New Zealand's Rare Yellow-Eyed Penguins Nearing Extinction and Climate Change Isn't the Only Culprit
New Zealand's Otago Peninsula is often called the wildlife capital of the country with an assortment of fur seals, sea lions and yellow-eyed penguins. Unfortunately, their numbers are dwindling, especially the latter whose population is alarmingly nearing extinction.
According to a report from Popular Science, the penguins have declined by 76 percent in the period between 1996 and 2015. If their conditions continue in the current trajectory, scientists predict that the yellow-eyed penguins could be locally extinct by 2043.
The warming of the waters in the South Pacific in the 1940s should have caused a population decline in the penguins, but the pristine records of school teacher and amateur ornithologist Lancelot Eric Richdale showed that their numbers increased instead. He suggested that the conditions of the era - a lot of the citizens fighting in the Second World War -- led to the decreased activity in New Zealand.
"In terms of agriculture and fisheries it was down to the bare essentials," lead author Thomas Mattern, an ecologist at the University of Otago, explained. "The penguins benefited from the reduced activities of humans."
Richdale's records suggest that climate change isn't the only reason behind the yellow-eyed penguins' deaths. While more individuals died in years with high temperatures, Matten pointed out that if the rising climate was the only reason, the animals would have adapted.
"Climate change is not the end of a species alone," he explained. "We just can't say all of the species are disappearing because the climate is changing. We also have to look at all of the other pressures that we're putting on these species, particularly regional pressures."
Mattern and his team used population data from two periods: 1937 to 1948 at Kumo Kumo Whero, and 1982 to 2015 at Boulder Beach. They found out that a third of the yellow-eyed penguin's population disappeared due to warming temperatures.
The other two-thirds is certainly significant, but while climate data is readily available, there is little quantifiable information on fisheries impact, rate of pollution, the impact of tourism and others. Mattern said, "We can't add these factors to our model, which inevitably means we end up with research that says climate change has this impact on population, which deflects from the problem that there are several factors at play here."
One of the factors that may contribute to the dramatic decline of yellow-eyed penguins is the use of gillnets, which are used to trap fish but can also entangle and drown other animals.
The study was published in the journal PeerJ.