As far as the second objection, the black mustard seed (Sinapis nigra) can grow to a height of several feet (2-12 feet), enough to have a bird such as a sparrow perched on its branches (In the above article by ChristianAnswers.net they cite Matthew 13:31-32 as saying the mustard tree can hold a bird's nest, but I only see the words lodge and perched in the KJV and NIV respectively, and lodged