Day 1,569

From a distance it looked like someone had duct-taped a bin bag to the brick wall but bin bags don't have vulture-like heads tucked behind them. We call them Tar Birds for their oil-slick, black rubber like feathers and the way they manage to camouflage perfectly in an urban environment.

Nobody can quite pinpoint when they evolved or how they evolved or even find a midway species to backtrack their unusual development over the years. All we can say for sure if that they hatch in landfills and steadily migrate towards neighbouring cities where they live out the rest of their lives... at least we assume so.

Nobody's found a dead one yet and all the live ones outsmart our traps and vibrate to blur themselves when we try to photograph them. We claim that they eat our rubbish but there's no concrete evidence for this, just the happenstance of them being where garbage used to be.

There are rumours that Tar Birds never stop growing, they just move from the surface to our greatest source of filth - the sewers. Cleaner crews refuse to go to certain areas because they've apparently found nests made of hair and bones spanning eight or nine feet in length.