Common adder, Vipera berus (Squamata, Viperidae) in Croatia: Population ecology, microhabitat preferences and termoregulation

Riđovka, Vipera berus (Linnaeus, 1785) je najšire, a ujedno i najsjevernije rasprostranjena terestrička vrsta zmije u svijetu. U Hrvatskoj nalazimo dvije podvrste u tri odvojene populacije. Terenska istraživanja provedena su na dva različita lokaliteta u Hrvatskoj: Okuje (Turopolje, dolina rijeke Save; V. b. bosniensis) i Begovo Razdolje (Gorski kotar; V. b. berus). Monitoring vrste proveden je Capture – Mark – Recapture metodom tokom četiri godine u Okuju (2009. - 2012.), odnosno tri godine u Begovom Razdolju (2009. - 2011.). Cilj istraživanja bio je utvrditi postoje li interpopulacijske i intrapopulacijske sličnosti i razlike u odabiru mikrostaništa, termoregulaciji, dnevnoj i godišnjoj aktivnosti, spolnoj strukturi te analiziranim merističkim karakteristikama. Analizirani uzorak obuhvaćao je ukupno 106 jedinki (50 iz Begovog Razdolja, 56 iz Okuja). Utvrđeno je da postoje statistički značajne razlike u duljini i visini glave te tjelesnoj težini jedinki. Jedinke riđovke u Okuju preferiraju zatvoreni tip, a jedinke u Begovom Razdolju otvoreni tip mikrostaništa. U obje populacije postoji razlika u spolnoj strukturi te termoregulaciji prema spolu i tipu obojenja. U Okuju riđovke počinju svoju aktivnost u mjesecu ožujku, a u Begovom Razdolju u mjesecu lipnju.The Adder, Vipera berus (Linnaeus, 1785) is the most widespread and also the northernmost distributed terrestrial snake species in the world. In Croatia, there are two subspecies of the adder in three separate populations. Field work was conducted on two different localities in Croatia: Okuje (Turopolje, river Sava Valley; V. b. bosniensis) and Begovo Razdolje (Gorski kotar; V. b. berus). The monitoring was conducted by Capture – Mark – Recapture method during a four year period in Okuje (2009 – 2012), and a three year period in Begovo Razdolje (2009 – 2011). The main goals of this study were to determine if there are intrapopulation or interpopulation similarities or differences in microhabitat preferences, thermoregulation, daily or yearly activity period, gender structure of population and meristic characteristics. We collected 106 adders (50 from Begovo Razdolje and 56 from Okuje). The analyses have shown that there are statistically significant differences between the two populations in head length, head height and weight. The individuals from Okuje prefer a closed type of microhabitat, unlike individuals from Begovo Razdolje that prefer an opened type of microhabitat. In both populations, there are differences in the gender structure, and thermoregulation which is sex and colour morph dependent. In Okuje, Adders begin their activity period in March as opposed to individuals from Begovo Razdolje whose activity period begins in June