Ruth and Cynthia Landall, of Wellington, asks :-
Can you please tell us why our sparrows have suddenly started eating our lavender seeds. We think they might be copying the Goldfinches.
Ben Bell, an ecologist with Victoria University of Wellington's School of Biological Sciences, responded.
The main diet of the House Sparrow is plant material, especially seeds, although they feed their young on animal material, such as flies and caterpillars. Adults also take some animal material during the breeding season, including cicadas. At any one time what they eat also depends on which foods are available, and this varies seasonally.
To have them feeding on lavender seeds is therefore not too unexpected - I have seen this in my Wellington garden. You correctly note that this habit occurs in the Goldfinch, a frequent feeder on lavender seeds in New Zealand. I doubt whether Sparrows learnt directly from Goldfinches, although it is possible that Goldfinches might attract local House Sparrows to a lavender seed source. Seed-eaters, like buntings, finches and sparrows, often form mixed-species flocks when a good seed source is available.
In seeking out their food supplies House Sparrows are opportunists, and of course they feed also on a range of human foods, such as bread and cakes, as those of us eating at outdoor café tables can testify. Some House Sparrows manage to feed at tables indoors also, mastering entry routes through windows and doors, even if the latter automatically open and close. Indeed, some years ago Bob Brockie and Barry O’Brien reported House Sparrows triggering automatic doors, but were then (2004) unable to find reports of them doing this overseas, concluding that either foreign ornithologists had not reported this, or that some sparrows in New Zealand were smarter than those in other countries!
Another case of House Sparrow opportunism is individual birds plucking feathers from other live birds, evidently to line their nests – cheeky sparrows indeed! I have seen them doing this to nesting domestic rock pigeons in Wellington, and in cities as distant as Poland.