Answer by  
                                                                                          caitchison (76)
                                                            
                          
                          
                                                          Holly berries are mildly poisonous. It would take about twenty berries to kill an average sized adult, even though many birds enjoy them as a wintertime treat. However, it should still be safe to decorate with them as long as you don't have any pets- the berries would case vomiting and diarrhea once ingested.