A rocket net is a kind

Kind

Kind can mean:* Kind , the type of types in a type system* Natural kind, in philosophy a grouping of things which is a natural grouping, not an artificial one.* KIND is the ICAO designation for Indianapolis International Airport...

 of animal trap used to trap a large number of live animals, usually birds. It consists of an accordion folded rectangular net with one edge attached to the ground. The corners of the opposite edge at the top of the folded heap are attached to heavy tubes with one closed end. These tubes are placed over stakes set at an angle. The stakes have a hollow in the end where an electrically activated shell is placed. When the shells are activated the heavy tubes shoot up at an angle and the net is spread across an area that was previously baited to attract the desired animals.

Rocket nets, as well as the very similar cannon nets

Cannon netting

Cannon-netting is a method of catching large numbers of animals, often birds, usually to band them, or otherwise tag them, as well as acquiring biometric data , in order to find out about their movements, migration routes, survival rates and metabolism...

, are used in conservation

Wildlife conservation

Wildlife conservation is the preservation, protection, or restoration of wildlife and their environment, especially in relation to endangered and vulnerable species. All living non-domesticated animals, even if bred, hatched or born in captivity, are considered wild animals. Wildlife represents all...

 programs where a large number of live animals need to be captured for analysis, veterinary care

Veterinarian

A veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....

or relocation.