Mammals of Pennsylvania Online Resource

What is a mammal?

A mammal is a hairy, milk-producing endotherm. The following is a brief description of mammalian characteristics:


  • Mammals have hair or fur  
  • Mammal mothers nurse their young
  • Mammals are “warm blooded”
  • Mammals have four-chambered hearts
  • Nearly all mammals bear live young (all Pennsylvania mammals do)

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