How no do-migratory birds survive?

Question

How do crows, magpies and sparrows survive the long Canadian winters even when it gets to 30 below zero?

Sorry, I mean "how do non-migratory birds survive..."

Answer 1

Possibly by adaptations like these, that the Chickadees make:

http://www.theherbsplace.com/ATN/ATN2002/100102.html

Also, flocking, huddling, sleeping in roosts (which crows do) all help. Sparrows especially are great for huddling under leaf litter and fluffing up all their feathers until they are about twice their normal size. This extra air space in the feathers acts just like you putting on a down jacket!

Answer 2

Because they're garbage breeds that will eat anything and are very crafty at storing their food cache's. Migratory birds could never survive like this because their food demands are higher.

More discussion here:
http://www.auelfans.ca/discus/messages/14/454.html

http://www.vetscite.org/publish/items/002306/index.html