It eventually proved to be the non-harmful avian strain as opposed to the more virulent strain found in possums and other pests, albeit only after repeated and costly testing.
"It took five tests to clear our herd, and the one cow that showed a positive test (which cost about $1200) had to be culled," he said.
"It wasn't the dangerous Tb but it was still a lot of work and quite a bit of hassle. You can get locked down, and you can't do anything, coming up to selling your calves and you haven't got clearance."
He knew of several farmers throughout the district who had stopped growing chicory, with the view that it was only good for "feeding the ducks" becoming increasingly common.
There was also serious concern that the increasing presence of the birds represented a huge risk to the multi-million-dollar dairying industry.
On a bad day he would see hundreds of ducks in one paddock, compared with a handful that frequented the farm before he began growing chicory.
He believed the situation was equally dire on a number of other farms around the district, and in Whangarei, the Hokianga and Dargaville, where the ducks just "breed, breed and breed".
"They have absolutely multiplied. Totally overpopulated. They are out of control," he said. And while farmers could obtain special permits to shoot them, outside of annual shooting season, that wasn't enough.
Northland Fish and Game manager Rudi Hoetjes said the Minister of Conservation would never approve a year-round open season on an indigenous species, however.
"That's just not going to happen.
"These birds are unique, and a precious species to New Zealand," he said.
Fish& Game could help assist land owners by including issuing special permits for a two-day shoot, as had been done for Mr Senn earlier this year, and it did offer an annual two-day summer season specifically for paradise ducks, over and above the traditional shooting season starting in May.
