried by a pair of Rose-ringed Parakeet Psittacula krameri
, but could not succeed to enter into the nest box as the entrance hole can only fit and permit the entry of House sparrows. By these observations, a specific protective nest design was made. Sparrows can be attracted easily to this model and as well feel secured. In our study, we have observed that one of the nest boxes (Nest Box No. 275) was occupied within 30 minutes after installation.
Studies of Bhattacharya et al., (2011)
using artificial nest boxes made up of wood with flat top, showed that 60-70% nests were occupied by House Sparrows and were used for breeding. Their study was conducted for 3 months, with 25 nests. In their design, the depth of nest box is 190 mm and such a depth creates more space than what is required, which increases the labour to construct the first nest at bottom. Our nest model has a depth of only 100 mm and this reduces half of the effort to build the first nest. Balaji (2014) used shoe boxes as nesting habitats and among the 50 installed nests; only 30 nests were occupied by sparrows giving 60% occupancy. Studies of Akhilesh et al., (2014)
showed that sparrows give first priority to wooden nests for breeding and this could be the reason for decreased occupancy observed by Balaji (2014)
with Carton boxes (shoe boxes).
In our case, the nests installed were made up of wood (owing to their durability, longevity and ease of handling) and sparrows also preferred our nests as is indicated by an occupancy rate of 97% indicating the suitability of our nest design.
The suggested diameter of entrance hole for House Sparrow by BTO is 32 mm. Conservation studies conducted by Gitanjali et al.
(2017) used artificial nest boxes that had a nest mouth with a diameter of 64 mm, which is wider and allow the entry of other birds that are larger than sparrows. In their model, the entrance hole is also placed at the middle of the nest box and it is just 75 mm from the base. It doesn’t give much security for nestlings and in addition, leaves little depth inside the box which is comparatively too less to construct more nests. Where as in our model, we made entrance hole 180 mm above from the base. It not only provides mere security to the nestlings (extended roof planks will only allow sparrows to pass through the entrance hole) but also facilitates construction of more nests inside the nest box. In our study, we have observed a maximum of 15 constructed nests inside the nest box (Nest box No.23), during the last summer (April, 2020) when we removed the abandoned nests form nest boxes.
The model developed by Chetan (2012) has a wider bottom than our design which increases the labour of the sparrows to build their first nest in the nest box. Our present model reduces this burden on sparrows. Coming to the installation of nest boxes, Bhattacharya et al., (2011)
installed nest boxes in open areas, public places and near to water tanks. They observed some disturbance to the nest boxes by other bird species (name of other bird species not mentioned) and to avoid that they have arranged mesh-like guard on the top of the nest boxes. No specific disturbances have been reported by Balaji (2014)
because they arranged their nest boxes in secured areas. In our study, we have arranged nest boxes in the houses requesting the house owners, under the slab, at open space, where the sparrows can approach easily. During the past seven years of our study, only a very less disturbance has been observed by other species. Extended roof planks placed in our model obstruct the entry of other species that are larger than sparrows. Thus our model specifications provide protection from other competing species and predators like crows. An occupancy rate of 97.59% clearly indicates the specificity of our model. Only 2.41% of the nests were not occupied and it could be due various reasons like- entry of lizards into those nests, cat predominant areas, invasion of other bird species (Indian Myna) and entry of animals like Squirrel and Rat.
The success of occupancy is in consistent with increasing population. From 2014 to 2020, 570 nest boxes were installed in Jangareddigudem town, at periodic intervals. Each nest has been utilized on an average thrice for breeding in a year. Sparrow population in our study area has been significantly increased after installation of nest boxes indicating the demand for artificial nest boxes.