Experiments to limit predation of wading bird nests??have shown that the use of protective cages and decoy eggs can be very??effective. Studies in Sweden looked at non-lethal ways to prevent??predation, including a??form of aversion therapy.In an attempt to find ways to halt the decline in??breeding wader species in Sweden, scientists at the University of??Gothenburg have tested drastic new methods to protect Northern Lapwings??and Redshanks from??predators.
Image by Mikael Larsson
Researcher Daniel Isaksson, from the Department of??Zoology, protected nests by enclosing them in a protective cage. “Both??Lapwings and Redshanks hatched more eggs when their nests were inside??the cages,” said??Isaksson. “But this technique works only for species??that leave the nest early when a predator is in the vicinity, as species??that stay longer risk being trapped and themselves becoming the prey.”Another method tested involved putting out artificial nests containing??hens’ eggs painted to resemble waders’ eggs and injected with a drug??that induces vomiting. The idea was to ‘teach’ predators that waders’??eggs are??inedible. “We found that predation of the real waders’ eggs??immediately decreased during the first three weeks in areas with the??decoy eggs, which suggests that the method had an effect,” said??Isaksson. The studies also show that nest-robbing and the positioning of waders’??nests are to a great extent governed by the surrounding environment.??Crows preferred elevated perches such as fences where they can keep??watch and avoid attacks by waders. In two out of three years, Northern??Lapwings positioned their nests further and further away from such??sites, limiting the breeding area and probably impacting on the size of??the??local population. See??University of??Gothenburg (http://gupea.ub.gu.se/dspace/handle/2077/18848)