Sea Aster

Sea aster Aster tripolium comes into flower just as most other saltmarsh plants, like sea lavender and sea pink, are past their best, and it continues to flower well into early autumn. This fine specimen was one of many flowering on the saltmarsh at Warkworth recently. It's a very variable plant, tolerant of a wide range of conditions. On the saltmarsh it's periodically inundated with sea water during spring tides and it grows in extremely saline mud. Salt-tolerant plants like this are classified as halophytes.

In other places it tolerates brackish conditions. I photographed this population of the plant on the banks of the Tyne last week, seventeen miles inland from the coast, near Newburn near Ryton Willows Local Nature Reserve. The river is still tidal at this point and here the water must still be only slightly salty, compared with the coastal conditions. The plants here are much taller, more on the scale of garden Michaelmas daisies, which may be because the plants are inundated twice a day and grow on sloping river banks, so it's more of a struggle to keep their heads above water, unlike the saltmarsh plants that grow on an almost flat surface and are only infrequently flooded during very high tides.

There has been a significant amount of research interest around the world on this species in recent years, because of its potential as an animal fodder crop that will grow on very saline soils, with the potential to return land to productivity after it has suffered salinisation through excess irrigation .

Something to Celebrate

Much that is reported in the media about wildlife is bad news - usually about catastrophic declines in species abundance, so the rapid northwards extension of the range of the speckled wood butterfly has been somewhat under-appreciated. This butterfly was known in Victorian times as the Wood Argus or Wood Lady and in the 1870 edition of his History of British Butterflies the Rev. F.O. Morris described it a being "...a common species in all parts of the country, from the extreme north to the extreme south..." but it seems that by then it was already declining in the north. By 1986 T.C. Dunn and J.D. Parrack, in their Moths and Butterflies of Northumberland and Durham  lamented that "We must now consider it to be extinct in out two counties, but it still survives in Yorkshire and it is theoretically possible for it to return". I don't think I'd seen one of these delightful insects in County Durham until about five years ago, although I'd occasionally seen them in North Yorkshire, but now they are just about everywhere I look. They arrived in woodlands around Durham city about three years ago and are now so frequently seen that the novelty has already worn off. They have even turned up in my garden on several occasions this year, where I hope that their larvae might make inroads into the common couch that is one of their food plants, along with cock's foot grass and Yorkshire fog.

The speckled wood's ability to produce two generations a year and overwinter as a larva or a pupa must have some bearing on the speed that it establishes itself once it arrives. This is a species where the males are highly territorial and in the ten minutes that I spent watching the individual in these photographs it twice fought short but furious aerial dogfights with an intruder, spirally upwards before returning each time to this sunlit leaf once it had seen it off; a remarkable display of aggression in such an apparently fragile insect. The butterfly literally defends its own personal patch of sunlight, where it poses to attract the attention of a female. Dr Paul Whalley, an entomologist at the Natural History Museum described this territoriality in detail in his book Butterfly Watching in 1980 and suggested that the males probably scent mark their territory. Describing six contesting the same patch of sunlight, he wrote "They flew in an up and down, follow-my-leader fashion which resembled a well-drilled dance routine". Male and female speckled woods are hard to tell apart but the artist and naturalist David Measures came up with a sure-fire solution to the problem in his book Bright Wings of Summer. "Unless you have a male and female side by side it is difficult to distinguish the sexes by the markings" he wrote, but noted that it's 'undoubtedly a cock if it flies up at everything that passes, in true territory-claiming style..." Measures' book, published in 1976, is full of delightfully spontaneous watercolours of butterflies, produced during a decade of patient and meticulous field studies of butterfly behaviour, that perfectly evoke the vibrancy of these wonderful insects - it's well worth reading if you can find a copy.

Beachcombing

There are few more pleasant ways to idle away an afternoon than to indulge in a spot of beachcombing, discovering what the falling tide has left behind, and when we arrived at Warkworth beach last Saturday lunchtime the tide had just turned, leaving a trail of marine artefacts, like the crimped pie-crust carapace of this edible crab .....

... and the saw-toothed carapace of a shore crab.

Recent rough seas had scoured the sand and cast up thousands of these sand mason worms, with their tubes constructed from grains of sand ....

... but this dog whelk, with its tough, thick shell may have been rolling around in the surf for weeks.

This is a mollusc that doesn't belong on the shore at all - it's a grove or brown-lipped snail Cepaea nemoralis, which is an air-breathing species that lives amongst the marram grass on the sand dunes behind the beach. Maybe a bird caught it and dropped it on the beach, or it might have been dislodged when a spring tide eroded the edge of the dune. This species comes in a variety of background colours and banding patterns, but many on the dunes here are either pure yellow or sometimes pink.

 

This is the delicate mauve interior of the rayed trough shell, which is decorated with markings ....

..... like the rays of the setting sun on its outer surface.

Banded wedge shells come in a range of colours, including brown and purple, but the pure yellow ones are particularly attractive.  

The star find was this tower or auger shell, Turritella communis. It's common enough around much of Britain, especially on the west coast, but this is the first time that I've found it here in thirty years of walking along this beach.

And finally, a modern archaeological curiosity - a clay pipe. I wonder who lost this, and how long ago - maybe a fisherman who dropped it overboard? Whoever it belonged to, it must have remained buried in the sand until a convergence of rough weather and high tide scoured it out and left it on the tide line.

For more beachcombing on Warkworth beach, visit

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