Definition
To track down a political candidate to a public event and get in a position to ask him/her questions on issues they would rather not talk about, and to ask follow-up questions if answers are evasive. A bird dog is a retriever who runs into the bushes and flushes birds out into the open. Term has also been used in 2016 US presidential campaign by some players to go well further by inciting violence at opposition campaign rallies.