What characteristics of the circulatory system are similar in the pigeon and rat?

Both pigeons and rats possess a closed circulatory system, where blood is contained within vessels, allowing for efficient transport of nutrients, gases, and waste products. They share a four-chambered heart structure, which aids in separating oxygenated and deoxygenated blood, ensuring efficient circulation. Additionally, both species have a network of arteries and veins that transport blood throughout their bodies, supporting their metabolic needs. These similarities reflect their adaptations to active lifestyles and the requirement for efficient oxygen delivery.