On Sunday, following almost a week of form-filling, covid-testing and passport-stamping, Karin and I flew back to the UK to see friends and spend time with our kids. We’ve rented a large cottage in Glastonbury for the duration and the above image is taken from the back garden.
I hope that all of my blog readers have a healthy and happy Christmas, and that the New Year is both more prosperous and more biodiverse for you.
After being in rural Denmark for five months, Britain feels very congested and busy. All going to plan, we’ll be back walking the beaches of Odsherred and enjoying the scenery. See you in 2022!
A couple of weeks ago we visited Karin’s family in Jutland and went for a couple of long walks around the area. One of these took us through some very nice mixed pine, oak, and birch forest close to a river. The forest was anchored into a thin horizon of mulchy topsoil, beneath which was almost pure sand, a post-glacial legacy of the wider, wilder rivers that ran through the region at the end of the last Ice Age.
Where our path ran parallel to the river I noticed that the exposed vertical sections were far from lifeless: the sandy faces had been colonised by algae, lichens, fungi, cyanobacteria, and mosses. These biological crusts had stabilised the sand and prevented it from eroding further back into the bank. On a miniature scale they were doing what forests and other vegetation does in mountainous areas all over the world: preventing landslides.
Biological crusts in turn provide opportunities for ferns and seed plants to germinate and gain a foothold: they are often the starting point for further ecological succession.
Not only are these crusts acting as substrate stabilisers and seed beds, but all of the usual ecological processes of photosynthesis, nutrient acquisition, decomposition, carbon storage, symbiosis and competition are taking place in just a few millimetres of biodiversity. There’s a lot going on in these thin veneers of life.
When I was teaching undergraduate ecology I always impressed upon my students the idea that the categorisations we use to describe “communities” and “ecosystems” are really loose, artificial attempts to put boundaries around borderless ecological systems. Nowhere is this more true than in coastal ecosystems, where the transition from “sea” to “shore” to “sand dune” to “coastal woodland”, for example, is a blur of overlapping habitat types linked by the movement of organisms, nutrients and energy from one to another.
Birds are especially important linkages in this respect, because they are highly mobile and thus effective at connecting “land” to “sea”. Consider gulls, for example, which may be feeding in coastal waters and on grasslands some distance away, and defecating and being preyed upon in both, resulting in transfer of sea-derived nutrients and energy into terrestrial ecosystems, and vice versa. There’s considerable interest amongst ecosystem ecologists in understanding such transfers; for example, here’s the opening sentences from the abstract from the 2013 paper Donor-Control of Scavenging Food Webs at the Land-Ocean Interface by Thomas Scholar and colleagues:
Food webs near the interface of adjacent ecosystems are potentially subsidised by the flux of organic matter across system boundaries. Such subsidies, including carrion of marine provenance, are predicted to be instrumental on open-coast sandy shores where in situ productivity is low and boundaries are long and highly permeable to imports from the sea.
Here on the coastal beaches of the Kattegat I’ve been intrigued by the behaviour of hooded crows (Corvus cornix), which are acting, it appears, as just such facilitators of the “flux of organic matter” from sea to land.
There are six corvid species in the area, and hooded crows are by no means the most common: there’s at least as many rooks (Corvus frugilegus) and jackdaws (Coloeus monedula), and we often see all three species foraging together on ploughed fields or suburban grassland. That’s not surprising, because like many members of the crow family these species are opportunistic omnivores that eat a wide range of animal and plant material, both living and dead, as well as clearing up human food waste, which I described a few years ago during a visit to Kathmandu.
But hooded crows are the only species that we see scavenging on the shoreline.
On Sunday, for example, I took a late afternoon stroll along the local beach with my binoculars and, as usual, I saw hooded crows in small groups of two or three, sometimes in the company of gulls. As I watched, in quick succession I saw two lesser black-backed gulls (Larus fuscus) paddle onto the beach, one with a large, flapping flatfish in its beak, the other with a struggling shore crab. As the gulls tore apart their respective prey they were quickly joined by some hooded crows that had been hanging around nearby. Once the gulls had eaten their fill the crows moved in and demolished the rest. The crows seem to be particularly adept at getting the last bit of meat from inside crab carapaces.
