Trees to towers shift: Power lines emerging as a novel habitat for birds in Gujranwala, Pakistan

Abstract

Power infrastructure (electricity towers, mobile phone towers, transmission lines and wires) is a unique anthropogenic structure in terms of material composition, design and continuity serving as artificial habitat to avian wildlife for roosting and nesting. This study aimed at finding out the diversity, abundance and behaviour of birds using the power structures as artificial habitat in the Gujranwala city area, Pakistan. Field data was collected in Feb-Mar 2021 during the COVID-19 pandemic and resulting lockdowns in the city by recording all birds' species and nests on power lines along a circular path (~32 km) by dividing into sampling zones. A total of 24 bird species of 16 families were found to be using these structures as roosting and nesting sites. The occupation rate of mobile phone towers is found to be 61%, transmission lines 32%, and electricity towers 1.8%. House crow was the most common species (~20% population) followed by the Black kite (~ 18% population). The spatial distribution pattern of nests on power structures indicated higher concentration in the southwestern area contrary to the highest abundance and diversity in the northwestern area close the urban forest planation. Total 112 nests of 4 species (Black kite, House crow, Common myna and Eurasian collard dove) were present on power lines. Black kite is the most frequent nesting species (>80% of all nests), preferring high structures i.e. transmission lines (99% of all nests) and mobile phone towers (78% of all nests) for making nests. House crow and Common myna make nests on electricity towers at low height. It is found that the area where cutting of trees during the past time period occurred, birds have shifted their nesting habitat from trees to towers (i.e., power structures). Moreover, if habitat destruction continues these power lines will be the new nesting habitat of the birds in the urban area, hence, posing risks to both birds and utility structures. This study also highlighted the importance of strategic plantation in relation to spatial distribution and protection of urban birds.