In extreme cases of house sparrow aggression or entrenched populations, it may be necessary to resort to stronger control techniques that actively reduce the house sparrow population. Options include shooting house sparrows, trapping birds to kill them (relocation is not desirable because that simply moves the invasive problem to another region), and destroying eggs or nests to prevent population growth. Before attempting aggressive controls, however, it is wise to consult a wildlife management office, as not all tactics may be legal or suitable in certain areas. Any aggressive techniques should also be carefully monitored so they do not impact other species that are protected under the Migratory Bird Treaty Act. It can be hard to distinguish an invasive house sparrow from native sparrows, so make sure you are an expert at identification before you consider lethal methods.