Ilian Velikov wrote:Well, there might be some decrease of snake numbers but 25 snakes in 12 days is a very good number of snakes too. And having in mind that you only looked for a couple of hours per day for them I'm not sure if your result could be taken as a proof of lower numbers. If the numbers are indeed lower I would put my bet on alteration or destruction of habitat. Ruggero, I don't think that direct killing of snakes was ever a major threat to any snake population, especially on the Balkans. It could be a factor if it's a small population with restricted habitat but knowing the environment on the Balkans I don't think shepherds are any real threat, in fact I'm sure they kill far less snakes per year then natural predators.
Ilian, the territory around Parga is not a sort of "amazon forest" but a restricted mediterranean habitat inside a touristic region, with many agricultural areas, many hotels (old and new), trafficked roads, mass tourism, livestock with shepards and so on. A very "delicate" and fragmented habitat. I've seen there in the past many snakes killed by people (directly or indirectly): leopardsnakes, ammodytes, malpolon and so on. It's not important if they were killed by a shepard, by a tourist, by a car or by a new hotel's owner: there were tens of snakes killed every time I was there. And that type of killing was not a natural one! I mean: snakes population had reached in thousands of years an equilibrium with natural predators. And natural predators obviously become of less impact if a snake population become less abundant: the balance remains anyway. With killing by humans' hand no balance is possible: deaths from humans, even if less in number (at least at first) than natural predations, tend to go straight on till the total extinction of a snake population. Human killing is not a natural type of predation: it's a new factor, which comes after thousands of years of equilibrium, and forcely tends towards the destruction of the victims (which are not "preys" in this case). If a snake population of, let's say 1000 snakes or what you want, produces every year 1000 new snakes which are predated by natural predators, you have a balanced situation. Small variations are compensated: snakes increase in number, so do natural predators and vice versa. But if humans come in and the snakes killed are no longer 1000 but 1300 of which 300 are killed without any natural selection (as it's the case with natural predators) you can be sure that the pristine equilibrium will be soon broken. And you can be sure that the last snake of a certain area will be killed by a man and not by a snake-eagle: simply because snake eagles would had already abandoned that territory years before!
25 snakes in ten days around Parga in spring is ridicolous, if I think about "my" old times. In two hours of herping I could observe there in good days more than 25 snakes: in my picture you can see probably about ten snakes or little less... Ten snakes just in one picture, not in two hours of herping! I can guarantee: those places were a gan-eden for snakes, a true open-air reptilarium.
Many factors contribute to snake decline, sure: direct human killing is probably not the first one in order of importance, I agree with you (for some "big" areas at least), but it's also surely not the last/least important one near Parga...