WELLINGTON (XINHUA) - Researchers from the University of Auckland are calling for more research on the impact of light and noise pollution on birds' sleeping habits, and the knock-on effects of sleep deprivation on their vocal communication.

Authors of the paper, published Wednesday (Aug 17) in the online journal Biology Letters, said there are good reasons to predict that sleep deprivation could affect song-learning and memory, mating and territorial behaviour, with important implications for bird conservation in urban areas worldwide.

Sleep is found in every animal studied to date, from jellyfish and flatworms to birds and mammals.

In humans, sleep deprivation affects speech and language learning, according to the paper, which is part of a doctoral project researching the effects of sleep disturbances on Australian magpies and common mynas.

Birds use vocalisation for recognition, mate attraction and resource defence, it said, adding that sleep disturbances will likely affect their vocal performance and learning.

Vocal changes caused by lack of sleep might have adverse consequences for birds' reproductive success and survival, according to the research.

"When we have a bad night of sleep, it's hard to communicate effectively. Our speech gets slurred, and we have a hard time expressing our thoughts. Birds seem to be having the same problem," said Ms Juliane Gaviraghi Mussoi, a doctoral candidate at the University of Auckland's School of Biological Sciences and one of the paper's authors,

Birds sing to protect territory, find mates and communicate with each other. Sleep disturbances, for example from light or noise pollution, can affect how they sing, which can have negative consequences on their reproduction and even survival, Ms Mussoi said.

"However, we are still learning about the effects a bad night of sleep can have on how birds sing," she said.