Posted on behalf of Katie Ellis
This time of year, our famed high tide watches at Parkgate Old Baths would usually be in full swing, with some of the best wildlife spectacles the Dee Estuary has to offer. Hosting these events is one of my favourite parts of working in the Dee Estuary reserve’s visitor experience team, sharing with the public the history, science and wildlife that makes the estuary so special.
But why a “phenomenon”, you wonder? Something that always strikes me is how few locals, and birdwatchers from further afield, have never had the fortune of catching the vast saltmarsh being flooded up to the old sea wall, often bewildered at the suggestion it can and does still happen.
For obvious reasons, right now we’re leaving nature to it, seeing through these challenging times safely and not encouraging people to gather at Parkgate to birdwatch. Instead, whilst we’re on pause, here’s some of last year’s highlights and answers to the top four questions I’m asked when at an event.
(Paul Jubb)
Why are high tides so great for seeing wildlife on the estuary?
The Dee Estuary holds some of the best wetland habitats in the country, particularly the vast saltmarsh that spans as far as the eye can see from Parkgate. When the tide washes in covering this wild expanse, all the wildlife that calls it home is disturbed, forced into closer view in search of somewhere drier or shallower whilst the tide peaks.
Not only is it the array of waders and wildfowl, but it creates the perfect feeding grounds for some of our rarest and most magnificent birds of prey, hunting for the countless small mammals that dwell in the dry grasses of the upper marsh. The sheer quantity and variety of birds present over the course of a couple of hours, along with remarkable historic tales of water rails seeking shelter in birdwatchers’ rucksacks and skylarks into open car windows, offer the kind of excitement wildlife enthusiasts travel from far and wide for.
With favourable weather conditions – more on that later – the tide alone can provide an incredible spectacle, transforming normally green and amber grasses to a blue-grey flood filling the estuary.
(D.Trotman)
What counts as a high tide?
The time and height of tides can be predicted with a high degree of accuracy. Tide timetables can be published well in advance, giving a full calendar year ahead of tide forecasts. Our go-to is the well-known Laver’s tide table for Liverpool. More details about the complexities of tides, and the Dee Estuary’s fascinating history, can be found on the NTSLF website.
For us to see a high tide at Parkgate we plan to host events for a tide with a forecast of 10metres or above. Weather, though, plays a big role in how far the tide will come on any given day, and the saying goes “the worse the weather for us, the better for the tide!”.
Storm surges can throw a last-minute change to tide predictions. They change the sea level short term and can only be predicted a couple of days ahead. The best conditions to see a high tide close in at Parkgate is when there is low pressure to the west of the UK coupled with a strong westerly wind which will push the tide in and provide a bigger surge. This surge can push the tide over the saltmarsh and on the rare occasion over the sea wall!
Don’t be fooled by the sight of a tide far out from the promenade; the tide doesn’t wash in like the typical beach scenes we’re all used to, instead it will slowly seep into the network of creeks and gutters before, sometimes quite suddenly, spilling out to consume the grasses. Even when the tide doesn’t come in as far as expected the raptors can still be drawn in closer and put on a good show, so it’s always worth a trip.
The highest tides typically occur in the months around the spring and autumn equinoxes, when the moon’s gravitational pull is at its strongest, which is convenient for showcasing the estuary’s impressive winter birds. Ironically for a year when we most likely won’t be hosting any such public events, 2021 is particularly poor for forecasts of 10metre tides, with two days in late March being the only daytime ones for the whole year. However as we witnessed in this week a year ago, a winter storm like Ciara turned a 9.4m forecast tide into one of the highest in a decade, estimated closer to 11metres!
High tide and natural debris around The Boathouse (Paul Jubb)
What are the wildlife highlights?
The Dee estuary is the winter home for over 100,000 wetland birds, and when the tide washes in they all get a shake up!
With the tide close in, you not only see the wildlife, but also hear it. The estuary averages over 10,000 pink-footed geese through the winter months, increasing towards spring as others move through on their northward migration. As the tide washes in, the surrounding sound of their ‘wink-wink’ calls can be heard as they move off to drier land.
Flocks of knot and dunlin swirl along the water’s edge, trying to avoid predators such as the speedy peregrines. Lapwings, redshanks and black-tailed godwits are also moving around in their thousands as they are evicted from their muddy homes. The wintering ducks such as wigeon and teal are also on the move, forced upstream with the waders to drier ground on the inner marsh and Burton Mere Wetlands.
Pink-footed geese in search of drier ground (Paul Jubb)
The reason we see so many birds of prey during the tides is due to the banquet that is put on offer to them and scenes can sometimes not be for the faint hearted. Along with lots of wading birds being subject to an easy catch, mice and voles are flushed out of their grassy homes and try desperately to scuttle to safety. Occasionally they manage to escape the tide and water rails are known to hide away under cars in the Old Baths car park!
Water rail in rising water (Paul Jubb)
The celebrity of the tides are the hen harriers. Sadly, they are one of our most threatened raptors in the UK due to illegal persecution on their upland breeding grounds. Sightings of these superb raptors are rare, with just a handful of breeding pairs left in England. The RSPB is working hard nationally to protect them, and we’re lucky enough here to have a suitable, safe habitat to support them on the estuary as they retreat from the uplands for the winter. We’re always excited to see the graceful “ringtail” female or juvenile passing by and a glimpse of a ghostly grey male is even more special.
Male hen harrier over the saltmarsh (Paul Jubb)
Another of the harriers, the marsh harrier, is a more common all year-round sighting with more seen in the winter coming from breeding grounds, will drift along similar to the hen harrier with barely a high tide watch without at least one seen. A winter visitor to the estuary is the merlin, the smallest of the UK’s birds of prey, usually seen only briefly as they dart past in pursuit of skylarks and finches, whilst kestrels are often hovering over eyeing the best mammal to catch.
One of the most sought after birds to see at a high tide are the short-eared owls. With only a few on the estuary each year, these day-flying owls that over-winter with us provide some spectacular views, hunting out mammals and landing on the not-yet-flooded parts of the marsh, and sometimes soaring high as they head for dry land. Towards the end of the day, barn owls can also come out from the neighbouring farmlands, giving close-up sightings. If very lucky, glimpses of a bittern – a fairly recent winter addition here – are possible. They roost in Neston Reedbed to the south of Parkgate and can be seen flying back to the reedbed at the end of the day. Strong optics are often needed though as they are quite far out on the saltmarsh.
Two short-eared owls soaring over the flooded saltmarsh (Paul Jubb)
The last of the highlights, standing out in bold bright white, heads peering above the tufts of grass are the little egrets and great white egrets. Part of the heron family, egrets are becoming a more and more common sighting as their populations increase with breeding success at Burton Mere Wetlands. The highest of tides push them more towards the drier land, but are one of the easier species to spot whilst waiting for the tide to come in.
How do I find out about the next high tide and when the RSPB will be at Parkgate?
Whilst restrictions remain around social distancing and gatherings of groups, the RSPB will not be hosting any events and strongly urge everyone to follow current Government guidance on staying local and only using greenspaces for essential, daily exercise. Hopefully as restrictions ease, we will be able to host these events again.
But for when things return to normal, details of the seasonal spectacles, and our events when happening are advertised on the Parkgate page of our website, rspb.org.uk/parkgate
What we tend to forget of course is that with a natural shoreline everything would be able to move just a bit further inland at high tides. It's only because we have produced a hard (in fact vertical) edge that all the small creatures have nowhere to go. It would still be a spectacle with a natural shoreline, but not such a hopeless situation for all the creatures living in the marsh.