What does 'odds' mean in 'overcome the odds'? [closed]

Odds is a reference to the probability of failure (or success). It's generally a betting term. If you are highly unlikely to achieve something, the odds are said to be against you. If you succeed nevertheless, you have overcome the odds.

Note that although the term is most closely associated with gambling, a bet does not have to be made for odds to exist. For instance, if there is very little chance of rain today, the odds are against it raining whether or not you make a bet!

In gambling games, there are payoffs associated with different bets that one could take. For example, in roulette, the house would pay $1 for every $1 bet on red, and the odds are 1:1. In the same roulette game, the house would pay $35 for every $1 bet on a single number, say green 0.

A similar notion of odds exist for horse racing, poker, and football (on either side of the pond).

PokerZone defines long odds as "An especially low chance of occurring; unlikelihood."

The animals in the BBC story are figuratively overcoming the long odds, that is, they are producing offspring despite the unlikelihood. There is no house or bookie making the odds; however, the environment is probably harsh and reducing the likelihood of reproduction.