New research from UNSW and the University of Sydney shows that dingoes have grown by about 6-9% over the past 80 years. However, growth is only seen in areas where poisonous insect bait is used. The results, published in the Biological Journal of the Linnean Society, compared the size of dingoes that lived in three pesticide-treated regions with data from a region that stretched from the Northern Territories to southern Australia.
A poisoned bait is a composition (liquid, solid, or gel) that attracts a target population of live species. This leads to negative consequences: either the animals die, or their normal behavior changes, which ultimately affects the population.
Scientists measured the size of the skull, which is a marker for animal size, from nearly 600 samples of dingo dogs originating from the area.
Skulls from pesticide-laden areas have grown by about four millimeters since the poisoned bait was introduced. This corresponds to about a kilogram of body weight.
While the male dingo was simply growing, the females experienced the biggest spurt in growth, with their skulls enlarged by 4.5 millimeters, which is almost 9% of their body weight. Male skulls have grown by 3.6 millimeters or 6% of body weight.
Why do dingo dogs grow in size in places poisoned by baits?
The most plausible theory is that dingoes that survive bullying campaigns have less competition for food.
Matthew Crowther, article co-author, assistant professor at the University of Sydney
Scientists explain that the main prey of the dingo, the kangaroo, increases in numbers when dingo populations are suppressed. With more food, the physical growth of the dingo is less limited.
The pesticide sodium fluoroacetate – known as 1080 (pronounced “ten eighty”) – is commonly used across Australia to control dingoes and other pest populations.
An odorless white powder, 1080 is usually left in meat lures and left in dingo distribution points. In the 1960s and 70s, there was a massive baiting of dingo dogs in regions of Australia.
No change in body size was observed in dingoes from the unpoisoned region, including indigenous lands and reserves.