Australian scavengers don't just eat everything and slink away. They approach a carcass like a buffet

When scientists discuss scavengers, they might envision an animal discovering a carcass, consuming as much as possible before disappearing. However, a dead animal contains various macronutrients—carbohydrates, lipids (fats), and protein—all within the same carcass. Just as an egg has a high-protein white and a higher-fat yolk, carcasses are similar.

Scavengers are typically considered as unfussy feeders that will consume whatever is available. Yet, a recent study in Royal Society Open Science indicates this isn't the case. The research aimed to determine which part of a carcass scavengers like dingoes, wedge-tailed eagles, and red foxes typically eat first. It's known that many species have a tendency to consume foods that meet their nutritional requirements, akin to an athlete aiming to hit a protein target.

Despite this, there's limited data on carnivores' feeding choices due to the difficulty of tracking them as they are elusive and often have large territories. Researchers monitored 40 eastern gray kangaroo carcasses in the Blue Mountains of New South Wales, recording the feeding behavior of three common scavengers: dingoes, wedge-tailed eagles, and red foxes.

The findings revealed that eagles consistently chose to feed on the kangaroo's head and abdomen, areas high in fat, while dingoes primarily targeted the tail. Foxes were outcompeted and limited to scraps. Apex scavengers, like dingoes and eagles, arrive at carcass sites quickly and can consume large amounts of biomass rapidly, leaving less choice for other species.

As they consumed their preferred parts, foxes had fewer options. Over time, scavengers shifted their preferences. Eagles began focusing on protein-dense areas, such as hindlimbs, while both dingoes and eagles increased their feeding on the abdomen in winter, likely due to cooler conditions and scarcity of alternative food. This preference for fat-rich areas when apex scavengers first found the carcasses could be explained by the nutritional geometry theory, which suggests that animals choose what to eat to balance different nutritional requirements.

The study highlights that scavengers make informed decisions about what to eat from a carcass, prioritizing fat-rich body parts before shifting to other areas, depending on availability and competition.