You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Bird_migration

Context:
Reverse migration, where the genetic programming of young birds fails to work properly, can lead to rarities turning up as vagrants thousands of kilometres out of range.

Question:
What does reverse migration lead to?

rarities turning up as vagrants thousands of kilometres out of range