Wildlife Column with Prof Ian Rotherham
Grebes outside of the summer breeding season quickly slip into a winter plumage of greys, whites, and other dull hues.
This takes place as youngsters also moult into adult plumage for the period until next spring when they will emerge in their full resplendent colours. The little grebes or dabchicks are still very active in ponds and lakes, and along rivers and canals, as they dive and bob in search of small invertebrates as food. On the Cromford Canal near Matlock, I was trying to discern what it was that had caused such a commotion amongst the floating pondweeds. There was a mass of large bubbles and a series of wavelets or eddies as if something was moving below the surface. Yet nothing was to be seen even though it looked like the disturbance was caused by a quite large animal. Then, suddenly, two birds popped up a little like corks bobbing in water, and close under the far bank of the canal. It was an adult little grebe and an immature, both now in their winter colours. Especially outside of the breeding season, during which the birds are strongly territorial, little grebes are quite approachable and almost bold. They are also busy in their constant hunt for tiny prey items. At this time of year, the defence of their territory which is so much of a priority from spring to summer is now relegated behind the need to survive the winter cold to come.
Grebes do have a particular problem if we get cold weather and water-bodies freeze over for long periods. In particularly cold winters, I have found grebes dead, trapped beneath the ice on local reservoirs. They seem to dive under from open water areas and then try to surface but become trapped under the frozen surface and drown.
The bigger water-bodies like lakes and reservoirs hold good numbers of relatively common great crested grebes, but may also attract rarer species too. In winter, look out for red-necked, Slavonian, and black-necked grebes, the latter also being rare breeding birds of smaller lakes.
Professor Ian D. Rotherham, of Sheffield Hallam University, researcher, writer and broadcaster on wildlife and environmental issues.