Hair and fur
Sometimes. Very small mammals will have small ears to help conserve their body heat. The exceptions to this are rabbits and hares. Also marine mammals (large and small) have lost their external ears for much the same reason. The exception to this is sea-lions who still have external ears. Large terrestial mammals have large ears as they have little need to conserve body temperature. The elephant has very large ears which they flap for the purpose of radiating away excess body heat.
Cold Blooded animals, they can't create body heat so they need to find it somewhere else. If warm blooded animals get to the point that their in a climate they are not suited for, they must conserve their body heat. But technically ALL animals conserve body heat.
A coat, and often, ear muffs.
Fat is the primary nutrient that helps to conserve body heat. It acts as an insulating layer beneath the skin, reducing heat loss and maintaining body temperature. Additionally, dietary fats provide a concentrated source of energy, which is important for metabolic processes that generate heat. Including healthy fats in your diet can help support overall thermoregulation in the body.
Shivering and vasoconstriction... B for plato users (:
Animals huddling together helps them to conserve heat and stay warm in cold temperatures. By grouping closely together, they can share body heat and reduce heat loss to the surrounding environment. This behavior is common in many species of birds and mammals during winter or in cold climates.
Rats can not regulate their body heat. Most mammals can regulate their body heat when their blood is high enough.
They do it to conserve and share body heat.
because mammals can produse there own body heat.
Peripheral vasoconstriction is the narrowing of blood vessels in the body's extremities, reducing blood flow to these areas. This helps to conserve heat by redirecting warm blood to the body's core organs, where it is needed the most for maintaining core temperature.
Mammals will shiver or posses what is called 'brown fat' that continuously produces heat.
When body temperature drops below normal, dermal vessels are likely to constrict to maintain core body temperature, limiting heat loss through the skin. In contrast, when body temperature is elevated, the vessels in the dermis are likely to dilate to help the body release excess heat.