White storks and "junk food"

Abstract

In the mid-twentieth century, White storks (Ciconia ciconia) suffered a marked decline along entire Europe due to the destruction of their natural habitat by human activities. Since several decades ago, its populations have been recovered impressively due to the occurrence of a new food source, rubbish dumps. It is well established that the use of these sites as food resource facilitates chick raising, thus making it easier to raise high numbers of chicks. However the quality of these resources is very questionable. Food availability at rubbish dumps is unlimited throughout the year, but consists of mostly manufactured products mixed with a wide variety of rubbish that may contain dangerous substances as shown in different studies. In order to study adaptation of storks the use of this food resource we sampled chicks of four colonies with confirmed different food sources exploited by their parents during 3 consecutive years. We compared blood chemistry and oxidant/antioxidant balance between colonies with chicks fed natural or completely rubbish dump based diets and between years. The results suggest and adaptive physiological upregulation of antioxidant systems in storks exploiting junk food as food source.