Do white pigeons or doves have an significance in the Sikh religion?

Answer 1

It's a symbol of the Holy Spirit in the Sikh religion.

THE KINSHIP OF AGES
by
BHAKTA NAMDEO

THE WHITE DOVE

In all ages, the life of the Spirit descends on man as Heaven’s great favour. It is truly the alighting of the ‘Holy Ghost’ on one’s shoulder as a little White Dove. Initiation into Discipleship, or Sikkhi as we in Punjab call it, is Inspiration. It is the intimate and perennial and companionship of the immortals, “the powerful Ones of the Unseen Realms” as Guru Nanak refers to them in Japuji.