Wednesday, August 18, 2010
Sunday, August 15, 2010
I am concerned about the increasing numbers of black-backed gulls and the impact that they are having on a wide range of native birds through direct predation, disturbance and klepto-parasitism.
Saturday, August 7, 2010
White-fronted terns, sea swallows, in decline.
As fisherman and boaties many of us are familiar with white-fronted terns. These agile and majestic seabirds are often visual markers of good spots to go fishing. Often when predatory fish like kahawai chase baitfish towards the surface, terns can be seen hovering in flocks above the kahawai marking out a good spot to go fishing.
Sadly recent observations, especially in Northland, but also from other locations suggest that numbers of these iconic coastal birds are declining. Of particular concern is the low numbers of young terns which are been sighted in recent years, suggesting that on the mainland of both islands terns are failing to breed successfully in many places. One factor is disturbance to colonies by four wheel drives, dogs and recreational uses along our coastlines. Fortunately terns also breed on offshore rock stacks, which offer an insurance policy for the species’ survival.
While white-fronted terns are a common sight, and the birds with their white plumage are often visible over large distances, it’s quite likely that we have an ageing population of birds. Terns are generally long-lived with records of marked birds reaching 30 years.
While overall the white-fronted tern only breeds in significant numbers in New Zealand, every autumn a proportion of young terns fly across the Tasman to feed along coastal waters in south eastern Australia. The young birds often suffer high mortality on this Trans Tasman flight. Why they do it not one knows for sure.
What is known is that white-fronted terns are declining and the decline is most pronounced in Northern regions. The Department of Conservation and community groups need to take more active role in monitoring this species and educating the public, including fisherman, about how to minimise disturbance around breeding colonies.
Sadly there is little research into white-fronted tern populations and for many this is a concern. Our coastal waters would seem very empty without the flocks of terns that we can still see, often in company with gannets and shearwaters. White fronted tern or as they are otherwise known Tara or sea swallows are without a doubt our most graceful seabird.
1. It is easy to see why terns are nick-named “sea swallows”- our most graceful seabird, but one in which we cannot take for granted as populations decline in many coastal regions, with a 1997 estimate of only 15,000 pairs.