Thousands of birds die at important wetland, from deadly disease caused by pollution strange silence has gripped Whangamarino. It is a deathly silence. The corpses of thousands of dead birds have piled up around the extensive mosaic of swamps, fens, bogs and open water between Waikato’s Meremere and Te Kauwhata. The wetlands are usually an oasis for rare wildlife. It is home to the largest population of matuku (or Australasian bittern) in the world, and its booming calls echo across the water. But large populations of Whangamarino’s birds have fallen sick with avian botulism, dying a gruesome death after losing the ability to walk and use their wings. The paralysis eventually robs them of the ability to hold up their heads, and they drown in the waters that were once a haven. Appalled by the outbreak, Fish & Game New Zealand launched a stinging attack on Waikato Regional Council, accusing the local authority of permitting dairy intensification and failing in its statutory obligation to protect freshwater environments. Fish & Game chief executive Corina Jordan​ said the disease outbreak, in its third month, was “appalling” and a wake-up call for “urgent action”. Devastated Fish & Game staff and community volunteers collected almost 2000 birds, including matuku, in the last month. Although classed as internationally significant, the wetland had long faced environmental challenges, overloaded with sediment and nutrients from farming and industrial run-off and storm water. Poor water quality, and changes to how the water flows, had contributed to low oxygen levels in the swamp. Lake Waikare​, one of the world’s most polluted lakes, was diverted into the wetland as part of a flood control scheme. Locals call it Fanta Lake, because of its vivid orange colour. As the pools become stagnant, this creates the perfect breeding conditions for bacteria that produces a botulism toxin deadly to birds but harmless to humans. The toxin is consumed by fish and aquatic invertebrates, which are then eaten by waterfowl. When Stuff visited the site on Friday, some of the waters were orange and there was an overwhelming, rotting stench. Jordan said even freshwater eels, which are hardy and able to tolerate low-oxygen environments for short periods, had perished. “We are concerned at the rhetoric we hear from authorities labelling these incidents as natural,” said Jordan, who is a freshwater ecologist. “Parts of this wetland have been without oxygen for the best part of three months, leading to massive aquatic deaths of even the hardiest freshwater species such as eels. This isn’t normal in healthy freshwater wetland systems.”