If you spend any time around saltmarshes here on the Cape, there’s a special but underappreciated bird I bet you haven’t noticed. For one thing, it’s a sparrow – the birds everybody loves to ignore. They’re “little brown jobs”, too hard to identify, not pretty enough – they’ve heard it all, but they haven’t let it get them down. But one mighty force is starting to get to this particular sparrow, and it’s the reason they are the latest addition to the Massachusetts endangered species list. It’s