The fishing line trick only works with a tangled mess of mono-filament. This type trap is commonalty used by the Fish & Wildlife folks to capture raptors for population and tagging studies.A raptor of some sort got one our pullers.Lots of feathers left.We now have fishing line w/CD's attached over their yard. Also a scarecrow in the middle.
Unless you plan on tagging your hawks with a Louisville Slugger it will prove useless because fishing line is invisible to birds and no one makes headphones small enough that a hawk can use them to listen to a CD.
http://www.mikesfalconry.com/Bal-Chatri-Noose-trap-p/5008.htm