Two people have reported seeing a black cat on pest-free islands in the Hauraki Gulf (file photo).

Cat-catchers have been scrambled to Auckland's Rangitoto and Motutapu islands after two possible sightings of a feline.

Two people have reported they saw a black cat on the shoreline at Islington Bay, which lies in between the two islands in the Hauraki Gulf.

Rangitoto and Motutapu are connected by a short bridge at the top of the bay.

One of the reported cat sightings was on the Rangitoto side of the bay, while the other was on the Motutapu side.

READ MORE:

* E-rat-icated: rodent removed from protected Tiritiri Matangi Island

* Use of banned rodent traps on ferries upsets public

The islands have been free of cats, rats, possums and mice since 2011.

They have since become a haven for native birds, including the North Island brown kiwi, tieke/saddleback, takahe, korimako/bellbird and kakariki.

Department of Conservation spokesman John Galilee said DOC was taking the reported sightings "very seriously".

Two conservation dogs – which are trained to detect cats – and their handler would arrive at Islington Bay on Thursday morning.

DOC would also place motion-sensitive cameras, cat-tracking devices and traps in the areas where the cat was reported.

Galilee said the traps had been approved by the National Animal Welfare Advisory Committee, which included representatives nominated by the SPCA.

"We have biosecurity systems in place because there's an ever-present risk of a cat, rat or mouse making it to one of these islands," he said.

"We want to remind the public that cats and dogs are not allowed on pest free islands. That's because of the serious threat they pose to native birds and other native wildlife on these islands."