Where have all the silvereyes gone? That’s the question being asked by many participants of last year’s New Zealand Garden Bird Survey. The dainty little native topped the 2010 survey but in 2011 the national average ofsilvereyes more than halved.
Survey organiser Eric Spurr says many factors can cause a decline but the most likely reason is the mild winter last year. “A lack of snow and frosts may have meant there was still plenty of natural food around in forested areas so birds weren’t forced into gardens in search of food.”
He points out numbers of silvereyes also decreased from the first survey in 2007 until 2009, though he suspects the cause then was the spread of avian pox.
With silvereyes relegated to second place, it comes as no surprise that house sparrows were the most common bird species spotted in New Zealand gardens for 2011. On average, 13 sparrows were recorded per garden during the survey, which asked New Zealanders to record the number of each bird species to visit their garden, school or park over an hour.
Starlings, blackbirds and mynas took out third, fourth and fifth place respectively. Tüï and fantails were the only other natives to make the top 10.
Results showed a marked regional difference. Tüï were the sixth most common species nationally but they ranked a lowly 28th in Canterbury. And Eric says several other species’ distributions showed a clear north-south variance. For example, silvereyes were much more common in Southland, Otago and Canterbury than other regions further north.
Overall, 85 species were recorded from a total of 3089 surveys. One respondent recorded a little blue penguin under the floor of her house in Paekäkäriki on the Kapiti Coast. Another discovered a New Zealand falcon disrupted usual bird activity during the survey.
“The survey was shortened by the kärearea zooming through – everything disappeared for 20 minutes or so,” the participant wrote. Other more unusual species included the red-crowned
parakeet, rifleman, stitchbird, a tufted guineafowl, shining cuckoo and Australasian crested grebe.
Others noted some birds’ unusual behaviour, especially around food choices. One grey warbler was seen eating apple-and-cinnamon cake placed outside to feed house
sparrows. Eric says this is very unusual behaviour.
“Grey warblers normally eat insects, though they do occasionally eat small berries. Also, cinnamon is normally repellent to birds.” Chaffinches, which usually feast on seeds, invertebrates and berries, were seen eating fat-balls, and some house sparrows were, unusually, spotted drinking from sugarwater feeders.
The long-term aim of the survey is to determine trends of bird numbers, with a particular interest in native species. Eric says it’s still too early to establish whether results show
normal fluctuations or are indicators of long-term trends. This year’s survey will be held between 30 June and 8 July.
Visit http://gardenbirdsurvey.landcareresearch.co.nz/GardenBirdSurvey.aspx for a survey form.