For those who are interested in such things, there is a downloadable version of the WCA 1981 at the JNCC website (its big though)
http://www.jncc.gov.uk/page-3614
To be clear the laws on Birds and Animals are different. There are provisions for
Specifically banned weapons for hunting purposes (notably bows and crossbows)
Specifically banned techniques & traps for hunting purposes (e.g. self locking snares)
Specifically protected animals (e.g. Red squirrels
)
Animals where certain techniques may not be used (you may not use a lamp to hunt badgers)
For hunting animals You need to refer to Section 9 of Part 1 of the Act and Schedules 5 & 6 for listed animals.
Additionally
(1)There is the Offensive Weapons Act to take into account that ban the ownership of certain weapons (notably blow guns as noted above) - the WCA only bans use in hunting
(2) Specific laws relate to the use of firearms and target species (notably the use of calibres on deer, Section 1 firearms on birds etc.)
(3) Above all else all laws relating to animal cruelty still apply (including as suggested above the WMPA)
Hope that helps a little - it means that such things as catapults aren't banned as "offensive weapons" in that they are legal to own although of course they could be used as such an result in prosecution - the same as any other item could be. Equally they aren't forbidden under the WCA as a specifically banned hunting tool.
Red