Words: Kate Risely, of the British Trust for Ornithology (BTO)
I was surprised to find out just how rare Great Crested Grebes once were – I wonder how many people know that in 1860 there were only around 50 pairs breeding in the UK?
In modern times we tend to look to habitat degradation, or climate effects, to explain declines in bird numbers, but back then human effects on bird populations could be much more direct. Great Crested Grebes were slaughtered on an industrial scale in the latter half of the nineteenth century, to feed the demands of fashion.
The fine chestnut head plumes were used to decorate hats and other accessories, and their densely feathered skins were used in the clothing industry as ‘grebe fur’. The eggs were also taken, as food and for sale to collectors.
Fortunately, and partly as a result of these kind of devastating declines, this period saw the birth of the modern conservation movement, and laws were passed to safeguard waterbird populations from hunting.
By the 1930s, seventy years later, wild birds were no longer generally seen as resources to be exploited, and the days of mass-participation volunteer bird surveys had arrived.
The Great Crested Grebe Enquiry in 1931 was one of the earliest national censuses of a single species, promoted in The Times, and attracting more than a thousand volunteer surveyors. Around a thousand water bodies were covered, and the results of the Enquiry, published in British Birds, concluded that the breeding population of Great Crested Grebes in England, Scotland and Wales was around 1,200 pairs.
The paperwork from the 1931 survey is preserved in the BTO archives, together with records from subsequent surveys in 1946, 1965 and 1975, the results of which were published in the BTO journal Bird Study.
By 1975 there were thought to be around 3,500 pairs, an increase that can be attributed to the cessation of persecution, and a huge increase in the numbers of flooded gravel pits due to the demands of the construction industry. Great Crested Grebe populations are now monitored via the annual Breeding Bird Survey, which shows that numbers are still increasing – by 28% since the start of the survey in 1994, and by 8% just between 2007 and 2008.
There are now thought to be around 12,000 pairs breeding in the UK, and this population estimate will be updated when the BTO’s forthcoming Bird Atlas 2007-11 is published. Any records of Great Crested Grebes would be of use to the Atlas, particularly those where the birds can be confirmed as breeding – which, for this species, can be very easy!
Pairs of Great Crested Grebes perform elaborate courtship displays, shaking their heads, dipping their necks, and rising out of the water with beakfuls of weed in the famous ‘weed dance’.
The nests are obvious platforms of weed, and when the chicks have hatched they can be seen riding around on the backs of the parents, with tiny black-and-white striped heads peering out between the feathers (I’ve yet to meet anybody who doesn’t go ‘ahhh’ when they see this). Interestingly, the parent birds can sometimes be seen feeding feathers to their young at this stage – this is thought to help them form pellets so they can regurgitate indigestible food items.
As familiar as they are today, it should be remembered that Great Crested Grebes are, in some senses, a conservation success story – and I’m sure that when the time comes for the next BTO Great Crested Grebe Enquiry, we will have no shortage of volunteers.