Which food is a raptor likely to gain the most weight from if fed equal amounts?

Raptors, such as hawks, falcons, and eagles, have specific dietary needs that influence their weight gain from different food sources. When considering the options, duck is a type of poultry that typically has a higher fat content compared to the other choices. Fat is a dense source of calories, and when raptors consume food higher in fat, they are more likely to gain weight effectively.

Duck provides a rich source of energy, which is crucial for raptors that require sufficient caloric intake to sustain their metabolism, especially during periods of active hunting or breeding. The other food options, while they may provide nutrients, tend to have lower fat content or are less energy-dense than duck. Chicken neck, washed meat, and rabbit can offer protein, but their lower fat levels result in less likelihood of significant weight gain when fed in equal portions compared to duck.