NEST SUCCESS – DOES BUILDING HIGHER REDUCE PREDATION RATE? Mary Ledger, Leyla Yusuf and Joel Turner (Year 9) Science Faculty, The Illawarra Grammar School, Western Avenue, Mangerton, 2500 Abstract In this study, artificial birds’ nests and eggs were created using coir and clay and were placed at different heights to test the hypothesis that the nests placed in elevated positions would experience similar levels of predation to those at lower levels. While improvements could be made to increase the reliability of the experiment, it was found that birds’ nests placed in higher elevated positions had a higher level of predation.
Introduction Predation on nests has been identified as the primary cause of breeding failure in open and cavity-nesting birds (Matessi & Bogliani 1999). Several studies have been conducted with artificial bird nests to investigate the effect of nest site elevation on predation. Although the effect of nest site elevation has been contested, in 1993 T.E. Martin evaluated the findings of several studies and stated that when nest predation on both types of nests is assessed in the same plot, ground nests are less preyed upon than elevated nests. In this investigation, artificial nests were made and placed in elevated and ground-level sites to monitor predation activity. In this study, it was hypothesised that the artificial nests placed in elevated positions would experience similar levels of predation as to those at ground level. Method
this affected whether or not the nests would be attacked. Every couple of days, each nest was checked for signs of predation, and if there were, the nests were removed and taken back to the classroom for further inspection. The number of attacked nests for each group was counted and recorded, and the predators responsible for the attacked nests were determined by analysing the scratches and marks left on the eggs. Results The number of bird nests that were attacked was greater than the number of bird nests that were not attacked. Of the nests which were attacked, the greater majority were placed at a larger height. Of the nests which were not attacked, it was found that each height had an equal number of nests that were not disturbed. From this, we can conclude that the higher a nest is built, the greater the chance it has to be attacked by a predator.
Using half a tennis ball, each student shaped a bird’s nest out of coir (coconut fibre) and glued it to the hemispherical shape. Two artificial eggs were made for each nest using a small ball of clay, then were placed inside the nests, and the nests were taken outside to the natural environment. Half of the nests were placed on the ground, and the other half were placed in trees to determine whether 16
