The Japanese also relied on native labour to transport supplies for their forces on the Kokoda Track. Around 2,000 indentured workers were transported to the mainland from Rabaul, and a further 300 residents of the north coast of Papua were recruited. These labourers were poorly treated, and suffered from overwork. Many carriers who became sick or injured were murdered by Japanese forces. This mistreatment caused high desertion rates among the Papuan carriers. As the Japanese had difficulty obtaining replacement carriers, the casualties and desertions contributed to shortfalls in the quantities of supplies which reached the combat troops.