Rocket net

A rocket net is a type of animal trap used to trap a large number of live animals, usually birds, but they also have been used to catch large animals such as various species of deer. Rocket nets, cannon nets, and other net launching devices are built upon similar principles have been used since the 1950s (Dill and Thornsberry 1950, Hawkins et al. 1968, Grubb 1988 and 1991).^[1][2][3][4]

Rocket nets, as well as the very similar cannon nets, are used in conservation programs where a large number of live animals need to be captured for analysis, veterinary care or relocation.

Materials

The Rocket Net consists of an accordion folded rectangular net with one edge attached to the ground by short ropes or shock cords. The net can be placed directly on the ground in a line or can be folded and placed in a specially designed box (Grubb 1988). Nets specifically designed for rocket nets can be purchased from several wildlife supply and net manufacturers.

The rockets are constructed from heavy gauge metal pipes with caps threaded and welded on one end with a removable cap on the opposite end that contains ports for the expanding gasses to escape. The rocket charges are made from black powder and an electric match enclosed that is used to ignite M6 Howitzer propellant. All 3 components are enclosed in a larger plastic bag with shunted leg wires extending out of the bag. Currently the primary manufacturer of rockets for rocket nets is WinnStar in Illinois.

In addition to the rocket net, other specialty equipment is necessary for the safe firing and storage of rocket nets and their charges. A blasting galvanometer, capacitor discharge machine, and electrical blasting line are recommended for the safe use of this equipment. In addition, an IME-22 container is necessary for the safe transportation of charges and an explosives magazine is required for long-term storage. Transportation and storage of the charges are regulated by the US Department of Transportation; Department of Alcohol, Tobacco, Firearms and Explosives; and by other state and local agencies (ATF: Explosives Law and Regulations, ATF P 5400.7 and 29 CFR, Part 1910.109 and IME Safety Library Publication Numbers 1,3,12, 22, and 14).^[5][6][7] The US Fish and Wildlife Service and State Wildlife Agencies regulate their use to capture birds and other wildlife.

Use

The rocket net or similar-looking item is placed at the target location after days or week of pre-baiting the target species in, or is place in an area where it is likely to capture the target animals, to allow animals to become accustom to its presence. When the biologist is ready to use the actual rocket net, the net is folded accordion style in a line or packed in the rocket net bock. The rear or trailing edge of the net is staked to the ground by ropes and the leading edge of the net is attached to a number of rockets (typically 3 or 4) via longer ropes. The rockets are placed on the box, staked to the ground, or placed on post for additional elevation when taller animals are trapped. The charges are placed in the rocket and the wires attached to a shunted electrical blasting line. Once all the charges are connected, the line is tested, and the area is safe, it is attached to the capacitor blasting machine. When the animals are in place, the operator activates the blasting machine and the electrical charge ignites the rockets, propelling the net over the animals. The biologists and their team then remove the animals for whatever study they are conducting.

Modifications

Over the years, biologists have modified this basic set up to catch various animals (Schemnitz et al. 2012).^[8] Portable platforms have been built to capture birds over open water. Boxes have been modified to capture wild turkey. Rocket nets have been fired from portable platforms to capture birds in water.

Similar Devices

Cannon nets are similar to rocket net except a cannon-net projectile is a heavy metal barrel which is fired from a launch-rod attached to a metal plate. Cannon propellant is smokeless gunpowder ignited by an electric match. The primary advantage of cannon nets is the lack of explosives, therefore storage and transportation is easier. However, cannon-net projectiles have to be cleaned after every use.

The Martin Engineering Net Blaster is a similar device that propels a weight attached to a rocket net via a rope without the use of explosives. The Net Blaster was developed between researchers at USDA APHIS Wildlife Services and Martin Engineering as an alternative to the rocket net where the use of explosive charges would not be advisable, such as capturing oiled birds at an oil spill. The Net Blaster is charged with a portable compressor and set out in a similar fashion to the rocket nets placed in boxes. The air powered cannon is much quieter than rocket nets, but are much more expensive.

References

1. Dill, H. S., and W. H. Thornsberry. 1950. A cannon-projected net trap for capturing waterfowl. Journal of Wildlife Management 14:132-137.
2. Grubb, Teryl G. 1988. A portable rocket-net system for capturing wildlife. Research Note RM-484. Fort Collins, co: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station.
3. Grubb, T. G. 1991. Modifications of the portable rocket-net capture system to improve performance. USDA Forest Service Rocky Mountain Forest and Range Experiment Station. Research Note RM-502.
4. Hawkins, R. E., L. D. Martoglio, and G. G. Montgomery. 1968. Cannon-netting deer. Journal of Wildlife Management 32:191-195.
5. U.S. Department of Transportation, Code of Federal Regulations, Title 49.
6. Institute of Makers of Explosives Safety Library Publication No. 22, Recommendations for the Safe Transportation of Detonators in a Vehicle with Certain Other Explosive Materials. 16pp.
7. Federal Explosives Law and Regulations. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. ATF P 5400.7.
8. Schemnitz, S. D., G. R. Batcheller, M. J. Lovallo, H. B. White, and M. W. Fall. 2012. Capturing and handling wild animals. Pages 64-117 in N. Silvy, Editor. Wildlife Techniques Manual: Volume 1 – Research (7th Edition). Johns Hopkins University Press, Baltimore, MD.