Photo Blog

I love observing nature through the changing seasons both in my Norfolk wildlife garden and the surrounding countryside. I blog about wildlife gardening as well as about Norfolk butterflies, wildflowers and other flora and fauna that I come across. Bookmark my Norfolk nature photo blog to keep up to date with my photographic adventures.

The Acorn and the Jay

An Eurasian Jay holding an Acorn in its beak about to bury it in the grass (photo taken through a glass window).

Earlier this month I had a wonderful encounter with an Eurasian Jay that was busy burying an acorn, which got me curious about the relationship between the two.

We've had Oak seedlings pop up in our garden before, which, in the notable absence of Grey Squirrels, almost certainly had to have been planted by Jays, but I had no idea of the importance or complexity of the relationship between the two species.

The Eurasian Jay has a fantastic Latin name of Garrulus glandarius, meaning "chatty" and "acorn" respectively, which is an indication just how close a relationship the bird has with Oaks and their acorns.

Jays collect and store large quantities of acorns of Quercus Oaks in a mutualistic relationship that disperses the keystone Oak species in open scrubland where the shade intolerant tree can establish itself well, even choosing the largest most viable acorns. An estimated 2,200- 5,700 acorns are "scatter hoarded" in this way during autumn.

The Jay, a highly intelligent member of the Corvid bird family, then utilises vertical structures nearby to remember the location of approximately 75% of its cache, leaving around 25% of the acorns to germinate. Jays are only able to find acorns they've cached themselves or observed another bird caching.

Jays are believed to prefer the most nutritious acorns, selecting large acorns of Quercus ilex, Quercus suber, and Quercus faginea, whilst avoiding acorns from Quercus coccifera. Quercus ilex acorns having the highest fat content while Quercus coccifera acorns contain the most tannin of the four species.

In my case the acorn was cached 77 yards / 70.4 metres away from the parent tree, which corresponded well with research I found on their scatter hoarding behaviour. In one two year study dispersal distance ranged from 3m to 456m from the parent tree, with most acorns cached less than 100m from the source Oak.

Jays seasonal foraging behaviour further helps the Oak in that they hunt acorns least during the acorn's sensitive early spring germination phase. Jays then resume acorn hunting more intensively during May to July once it has offspring to feed. When a Jay comes across an Oak seedling growing in a spot where they recall caching an acorn, they will uproot the young plant, eat the acorn, and then crudely replant it, which the seedling usually survives.

Thanks to the Jay's important role in the spread and renewal of keystone Quercus Oak tree species in the landscape they have become known as "ecosystem engineers". One Swedish study even attempted to calculate the replacement cost of the oak planting "ecological service" that Jays provide for a particular municipal parkland area.

Resources and References

This insightful Aboriculture Blog summarising a chapter from Vera, F. (2000) Grazing Ecology and Forest History

Animal Diversity - Eurasian Jay Species Account

Dispersal Distance and Burial Mode of Acorns in Eurasian Jays Garrulus glandarius in European Temperate Forests , P Kurek, D Dobrowolska, B Wiatrowska, Acta Ornithologica, March 2019

Observations on the collection and burial of acorns by jays in Hainault Forest, MR Chettleburgh, British birds 45, 359-364, 1952

Spatial patterns of dispersal, seed predation and germination during colonization of abandoned grassland by Quercus petraea and Corylus avellana, Johannes Kollmann, Hans-Peter Schill, Vegetatio 125, 193-205, 1996 

Acorn dispersal estimated by radio-tracking, Pons, Josep & Pausas, Oecologia153(4):903-11, 2007


A Marauding Devil's Coach-horse

It seems Halloween came early to Nar Cottage this year, with the arrival of a maurading Devil's Coach-horse, and a poisonous Brown Roll-rim toadstool!

Devil's Coach-horse beetle, Ocypens olens

The Devil's Coach-horse, Ocypus olens or Staphylinus olens, is the largest of the Staphylinidae or Rove family of beetles, unsurprisingly so-called because they are always on the move. This is the largest beetle family with around 63,000 species worldwide and 1000 in the UK, making up roughly 25% of British species.

Devil’s Coach-horses are common and widespread in the UK. They are native to the UK and Europe, but introduced to parts of Australasia and America. I remember them being called a Devil’s footman in my childhood, one of many alternative names for them, but the main English name of Devil’s Coach-horse name has been firmly in use since 1840.

Although generally nocturnal, they can sometimes be seen during the day hunting for food and, due to their large size (they can grow up to almost 3cm) and striking appearance are very hard to miss! They reproduce in autumn, so it's very possible this individual was busy seeking a mate.

Their appearance is undeniably eerie, they have disproportionately large powerful mandibles for their size, an elongated jet black body and a shortened wing-case. Although they can actually still fly they rarely do so, preferring to hunt on foot. You could certainly imagine them in a fairy tale playing the role of sinister Coach-horses pulling along a fantastical evil overlord in a dark alternative to Cinderella's pumpkin-chariot.

They are indeed ferocious predators, hunting slugs, caterpillars, worms, spiders, woodlice, other invertebrates and carrion. They prefer damp places and will shelter under rocks, logs or leaf litter during the day. The female lays eggs singly in Autumn under damp moss or leaves. The resulting larvae are as carnivorous as their parents and grow through 3 instar (larval stages) over 150 days before pupating and emerging just over a month later in adults form. Devil’s Coach-horses are largely active April through to October. Adults overwinter either by staying active or by hibernating and can live up to two years.

