Why can some animals not live in captivity or have lower life expectancy in captivity?
In: Biology
It depends on the species. Some live longer in captivity. Instead, others have a lower life expectancy when captive.
Animal species can be classified in two groups by the balance between the amount of offspring they yield and the quality of it.
_r_ strategists:
– High reproductive rate.
– Sexual maturity achieved at an early age.
– Tendency towards sexual promiscuity.
– Minimal parental investment.
– Simple cognitive and behavioral complexity.
– High availability of food and resources.
– No hierarchy.
– No territoriality.
– Weak body. Tend to be easy preys.
– Examples: rabbits, rats, mice, cockroaches…
_K_ strategists:
– Low reproductive rate.
– Sexual maturity achieved later in life.
– Generally monogamous.
– Great parental investment. Parents need to invest lots of energy and resources to ensure their offspring will survive.
– Complex cognitive capacity, behavior and social structure.
– Highly hierarchical and territorial.
– Food and resources are limited and need to be carefully managed.
– Strong body and efficient offensive and defensive mechanisms.
– Examples: wolves, eagles, rhinos, elephants, lions…
K strategy species have many more behavioral, social and territorial requirements to lead a healthy life, that’s why they tend to have a shorter lifespan in captivity as opposed to _r_ strategists, who actually thrive in the absence of predation provided by captivity.
It can be very stressful for many species to be in captivity. Without the wide-open habitat they are used to, they suffer perpetual stress which can be detrimental to the point where they don’t eat or otherwise don’t take care of themselves as much as they would in the wild and thus die earlier. Note that this does vary from species to species with some doing just fine in captivity and others not at all.
This is an active area of research as we do not know what causes it, or even if there is a common reason. The conditions in captivity is very different from the conditions in the wild. The area is smaller, there is less predators and live pray, the animals is watches very often, etc. This can result in very different life expectancy and behavior, in some cases for the better and in some cases for the worse. One factor which have been recently discovered is that some animals show a longer life span when kept as work animals rather then as pets or display animals. But again this only applies to some animals.
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