SS, you miss my original point, so keen were you to jump in with criticism. Which IS: If you operate all the time in the bit of sky where there are more birds, then the risk of birdstrike is more likely. If you can fly higher, you reduce the risk. Glad to hear this has prompted you to read the CAA safety leaflet. Perhaps the first time as you seem surprised by the content?
Yes, some big birds of prey can be aggressive to anything airborne, which is what I meant when I said that the Buzzard is territorial.
During my time in Belize in the late 1970s / early 80s, RAF Harrier pilots often found out the hard way that a local hawk species mistook the head-on profile of their jets, with their pronounced wing anhedral, for a "stooping" competitor and they were very prone to "tip in" for a fight. This resulted in a bit more of a fight than they thought - as the jets were doing 420 kts....
As there were no low-flying restrictions at all out there, we sometimes used to fly down from APC to Rideau (100 nm) at low level, just for fun. One day I came within a gnat's wotsit of hitting a big formation of brown pelicans which certainly taught me a lesson - after that I usually stayed up at medium level for those transit flights.
Gulls are also very dangerous as you say, because although they aren't aggressive they fly in large unruly flocks and seem to have no fear of a mid-air collision. If you watch a flock of them you can see it for yourself - they often bump each other in flight. They are careless fliers - bad news for an aircraft in the same bit of airspace as they are BIG birds.
Some years back I had a heavy birdstrike at around midnight, over the sea at 500', with a casualty on board, flying under a September moon in hazy conditions. Whatever we hit blotted out the lights of Hong Kong Island and the moon just before it hit us - it was VERY big. I suspect it was a large black-eared kite (wingspan well over a metre). It hit the front of the aircraft just above my head, solid structure rather than glass windscreen and it bounced off, or I might not be here arguing with you. We landed with blood, feathers, meat and guts all over the top of the aircraft, including on the main pitch rods but no real damage occurred other than some big scratches through the paint right down to the composite fibre flight control cowling.
In my most recent employment we tend to cruise at 2000 ft or above and there are certainly FAR fewer birds up there. Something I am very conscious of as I don't have the luxury of wearing a clear visor these days.
John - YES, we switch on the searchlight as we descend from the cruise - it's a checklist item.