2007-03-04 07:13:27 · 3 answers · asked by mobkab49 1 in Pets ➔ Birds
The main factor is probably the length of day. Birds can sense the change of season by this and will move to areas where they can better survive. If you look at a species like the Ruby-throated Hummingbird, it will leave an area even if there are still abundant flowers and plenty of food in fall and head south. Obviously this movement is not triggered by food.
2007-03-04 07:57:49 · answer #1 · answered by sngcanary 5 · 0⤊ 0⤋
The need to eat. Usually in the north the ground is covered by snow all winter. Robins like to eat berries and worms. Pretty hard to find either in the winter. Some do stay around up north now as our weather is changing and there is less snow.
2007-03-04 15:21:09 · answer #2 · answered by peach 6 · 0⤊ 0⤋
Cold weather sends birds that eat worms and bugs south when the supply in the north is cut due to the killing off weather.
2007-03-04 15:20:31 · answer #3 · answered by Anonymous · 0⤊ 0⤋