They look pretty small (young) which means they would not be as hearty in cold as an adult would be.. being that you are in Vermont I would guess it can get pretty cold and snowy there in the winter.. on reallllly cold (single digits and below I keep mine locked up in barn .. they produce heat by cudding ( regurgitating their food and chewing it and doing this over and over so make sure they have a good diet and quality hay this winter) I would also recommend heated water buckets or provide them with warm ( not hot ) water a couple times a day.. my herd refuses to drink cold water when the temps drop and love warm water.. kinda like a good hot cup of tea or chocolate for us after being out in the cold for awhile. As long as your shelter is relatively closed in on extremely cold days they should do fine.. if you noticed them hunched up and or shivering you may want to keep them inside.. I caution about using any type of heater device/heat lamps due to safety issues and preventing them from building up tolerance to cold.. last winter here in NE Ohio we had some very extreme cold days.. minus temps without windchill.. there was actually ice/frost build up inside my barn due to their breathing/body temps.. on those days I kept the doors closed and made sure they had good dry bedding down and they did not even want to go outside on those cold days.. for young goats you can fashion a type of goat coat too.. they don't particularly like them but I use cheap extra small dog coats (for chihuahua and other petite dogs can do in a pinch) helps keep body temp from dropping.