Do European Ground Squirrels (Spermophilus citellus) in Austria adjust their life history to anthropogenic influence? [Odráží se vliv člověka na změnách biologie sysla obecného (Spermophilus citellus) v Rakousku?]
Michaela Brenner, Tabea Turrini, Ilse E. Hoffmann
|Citation||BRENNER, Michaela, TURRINI, Tabea a Ilse E., HOFFMANN. Do European Ground Squirrels (Spermophilus citellus) in Austria adjust their life history to anthropogenic influence? [Odráží se vliv člověka na změnách biologie sysla obecného (Spermophilus citellus) v Rakousku?]. Lynx, new series. Prague: National Museum, 2008, 39(2), 241–250. DOI: https://doi.org/. ISSN 0024-7774 (print), 1804-6460 (online). Also available from: https://publikace.nm.cz/en/periodicals/lns/39-2/do-european-ground-squirrels-spermophilus-citellus-in-austria-adjust-their-life-history-to-anthropogenic-influence-odrazi-se-vliv-cloveka-na-zmenach-biologie-sysla-obecneho-spermophilus-citellus-v-rakousku|
While the European ground squirrel in Austria is sometimes near to extinction in its natural habitat, aggregations in altered habitats often achieve exceptional densities. In an effort to clarify this phenomenon, we compared demographic and life-history variations of five focal populations exposed to different environmental conditions. The respective habitat types were: secondary steppe, semi-arid grassland, a meadow renaturated from arable land, a wine-growing area, and a meadow altered by alfalfa. The study plots also differed in the degree of inclination, fragmentation and isolation. The populations were examined in 2006–2008 from April to July of each year by capture-mark-recapture and observation. At initial capture, each ground squirrel was categorised (sex, age, reproductive state), marked with hair dye, tattooed and/ or equipped with a PIT tag. Body mass, head length and gonadal development were recorded continuously. Our results indicate that population densities increased with anthropogenic influence (range: 9–43 individuals/ha), whereas sex ratios varied inconsistently among study plots. Each focal population contained reproductive yearling males. Their highest and lowest percentages, respectively, occurred on the alfalfa meadow (83%) and in the vineyards (40%), indicating that habitat alteration might either delay or accelerate puberty. We conclude that anthropogenic influence may have beneficial effects on European ground squirrels in terms of population growth. However, this conclusion is ambiguous in short terms. Thorough analyses of our data will provide information not only on the species’ habitat requirements, but also on the artificial constraints it is yet able to cope with.