Highly unlikely for an individual isn't the same as highly unlikely across a population. 0.1% is only one chance in 1000 - rolling the same number 3 times in a row on a 20 sided die has a probability of 1 in 8000, but you'll find loads of stories of it happening because there's a lot more than 8 thousand people who play D&D.
Your chooks are rolling along the edge of probability, but there's more than 1000 chickens in the world so the probability someone will hit that jackpot is close to 100%.
Highly unlikely for an individual isn't the same as highly unlikely across a population. 0.1% is only one chance in 1000 - rolling the same number 3 times in a row on a 20 sided die has a probability of 1 in 8000, but you'll find loads of stories of it happening because there's a lot more than 8 thousand people who play D&D.
Your chooks are rolling along the edge of probability, but there's more than 1000 chickens in the world so the probability someone will hit that jackpot is close to 100%.