Marine scientist Dr Townsend and ecologist Dominique Potvin from the University of the Sunshine Coast studied nearly 900 preserved bird nest specimens collected between the years 1832 and 2018.
Their world-first research on bird nests at Museums Victoria and the CSIRO in Canberra was published this month in the scientific journal Oecologia.
It was the first study of its kind to use museum specimens to determine the effects on wildlife in rural and urban backyards.
The number of manmade materials — mostly plastics — in nests coincided with the urbanisation in Australia and increased from about 4 per cent in 1832 to almost 30 per cent in 2018.
Dr Potvin said while the presence of plastic in nests may have made nests stronger, it was detrimental to birds' health.