Seven tūī are currently being treated at Wellington Zoo’s native wildlife hospital for lead poisoning.
The Nest Te Kōhanga senior veterinarian Baukje Lenting says it’s likely the birds ingested the metal by drinking water contaminated by runoff from roof construction.
Last year, 23 tūī were diagnosed with lead toxicity, which comes with serious side-effects including seizures and lack of balance - making birds vulnerable to flying into car windows and being caught by cats.
The zoo has also treated other birds for lead poisoning, including kākā, harriers, pūkeko and ducks.
The birds in hospital receive an injection twice a day to flush out the lead in the blood stream, which can take several weeks, or in some cases up to a month.
Ms Lenting urged people renovating to try to use materials with alternatives to lead - but if you do use lead products, do not expose it to wildlife.