Gibraltar Bats and Caves: The Colonies Inside the Rock Are Almost All Gone

16 September 2026 Last checked 2026-09-16

Martin's Cave held about 6,000 bats in the 1960s. A 2002 survey found none. What happened to Gibraltar's cave bats, and where you can still see one.

Martin's Cave sits more than 700 feet up the eastern cliffs of the Rock, behind a padlocked gate. In the 1960s it held roughly 5,000 Schreibers' bats and 1,000 greater mouse eared bats. A survey in 2002 found no bats in it at all.

That single cave is the whole story of bats in Gibraltar in miniature. The popular version of this subject imagines thriving colonies hidden inside 55 km of military tunnels, waiting to be discovered. The real position, according to the Gibraltar National Museum's own Gib-Bats project, is that more than 98% of Gibraltar's bats have disappeared since the 1960s. Five species are locally extinct. There is no secret colony. There is a small, closely watched remnant, and a project trying to work out what is left.

The census nobody has been able to repeat

The first bat counts in Gibraltar date from the 1960s and 1970s and came to more than 36,000 animals, overwhelmingly two cave dwelling species: Schreibers' bat and the greater mouse eared bat. The museum is honest that those counts were not scientific and were made by people who were not specialists. They are still the only baseline anyone has.

Set that 36,000 against the present. The species lost locally since then are the greater mouse eared bat, the brown long eared bat, the barbastelle, and two horseshoe bats, the lesser and the Mediterranean. Those are not species that became scarce. They stopped being recorded here.

A 98% loss is not a decline. It is a collapse that happened while almost nobody was counting.

What is actually inside the tunnels

Gibraltar looks purpose built for bats. There are thought to be more than 200 caves in a territory of 6.7 square kilometres, and about 34 miles, or 55 km, of tunnels driven through the limestone between 1782 and 1968. The Second World War phase alone took the network from about 11 km to 40 km. That is nearly twice the length of Gibraltar's entire road network, all of it dark, and much of it at a steady temperature year round.

The habitat is there. The bats are not. The museum's summary is that protected roosts abandoned decades ago are now showing early signs of reuse by species that had gone, but in low numbers. Those roosts are monitored rather than promoted, which is the correct decision and also the reason you will not find a tunnel on any tour that is sold as a bat cave.

Eight species on the list, and seven that are named in public

Gib-Bats started in 2013, when a team of UK bat specialists led by James Shipman approached the Gibraltar National Museum, the Department of the Environment and the Gibraltar Ornithological and Natural History Society. GONHS has held the brief for bats through its Mammal Section since it was founded in 1976. By 2016 the project had taken Gibraltar's official species list from three to eight and trained three local workers to full bat licences.

The eighth species is where honesty beats guessing. The museum states the list stands at eight, but its public summary names seven. We could not find the eighth named in any source we could verify, so we are not going to invent it. If you need the complete current list, the Gibraltar National Museum and GONHS are the two bodies that hold it.

One point of detail that gets mangled elsewhere. The horseshoe bats recorded as locally extinct are the lesser horseshoe and the Mediterranean horseshoe. The bat found in August 2016 was a greater horseshoe, a different species, and a first for Gibraltar. Dr Geraldine Finlayson found it deep inside the Rock, and it was identified by Stewart Finlayson and Giovanni Santini with Dr Rhian Guillem of GONHS and trainee Kelsey Rowbottom. It was a juvenile female, born that year, almost certainly dispersing in search of feeding grounds. One young animal, not a colony.

The one bat you can hear without a detector

Most bat watching needs a detector, because pipistrelles call somewhere around 45 to 55 kHz and you will never hear them. The European free-tailed bat is the exception, and it is the single most useful fact on this page.

It hunts in open air above rooftops and its calls peak somewhere between 12 and 17 kHz, typically near 13 kHz, and as low as 11.4 kHz in one Swiss study. Sources vary on the exact figure, which is worth knowing before you argue with anyone about it. What they agree on is that this is one of very few bats in Europe whose echolocation is audible to the naked ear, at up to about 100 metres. Stand outside after dark in a quiet street, stop talking, and listen for a hard, regular tick overhead, roughly once a second. Hearing at those frequencies drops off with age, so a child will often catch it before an adult does.

It is also the species most likely to be using the Rock itself. The European free-tailed bat roosts in narrow crevices in high, inaccessible cliffs, and in cracks in the faces of tall buildings and bridges. The Rock tops out at 426 metres and its eastern side is close to vertical for much of that drop. Colonies are small, usually 5 to 50 animals, occasionally up to 400. Nobody is going to show you one, and that is the point: this bat does not need a cave that can be gated, which may be part of why it is still here.

