These stunning birds, with their glace-cherry eyes and striking bright orange-yellow tufts on their heads during the breeding season, have virtually their entire breeding range confined to within the Highland region. For many a keen birder and wildlife enthusiast, their rarity, beauty, mystery and favoured choice of nesting on lochs that are amidst the most glorious scenery in the British Isles put them near the top of any tick list.
Slavonian grebe breeding pair, Speyside. Photo: David Kjaer
Although they have been winter visitors to Britain for a long time, as a breeding bird they are relative newcomers; the first recorded nesting was at Loch Laide, west of Loch Ness, as recently as 1909.
Over the course of that century as a breeding species, they have had a mixed bag of fortunes, and still seem to be beset with problems that lead conservationists and bird lovers alike to worry about their ongoing status.
Last year, only 29 pairs were counted, and they only occupied some 11 lochs. They have always been rare, never rising above 100 pairs, but more recently they have been in decline. But this wasnâ€™t always the case. We know this because Slavonian grebes are in the privileged position of being probably the most comprehensively monitored of any UK breeding bird, with a 40-year continuous data set going back to 1971. For the first half of this period, their numbers were stable at between 60 and 80 pairs, but between 1992 and 1993 there was a sharp fall and this continued throughout the remainder of the 90s. Despite some recovery in the early 2000s, a further decline took place from 2004, with just 23 pairs recorded in 2009 â€“ the lowest since records began.
The reasons for this decline are still not fully understood. In the early 1990s, the RSPB carried out an intensive programme of research into the grebes and some of the important factors affecting them were identified. Research efforts intensified following the 90s decline; in 2001 and 2002, cameras were deployed to discover the causes of nest failure and a programme of catching and colour ringing the birds began. The recent significant declines have led to a further pulse of RSPB research which is still underway and now carries a greater imperative â€“ there is real concern that if the causes of these declines canâ€™t be determined and reversed, Slavonian grebes could be lost as a UK breeding species.
Male with distinctive breeding plumage. Photo: Steve Knell
It is for this reason â€“ to try and boost their numbers back to their former glory and relative stability â€“ that RSPB Scotland has chosen to direct all of the revenue generated from theÂ Scottish BirdfairÂ to the conservation of the Slavonian grebe.
With such a restricted distribution, it might be thought that our Slavonian grebes have very exacting requirements but this isnâ€™t necessarily the case. Although less than a dozen lochs are now occupied each year, in their heyday this figure was well over 30. In addition, former and existing sites range from small ponds to large lochs, at altitudes from sea level to high in the hills, and are surrounded by many habitats from intensive farmland to open moorland, all of which might suggest that the grebes arenâ€™t particularly choosy where they nest.
It emphasises how difficult it is to understand the decline. Some sites have had houses built next to them or had rainbow trout, pike or perch introduced, thus altering the prey balance, and it is reasonable to assume that they have been abandoned for these reasons. But these are the exceptions and, superficially at least, most lochs still appear suitable and it is not obvious why Slavonian grebes no longer use them. Moreover, some lochs (such as Loch Ruthven, an RSPB reserve southwest of Inverness) show marked fluctuations in the number of pairs they hold each year and it is hard to imagine that conditions at the lochs themselves are changing quite so rapidly too.
As with all birds, Slavonian grebes need somewhere to nest and, in Scotland, this chiefly means beds of Bottle sedgeÂ (Carex rostrata)Â or other â€˜emergentâ€™ vegetation. Dense beds or those in sheltered locations are best as nests here are less vulnerable to wave action (the main cause of failure in 2001 and 2002 as shown by the cameras) and such sedge beds are likely to become even more important in the future if the predictions that our summers will get stormier are correct.
