Plants on walls

 Chasmophytes are specialised plants that colonise crevices in bare rock faces - ivy-leaved toadflax is a notable example, that even produces seed capsules that grow towards dark cavities, planting their own seeds back into the wall. But there are a surprising number of plants that colonise the man-made equivalent of rocky cliff faces - either drystone walls or walls constructed with mortar. 

Here are a few of the accidental wall colonists that I've encountered recently.

Native wild strawberry on a wall top at Stanhope in Weardale, undoubtedly arriving as a seed in a bird dropping

Native dog violet in a damp retaining wall beside the railway line at Hexham in Northumberland. It has a ballistic seed dispersal method, firing out seeds when its capsule splits and contracts

Native shining crane'sbill in a drystone wall at West Blackdene in Weardale. This plant, a wall specialist, has leaves that turn bright crimson as summer progresses, perhaps induced by stress as conditions become drier.

Non-native trailing bellflower, on a wall top beside Quarry Heads Lane in Durham city. Escaped from a nearby garden.

Native wall lettuce, another wall specialist with plumed seeds that are carried on the wind. Growing here on a ledge below the parapet of Prebends bridge, spanning the river Wear in Durham city.

Moth mullein, a non-native, well established in the wild. Here, on old walls beside Sunderland Marina. 

Wallflower, doing exactly what its name dictates, growing in a wall beside Sunderland Marina. Cultivated since medieval times but well established on walls in the wild.

Pocket plum disease

 This summer there have been some spectacular local outbreaks of pocket plum disease, affecting sloes on blackthorn on the Durham coast near Hawthorn dene  and bird cherry fruits in Weardale. It's caused by the fungus Taphrina pruni, which induces the fruits to swell, become spongy and fill with watery fluid. In bird cherry (bottom picture) the normally spherical, shiny black fruits become banana-shaped. No seeds are formed inside these deformed fruits, instead there is an empty 'pocket'.

Longhorn moths' dances curtailed by breezy weather

 Over the last couple of weeks I've seen a lot of these male yellow-barred longhorn moths, which have extraordinarily long antennae. They are at their most fascinating when the males congregate and perform aerial dances to impress females, rising and falling in the air, as if attached to invisible bungee cords. 

This one was resting on a bramble leaf in Backstone Bank wood, in the Tunstall valley in Weardale, where I suspect the breeze blowing through the trees prevented it from dancing. Those long antennae make the insects aerodynamically unstable on windy days, but do allow them to detect the scent of females, which have shorter antennae, from a long distance.

Bumblebees and poppies: do they see red?

 Human colour vision allows us to see a spectrum of colours that extends from violet to red - the colours of the rainbow - but bumblebees' colour vision is different. They can see ultraviolet, at the short wavelength end of the spectrum, but don't perceive the colour red at the long-wavelength end. But they are constant visitors to scarlet poppies in my garden, so there must be another cue that attracts them from a distance. My guess is that the lure must be a chemical one, a scent that they can detect but we can't, although the contrasting dark whorls of stamens in the centre of the flower would also  be visible to the visitor once they are close enough to see inside the flower. 

I watched this bumblebee make multiple attempts to find its way into the poppies waving in the wind, and once it found its way inside I could hear it buzzing, to shake pollen from the mass of stamens in the centre of the flower. You can see the bluish-grey poppy pollen packed into pollen baskets on its hind legs in these photographs.

Goosanders

 We encountered this female goosander and her nine ducklings, not long out of the nest, when we were crossing the footbridge over the river Wear at St. John's Chapel in Weardale recently. We caught her  by surprise, tapped between a low waterfall that her ducklings couldn't navigate and us on the bridge. 

Outside of the breeding season she would have taken flight in an instant, but she had no option but to stick with her flightless ducklings, swimming in agitated circles, with her ducklings clambering on her back. We moved on quickly, leaving her and her family to white-water raft down river and away to safety. 

This was a single-parent family: drake goosanders undertake a moult-migration to Norway while the duck is still incubating her eggs; he won't be back until late autumn.

I wrote about this encounter in the Guardian Country Diary this week.

Magpie fledglings

 At the end of January I wrote a post (here) about the conflict at the end of our garden between carrions crows and magpies, competing to nest in the same tree. Well, the magpies prevailed. They successfully dismantled the crows' nest, stealing twigs faster that the crows could add them. Now the magpies' first brood, an unruly bunch, are in the garden every morning and it's interesting to watch their development.

The fledglings are fairly easy to spot because their tails are shorter and more rounded at the ends than those of their parents.

To date, the fledglings don't seem to have much idea about how to feed themselves. They spend a lot of time pulling leaves off the trees, while the parents attempt to broaden their diet. 

A raucous fledgling calling for food (above) and harassing a parent (below). The longer, more slender tail of the parent is evident in the lower picture.

Occasionally, the parents will bring them meat, which almost always looks as though it must have been roadkill. Their offspring are sometimes not sure what to do with it. This one pecked at the meat, but then left it and flew away.

Many people don't like magpies because they have a reputation for taking other birds' eggs and nestlings, but much of the food that I see them carrying is roadkill - animals that people have killed with their cars. The abundance of roadkill is surely one reason why magpies are such a successful species - we humans, inadvertently, feed them. Hedgehog meat would be a rare item in a magpie's diet if it wasn't for the impact of motorists, but I often see magpies pecking at squashed hedgehog carcasses on roads.