Aggressive “Scorpion-like” Defensive Posture

They have a deservedly pugnacious reputation, mine was right out in the open in broad daylight marching around fearlessly. They are notorious for curling up their abdomen and opening their mandibles in an agressive, scorpion-like defense pose when threatened, presumably to appear large and threatening, as they aren't actually venomous and don't have a sting.

When threatened, the Devil's Coach-horse beetle, Ocypens olens, arches its abdomen in a "Scorpion" style defensive posture, opens its jaws and secretes a foul liquid from its glands

Another defense mechanism is the ability to emit a noxious substance from white glands on their abdomen, which the second half of their binomial name, olens, meaning "smelling", alludes to. If further threatened, their strong jaws can also give a nasty nip.

Devil’s Coach-horse in Folklore

They've been associated with magic, evil forces and the Devil in British superstition and folklore since mediaeval times. One theory is that the name developed in parallel with Ladybird (derived from Our Lady, referring to the biblical Mary) and was established by 1840. Other English names include Devil's coachman or footman and Devil's steed. In Irish they are called "Darbh-daol" devil's beetle and "Coffin cutter". There are a host of dark folklore superstitions surrounding Devil’s Coach-horses, which hasn't exactly helped their reputation.

In some superstitions, as well as being directly associated with the devil himself, they are purported to have eaten the core of Eve's apple and to even have acted as a kind of beetle form of Judas Iscariot and have arched its abdomen to point the way Jesus went during his betrayal. They were also believed to be endowed with magical powers and that when they arched their tail towards someone they were cursing them.

In Ireland it was even believed the beetle could strike a person dead on sight and would eat any sinners they came across. Sadly as a consequence some superstitions rewarded killing them. Although some scythers would put one in their scythe handles to improve their skill (or perhaps speed given their nasty bite!).

Gardening Value of the Devil’s Coach-horse Beetle

Despite their fearsome appearance and agressive defensive mechansims, they do get an unfairly bad rap. Devil's Coach-horses are in fact highly valuable insects to have in the garden and act as a “Gardener’s friend” by hunting garden pests like slugs and caterpillars. In fact one of the Devil’s Coach-horse’s smaller cousins in the Rove beetle family, Atheta coriaria, is even used commercially as a form of biological pest control against certain greenhouse insect pests, including fungus gnats, shore flies and thrips.

Wildlife Value of the Devil’s Coach-horse Beetle

Through their role as a dominant predator species in their niche, they provide eco-system benefits by keeping populations of potential pest species in check naturally, in addition they consume carrion and ensure that nutrients are recycled and returned to the soil.

Brown Roll-rim Mushroom

Gills of a mature Brown roll-rim mushroom, Paxillus involutus

As if that wasnt spooky enough, a large area of my garden surrounding my Birch trees has been beset by the fruiting bodies of what turned out to be a poisonous toadstool called the Brown Roll-rim.

Apparently it is notorious for being particularly treacherous. Originally boiling them was thought to remove all toxins and make them safe to eat, but it was later discovered that the mushroom held a second toxin that build up over a long time and then suddenly kill you by triggering an auto-immune reaction that causes the body to attack its own blood cells. Definitely not one for the pot!

Last Butterflies of the season

What was probably my last butterfly shoot of 2022 happened one evening in beautiful golden light when I spotted not one but four female Common Blue butterflies settling down to roost in a very small strip of our wildflower meadow that we’d decided for the first time was mature enough to leave uncut over winter.

It was a timely reminder to me that the less we humans do to intervene, “control” and “manage” things and the more we resist the urge to “tidy up”, the better chance wildlife has to thrive in our man-made garden, park and urban environments.

Butterflies in particular are vulnerable to disturbance at pretty much any time of year as their eggs, caterpillars or pupae lifestages may all be needing to shelter amongst or feed on plants even when adults are not on the wing. If at all possible, its a good idea to try to leave a section of meadow untouched for a full twelve month cycle at any one time to allow larval stages to overwinter successfully undisturbed.

Nature just isn’t a tidy phenomenon, its chaotic and unpredictable. But the innate human desire for what is ultimately a false sense of control is a perennial urge played out in our gardens and very hard to resist, especially when accompanied by societal pressures of convention and fashion. Over the years this along with the globalisation of plant production resulted in the creatiion of a modern aesthetic that is surprisingly wildlife unfriendly from an ecological perspective, with large showy double blooms with little nectar to offer pollinators, exotic non-native flowers that can’t be used as host plants and monoculture green-baize lawns doused in weedkiller to prevent even a daisy or dandelion, and these days, a great deal of hard landscaping too.

Thankfully the emergence of the wildlife-friendly gardening trend and greater awareness of envirnomental issues is gradually encouraging the development (and revival) of more naturalistic planting schemes and is evolving that traditional aesthetic towards more sympathetic wildlife-friendly designs such as prairie style and cottage-garden planting, low mow flowering lawns and the inclusion of mini wildflower meadows and even wildlife ponds.

After all, who wants a dull old bowling green lawn when the reward is enjoying beautiful wildlife sights like these little roosting butterflies instead!

 

© Kiri Stuart-Clarke 2008-2022.
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