CROATIA 2013

 

Reptilia: SERPENTES (Snakes)

The main target species were the two vipers which eluded us on the Greek herp photo trip in 2012 but as usual I was interested in photographing any Croatian/Balkan snakes we encountered. Although we only had three field-days we did find eleven snakes of five species.

Colubridae:

Coronella austriaca austriaca - Smooth snake
The Smooth snake (Coronella austriaca austriaca) is Britain's rarest and most protected reptile, being confined to the Southern Heathlands of Dorset, Hampshire,Wiltshire and a small portion of Surrey. In the 1970s-80s I saw about five specimens during my annual to twice-annual visits to Purbeck and found two more in Hampshire when I took a film crew south to film British snakes a few years ago. Considering the status of this species in the UK it is sure to create excitment for British herpetologists when they find it on the Continent, something our European colleagues may find hard to understand since it is such as widespread and frequently encountered snake over there.

Smooth snakes are relatively small, rarely exceeding 0.7m in length, they are diurnal and fairly slow-moving. Prey consists of lizards, snakes and small mammals, which are constricted in their coils. In Europe they inhabit a wider range of habitats than they do in England, entering forests, vineyards and even occuring on lowlying hillsides. Near Velika Gorica we encountered a single specimen as we were leaving the Balkan adder locality. Smooth snakes are also remarkably fidgety and difficult to settle for photography and it took a long time to obtain half-a-dozen good images.

Smooth snake,
Coronella austriaca austriaca

near Velika Gorica, Turopolje, southeast of Zagreb

 

Hierophis viridiflavus - Western whipsnake
The Western whipsnake (Hierophis viridiflavus) is a large (1.5m) fast-moving snake, seen abroad during the heat of the day but its speed often makes it difficult to capture. It occurs through most of France, except the north, and down into Italy, Sardinia and Corsica, and then eastwards into coastal Slovenia and the Istria Peninsula of Croatia, where we encountered this specimen. The melanistic colouration of specimens from the east of the range once led to this population being treated as a subspecies, Coluber viridiflavus carbonarius, but this classification is no longer accepted.
Western whipsnakes prey on mammals, birds, reptiles and amphibians and they have a preference for overgrown or scrubby habitats.

We captured our single specimen in Istria when Neven, Ivo and I were searching for snakes while Dušan and his team were diving for Olms. It had been raining hard all morning, not good for snake-hunting, but had recently abated so we searched under trash and boards around the outskirts of a vineyard near Novigrad. The whipsnake was sheltering under the floor of a large platform and was taken unawares. It was photographed, with some shedding of blood (by us) and then released back under the same floor.

Western whipsnake (melanistc specimen),
Hierophis viridiflavus

near Novigrad, Istria

 

Zamensis longissimus longissimus - Aesculapian snake
The Aesculapian snake (Zamensis longissimus longissimus) is another species that may be found it the United Kingdom, it is our fourth snake, there are established introduced populations at Colwyn Bay, N.Wales, and along the Regent's Park Canal in London. We also encountered a juvenile specimen on the road in Greece, juveniles having very 'grass snake-like' patterning.

Aesculapian snakes are widespread through southern and eastern Europe (excluding Iberia), they reach around 1.5m in length, inhabit a variety of habitats and feed on small mammals, birds and lizards. We met two adults whilst searching for Nose-horn vipers (Vipera ammodytes) in the Western Medvednica Mts. northwest of Zagreb, but one evaded capture. Both were found crossing a trail along a wooded hillside. The specimen captured still clearly possesses the remnants of the juvenile 'grass snake-like' neck collar.

Aesculapian snake,
Zamensis longissimus longissimus

western Medvednica, northwest of Zagreb

 

Viperidae:

Vipera ammodytes - Nose-horn viper
We had searched for Nose-horn vipers (Vipera ammodytes) in the Dadia Forest of Thrace, Greece, in 2012 but apart from a specimen briefly sighted fleeing into a dry-stone wall, we had been unsuccessful. I was not to be disappointed this trip when viper researcher Mladen took Neven and myself, and a Croatian TV film crew, out to one of his study sites in the western Medvednica Mts., northwest of Zagreb.

Almost immediately we encountered a male Nose-horn viper besides the trail onto the site and after a hard climb and some more searching a pair were found together, actually by one of the film crew (fare play there). A fourth specimen was briefly sighted diving under a large boulder towards the end of the excursion, a refuge from which it could not be extracted. The captured threesome were photographed, the pair as soon as we had filmed them, the single male being retained for data collection by Mladen. The subspecific status of this population is apparently open to question.

Nose-horn adder (male),
Vipera ammodytes

western Medvednica, northwest of Zagreb
Nose-horn adder (male and female),
Vipera ammodytes

western Medvednica, northwest of Zagreb
Nose-horn adder (male of pair),
Vipera ammodytes

western Medvednica, northwest of Zagreb
Nose-horn adder (female of pair),
Vipera ammodytes

western Medvednica, northwest of Zagreb
Nose-horn adder slough,
Vipera ammodytes

western Medvednica, northwest of Zagreb
can you spot it?
click to view the slough in close-up

 

Vipera berus bosniensis - Balkan adder
The Northern adder (Vipera berus) is the most widespread, naturally occurring land-snake in the world, beign found from Britain and Scandinavia, throughout northern and eastern Europe and eastwards across Asia to Mongolia and Lake Baikal in eastern Russia. Two former subspecies are now treated as full species: Seoane's viper (Vipera seoanei) in northern Spain, and the Sakhalin viper (Vipera sachalinensis) on Sakhalin Island and in far eastern Russia. Only one subspecies is now recognised as different from the nominate form, the population from the Balkans which is known as the Balkan adder and which constitutes the southern-most population of this widespread northern snake.

The Balkan adder (Vipera berus bosniensis) had been our third target species in Thrace, Greece in 2012, had we found both the Ottoman viper (Montivipera xanthina) and the Nose-horn viper (Vipera ammodytes). We had succeeded well with the former but failed with the latter so never moved onto the Balkan adder location. My visit to Croatia was in part driven by a desire to see this species in the wild and accompanied by Neven and Ivo I made a trip to a semi-agricultural area near Velika Gorica, in Turopolji, southeast of Zagreb, where we encountered three specimens, one of which evaded capture. The three snakes sighted were a young male, a partial-melanistic male, and a melanistic male which was the one that escaped. Ivo had two snakes with him from the day before, a melanistic male and a regular female, so I was still able to photograph all the sexes and colour phases on the site.

Balkan adder (female),
Vipera berus bosniensis

near Velika Gorica, Turopolje, southeast of Zagreb
Balkan adder (melanistic male),
Vipera berus bosniensis

near Velika Gorica, Turopolje, southeast of Zagreb
Balkan adder (young male),
Vipera berus bosniensis

near Velika Gorica, Turopolje, southeast of Zagreb
Balkan adder (partial melanistic name),
Vipera berus bosniensis

near Velika Gorica, Turopolje, southeast of Zagreb