At last month's EcoTas13 conference, the joint annual conferences of the New Zealand and Australian Ecological Societies, I presented some preliminary calculations of the number of birds killed on New Zealand roads. I've been counting road kill on my bike to work from Christchurch to Lincoln since 2003 so I now have a fairly good idea of how many birds are being killed in this landscape. The rates of birds killed on these roads are similar to statistics from European and North American countries. Extrapolating these out to New Zealand's road network of highways and rural roads suggests that around a million birds could be killed each year.
This is much less than the estimated numbers of birds killed each year by mammalian predators throughout the country, but much larger than the numbers of birds killed by the likes of wind farms or the Rena oil spill.
Of course, most of the birds killed are exotic species, like blackbirds and house sparrows, since these dominate in and around our towns and cities where most roads and traffic are. Still, native birds appear to be equally vulnerable. This additional source of mortality may be having an impact on native bird species in these habitats which are already struggling to persist in suboptimal and fragmented habitats and with abundant predators. A more detailed analysis of my data will be needed to assess that.
You can read the details over on my blog.
A fantail killed on a busy 80 km/hr stretch of Sparks Road near Halswell, Christchurch (see the associated observation on NatureWatch NZ).