 While the range of the noisy miner has not significantly expanded , the density of the population within that range has substantially increased . High densities of noisy miners are regularly recorded in forests with thick understory in southern Queensland , 20 kilometres ( 12 mi ) or more from the forest / agricultural land edge . Many of these sites have extensive road networks used for forest management , and picnic areas and walking tracks for recreational use , and it has been found that these cleared spaces play a role in the abundance of noisy miners in the forests . There is evidence to suggest that higher road densities correspond with higher noisy miner population levels . Field work in Victoria showed noisy miners infiltrated anywhere from 150 to 300 m ( 490 to 980 ft ) into remnant woodland from the edges , with greater penetration occurring in less densely forested areas . This has implications for the size of woodland habitat needed to contain miner @-@ free areas — around 36 hectares ( 89 acres ) . <unk> projects restoring <unk> woodland , a species of she @-@ oak integral to the survival of the red @-@ tailed black <unk> ( <unk> <unk> ) , have been <unk> with a nurse species , usually fast @-@ growing eucalypts . Noisy miner populations were more likely in those <unk> woodlands where eucalypts had been planted at densities of up to 16 per hectare ( 6 @.@ 4 per acre ) . The presence of noisy miners was accompanied by a substantial difference in number and types of other birds found in the woodland . 
