Answer with Explanation:
The "passenger pigeon" used to be North America's most popular bird. Their population even reached 3 billion (or even more). They always traveled together. Their decline in number was noted in the 19th century. People became interested in hunting them for food because they were relatively cheap and tasty . They were also a great source of protein. It was easy to hunt them down although they could fly very fast because their flocks were huge in number. Some people killed them because they didn't want the birds ruining their crops. Their nesting grounds were also disturbed, which ultimately drove them away from the forests. People were overkilling them, and this sped up with the advancement of technology. The number of pigeons killed outnumbered the newborn pigeons, and after decades of hunting them down, their number dwindled with the last one passing away in 1914.
