Articles in ‘Reptiles’

Viperine snake takes on large Water frog (and gives up)

Written by Lucy Brzoska

Walking along a hot, dusty track in the Alt Emporda, a woodchat shrike singing in a nearby tree and bee eaters dipping and diving over the olive groves, we heard a piteous crying sound.   It was coming from the long trough-like irrigation channel at the side of the track: a strongly protesting Iberian water frog (Pelophylax perezi) was in the grip of a Viperine snake (Natrix maura).

viperine  snake (Natrix maura) captures Iberian water frog

The aquatic snake had seized the frog by the leg and was swimming vigorously up and down the channel, the belly of its helpless prisoner flashing white in all the whirling.

viperine snake swims with captive water frog

The non-venomous snake next tried tightly knotting itself around its resistant prey, its mouth still gripping the leg.

viperine snake knots itself around iberian water frog

Suddenly it seemed to tire, released its coils and swam to the side of the channel.  The frog waited a moment, and then tried to swim away.  But its movement immediately triggered a reaction in the snake, which this time seized the amphibian by the back.

viperine snake (Natrix maura) biting iberian water frog (Pelophylax perezi)

Despite the considerable gape of the Viperine, it was clear the frog was too big for it to swallow. Eventually the frog was allowed to make a getaway, but fatally weakened, it didn’t survive the attack.

Montjuïc Castle: the importance of holes

Written by Lucy Brzoska

A young Montpellier snake, hatched in the walls of Montjuïc Castle, surveys the world outside.  The sandstone wall, mellowing through the centuries, is structurally sound but honeycombed with holes.

An exploring ant gets a foothold on the snake’s mouth, probing hesitantly with its antennae.  The tiny snake doesn’t move and observes cross-eyed.

There’s always lots to observe in an old sunny wall.  Fortunately, Galanthus, who work at promoting and preserving Barcelona’s biodiversity, have so far thwarted misguided attempts to fill the holes of Montjuïc Castle with concrete.

(NB. This photo is not upside-down.)

Zooming in on Montjuic (v): gecko

Written by Lucy Brzoska

The craggy old gecko lies fossilized on the stone wall, flattened against the warm rock. A bug comes briskly by, and the gecko comes to life, peering down.

The bug quickens its pace, but the gecko’s tongue is faster.

Nothing more to do but lick one’s lips, settle back down into the warm rock, and wait to see what else turns up.

Zooming in on Montjuic castle(ii): a Montpellier snake

Written by Lucy Brzoska

A fierce northerly wind had blown November’s mild mist into space.  But on the south side of Montjuic castle, in early December, it was warm enough for the geckos to materialise from their nooks and for a very small Montpellier snake to go in search of them.

I found it coiled at the foot of the wall, pale brown and very slender, gazing upwards. When it began to negotiate the irregular stones, it revealed a length of only about 30-40 cm.  Montpelliers are Europe’s largest snakes, with adult males reaching 2 metres or more, so this was still a baby.

young-montpellier-snake

For the moment it was perfectly suited for life in the castle wall, threading neatly in and out of the crevices, among the snail shells and woodlice.

montpellier-snake-moving-on-wall

Despite the scrutiny, the young snake didn’t go into hiding.  Instead it began gathering information by flickering its forked tongue at me, the equivalent of twitching a nose in the air, picking up scent particles.

malpolon-monspessulanus-montpellier-snake-tongue-flickering

From a distance the snake was well camouflaged and plain.  Close up, it showed intricate and rhythmic patterns.   The particularly striking markings on the head will soon disappear as the snake grows.  The juvenile Montpellier spotted here a year ago had already lost them.

Varied in size and shape, each scale on a snake’s head is carefully labelled and mapped out for identification.  The Montpellier is distinguished by having two loreal scales, located between the eye and nostril but without touching either.  The narrow shape of its small head means the frontal scale, centre-top, is also long and thin, squashed in by the supraoculars.

young-montpellier-snake-malpolon-monspessulanus

Grateful for letting me have such a good look, I left and let the little Montpellier get on with the business of hunting.

A Moorish gecko

Written by Lucy Brzoska

The richly patterned sandstone wall of Montjuic castle is full of chinks where a gecko might lie, safely basking in the sun. It takes a lot of staring to find one: you suddenly realise the dark patch has toes, and what might be a glinting shard of glass is an eye.

It’s the end of winter, and we all feel like basking in the sun. The Moorish gecko (Tarentola mauritanica) varies in colour – this one appeared almost black, effective for soaking up heat. At night, when actively hunting their prey, they turn pale and interesting.

The gecko let me approach and have a close-up look, perhaps confident that refuge was only a flicker away. Its eyes are split in half by a vertical pupil, sharply contracted against the strong light. Intricate veins cover the dark golden iris. Cleaning is done by a sweep of the tongue, since the gecko has no eyelids.

