[Birds Of The Estuary] Black-backed gulls-Innovative gull dominates other birds

Tanya Jenkins is the manager of the Avon-Heathcote Estuary Ihutai Trust, a non-profit organisation formed in 2002 to protect one of New Zealand's most important coastal wetlands. Each week she introduces a new bird found in the estuary. Her column aims to raise the understanding of the values and uniqueness of the area.

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Words like innovative, adaptable, cunning and survivors spring to mind when talking about the black-backed gull or karoro-the largest and most common gull species in New Zealand.

 

They are found anywhere across the country in non-forested areas, from coastlines to high country farming areas. Since European arrival, numbers of these large birds have exploded due to the fact that they quite like the introduction of farms and especially landfills where these not too fussy eaters have done extremely well.

 

With an appetite for anything from newborn lambs, rabbits, eggs and chicks from other bird species, landfill waste, public rubbish bin contents and fishing offal from fishing boats, numbers have increased from a few thousand to an estimated half million plus, with some colonies reaching up to 1000 birds. 

 

Carrying the disease salmonella, their waste can actually 'pollute' grassed areas which can be detrimental to farm animals and cause pollution in our waterways.

 

In Christchurch with the closure of the Burwood Landfill in 2005 this bird has dispersed throughout the city where it manages quite well. In 2018, black-backed gulls managed to raid the chicks from every single nest of the critically endangered black-billed gull in Charlesworth Reserve and they have, understandably, not returned there since (and neither have other nesting birds such as the pied stilt).

 

Due to the current risk of losing a number of other bird species in and around the estuary a black-backed gull management strategy is currently under review. Watch this space.

 

How can we help prevent these birds from taking over the estuary? Please do not encourage these birds to stay here by making it just too easy for them by feeding bread or left-over fish and chips near the estuary.