The Sierra de Montejunto is an integral part of the "Limestone Massif Estremenho" and in it is the highest point of the West region. Its geological structure provides the existence of several dozen caves and algae distributed throughout the space of the mountain range, however its exploitation, due to the risks involved, is reserved for specialists. Due to its very characteristic micro-climate, the transition between maritime and continental influence, and the geo-morphological conditions of this mountain, its fauna and flora are very different from those of the surrounding ecosystems. Thus, the plant communities of castinçal, oak and pine are important where stands the pine (Pinus pinea). But Montejunto is mainly rich in ornithological species and there have been identified about 115 species of birds.