There are now three species of crossbills in North America. The White-winged Crossbill, Red Crossbill and the newly accepted Cassia Crossbill that is found in Idaho. These types of birds live off the seeds of pine and spruce cones.
The White-winged Crossbill lives more north than the Red Crossbill and is not likely to migrate into the southern states such as the Red Crossbill will when the food supply becomes scarce.
The crossbills are nomads and follow the pine and spruce cones as they harvest and mature. They have no real nesting schedule, unlike most birds who tend to nest in Spring. The abundance of cone seeds plays a major role as to when they will decide to lay their eggs and raise their young rather than what month of the year it is.
Avibase - the world bird database This site provides the user with a complete list of bird species, broken down per country, or in the example of the US or Canada, per state and province. Here, bird species names are available in other languages, a great asset to be used as a translation of foreign bird names.
ABA - American Birding Association This site represents an organization that maintains official records of all birds species that have been proven to have been seen inside the perimeters of the North American Continent and the surrounding bodies of water. Regular revised versions are posted to keep the bird list current at all times. This is the list used by all serious birders over their lifetime. You may be aware of the movie called the "Big Year". It was with this list that all the competing birders used in an attempt to set a new record as to how many bird species that could be seen by an individual birder in one calendar year.
I hope you will take advantage of these suggested websites. I have used each of them, in one way or another, throughout the years in my quest to better identify and understand our fine feathered friends.