Why do you cover your birds at night and is it ok not to cover them?

Are canaries sexually dimorphic? What is Crows Are Universally Black in Chinese characters? How to make noisy ducks quiet? Do Hamsters get along with Cockatiels? Are Flamingos K-Strategist or R-Strategist? Do birds sleep in nests in winter I was going to put out dryer lint like I do in the spring but its winter here and my husbands thinks they may not have nests in winter without babies? When was Will R. Bird born? What is the worlds shortest living owl? Do rainbow lorikeets have a kind personality? What are Kookaburra adaptations structural? What is the science of birds eggs? Did you hear the story about the peacock that lost its feathers? Why can't you have a bald eagle? What type fertilizer is made of bird droppings? Is the eagle endangered in Texas? What do baby ducks eat and what kind of corn do they eat? Why the number of great tit might decrease? What is the tree swallows enemies? Do eagles eat spider eggs? When are sparrows active?