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Monthly bird counts were recorded for Kaikorai Estuary, Otago from July 1989 to June 1991. Fifty species were noted, including passerines on the estuarine fringe. The predominant species was the Southern Black-backed Gull (Larus dominicanus), which accounted for 61% of the birds surveyed. They overwhelmed the Dunedin City Council refuse up site at Green Island and, to a lesser extent, a tip in private use. Mallards (Anas platyrhynchos) and Starlings (Sternus vulgaris) were the next most common species. Numbers of birds decreased with distance from the tip sites but, conversely, the number of species increased. Numbers were highest in March-April, but declined rapidly by two-thirds to a July-August low. This decline was due to the dramatic fall in duck numbers with the opening of duckshooting season and to the onset of winter. The total annual count for the second half of the survey (July 1990 to July 1991) was 4% down on the previous 12 months, but this was not statistically significant.