Physical and Migration Metrics of White Storks (Ciconia ciconia) and the influence that landfills play in their variation

Andrew Christopher Slater 

1. White storks (Ciconia Ciconia) are a traditionally fully migratory species and their numbers in western Europe were decimated in the last century. Their numbers have since boomed and they have altered their migratory strategy to have become a partially migratory species. This change has been ascribed in large part to anthropogenic food subsidies, particularly in the form of landfill sites. 2. We measured the size, and using GPS logger data monitored the movement, of 73 juvenile white storks in their first migration from southern Portugal to the Sahel. We compared their sizes and migration timings and movement metrics with each other and compared all with the minimum distance between their nest and a landfill site. 3. Birds were larger and left their nests later the closer to a landfill they were raised. Some variations in migration were noted in north Africa and crossing the Sahara. Birds raised closer to landfills traversed from Tangiers south across the Atlas Mountains more efficiently, but then crossed the Sahara more slowly, than those raised farther from landfills. Additionally, based on landfill distance, variations in easting whilst crossing the Sahara were noted. 4. We conclude that landfill proximity impacts on the fitness of a bird and that fitter birds successfully complete more migrations. The impact of removal of landfill food subsidies could severely impact the annually resident population of white storks within western Europe but is unlikely to cause serious issues to the migrant populations.