That’s behaviour I’ve seen a many times since we arrived here in August, crows picking over the remains of fish or crabs or (in one instance) a dead harbour porpoise that had also attracted the interest of gulls.
This focus on relatively large carrion items by the crows is understandable, but relatively rare because it’s controlled by the frequency with which such dead animals become available on the shore. It´s much more common to see the crows working their way systematically along the strandline, turning over seaweed in search of insects, crustaceans, and other small food items. I’ve even seen them hack away at washed-up acorns in the beach. It must be a productive way of finding food because they do it with such regularity.
But there’s a number of things about this behaviour that are puzzling me.
For example, why is it only the crows that work the strandline? Why do we never see jackdaws or rooks, which are at least as common, and equally omnivorous scavengers? They are also just as intelligent as the hooded crows and presumably could learn that this is a good place to find food. Also, are the crows that we see strandline “specialists” that spend most of the time on the beach, and nest in the nearby dune woodlands? Or is there a constant turnover of individual birds from the surrounding countryside to the beach and back? Do the birds learn this behaviour from one another and is it passed down from parents to offspring?
I’d be interested in your comments on these observations, as always. If you’d like to know more about corvid behaviour and ecology, I can highly recommend Dr Kaeli Swift’s Corvid Research Blog.
As well as working on a variety of writing and research projects, Karin and I have spent the last few weeks getting out and about in the Odsherred region of Denmark, exploring the culture and ecology of our new home. Not far from where we are living is the Hov Vig bird reserve which I’d put off visiting until last weekend when my friend and colleague Bo Dalsgaard was due to come and stay with us. Bo is primarily an ornithologist (we’ve collaborated on quite a few hummingbird-flower network studies), so it was going to be a good opportunity to get to know more about the birds of this part of the world.
After an early breakfast we set out for Hog Vig and I have to say that I was extremely impressed by the reserve. As you can see from the map below it’s been created by installing a low causeway across a bay in the fjord, resulting in a shallow, brackish lagoon that is absolutely teeming with bird life! Shallow lagoons like this are very productive, with lots of invertebrates and plants on which the birds can feed.
You can see the start of the causeway on the middle left of this photo:
I hadn’t realised just how shallow the lagoon was until I spotted a Great White Egret wading across the centre, the water barely reaching the middle of its legs. In all we counted 8 of these egrets, though a local birder we encountered told us he’d seen 14 that day. Interestingly, Little Egrets are considered quite uncommon here, a reverse of the situation in the UK.
Although the total area of the reserve, including woodland, is only 334 ha, an extraordinary 267 species of birds have been recorded there:
On the reserve itself we identified 39 species, and a handful more when we visited the nearby coast. Including those that we were unsure of we had just over 50 species, not bad for a day of birding. As well as the egrets, particular highlights were huge numbers of Teal, on the water, large active flocks of Golden Plovers and Lapwings set into motion by a hunting Sparrowhawk, and Bar-tailed Godwits, Stonechats and Eiders.
The most exciting birds for us, however, was a pair of White-tailed Sea Eagles that descended onto one of the low islands in the lagoon to feed on a dead cormorant! The locals describe these birds as ‘flying doors’, very apt given their huge wingspans. Needless to say, their appearance also sent much of the bird life into the air. Here’s a poor photo taken with my camera through Bo’s telescope:
At the end of August I was back in Copenhagen for a couple of days to take part in the PhD defence of Céline Moreaux, who has been working on coffee pollination and bee conservation. While I was there I snapped a couple more images for my Copenhagen Bestiary series. However I’ve also seen some interesting sculpture and building decoration further afield this month, in Aarhus, Silkeborg, and Nykøbing Sjælland. I especially like the wooden carved canopy support in the form of a duck, from Aarhus: it’s very subtle and I almost walked past it.
