The Great Emu War describes actions taken by the Australian military in 1932 to reduce the numbers of emus that were destroying crops. According to Wikipedia,
On 2 November the men traveled to Campion, where some 50 emus were sighted. As the birds were out of range of the guns, the local settlers attempted to herd the emus into an ambush, but the birds split into small groups and ran so that they were difficult to target. Nevertheless, while the first fusillade from the machine guns was ineffective due to the range, a second round of gunfire was able to kill “a number” of birds. Later the same day a small flock was encountered, and “perhaps a dozen” birds were killed.
The next significant event was on 4 November. Meredith had established an ambush near a local dam, and over 1,000 emus were spotted heading towards their position. This time the gunners waited until the birds were in close proximity before opening fire. The gun jammed after only twelve birds were killed, however, and the remainder scattered before more could be killed. No more birds were sighted that day.
In the days that followed Meredith chose to move further south where the birds were “reported to be fairly tame”, but there was only limited success in spite of his efforts. At one stage Meredith even went so far as to mount one of the guns on a truck: a move that proved to be ineffective, as the truck was unable to gain on the birds, and the ride was so rough that the gunner was unable to fire any shots. By 8 November, six days after the first engagement, 2,500 rounds of ammunition had been fired. The number of birds killed is uncertain: one account claims just 50 birds,[6] but other accounts range from 200 to 500—the latter figure being provided by the settlers. Meredith’s official report noted that his men had suffered no casualties.
Summarizing the culls, ornithologist Dominic Serventy commented:
The machine-gunners’ dreams of point blank fire into serried masses of Emus were soon dissipated. The Emu command had evidently ordered guerrilla tactics, and its unwieldy army soon split up into innumerable small units that made use of the military equipment uneconomic. A crestfallen field force therefore withdrew from the combat area after about a month.
That’s right. Not only did the Australian military attempt to take on large groups of emus with machine guns, but they ultimately lost. Eventually, Australia gave up on the idea of using the military, and instead relied on offering individual bounties for the killing of emus. According to Wikipedia, this was effective with more than 57,000 such bounties being collected over the first 6 months of 1934 alone.