[LeeH]

Assuming the bird is actually sitting on the flat part of the chimney cap...

http://www.amazon.com/Tanglefoot-300000703-Bird-Repellent-Caulking/dp/B000BOC4MW

http://www.amazon.com/Aspectek-Polycarbonate-Bird-Spkes-Feet/dp/B00EJXMJU8/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1432139255&sr=1-1&keywords=bird+spikes