IT IS a migration that would make David Attenborough's jaw drop - and it all begins in a murky pond in the heart of Sydney.

The eels of Centennial Park may be among the city's least attractive native residents but the journey they take to breed is nothing less than astonishing.

Park life ... a long-finned eel at Centennial Park. Credit:Janie Barrett

Once in its life, every eel in Sydney gets the urge to reproduce.

When conditions are right - usually during a rainy autumn - they set off from Centennial Park and cross into Randwick Racecourse. The eels slither part of the way over land but mostly stick to stormwater drains and other water courses.