Wildlife crime

I want to know an expert opinion , is something constitutes a wildlife crime - basically close to where I live contractor cut back reeds, just the other day so with the March - aug window,  in a balancing pond , there were Reed bunting and Reed warblers using the reeds , I believe they were nesting within the reeds. I tried to stop the contractors and inform them that I felt they were committing a wildlife crime , and they need to stop and carry out further observations , however they basically refuse and said they carried out a sufficient assessment, although as I was trying to discuss with them the Reed warblers was flying in and out of the area they are cutting back . Was this a wildlife crime ?