Chatham Island warblers are solitary nesters, with defined territories defended against conspecifics.
Disputes are mainly carried out by the male birds, and you can observe long chases occurring when boundaries are threatened.
Although very territorial, boundary disputes never result in contact.
The warblers are monogamous and the same breeding territories have been known to be defended for up to three years in a row.

The breeding season for these warblers varies from year to year, but can be seen to average from around September to January.
The nest style produced is the enclosed pendant, very similar to that of the grey warbler.
The female birds are the sole nest builders, and incorporate mosses, lichens, leaves, bark, feathers, small twigs and spider webs into the nests.
The nests are also seen to be lined with soft feathers.
The location of the nests differs depending on the island.
Nests on the largest island tend to be hanging freely in the open and in gaps of vegetation, while nests on the surrounding islands are in dense foliage.

The female is in charge of brooding, and her eggs are an off-white colour flecked with reddish brown.
On hatching, both male and female contribute by feeding the chicks.
The Chatham Island warbler has a high breeding success rate of 87%, significantly higher than the mainland grey warbler which sees only 38% breeding success.
Chatham Island warblers are solitary nesters, with defined territories defended against conspecifics. Disputes are mainly carried out by the male birds, and you can observe long chases occurring when boundaries are threatened. Although very territorial, boundary disputes never result in contact. The warblers are monogamous and the same breeding territories have been known to be defended for up to three years in a row.
The breeding season for these warblers varies from year to year, but can be seen to average from around September to January. The nest style produced is the enclosed pendant, very similar to that of the grey warbler. The female birds are the sole nest builders, and incorporate mosses, lichens, leaves, bark, feathers, small twigs and spider webs into the nests. The nests are also seen to be lined with soft feathers. The location of the nests differs depending on the island. Nests on the largest island tend to be hanging freely in the open and in gaps of vegetation, while nests on the surrounding islands are in dense foliage.
The female is in charge of brooding, and her eggs are an off-white colour flecked with reddish brown. On hatching, both male and female contribute by feeding the chicks. The Chatham Island warbler has a high breeding success rate of 87%, significantly higher than the mainland grey warbler which sees only 38% breeding success.
Chatham gerygone