Japan began killing some 90,000 chickens today to contain another outbreak of a highly contagious strain of avian flu. The new drive means more than a million farm birds will be killed in seven mass culls this season as officials work to prevent the spread of the virulent H5 strain, which has been detected at several farms across the country.<br/><br/>Kumamoto prefecture in southwestern Japan started slaughtering some 93,000 farm birds Tuesday after confirming the H5 strain was found in the town of Nankan, officials said.<br/><br/>Japan's first outbreak of avian flu this winter hit in November, which led to the killing of some 18,000 ducks in northern Aomori prefecture. Several more outbreaks have since hit throughout Japan, from the northern main island of Hokkaido to Kyushu in the southwest.