WELLINGTON, May 22 (Xinhua) -- New research has shed light on how one of New Zealand's most recognizable seabirds, the Southern black-backed gull, or karoro, has dramatically altered its diet and behavior in response to human-driven environmental changes.
Once top marine predators along the coast, karoro have become resilient urban survivors, increasingly dependent on city waste as traditional coastal food sources dwindle, according to a release from the Auckland War Memorial Museum on Thursday.
The study, a collaboration between Auckland Museum and Unitec Institute of Technology, documents a striking dietary shift in these native gulls -- from consuming fish and sea mammals to scavenging on fast food scraps and roadkill.
Researchers tracked changes in the gulls' diet over more than a century by analyzing feathers from museum specimens dating back to 1914, regurgitated food pellets collected from breeding colonies, and fossilized bones from thousands of years ago. The findings were recently published in the New Zealand Journal of Ecology.
"Karoro are truly opportunistic eaters. Historically, they were coastal marine predators and scavengers, feeding on fish, marine invertebrates, and even the remains of sea mammals like sea lions," said Matt Rayner, senior researcher at Auckland Museum.
"Today, they're just as likely to chow down on a discarded KFC drumstick or a roadkill mouse as they are to hunt for fish," Rayner said, noting that their adaptability is extraordinary. However, he added that their modern diet reflects a worrying decline in the health of the Hauraki Gulf, driven by pollution, overfishing, and coastal development.
While karoro have adjusted to the changing environment, many other native seabird species are not as adaptable. Birds such as terns, petrels, shearwaters, shags, and penguins rely heavily on thriving marine ecosystems and are increasingly vulnerable as these ecosystems degrade, Rayner said.
Although the karoro now serves as a symbol of adaptability and survival, Rayner cautioned that not all wildlife can adjust to such rapid environmental changes. He called for greater efforts to protect the Hauraki Gulf and New Zealand's broader marine environment to safeguard the future of the country's diverse seabird populations. ■
