Bellbird / Korimako - Restoration
(Anthornis melanura)

Current Status

94 bellbirds were released in the Sanctuary between 2001 and 2003.
Bellbirds are regularly seen and heard in areas adjacent to the Sanctuary, but most of these are residents from the Sanctuary foraging outside.

Two puffed up male bellbirds
Photo by Peter Reese

Returning Bellbird to the Karori Wildlife Sanctuary

Prior to European colonisation, the bellbird would have been a typically vocal part of the birdsong heard in the valley now occupied by the Sanctuary, as it was throughout New Zealand.

Bellbird numbers were reduced by habitat destruction and seem to have been reduced particularly by introduced disease, especially in the North of the country. Before we released bellbirds in the Sanctuary, the bellbird was considered functionally extinct in the Wellington area because the only birds seen were single males.

Despite these challenges the bellbird has proved resilient to changes in land use and introduced predators. The species is considered common elsewhere in New Zealand, and has demonstrated its adaptability by colonising plantation forests and suburban gardens in some areas.

The key to reintroducing bellbirds to the Sanctuary was to overcome the species’ history of unsuccessful translocations.

In the past, whenever bellbirds were moved from one part of the country to another, they never established a breeding population at their new location. The reasons for these failures were not well understood - it was thought the birds' tendency to be nomadic and solitary when not breeding encouraged their dispersal from release sites.

To determine what technique would increase the likelihood of a successful transfer to the Sanctuary, several different components were trialled as part of the Sanctuary transfers.

The transfers were undertaken between May and August to see if timing was critical, with the first release undertaken in August, just before the breeding season, and later releases earlier (when no breeding was detected after the first release).

All transfers involved a period in captivity at the release site (until enough birds had been caught for the transfer and had adapted to artificial food) and at the release site, but we released females earlier than males at the Sanctuary to see if this would reduce the risk of dispersal. Supplementary feeders were installed from the outset, also to try to minimise dispersal.

Between 2001 and 2003, 94 bellbirds were transferred and released in the Sanctuary, with most of these birds being sourced from Kapiti Island. The most successful transfer was undertaken in May 2002, with birds from this transfer and 1 from the earlier transfer establishing territories and breeding successfully for the first time in the 2002-3 breeding season.

The re-establishment of bellbirds in the Sanctuary is a triumphant first for this species, with the Sanctuary being the first to achieve breeding of bellbirds following their transfer to a new site.

Bellbird monitoring

Birds have unique combinations of colour bands on their legs so that when they are seen, staff and volunteers can monitor the survival, dispersal and breeding behaviour of individuals. Each group of bellbirds released in the Sanctuary had one leg banded with a “cohort” colour (eg. Red over metal in 2001, white over metal in 2002) and the other leg banded with two colours, to uniquely identify each individual and allow staff and volunteers to immediately know when the individual was transferred. This convention has continued since the transfers, with all nestlings or fledglings banded in the Sanctuary given a “cohort” colour identifying the season hatched (eg. Yellow over metal in 2003-4).

Bellbirds are monitored throughout the year to assess survival, dispersal and use of the supplementary feeders, but most monitoring is undertaken during the breeding season to determine where the territories are, which birds are in residence, and their breeding success. If nests are accessible (and most are not), they are checked to determine the number of eggs laid and hatched, band the chicks and determine the number of fledglings produced. Where nests are inaccessible, they are monitored to determine nesting success and number of fledglings produced, and wherever possible, these unbanded fledglings are caught in specially constructed portable catching cages and banded.

The Future

Given the species’ nomadic and territorial tendencies, it is not surprising that some birds have already begun investigating the area outside the Sanctuary.
Despite the bellbirds having high annual productivity in the Sanctuary (averaging 11.0, 8.3 and 9.3 fledglings per pair in the last 3 breeding seasons), the population status of bellbird in the Sanctuary still remains vulnerable for several reasons:

only a small number of transferred bellbirds bred successfully so the genetic diversity of the population is likely to be narrow;
there has been an imbalance in numbers of each sex produced (with far fewer females than males fledged);
fewer females than males have reached breeding age;
and there have been losses of adult females during the breeding season, probably because they have been placed under additional stress from more dominant males competing for their attentions.

We aim to do another bellbird transfer sometime in the future to address the situation. This will be carried out preferably after hihi (stitchbird) have bred successfully to ensure the subordinate hihi have a chance to establish a self-sustaining population.

Welcome back to Wellington the bellbird and its song!

More Information

For contemporary bellbird information and research, see the Landcare Research website.

This article was written by Sanctuary volunteers Lisa Clephane and Blake Dearsley. All photos copyright Peter Reese.

Published 20 Oct, 2005.