The aim of this thesis was to extend the existing database of literature thematically focused on the issue of feeding ecology of predators . Further localize the marsh harrier nest on the ground and analyze the foraging ecology of prey remnants and estimate the weight of the different kinds of food. The next step to evaluate the collected data to determine the species composition and numbers of prey . Assess the food supply in the area monitored nesting sites , and factors that could affect it . Finally, data evaluation and their confrontation with the literature , and on top to achieve viable squibs impact on small game