An examination of the negative effects of wild bird feeding in New Zealand. (2022)
Type of ContentTheses / Dissertations
Thesis DisciplineBiological Sciences
Degree NameMaster of Science
Bird feeding is a global activity that takes on a variety of forms, from ordinary people feeding birds for fun at their local park to government and conservation organisations using supplemental feeding at a landscape scale to manage endangered species. It is an activity that makes people happy and often increases the general wellbeing of many birds involved. However, bird feeders can also have a number of negative effects, from changing the community structure of the avian guild to increasing levels of aggression and the risk of disease transmission. I focused my research on the negative effects of bird feeders and how these might be mitigated. I first compared the aggression rates of native and introduced waterfowl in the urban waterways of Christchurch, New Zealand while they were being provided with supplemental food. Introduced waterfowl were significantly more aggressive than native waterfowl and I suggest they are more likely to benefit from supplementary feeding by the public than native waterfowl. Next, I compared the rates of aggression of silvereyes (Zosterops lateralis) in relation to the number of bird feeders in suburban gardens. I found that aggression was higher at feeders than in silvereyes feeding naturally (no feeders) but that aggression levels did not decrease when I increased the number of feeders from 1 to 3 in the garden. This result is likely due to the limited space available to feed at each feeder. This allowed more birds to feed at a given time and may reduce the number of individuals excluded from feeders by dominant birds. I then ran an experiment to determine if bird feeders have an negative effect on natural prey sources in the local vicinity as a result of the increased concentration of birds. Using artificial prey (mealworms glued to branches around a bird feeder), I found there was a slight effect of insect depopulation around bird feeders in my study site at Kowhai Bush, Kaikoura suggesting bird feeders may lead to higher rates of insect predation in the local area. Finally, I summarise my findings and discuss possible future actions that could be taken to minimise the potential costs of bird feeders.
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