Perhaps because it sounds more exotic, the pet trade likes to refer to this species as the “Crocodile gecko”. I noted the allusion in the gecko’s bumpy skin. But the tail had a completely different texture: you could clearly see the fault line where the gecko had broken in two to escape from a predator. Once dropped, the tail continues twitching – a useful distraction device. I wondered if the tail, now in process of regeneration, would ever match the original one.

Just as humans have wanted to emulate the flight of birds, they envy geckos for their grip. Sticky hairs on prominent toe pads allow these reptiles to cling to the smoothest surface. A researcher into the phenomenon, interviewed in New Scientist, was flabbergasted by how “vastly over-engineered” they are: “One gecko could resist the weight of 130 kilograms”. Yet they can also detach themselves at lightning speed.

Cattle Egret in the Park

Written by Lucy Brzoska

An unusual visitor came to the park this week. While people lolled on the grass, kissing, reading and eating lunch, it quietly decimated the park’s lizard population.

Cattle egrets (Bubulcus ibis) breed in Barcelona zoo within the Grey heron colony. Unlike their bigger relatives, they are mainly land foragers and can usually be seen in the fields around the Llobregat Delta. Their adaptability to man-altered habitats is one of the reasons for the Cattle egret’s spectacular worldwide expansion over the last century (first pair bred in UK this year).

The opportunism of the egret in the park was richly rewarded. It stalked the ivy-covered ground, alert for rustling movements. Whenever potential prey was spotted, its neck would start wobbling. The undulation would travel back in waves, till even its tail was shaking. Its head, however, remained quite still. The sinuous movements seemed to be a way of warming up for the final pounce, which was nearly always successful.

The egret’s bill was an efficient pincer, applied with masterful technique. Each lizard was grabbed firmly by the body, away from the detachable tail. Sometimes the helpless lizards would wrap their tails around the egret’s bill, as if desperately trying to bind it. But struggling was useless. Inevitably they would be swallowed head-first, to join the ever-growing pile in the egret’s powerful digestive system.

On a short break, it stopped to preen, and caught a couple of flies, particularly annoying at this time of year. It was a reminder why Cattle egrets are valued by ranchers as an alternative to pesticides. They are often to be seen delicately picking bugs off animals’ backs. But the egret in the park soon went back to its more solid menu, swallowing reptile after reptile.

I began to worry about the park’s lizards, (mainly Podarcis hispanica), who normally enjoy a placid predator-free existence. But later I read about a study of an island population of lizards – the park is like an island in the city, after all – which involved unleashing an alien predator and observing the effect on the resident reptiles. The population was badly hit initially, but the species triumphed, exhibiting longer legs at first (better to run with) and then shorter legs (more useful when they took to the trees). An example of rapid evolutionary resilience.

The Cattle egret returned to hunting, but I’d had enough of observing. My lunch-break was nearly over, and I was starving.

Snake in the Wall

Written by Lucy Brzoska

What drew my attention was the lizard dropping off the wall.

I was on the Camí del mar, a path that circles Montjuic castle and overlooks the sea, which on this misty, warm day merged seamlessly into the sky. People were walking, running or cycling. An old man sunning himself on a bench had brought along a goldfinch, which sang in its cage. The fig trees were still green, but their large leaves had stiffened and occasionally one came clattering down.

From a distance, the castle looks a warm sandy colour, but close up each of the stone bricks is unique, the faded red and yellow patterns sometimes erupting into psychedelic swirls. The quarries of Montjuic have yielded a lot of sandstone for the city’s buildings.

In places the stones have been crudely patched up with cement, but fortunately plenty of cracks and holes remain. There’s no shortage of nesting sites for House sparrows, or refuges for ants, woodlice and spiders. The south-facing slopes of Montjuic are a suntrap, and as the wall heats up, it begins to flicker with lizards.

Approaching the spot where the lizard had made a sudden dive, I noticed a Moorish gecko (Tarentola mauritanica, Salamanquesa común) clinging on near the entrance of a tiny cave. Another step and it withdrew inside.

But there was something far more dangerous than me only two stones away.

The snake, long and slim, lay apparently lifeless, draped on a narrow ledge. When you spot a snake, there’s a tingle of excitement and you hold your breath, almost with disbelief. It came to life and slid into a crevice, keeping watch from within. When I moved, it stretched out its head to keep track of my position.

I didn’t know it was a Montpellier snake ((Malpolon monspessulanus – culebra bastarda) till I got home and checked. The ones I’d seen before were adult, much larger and darker than this slender, well-camouflaged specimen. The unforgettable photograph on Iberianature left no doubt. I recognised the penetrating stare, tapering head and white stripes, like war-paint, below the eyes, although I don’t know if this young one was quite ready to tackle a sparrow yet.

There was a wall-full of prey there, but the Montjuic Montpellier snakes have a reputation for reaching a fiercesome size on a diet of rats.

