Context: Large scale climatic changes, as have been experienced in the past, are expected to have an effect on the timing of migration. Studies have shown a variety of effects including timing changes in migration, breeding as well as population variations.

Question: What is expected to have an effect on migration timing?
Answer: climatic changes

Question: What have studies shown regarding climate change?
Answer: timing changes in migration

Question: What else is climate change been shown to change?
Answer: breeding as well as population variations