Dog owners are being urged to keep their pets on a leash as penguins flock back to Kiwi shores for the breeding season.

Wellington's kororā, or little penguin, will be heard in the evenings calling to reunite with their mate from last year, or forming a new pair bond.

Hanging out in 'penguin night clubs' while courting makes the usually reclusive birds easy targets for predators.

KOREN ALLPRESS/STUFF Kororā like rocky shorelines for their nesting grounds.

Places For Penguins spokeswoman Karin Wiley said there were at least seven reports of dogs mauling penguins in the region last year during the two week breeding season, including one photographed after an attack at Frank Kitts Park.

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"Within the following two weeks two little penguins were mauled at Houghton Bay buy one dog and three at Whitereia Park (Plimmerton).

SUPPLIED This little penguin was photographed after it was mauled by a dog at Frank Kitts Park last year.

"Several more dead penguins were found around this time also, but the cause of death may have been difficult to establish or undetermined because the carcases were too decomposed."

People needed to be aware that the penguins were nocturnal, she said.

"The majority of dog owners walking dogs do not know little penguins are nocturnal on land and because the never see them on land during the day, assume they are not there at night either."

Of particular concern are dog walkers who visit rocky shorelines, and areas with coastal vegetation.

Wiley said the smell of a penguin was attractive to dogs despite humans not smelling it.

"All dogs, even well-trained ones, will be instinctively driven to attack the birds because of their smell and their movement."

Attacked penguin often appear uninjured, but dogs jaws can crush the animals' ribcages and cause organ damage.

"Just one dog bite can kill a little penguin in seconds."

Kororā are a protected species and either classed as at risk or in decline nation-wide.