This cave was named after a gunner of the Royal Artillery in 1821. According to Palao (1969), the cave was first explored in 1840 by Captain Webber-Smith of the 48th Regiment. In 1867 Captain Frederic Brome also visited and excavated part of the cave. He unearthed two ancient swords of the 12th –13th century, together with a number of human remains including pottery, stone axes and flints. A number of bones were also retrieved, which included birds and reptiles. To commemorate his visit there is an inscription close to the entrance wall that reads, “This cave was explored by authority in June and July, by J. F. Brome Esq.”.
Martin’s Cave has a large entrance facing the Mediterranean. Access to the cave is gained along a narrow ledge of sandstone and conglomerate. Inside is a large chamber with the floor sloping down westwards. There are several columns and some small stalactites and stalagmites. At the end of the chamber the floor levels off into a muddy pool formed by water percolating through fissures and dripping from the formations above. The roof is quite dry in places, without the classic build-up of calcite deposits. The rest of the cave shows evidence of a time when the climate was much wetter, producing the formations found along the walls of the slope and nearer the entrance, which have now dried up. Cpl. J. C. Marshall (in Palao 1969) said that ‘during and after rain one can hear torrents of water gushing in the roof of the cave’. Cpl. Marshall also stated that the cave was home to hordes of common bats, which ‘all of a sudden disappear and then return at a later date’.
In the 1960s the cave held a very important breeding colony of bats, with an estimated 5000 Schreiber’s bat Miniopterus schreibersi, and 1000 mouse-eared bat Myotis myotis (Palao 1969). From the 5th to the 12th November 1966, the Cave Research Group recorded hundreds on the roof and caught two, yet by the 19th November only small groups were resent and a week later none were seen. On the 24th March 1967 the Gibraltar Cave Research Group recorded the presence of a noctule bat Nyctalus noctula, inside the cave (Palao 1969). Protection for the bats was provided by a strong metal gate that was installed by the military, presumably as part of the fortifications during WWII, as there are numerous power cables littered within this cave. This gate permitted little disturbance to the bats for many years, especially when the Upper Rock was in MOD hands.
With the transition of the Upper Rock to the Gibraltar Government, the number of visitors to this area increased. Vandals forced entry into the cave, breaking the gate and disturbing the colony of bats. There is also evidence that fires were lit inside the cave to force the bats out of their hiding places. With so many disturbances, the colony dramatically decreased in numbers by down to 10% or less of the original number. Therefore, during the late 1990s the GONHS’s Mammal section, under the auspices of Mr. A. Santana, embarked on a project to seal off the entrance to the cave to visitors by installing a new gate. Some of the bats moved up to a tunnel at the top of Mediterranean steps where G. Palao recorded some 200 individuals, but this colony, which only consists of Schreiber’s bats, now numbers a few dozen at most. This is augmented by wintering Schreiber’s moving down from Malaga province to hibernate in this tunnel. Evidence of this has been found from two ringed individuals, one of which came from a cave close to the town of Benabarra in Malaga province (J. Cortes, pers. comm.).
Several interesting plants and ferns grow in the shade and cool environment that the cave entrance has to offer, including the maidenhair fern Adiantum capillus-veneris. In the summer fruit flies aestivate in the caves on Mediterranean steps. The walls of the cave turn black with millions of individuals covering the entire surface close to the entrance, an incredible spectacle worth seeing. It is possible that this formed part of the food resource for the bats that lived within, and is probably also of immense benefit to the many spiders living around the entrance. Hibernating moths also use the caves in the area during the winter.
Perez, C.E. & Bensusan, K. (2005) The Upper Rock Nature Reserve, A Management and Action Plan. The Gibraltar Ornithological & Natural History Society. Gibraltar.