Urban Noise and Light Disturbances Modifying Foraging Behaviors and Reproductive Success of Nocturnal Bats

Abstract

Urbanization brings a lot of anthropogenic disturbances such as noise pollution and light pollution,
which affect nocturnal wildlife. This experiment attempts to examine the effect of urban noise and
light pollution on foraging activities and reproduction success of bats in the city of Bengaluru, India.
Three urban gradients consisting of high, moderate, and low-disturbance areas such as commercial,
residential, and semi-urban areas were selected. The foraging activities were observed using ultrasonic
sound recordings and infrared video recordings while maternity roost observation and pup survival
rates were used to estimate reproductive success. Our results suggest that feeding buzz rate was
decreased by 30-40%, increased echolocation call amplitude, and disorganized foraging pathways in
high-noise zones, indicating difficulty in prey detection and high energy consumption. Likewise, the
reproductive success was delayed by 5-7 days, produced 20% less pups per season, and had lower
survival rate among juveniles in bright areas. From our comparison with past experiments, it is clear
that tropical urban bats are more vulnerable to multiple stress factors than bats in other regions.
Conclusions drawn from the study are based on scientific facts, highlighting the importance of
reducing noise and light pollution for the protection of bat communities at night.