The ups and downs of the Tree Frog in a nature reserve in North Brabant De Brand, part of the large nature reserve Loonse en Drunense Duinen in the province of North Brabant since 2002, has been subject to a thorough herpetological survey each year since 1985. At first, the Tree Frog (Hyla arborea) was not seen, although historical sources recorded its presence until about 1975. In the late eighties a very small number of tree frogs was discovered. During the 1990s, after a number of pools had been restored, and eleven new pools created as part of a provincial species protection plan, the population seemed to be on the path to recovery. The management of the pools played a crucial role. In 2012, more than 1100 adult males and 625 juveniles were counted. Although the population has grown enormously since the mid-nineties, research in 2011 gave cause for concern as the genetic base proved to be quite narrow. Additional genetic material from populations in neighbouring nature reserves would help improve the situation. This could be done by adding individuals from these reserves to the population in De Brand, and by improving the connecting areas between De Brand and the neighbouring nature reserve De Leemkuilen.