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Editorial Content     Laurinda     082 738 8011         ed.gbp @ greatbrakpost.co.za
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A Great Brak River and Surrounds Community Newspaper

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 Published by Targa Publishing all rights reserved - 2016 No content of this website or Tabloid may be reproduced in any form without the consent of the owners. CONTACT DETAILS Advertising Sales    Mike 	   	  044 620 4042      									  sales @ greatbrakpost.co.za Editorial Content     Laurinda   	  082 738 8011       									  ed.gbp @ greatbrakpost.co.za Article & Proofing	   Marianne	  	  072 025 0153      									  articles @ greatbrakpost.co.za
By Sally Adam Our local migrants have been streaming in over the last couple of months. It now feels like summer what with cuckoos calling endlessly and Greater Striped Swallows flitting in and out of the donkey shed (where they will hopefully produce a brood before the White-rumped Swifts turf them out). Recent research is showing that migratory birds undergo some quite extreme physiological changes prior to migrating. We've all seen birds stuffing themselves before flying north (even seed-eaters feast on fat-rich insects to boost their nutrient intake). Some of the smaller birds, for instance warblers, double their weight in preparation for the long flight. Have you ever wondered where the extra fat gets stored? Some is tucked into the lower back and in other areas where it won't add much drag. In a study looking at the physiology of the Bar-tailed Godwit, researchers discovered that in order to make space for the extra fat while still maintaining a good flying weight, the birds absorb up to 25% of the tissue of the liver, kidneys and gut. Once the migration is complete, the organs are reconstituted. Many migrating bird species will shrink the size of their testes and ovaries to almost nothing to help reduce body weight. There can be other changes too. The pectoral muscles of the Red Knot swell by 40% and the extra muscle mass will help fuel the trip. Migrating birds also produce higher levels of haemoglobin, which allows more oxygen to be delivered to their muscles, helping them so sustain flight over long distances. As a final preparation, birds undergo a moult - the fresh, new feathers are more aerodynamic, and for birds who have a different costume for each hemisphere, a duller outfit will provide them with more camouflage on their journey.

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