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A resting hummingbird’s heart can beat up to 225 times per minute, while a blue whale’s heart can beat as slowly as twice per minute.
The animal kingdom’s wide range of resting heart rates shows how size, activity levels, and environmental demands shape each animal’s physiology.
This graphic shows the resting heart rate range of 15 animals in beats-per-minute (bpm) using data from Merck Veterinary Manual.
Small Animals Have Higher Resting Heart Rates
Typically, smaller animals like rats, guinea pigs, and rabbits have higher resting heart rates compared to larger ones.
Animal
Average Resting Heart Rate (bpm)
Elephant
25-35
Horse
28-40
Ox
36-60
Dairy cow
48-84
Human
60-100
Goat
70-80
Sheep
70-80
Pig
70-120
Dog
70-120
Cat
120-140
Rhesus monkey (anesthetized)
160-330
Rabbit
180-350
Guinea pig
200-300
Chicken (adult)
250-300
Rat
250-400
One reason for this is that smaller animals have higher metabolic rates per unit of body mass than larger animals.
The metabolic rate is the rate at which a living thing consumes energy to maintain basic bodily functions while at rest.
As a result, their hearts need to pump blood more frequently to deliver oxygen and nutrients to cells, leading to higher resting heart rates.
Bigger Animals, Bigger Hearts
Larger animals’ hearts have a greater stroke volume (the amount of blood pumped from the heart to the rest of the body) than smaller animals.
This enables them to have a lower resting heart rate as each heartbeat pumps more blood to the rest of their body.
Want to learn more about bigger animals like mammals? Check out the Average Lifespan of Mammals on Visual Capitalist.