Jamesdevice,
You're speaking with local knowledge available. When crews plan a route, they generally plan to avoid certain areas that are highlighted by various markings on a chart. Although they can then go to various documents to find out more detail about those 'avoids', they won't know that some of those areas contain:
the largest gull colony in the UK, over a nature reserve stuffed full of thousands of geese, out over Morecambe Bay (ten of thousands more geese and waders), over another wetland reserve full of large birds) and then up one of the Furness/Cartmel valleys and over a large lake (more ducks and geese)
Every known bird strike results in an incident report, so if the route you describe is indeed utilised heavily by rotary aircraft and unless multiple reports are being ignored, I can only come to the conclusion that the actual (not theoretical) threat isn't as high as you state?