what’s the difference between a rare animal and one that’s going extinct?
In: Biology
There’s not a specific definition of “rare”
It might be an apex predator that’s highly territorial and requires a large range, limiting their population. Even in the best of times, tigers and jaguars are widely dispersed throughout their habitats and have a low but stable population.
It might be transient or migratory, and only present in the area for a few weeks out of the year. Boreal chickadees are quite rare in my area, but their population in general is fine.
It might just be really good at hiding, and so rarely seen despite a healthy population. There’s a million bush crickets around here, but you’ll never find them.
A species that’s critically endangered may or may not also be rare, but their population has undergone significant decline for some reason. They may still be common in certain areas, but have also lost huge swathes of habitat that endangers their long term survival.
Its a few factors.
But in short; Species become endangered for two main reasons: loss of habitat and loss of genetic variation
There’s also a sliding scale of rareity, with least concern at one end, and extinct at the other.
Population trend.
It’s possible to have a very small but stable population – for example if it’s a species that seems to have evolved to thrive in some very specific environmental conditions unique to its habitat. That would be, in your words, just a “rare” species.
But if the population is in decline, then we can guess that there is some factor which is killing the organisms off or causing them to not reproduce well enough to sustain the population. So, by definition, that species would be “at risk” or “endangered” because if things don’t correct themselves the species could continue to decline all the way to extinction.
Consider two animals. A population of 100 rare blind fish that only exist in one deep cave that hasn’t changed much for millions of years, and a population of 100 rhinos being hunted by poachers.
The blind fish are few in number because their habitat can not support more, but they’re not really in danger because their environment is stable. They’re not likely to face any threats unless something drastic happens like an earthquake breaking up their cave or humans drilling into it. Assuming things go on as they are, they’ll stay around for another million years.
The rhinos on the other hand used to have a much bigger population, but now they’re on the decline. They’re in the process of being hunted to extinction. If things continue as they are, poachers will hunt them faster than they reproduce until they’re eventually all gone.
The difference is that one faces a relatively new threat that has it on the decline while the other is in a stable situation.
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