This week’s subject matter came about as the cumulative result of several recent (and unprompted) conversations with neighbours, visitors and colleagues. The topic of conversation in each case was the Sand Loch, and the consensus was that it used to be rubbish for wildlife. In recent times, though, something seems to have changed, and these days the loch is a proper little biodiversity hotspot.

This represents good news on two fronts. Firstly that the loch appears to be improving for wildlife, and secondly that the good people of Collieston (who overlook the loch), as well as the many folk who regularly visit the top end of the Reserve, have noticed the change and commented upon it. As a subject of conversation, wildlife is a great leveller, and a nice change from the usual chat about the weather, or whatever dreadful stuff is happening in the news at any given time.

So what’s going on here then? Speaking to folk who have lived in Collieston for many years reveals a different Sand Loch to the one that we know today. In years gone by, this was a very open, exposed and barren place, not much more than water and bare sand, with little in the way of vegetation either in or around the loch. Over the years, and in common with other areas of the Reserve, the loch has become greener and lusher, for a number of possible reasons. Atmospheric nitrogen deposition, nutrient-rich topsoil blown from adjacent farmland, and the gradual buildup of silt from the continued growth and decay of aquatic plants may all have played a part. The net result is a richer and more complex environment than was the case when the loch was first formed.

As with all other fresh water bodies, there is a ‘sweet spot’ in terms of nutrient levels – depending on what species you are. Some species favour low-nutrient (oligotrophic) water bodies, where there is little competition from other species. Others prefer very nutrient-rich (eutrophic) waters in which to grow, live or breed. And the sliding scale between highly-oligotrophic and highly-eutrophic waters supports a continuously variable cross-section of aquatic life.

The modern-day Sand Loch probably sits somewhere in the middle of the sliding scale, and like Goldilocks’ porridge, this is just right for a wide range of species. The loch retains a large area of open water, but also now has well-vegetated margins, a bit of emergent vegetation, plenty of submerged plants, and a nice area of mire at the Collieston end of the loch, rich in sedges and horsetails. The array of water plants supports a micro-fauna of tiny invertebrates, which in turn support aquatic insects, which in turn support amphibians and fish, and on top of the food web sit predatory species such as waterbirds and perhaps a roving Otter.

The other long-term change – once again in common with other parts of the Reserve – has been the establishment and spread of scrubby trees around its margins. These are chiefly willows, but with some Alder and Silver/Downy Birch mixed in for good measure. This additional and varied habitat further increases the range of species that are now able to call Sand Loch their home. In spring, these scrubby areas resound to the excitable chatter of Sedge Warblers, the disjointed song of Reed Buntings, and now and then the strange whirring of a Grasshopper Warbler. As well as the breeding species, various migrant birds also use these areas when breaking their spring and autumn journeys.

Forvie staff are a largely terrestrial species, and as such we know very little about what goes on beneath the surface of the loch. There is a rumour that the loch contains (or contained) Pike, a ferocious predatory fish, which was allegedly introduced for angling purposes somewhere in the dim and distant past. In recent years it was thought that Pike were perhaps responsible for the short shelf-life of any ducklings hatched on Sand Loch (although, of course, there are many other suspects in cases of disappearing ducklings besides Pike). We know there must be a reasonable population of fish in the loch due to the frequent visits of piscivorous birds like Cormorants and Goosanders. But so far, the only fish we’ve seen have been Stickleback – and even then, usually only when they’re being swallowed by one of the aforementioned birds!

It’s probably the loch’s birdlife that has constituted the most obvious change. I well recall being asked, more than once, why there were never any birds on Sand Loch. Right enough, save for the odd Tufted Duck or gang of visiting gulls, I never saw much there in my first few years at Forvie. Fast-forward to 2024, though, and the loch now boasts a proud track record. All the common duck species have occurred, some of which are resident for large stretches of the year. A typical walk around the loch in recent weeks would produce Mallard, Teal, Wigeon, Tufted Duck and perhaps the odd Shoveler, Goldeneye, Goosander or Red-breasted Merganser. Not a bad haul for a small stretch of water.

There have also been increasingly frequent records of scarcer species turning up, and sometimes sticking around for days or weeks afterwards, having unexpectedly found Sand Loch to their liking. These have included oddities like Black-throated Diver, Slavonian and Red-necked Grebes, Smew and Ring-necked Duck, as well as storm-driven seabirds such as Gannet and Arctic Skua.

The loch margins, meanwhile, are havens for Grey Herons and Snipe, as well as being the breeding site for the famous Sand Loch Mute Swans. The loch has never had a great record for breeding waterfowl; it is more-or-less surrounded by footpaths, waymarked or otherwise, and the daily presence of people and (particularly) dogs is enough to put off most species from even thinking about nesting here. The swans are the exception, and they seem unfazed by all the human and canine activity going on around them. Even so, at least one of their fledglings in 2023 was killed by a dog (or perhaps an extremely intrepid and burly Fox), so they don’t have it all their own way. But their daily lives are followed closely by our regulars and residents, in a sort of Springwatch-like natural soap opera. In this sense, the swans are a real asset: if folk keep their dogs on the lead to help the swans, they’re also inadvertently helping the plethora of less-obvious-but-no-less-sensitive wildlife in the area.

But there is evidence of other aquatic life in the Sand Loch besides just birds. The regular appearance on the loch-side road of Palmate Newts, Common Toads and Common Frogs suggests that the loch plays an important part in their respective life-cycles. Insects are represented by Common Blue, Large Red and Blue-tailed Damselflies among many others (perhaps the less said about the ubiquitous Biting Midge the better). And, of course, there was last year’s momentous Water Vole sighting (I say this because it was the first one I’d ever seen on the Reserve in all the years I’ve been here!).

In summary then, it appears that Sand Loch through the ages has taken much the same course as a newly-established garden pond – initially rather empty, slow to get going, then gradually being colonised by vegetation, and eventually maturing into a haven for wildlife. These days it’s a well-loved and nature-rich corner of the Reserve, rightly popular with visitors and locals alike – surely one of the jewels in Forvie’s remarkable crown.