My two pence worth!
At 400 feet, presuming no lfaps etc you could probably avoid a large bird - avoiding a swallow or something that size - be bloody hard to spot it - particularly with their speed and maneourvability (oops!).
These smaller birds can do some damage but they should n't spoil your day. Once ytou get to seagulls and larger then the damage can be substantial. One of the local club 152s hit a gull which took out the windscreen and literally exploded in the cockpit, there are still photos knocking around showing the mess. More seriously one of them was injured, probably by the screen. So trying to avoid the ones you see is a good idea!
But on a much brighter note I encountered two eagles sparring at around 1500 a few years ago on the West coast. They locked talons and whirled down spinning around each other . I followed in my trusty stead and was able to just keep with them in a very steep spiral dive. Amazing experience (particularly recovering at not a lot of feet!). Only ever seen one since - on telly!!!