Breeding biology of Eleonora 's Falcon (Falco eleonorae) and Cory´s Shearwater (Calonectris diomedea)

The breeding biology of Eleonora's Falcon was studied at a colony in the Mediterranean Sea. Data were collected on the synchronization of egg laying, hutching, pesticide residues in unhutched eggs,  clutch size and possible factors affecting it, such as the fitness of the male.

The growth of the young was described and related to food supply during August-October. When food was abundant, food caching was a regular phenomenon. Factors for egg clutch losses were discussed of which predation by rats seemed to be the most severe. Other factors which affected productivity have been assessed.


A colony of Cory's Shearwater had been studied. Ringing results showed a very high degree of philopatry for males, and site tenacity and mate fidelity for breeding birds. The
importance of these findings had to be discussed in relation to gene flow and formation of subspecies.

In addition, approximations for other population parameters were given (productivity, juvenile and adult mortality, longevity, age of first breeding). There were indications that irregularities in mortality figures could correspond with changes of the sea water temperature in the South Atlantic (El Nino effect).



The author participated  in the interdisciplinary project by supporting data collection in the field studies as student of the University of Braunschweig (Biology/Zoology). The population biological data were the basis of a later conservation project of the EU.

Related Papers