Doves are birds rich with symbolism. In Christianity, they symbolize the Holy Spirit. It was also a dove that Noah released to see if the flood waters had receded. On its second flight back, it held an olive branch in its beak. It is a symbol for peace. Colloquially the term "doves" signifies those who prefer peace, as opposed to those who do not – the "hawks".
A white dove is a symbol of purity. A variety of doves is the oft-despised pigeon, which is notorious for causing annoyances in big cities.