And before anyone asks, no, Karin and I are NOT part of the bestiary, but I didn’t get a shot of the troll by itself.
Cycling back from town this afternoon, Karin and I passed a hedgerow that was bursting with wild myrobalan or (cherry) plums (Prunus cerasifera). We had to stop and collect some, and soon filled a bag. What’s always intrigued me about these small, tart little plums is just how diverse they are: the image above shows the plums from six different trees. All of these are, in theory, the same species; but clearly there’s a lot of genetic diversity. In colour, the ripe fruits range from golden yellow through to dark purple, and vary in the amount of dark-contrasting streaking, lighter speckling, and waxy bloom. They are also variable in size, shape and taste.
All of this variation probably reflects the long history of cultivation of this European archaeophyte. The species is originally native to southeast Europe and western Asia, and was likely spread throughout Europe by the Romans. The local deer population is very fond of the fruit and we’re seeing a lot of deer droppings that are packed with seeds. We don’t usually think of these large mammals as seed dispersers, but I suspect that they are very successful in that ecological role.
As well as being a great source of wild fruit, for humans and wildlife alike, at the other end of the year these trees are important for pollinating insects. As I pointed out in my book Pollinators & Pollination: Nature and Society, Prunus cerasifera is one of the earliest flowering woody plants in northern Europe, and its flowers are an important nectar and pollen source for early emerging bumblebee queens, hoverflies, and honey bees.
Delicious, abundant fruit combined with a valuable role for pollinators: what’s not to like?
We have now left Copenhagen, taking a (very comfortable) train over to Silkeborg to catch up with Karin‘s family for a week. So this is the final installment of the Copenhagen Bestiary for now, but I’m sure that I will add to it as I return to the city and explore further. I suspect that there are many more creatures to discover adorning the architecture of that wonderful city. And then there’s Aarhus, Odense, Roskilde….
Since arriving in the city we seem to have settled into a pattern of waking very early, working through the morning (Karin on her second book, me on a large biodiversity report), then going out and exploring Copenhagen in the afternoon and early evening. So there’s been lots of opportunities to add to the Copenhagen Bestiary during these perambulations. Here’s a third set of pictures.
For the second part of my Copenhagen Bestiary series I’m devoting the post to our visit last week to the old Carlsberg Brewery site, and specifically its Elephant Gate. I’ve included some images that aren’t of beasts because I really enjoyed seeing how the old brewery buildings have been renovated and incorporated into a new living and working neighborhood called Carlsberg Byen. It’s the best example of regeneration of culturally important post-industrial buildings in the world. Probably….
Since my first visit to Sweden in 1991 I’ve frequently traveled to Scandinavia for conferences, PhD defences, grant review panels, to catch up with friends, and to see my wife Karin‘s family in Denmark. So arriving in Copenhagen almost two weeks ago felt familiar and welcoming. There’s much that I love about Scandinavia, from the landscapes to the history and the peoples, but I am particularly enamoured by the city architecture of the early 19th to mid-20th centuries.
The old buildings of Copenhagen, where we are based for a few weeks, are at once familiar and yet alien, with respect to buildings of similar age in Britain. In particular, the unconstrained use of animals as ornamental adornments is fascinating, inventive and often bizarre. Some of these are real creatures, especially fish which represent the fishing industry on which the city was founded. Others are mythical beasts of traditional Scandinavian fables. And there’s a subset that are clearly the products of the (deranged? drugged?) minds of the sculptors.
Finland’s capital Helsinki tops the league when it comes to animals on buildings, but Copenhagen also has its fair share. I’ve taken to snapping these creatures as I encounter them so it seemed fitting to collect them into a bestiary – a compendium of beasts. Here’s the first set, presented with no commentary – the animals speak for themselves.