Zandhagedissen op de Leusderheide

The Sand lizards at Leusderheide Heath Sand lizards were studied at the military training area Leusderheide Heath (The Netherlands) in 2008, emphasizing population size, egg laying and nature management aspects. A new method enabled us to make a reliable estimate of the absolute number of lizards, using ‘timeconstrained searches’ and then applying a conversion factor. The area of 900 ha harboured a population of approximately 25,000 adult and subadult sand lizards. The animals displayed a discontinuous distribution across the heath and kept clear of dense forests and open sand flats. The highest densities were found in vegetation dominated by Scotch heather, where lizards could reach a maximum density of over 300 individuals per hectare, one of the highest known densities in The Netherlands so far. However, there were also other heather areas where lizards were totally lacking. The average densities for heather (81 individuals /ha) matched those of other reference areas. Egg laying occurred across the whole area at open sandy places with a favourable position and the soil holding moisture. Many of such places were surveyed and their physical characteristics recorded. Sandy places that had been artificially created were less utilized for the purpose of egg laying than expected. The military use of this area covered a wide spectrum of activities, but they were conducted on a comparatively small scale. This was preserving favourable conditions for the sustainable survival of the lizard population. They further benefitted from specific measures such as removing bushes, creating connection zones and protecting the edges of tank tracks. This heath is one of the very few heathlands in the country where animal grazing is not practiced. Op het militaire oefenterrein Leusderheide leven veel zandhagedissen. Waar zitten ze precies, hoeveel zijn er, waar leggen ze eieren, en wat is de invloed van het terreingebruik op de populatie? De gevonden aantallen konden worden omgerekend naar dichtheden en werden gerelateerd aan de structuur van de vegetatie. Het militaire gebruik had een positieve invloed door de grote variatie in intensiteit en plaats van uitvoering in samenhang met de grote oppervlakte van het gebied.