One of three chicks that hatched in a peregrine falcon nest perched high on a Melbourne skyscraper has died, marking the third year in a row the nest has suffered such a loss.

Key points: A falcon chick born in September has died, with a disease carried by pigeons likely to be the cause

A falcon chick born in September has died, with a disease carried by pigeons likely to be the cause Followers of a Facebook page that monitors the birds have expressed their grief at the news

Followers of a Facebook page that monitors the birds have expressed their grief at the news An expert says that the state's warm, dry conditions may be contributing to the prevalence of the disease

Birds of prey have lived in nest boxes on the building's ledge since the early 1990s, and the current crop of falcons have thousands of online fans who watch a video stream on the 367 Collins Falcons Facebook page.

Victor Hurley, the project leader of the Victorian Peregrine Project, believed several deaths since 2017 were caused by a disease called trichomoniasis, which was carried by the falcons' prey.

He said drier winter conditions across the country and hot spring temperatures were to blame for an increase in pigeons and starlings carrying the disease.

"That is something that I think will change the moment we have good rain in winter and good spring conditions," Dr Hurley said.

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A report released by the Bureau of Meteorology last week said Australia experienced its ninth driest winter in 120 years.

Minimum, maximum, and average temperatures were also well up, on average, in Victoria.

While an autopsy would confirm how the chick died, Dr Hurley said retrieving the body from the building's ledge could pose serious risks to the remaining young and handlers themselves.

"There's a high risk, with the nestlings having their wing feathers half or three-quarters grown, that they will scurry off the ledge and that will end badly for everyone," he said.

The most likely outcome is one of the adult birds will remove the carcass themselves.

Windows, wires and trains put city birds at risk

The chick's death was announced on the falcons' Facebook page and prompted a flood of tributes.

"I just saw the news and felt a pang in my chest. Sad news and you cannot help but feel some attachment when we watch them so much," one woman wrote.

"RIP little baby," wrote another.

The falcons have gained a cult following. ( Facebook: Ronan Reid )

Until the carcass is cleared, the web stream administrators have switched off the stream's main camera.

Even though falcons are at the top of the food chain, Dr Hurley said life in the big city comes with risks, including other peregrine falcons who could try to take the nest by force.

"They can fly into windows, they can hit overhead wires, they can get hit by cars and trains, they can drown in a rooftop swimming pool in Flinders Lane with four inches of water," he said.