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Common Population Reduction Techniques
Identify the behavior of the most populous cormorant species in Australia. The Great Cormorant (Phalacrocorax carbo), often called the Black Cormorant because of its color, is the most common of the five native Australian cormorant species. It is mainly found in the southeast and southwest parts of the continent, and prefers inland freshwater estuaries, and occasionally can be found on the coast. It feeds mainly on fish, and nests in large colonies in trees or on the ground. Most conflicts with cormorants occur in these inland waterways, in which cormorants prey on the catches of commercial and recreational fishing boats.
Scare the birds away from the inland waterways where they tend to nest. This would rid cormorants from desirable fishing areas. Scaring techniques include both visual elements, such as scarecrow figures and balloons with "eyes" painted on them, and audio or physical methods such as noisy alarms, shell explosions, water sprays and gas explosions.
Reduce the natural nesting habitat of cormorants. Since Great Cormorants in Australia require certain environmental conditions to breed, steps can be taken to remove dead trees that may provide ideal nesting spots. Inland fish ponds are also a prime location for cormorants. These can be covered with nets, allowing anglers to continue to fish but keeping the cormorant population structure intact.
Consider other methods as a last resort, such as egg oiling and national hunting. The Danish government oiled cormorant eggs to prevent hatching, but the fluctuations in population were too great. In Europe, Great Cormorants have been opened up to limited hunting, but there are several drawbacks. Even though hunters require special licenses to hunt cormorants, difficulty in regulating unlicensed hunting has become a problem.