Passage Summary: Some people think birds are born with a built-in GPS, but the research doesn't actually prove that, and it's possible they just navigate by looking at the landscape like we do.

Conclusion: There is insufficient evidence to support the claim that migratory birds possess an innate homing sense.

Reasoning: The studies intended to prove this innate ability have yielded inconclusive results, and the birds' behavior could be explained by their use of landmarks.

Analysis: This is a classic 'Identify the Conclusion' structure where the author introduces a common belief and then pivots to their own stance. The word 'However' in the second sentence signals the author's main point: that the evidence for an innate sense is lacking. The final sentence serves as a premise, offering an alternative explanation (landmarks) to show why we shouldn't jump to the 'innate sense' conclusion. Focus on the second sentence as the core claim being defended.