by Andy Johnston
Recent storms brought us the largest fall of North American migrants for 30 years. Most of these birds are warblers heading to South America and included a magnificent male Baltimore oriole. Long distance migratory birds eat excessively before departure, in some cases doubling their body weight. The fat produced must be distributed properly. Many birds’ bodies can shrink and grow their internal organs. Godwits, which summer and breed in Alaska, winter in New Zealand, completing the journey non-stop, taking 8 or 9 days! In order to do this and make room for the energy rich fat, they absorb 25% of their liver, kidneys and digestive tract and increase the size of their heart and chest muscles. In New Zealand they quickly return to their normal physiological state. If this is not surprising enough, I won’t explain how they navigate, as this involves quantum physics! Perhaps being called ‘bird brain’ is rather a compliment! Birds have been around for one hundred and fifty million years, so of course they have evolved complex strategies for survival!