Eagles are apex predators known for their formidable hunting skills and impressive size. The question of whether these birds consume rats is often raised, particularly where human and eagle habitats overlap. Understanding the eagle’s dietary flexibility is important, as it directly relates to a serious environmental concern: the danger posed by rodenticides carried by their prey.
Defining the Eagle Diet: Preferred Prey
The diets of the two most common North American eagles, the Bald Eagle and the Golden Eagle, differ based on their habitats and hunting strategies. Bald Eagles primarily subsist on fish, often comprising over half of their diet, making them creatures of aquatic environments. They are highly opportunistic, frequently hunting aquatic birds or scavenging carrion near water bodies. Golden Eagles are powerful hunters of open landscapes like mountains and grasslands, preferring medium-sized mammals such as hares, rabbits, and ground squirrels. While both species are adaptable, their preferred food sources generally focus on fish or larger, wild prey rather than common urban rodents.
When and Why Eagles Prey on Rats
Eagles will consume rats, but this is usually an opportunistic choice rather than a primary food source. Golden Eagles, which regularly hunt small mammals, may occasionally take rats, especially in agricultural or rural areas. For the Bald Eagle, consuming a rat is more likely to occur through scavenging dead animals. Rats become a viable meal when preferred prey is scarce or when rats are numerous and easily accessible near human activity. Their size provides a substantial energy source, and their presence in open areas makes them vulnerable to aerial attack. The consumption of rats by eagles is thus a function of convenience and availability rather than preference.
The Risk of Rodenticide Poisoning
The consumption of a rat, particularly one found in human-dominated landscapes, introduces a significant danger: secondary poisoning from rodenticides. This threat is severe due to the widespread use of Second Generation Anticoagulant Rodenticides (SGARs). These chemicals interfere with the liver’s ability to recycle Vitamin K, which is necessary for blood clotting. SGARs cause a delayed death in the target rodent, often taking several days to cause fatal internal hemorrhaging.
During this time, the poisoned rat becomes sluggish and less coordinated, making it an easy target for a hunting or scavenging eagle. When the eagle consumes the contaminated rodent, the poison transfers to the raptor’s system, leading to secondary exposure. Because SGARs are potent and persist in the body for an extended time, they can accumulate in the eagle’s liver over multiple feeding events. This bioaccumulation can eventually lead to a lethal dose, resulting in the eagle suffering from uncontrolled internal bleeding. Even sub-lethal exposure can severely weaken an eagle, making it more susceptible to disease, starvation, or collision injuries. Scientific studies have documented widespread exposure to these compounds across raptor populations, highlighting the danger that rodent control methods pose to these birds.