chimneypot การใช้

At second-floor level, a chimney-breast projects slightly and steps up to the gable of the roof, which is topped with a short chimneypot.
This is just something I was musing about to myself as I was riding the bus this afternoon and watching the gulls hunkering down on the rooftops and chimneypots, all fluffed up and looking rather cold.
On a cold day, are urban gulls more likely to perch or sit on chimneypots that have gas fires ( I don't imagine that a gull would sit on top of one that was belching smoke from a coal / wood fire for long ) burning down below in order to take advantage of the heat from the flue gases?