The Indians had Neolithic technology and were hunters, gatherers, fishermen, and gardeners with stone and wooden tools.
The Europeans were farmers and herders with iron plows, hoes, and other tools, as well as draft animals for traction and transportation.
The agriculturalists produced far more calories per square mile than the hunter/gardeners. It was inevitable that they would out produce, out multiply, and take over the arable and grazing lands.
The same thing happened with the Russian expansion across north Asia, British in Australia and New Zealand, the Dutch in South Africa, the Spanish in Argentina, Chinese rice farmers in Asia, Anatolian farmers up the Danube Valley, steppe herders into Europe, and the expansion of Bantu herders across Africa.
The more productive economy wins.
Hence the slaughter of herds of cattle, destruction of birds, and stopping the use of fertilizer. It is meant to drive down the population, nicely said. The truth is, it is meant to SLAUGHTER the serfs, ie US.