The other headline species is the greater noctule, recorded here as a seasonal visitor. It is the largest bat in Europe, with a wingspan of 41 to 46 cm and a weight usually given as 35 to 60 g, and it is one of the very few bats anywhere that catches small migrating birds in flight. Gibraltar sits on one of the busiest bird migration corridors in Europe, which is a tempting connection to draw. We have not seen that behaviour documented over Gibraltar itself, so treat it as context, not as something to go and watch.

What emptied the caves

Three things, in rough order of local importance. Disturbance came first: people going into roosts, and, in the case of Martin's Cave, fireworks cited as a factor in the loss of its colony. A cave bat roused repeatedly in winter burns through fat reserves it cannot replace. Then roost loss, as caves were gated, blasted, wired up or simply visited. Then the wider European pressures the agreement on bat conservation lists for this species group: habitat loss, pesticides and loss of roosts.

There is a fourth possibility and it needs careful handling. In 2002 there were mass die offs of Schreibers' bats in caves across northern Spain, southern France and Portugal. Archived tissue from those deaths was re-examined in 2011 and found to carry the RNA of a previously unknown filovirus, later named Lloviu virus after the Asturian cave where the samples came from. Infectious virus was first isolated from live Schreibers' bats in Hungary in 2022. Two things are worth saying plainly. The virus is associated with those die offs rather than proven to have caused them, and there are no confirmed human cases.

The tempting move is to link the 2002 Iberian die offs to the 2002 Gibraltar survey that found Martin's Cave empty. We are not making that link, because we could not find a published source that does. Gibraltar's colony may already have been gone for years by then. Nobody was counting often enough to know, and that gap is the real lesson.

Where you can go, and where you cannot

Martin's Cave is gated and off limits. Gibraltar protects species and habitats under the Nature Protection Act 1991, and the government puts the protected share of Gibraltar's land area at up to 31%. Entering a gated roost is not an adventure. It is the specific act that emptied these caves in the first place.

What is open is the Gibraltar Nature Reserve, which covers 17 attractions including St Michael's Cave, the Great Siege Tunnels and the WWII Tunnels. Adult entry is 30 GBP and a child ticket for ages 5 to 11 is 22 GBP, with under fives free. Opening hours are 09:30 to 19:00 from May to September and 09:00 to 18:00 from October to April. The cable car is out of service until 2027, so plan on a taxi tour or the walk up, which we cover in our guide to the cable car closure.

Lower St Michael's Cave is the one deep cave visitors can get into, by arrangement, with three days of notice, a small group and no children under ten. Third party listings quote 25 GBP for the three hour trip, but it is not priced on the Nature Reserve's own ticket page, so confirm the figure when you book rather than turning up with cash. If underground Gibraltar is the draw, the sealed chamber behind Operation Tracer is the better story anyway.

The timing problem nobody mentions

Here is the practical catch, and it is the reason most visitors never see a bat here. The Nature Reserve closes at 19:00 from May to September. In mid July the sun does not set over Gibraltar until about 21:40 local time, and in mid September it is still up until about 20:30. Bats emerge at dusk. So through the entire season when bats are most active, the Upper Rock has been shut for anywhere from an hour and a half to nearly three hours before anything comes out.

Which means the bat watching in Gibraltar is not on the Rock. It is in town, after the reserve has closed, around street lights and gardens and anywhere insects gather. That is an advantage of staying in Gibraltar rather than driving back into Spain at six o'clock: you are still here at the only hour that matters. It is the same argument as for watching the raptor migration, which also rewards people who are on the ground early and late.

What actually helps

Do not enter gated caves. Do not use flash photography underground. If you find a grounded or injured bat, do not handle it with bare hands and contact GONHS or the Department of the Environment. In December 2018 the University of Gibraltar's Europa Point campus hosted the seventh SECEMU conference, bringing about 110 bat researchers from more than ten countries to the Rock for 16 talks and 22 posters. Gibraltar is taken seriously by the people who study this. The visiting public is the variable.

The honest summary is that Gibraltar's bat story is a loss, not an attraction, and it is more interesting for it. A territory with more than 200 caves and 55 km of tunnels lost 98% of its bats inside two generations, and the counting that would have shown exactly when and why was never done. The remnant is still here. So is the chance to hear a free-tailed bat ticking over a Gibraltar street at ten at night.

Victory Suites runs 100+ serviced apartments in Gibraltar, in town rather than up on the Rock, which puts you a short walk from the streets where the bats actually hunt once the Nature Reserve has shut for the evening. Rates are quoted in GBP and we list across 300+ booking channels, so book direct if you want the simplest answer on a late arrival.