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The North Island robin (Petroica longipes) was introduced to the Zealandia – Karori Sanctuary in 2001. The sanctuary is a mainland island (225 ha) in Wellington that is free from all mammalian predators except mice (Mus musculus), and enclosed by a predator-proof fence. During 2001 and 2002 a total of 76 robins were translocated from Kapiti I to the sanctuary. To assess changes in this population since its introduction, I surveyed and mapped territories of robins in a 37 ha section of the sanctuary in 2008. Density has continued to increase, from 0.7 robins/ha in 2003 to 2.5 robins/ha in 2008. This density is higher than other mainland sites. Of 46 adult robins seen within the study area at the start of the 2004-05 breeding season, at least 17 remained within the area in 2008, close to their 2004 territories. These included 4 robins from the original transfer. In all cases where both partners from 2004 were seen in the study area in 2008, the pair bond remained intact. My survey confirms continued increase in this introduced population and high pair fidelity.