Fortunately, creating new sedge beds is relatively easy (one was created at Loch Ruthven in the late 90s and birds now nest in it every year) and this technique could be rolled out more widely. This is one of the habitat management actions that RSPB would like to implement more widely using the money raised from the Scottish Birdfair. Another potential measure to help the birds could be to provide baffles off the more exposed reed beds to absorb and lessen the brunt of the wave energy. Dense beds are also more likely to protect nests from predation which the cameras showed to be the second greatest cause of nest failure. At that time, otters were the main predator involved (and, being protected, bring their own issues) but American mink have recently colonised the grebeâ€™s range. This arrival post-dates the main grebe decline and isnâ€™t thought to be responsible but a coordinated programme of control urgently needs to be instigated to ensure that they donâ€™t exacerbate an already poor situation.
Egg collecting has always been a problem and can have a major effect on such a small population. In addition, disturbance needs to be minimised at key sites and this is particularly true of bank fishing which can keep birds off the nest for prolonged periods and make eggs more vulnerable to predation or chilling.
Perhaps the most difficult issues to influence which are impacting on their population are immigration, emigration, and chick survival.
It is extraordinarily difficult to measure these factors in any wild animal population â€“ to get accurate measures of any of those factors requires huge volumes of data gathered over many years and, even then, it can be virtually impossible to disentangle how the different factors interact. Our Slavonian grebes are no exception and, whilst we have some of the pieces, the picture is far from complete.
On a pine-fringed Highland loch in early morning mist. Photo: Mark Hamblin
In Scotland, their basic movements are well established â€“ some birds can be back on the breeding lochs in February but the main arrival takes place during March and April. There is a fair degree of movement between lochs early in the season but most birds are settled by mid-May and remain until August or September. The majority have returned to the sea by October, although the wintering grounds of our population are currently unknown.
Beyond that it gets more tricky as you need marked individuals but we know from sightings of ringed birds that, on average, for every four grebes that are in Scotland one year, three return the following year. The likelihood is that a bird returns to the loch it previously occupied and, incidentally, this is likely to explain their distribution â€“ birds with such a strategy tend not to move very far from where they first colonise and whilst satellites, such as at Caithness, can spring up, their small size makes them vulnerable to extinction (similarly, abandoned lochs are more likely to stay abandoned unless the population increases). As for the fourth bird, it has either died or gone elsewhere (emigration) and, as one of our ringed birds subsequently turned up in Iceland, we know we â€˜loseâ€™ birds by both means. However, we also benefit from â€˜gainsâ€™ and such immigration is a very important influence on our population.
Whilst much of the above remains unknown, it will hopefully be easier to find out if we have data from abroad. To this end, two RSPB Scotland employees attended a conference on Slavonian grebes in Reykjavik in March to meet with other researchers from Norway and Iceland and share information and seek areas to collaborate in the future.
Clearly, some of the influences on Slavonian grebes appear to lie beyond our control. But much, and most significantly enough, is within our ability to change. A programme of management is underway at Loch Ruthven trialling various techniques, including sedge bed planting, nest raft construction, and predator control to see how the birds respond. Establishing precisely what we need to do and then doing it will ensure that this most superb of Highland birds will continue to be with us well into the future.
About the Scottish Birdfair
As home to some of the most stunning birdlife in the UK, so itâ€™s only fitting that Scotland now has its very own Birdfair. Held over two days in the grounds of Hopetoun House, near Edinburgh, the first Scottish Birdfair takes place on the weekend ofÂ 19â€“20May, and marks a fantastic celebration of the natural environment. And every penny raised at this major event will go directly to Slavonian grebe conservation work in Scotland.
Event goers will have the unique opportunity to â€˜try before they buyâ€™ from a large range of birding and nature-related clothes, holidays, optics and more â€“ all in one place. Throughout each day there will also be a colourful and informative programme of talksÂ andÂ workshopsÂ with fantastic Scottish and international content from some well known names such as The Urban Birder â€“ David Lindo, award-winning wildlife photographer Dean Bricknell, and the Fat Birder, Bo Beolens, to name a few. For more details and to book tickets, visitÂ www.scottishbirdfair.org.uk