Another round of bird flu could be on the way due to the annual fall migration of wild birds.

The avian flu affected 48.8 million poultry in 21 states this spring. Iowa and Minnesota were hit the hardest by the outbreak. Minnesota alone saw $600 million in losses as the virus spread to over 100 farms in the state.

Many believe that migrating ducks and geese are what carried the bird flu into the United States, but thousands of droppings have been tested and so far, the results have come up negative. Others blame lapses in biosecurity and other farmers blame the wind.

Agriculture Secretary Tom Vilsack stated that the situation could have been handled better.

“We understand there are issues involving biosecurity, there are issues involving depopulation, there are issues involving disposal, there are issues involving indemnification, and the time for repopulation,” Vilsack said.

The U.S. Department of Agriculture (USDA) has since issued a 57-page plan for this fall that reportedly can handle twice as many infections. The USDA is also hoping to stockpile the vaccine that will reduce the amount of virus created from an outbreak, but it won’t fully protect the birds.

The scare of another bird flu outbreak has also started a controversy on how to dispose of birds who are infected with the virus. U.S. agriculture officials have approved a new method that would entail trapping infected poultry in a sealed atmosphere, turning up the heat, and shutting off all ventilation. Animals rights groups immediately responded, stating that this method was cruel.

“We shouldn’t compound the problems for birds by subjecting them to a particularly miserable and protracted means of euthanasia,” said Michael Blackwell, the Humane Society’s chief veterinary officer.

U.S. agriculture officials state that this method isn’t the first choice as it can take 30 to 40 minutes for the birds to die of heat stress.