SPAIN 2011

 

 

Reptilia: SERPENTES (Snakes)

Snakes are always much harder to find than lizards. They are less numerous, more secretive, less likely to be seen out basking or displaying, and often quicker to disappear when disturbed. While most, if not all, the lizards of an area will be recorded in a relatively short time, a much lower percentage of the snakes present will be documented over a much longer period of time, and far fewer individuals of each species. For herpetologists who have chosen to work on snake ecology and population dynamics there is a term which sums up their frustration compared to colleagues working on lizard populations: Lizard Envy!

Colubridae:

Rhinechis scalaris - Ladder snake
The ratsnake of Iberia, Juan says numbers have declined due to many being killed on roads at night. Out first specimen was a road-kill on the fast road west from Valdemorillo, but thankfully Tom and Dave also managed to capture a living specimen near the stream site dubbed the "colubrid site" by Juan, as a place once good for snakes. This is a powerful constrictor that may achieve lengths of 1600 mm and occurs in rocky habitats and woodlands up to 2,200 m altitude. Its pointed snout and padded, enlarged rostral scale are adaptations for burrowing under rocks and logs and hunting in rock piles and stone walls.

Ladder snake,
Rhinechis scalaris

a road-kill near Valdemorillo
Ladder snake,
Rhinechis scalaris

a specimen from Valdemorillo
click on the images to enlarge
Ladder snake,
Rhinechis scalaris

the specimen at the capture location by Dave Nixon

 

Natricidae:

Natrix maura - Viperine watersnake
The commonest snake we encountered, the Viperine watersnake (Natrix maura) was found in almost all the locations where we searched, and all the locations with water courses running through them. We saw juveniles swimming at the stream site near Valdemorillo and the river at Robledondo, adults in the pools at Zarzalejo, the stream near Valdemorillo and the river at Robledondo. We found at least eight watersnakes. This is a very common name Southwestern Europe and North Africa being found in mostfreshwater watercourses up to 1,600 m, where it huints fish, in contrast to its amphibiophagous congener, the Grass snake (Natrix natrix).

Viperine watersnake,
Natrix maura

specimen from Zarzalejo
Viperine watersnake,
Natrix maura

adult from Robledondo
Viperine watersnake,
Natrix maura

juvenile from Valdemorillo
Viperine watersnake,
Natrix maura

adult from Valdemorillo
Viperine watersnake,
Natrix maura

adult from Robledondo by Dave Nixon


Viperidae:

Vipera latastei latastei - Lataste's viper
The target species of the trip, the Lataste's viper (Vipera latastei) exists as two subspecies in the Iberian Peninsula and Northwest Africa, with the nominate subspecies occuring in the north of the range. It is distributed over a wide range and up to altitudes of 3,000 m, but nowhere is it very common and with its fragmented distribution it is one of the species most at risk from habitat loss, fragmentation or alteration. It is also at risk from collectors so we were are pains to disguise the locality where we found three specimens and captured, photographed and released one male. Achieving a maximum length of 750 mm, the Lataste's viper is easily distinguished from other vipers in the Iberian Peninsula (Vipera seoanei, V.aspis) but its upturned snout. It inhabits rocky hillsides and scree-slopes, in the open and within deciduous woodland.

Lataste's viper,
Vipera latasei latastei

male from Robledondo