Autumn Bugs: hide and seek

At the road side near Vallvidrera, a cellulose gymnast was swinging through the stems. If you’ve grown up thinking of Stick insects as exotic pets kept in glass containers, it’s a thrill to find them ranging free. They look fragile, but can re-grow a damaged limb after a moult.

Another plant imitator, the Praying mantis (Mantis religiosa), is quite visible in Collserola in October. Like Norma Desmond in Sunset Boulevard, this elegant specimen couldn’t take its eyes away from the camera.

The black spots, which look eerily like pupils, are an effect of light reflecting from the compound eyes. The mantis also has three “simple” eyes between the antennae that act as an auxilliary light metre. With its swivelling neck and stereoscopic vision, there’s not much that goes on unnoticed around a Praying mantis.

From camouflage to aposematism – currently every Wild carrot nest has a Striped shieldbug (Graphosoma lineatum) inside. Experiments have confirmed that the colouring of these bugs helps predators remember their bad taste. As if testing out the theory themselves, they are often in prominent positions on the top of plants.

Its vivid red and black colouring probably saved this Firebug (Pyrrhocoris apterus) in Palau de Pedralbes park. Climbing up the rocks, it stumbled onto a sunbathing Wall lizard. After assessing the situation, it hurriedly changed direction. The lizard watched, but made no move.

Close encounters in Collserola

Written by Lucy Brzoska

While out walking on a warm evening at the beginning of September, it was Nick who first spotted this tiny snake on the track, rippling as fast as it could, anxious to reach cover on the other side. Once caught, it remained still, except for the flickering of its tongue. We weren’t sure of its identity, so it paid to have the camera at hand. The photograph clearly shows a black coronet and an elusive blue shimmer: the marks of the non-venomous Southern smooth snake (Coronella girondica).

We were lucky to stumble on it, as they’re not common in Collserola. Shy and secretive night hunters, they search out geckos, skinks and grasshoppers and kill by constriction. A passing resemblance to the viper is thought to work as a defence. We found the snake in the more open southern part of Collserola, an area of grass, shrubs and scattered trees, a summer hunting ground for Short toed eagles.

At the opposite end of the park, not far from a spring, this dragonfly was captured clinging to a bush. I’d have described it as red, till I got home and saw its range of fairground colours: a horse from a devil’s carousel. The rows of spikes on the legs are impressive, ensuring a firm grip on prey. The dimensions of its eyes immediately suggest extraordinary powers of vision.

When identifying the dragonfly, the yellow stripe along the length of the legs pointed me to the Common darter (Sympetrum striolatum), which was confirmed when Sue put her shots up on the forum.

Finally, in the centre of Collserola, the most disturbed and built-up part, this creature was rescued from a busy track. A convoy of cars was driving away from a restaurant, coating us and everything around in dust. The Eyed hawk moth caterpillar (Smerinthus ocellata) was carried to a safer place on a notebook, hence the garish studio background for its portrait.

The caterpillar has a distinguishing blue horn, slanting white stripes (7 in all) and red spiracles (breathing holes).

Pyrenees (iii): Two-legged and hoofless

Written by Lucy Brzoska

On my second attempt to walk to the Port de Ratera, I took the GR 11, which goes directly there and beyond. It takes you round the Estany (lake) de Ratera, with its marshy grass and hairy Bog cotton (eriophorum angustifolium).

Further up, the path narrows, and you reach the Estany de les Obagues de Ratera (the Lake on the dark side of the Ratera). Red and white poles stop you getting lost, so the map could’ve stayed folded, but once open, a tempting alternative materialised, leading away from the GR 11 up to some tiny lakes. The contrast with the previous day was brutal. The way was marked by cairns, to guide you over an avalanche of rocks. Going became a little easier as the path crept along a narrow strip of grass skirting a vertical wall. There were traces of chamois everywhere. What took me half an hour of awkward balancing they could skip across in 3 minutes. There was no sign of any lakes.

I reached an outcrop of Mountain pines (Pinus uncinata) and sat in their shade, as if for protection. Unsoftened by vegetation or water, this was the harsh side of the mountains. The dead silence was broken by the cawing of a raven. Back at the Estany de Obagues de Ratera, I noticed a round white spot in a crevice: a dipper (Cinclus cinclus). Scouting around the streams I found some late pink and white orchids (see discussion on forum). There were also Field gentians (Gentianella campestris), discrete but welcome flowers at the end of summer. Small details, but very reassuring after the stark wilderness higher up.

This time I kept to the GR 11, but in the other direction. Instead of taking one of the jeep taxis that wait on the hour at the Sant Maurici lake, I walked back to Espot. The path follows the sunny side of the Escrita river, through meadows and tunnels of hazlenut trees. The dark side is covered by a thick mass of uniform fir forest haunted by capercaillies. The setting sun escaped from the clouds, lighting up the valley and the leaf flurries shed by silver birches. Long shadows were cast eastwards towards the mountains of Andorra.