We've added several photos from Matt Downer, who has applied his pest detective skills while out walking in the reserves behind Nelson.
On one occasion, when up in Grampian Reserve behind the city, he noticed the possum pellets pictured here. They were easily distinguished by their size, characteristic 'jellybean' shape and greenish tinge.
Just 10 metres away was another very different single larger dropping.
At first glance the larger dropping (right) looked like that of a dog but there was no sign of the white chalkiness typical of dog faeces, especially in older droppings as these appeared to be. The size, elongated segments and pointy ends indicated, instead, a cat.
Some weeks later, Matt went further afield to a logging area near the Tantragee Saddle in the hills behind Nelson. He noticed pig tracks, which he followed along a logging road to see what further evidence he could find. The tracks eventually led to a skid site where fallen logs were lying.
"This is where I came across a hug old log on the ground with a lot of rooting sign," Matt recalls. "The logs had obviously been a source of food for the pigs and so they must use it quite often.
"Tracking an animal is fun from time to time."