In 1932 the Australian army lost to flightless birds.
Around 20,000 emus were stripping the wheat fields of the Campion district in Western Australia. From 2 November to 10 December 1932 soldiers went out with machine guns. Official figures claim 986 emus killed with 9,860 rounds – a disputed number. What actually worked later were bounties and fencing, not the military.
Useful: Attacking a problem with the wrong tool burns ammunition and solves nothing.
Source: en.wikipedia.org