300kt/1lb bird - m-v-squared
Robert's joke of a windscreen taking a 1lb bird at 300kts or a 300lb bird at 1kt brings up a useful scaling, as the kinetic energy of the bird goes as mass times speed squared.
The sobering kinetic energy of a 20lb goose at 300kts matches that of a 3000lb car at 25kt, or a 72,000lb boat at 5kt.
The damage done should thus rise quickly with speed, depending on how exactly the bird is `processed': how much of the bird's kinetic energy is dumped into how many fan/compressor blades. I speculate that the details of impact are relatively independent of speed, since the speed of sound in the (unfrozen) bird is probably like that in water, of order 1500m/s, well above closing speed (~150m/s), and above the maximum fan tip speed
(less than 800 m/s? - even for a 3m diameter fan at 5000rpm).
Just after departure at ~150kt there would only be 1/4 of the kinetic energy going in as at 300kt. Also, since geese are quite quick (~60 kt), a head on is probably going to more damaging than an overtake: impact at 360kt vs 240kt differs by a factor of more than 2 in energy.