Kererū numbers take off in the city

Bulky but beautiful kererū are enjoying a fruit smorgasbord at the Botanic Gardens and their population looks set to boom as a result.

Luke Martin, Curator for the Botanic Gardens' New Zealand Plant Collection, says the number of native pigeons resident in central Christchurch is steadily increasing.

Kererū are flourishing in the Christchurch Botanic Gardens.

“The kererū are definitely doing well and staff have seen at least four chicks hatch in the Botanic Gardens this season. They are slow, clumsy nesters and they only raise one chick at a time so they’re not prolific breeders, but we now have a resident breeding population in the Gardens of about a dozen birds with seasonal influxes of up to 30.

The birds are having a second round of nesting in the Botanic Gardens this season which is a positive sign.

“I think we’re reaching that critical mass stage where we should see a noticeable rise in the numbers of these gorgeous birds living in Christchurch.

"The more birds there are the easier it is for them to find a mate and the population growth could be exponential. Between the Botanic Gardens, Riccarton Bush, and the Ilam Gardens near the University of Canterbury, there’s a huge amount of maturing habitat available to them now.”

Mr Martin says kererū  – a heavy bird known for the noisy beat of their wings - love the Botanic Gardens for its tall trees, varied habitat and huge range of plant species. “The Gardens is like a smorgasbord for them. They are city-born pigeons and they’ve totally adapted to the modern ecosystem. Their diet is now 50 per cent exotic species and 50 per cent natives.”

Their favourite natives are kowhai, hinau and kahikatea and favourite exotics include most legumes (tree lucerne, brooms and laburnum) Malus (crab apples) and Prunus (such as plum and cherry trees). In the autumn months they enjoy dining on magnolia tree seeds.

Mr Martin says although kererū are doing well in the Botanic Gardens and Riccarton Bush their nests are still susceptible to predation by rats and cats, however there is pest control in place in the Botanic Gardens.

New Zealand pigeons are important because they are the only birds that can eat the largest fruits of the forest and they also travel long distances to reach food sources. This makes them valuable seed dispersers, taking seeds from one patch of forest to the next.

The Department of Conservation reports that nationally the kererū population is considered to be stable but numbers are gradually declining in areas where predation and illegal hunting are unchecked.