A nestbox scheme launched in Scotland during the 1970s had a huge impact on breeding numbers of Goldeneye
Nestboxes can be a game changer for Goldeneye, who nest high off the ground
CAN PUTTING UP nestboxes help birds? In many cases, the jury is out. Of course, a box will be very useful to those particular birds that choose to nest in it, and the great value of nestboxes is that they allow the success or failure of the nests to be monitored and recorded. In many cases, however, bird populations are limited by the availability of suitable food supplies, and simply increasing the number of nest sites available, while it sounds like it should help, will not necessarily cause the overall numbers of birds to increase. While nestboxes don’t always make a difference, for some birds they are a game changer – and one of these, perhaps surprisingly, is a duck. Goldeneyes are best known from our coasts and lakes in the winter, when the brown-headed females and striking black and white males stare back at us with their round golden eyes. Unlike most of our familiar ducks, they nest high above the ground, in hollow trees. The advantage of this strategy is that the eggs and ducklings are hidden away safe from ground predators, though as all ducklings leave the nest while they are still unable to fly, it does mean a long drop when the time comes to follow their mother to water! Another disadvantage is that ducks, of course, can’t excavate holes in trees, so the availability of suitable cavities can limit the numbers that can breed in a particular area, particularly as modern, managed woodland habitats don’t tend to contain much standing dead wood. Goldeneyes first bred in the UK in 1970, in Speyside. Scottish ornithologists, encouraged by reports from elsewhere that Goldeneyes had successfully nested in artificial sites, believed that a nestbox scheme could benefit the fledgling Scottish breeding population, and installed a number of boxes alongside lochs and rivers in the Highlands. They were not used straight away, but they were dutifully monitored, and in 1974, two of the boxes were used. After this the scheme really took off, and by 1982 there were 83 boxes supporting 41 pairs of Goldeneyes. Today, there are thought to be about 140 breeding pairs in the UK, proving the value of a well-thought-out nestbox scheme. From October to April, the UK numbers are rather larger, an estimated 27,000 birds, which ringing recoveries show are mainly from the Scandinavian population. They are found on lakes, large rivers and sheltered coasts, though, as winter progresses, they tend to leave inland sites and return to the ocean, perhaps as local food supplies are depleted or the fresh water freezes over. Males are heavier and larger than females and are able to make longer dives to forage for food; this difference in foraging ability means that males and females occupy different habitats, and it’s normal to see groups that are dominated by one sex. Goldeneyes breed across Eurasia and North America, with a world population numbering several million individuals. They have been evaluated as ‘secure’ both globally and in Europe, and appear to be doing well in Scandinavia, their main European breeding area. However, counts of British wintering birds made through the Wetland Bird Survey show that numbers have been declining since the early 1990s, thought to be due to milder European winters meaning that birds are able to stay closer to their breeding grounds, not needing to make the journey to the UK.
Ducks, of course, can’t excavate holes in trees, so the availability of suitable cavities can limit the numbers that can breed in a particular area
GOLDENEYE Who would have thought that such a duck would benefit from tree-mounted nestboxes?