A Portuguese spider rarer than the panda…

The Portuguese archipelago of Madeira comprises several islands in the Atlantic Ocean off the coast of Morocco. One of them, Deserta Grande, with an area of 10 km², is home to one of the most endangered spiders on the planet: the Deserta Grande wolf spider (Hogna ingens). This magnificent spider is considered to be the largest lycosis in the world, as its bodies reaches up to 40 mm. This endemic species originally occupied a 83 hectare valley (Vale da Castanheira) in the north of the island. In 2012, a health assessment of this population of lycosis showed that it occupied only about 23 hectares and that the adult population had fallen to an estimated 4,000 to 4,500 specimens. This is a dramatically low number which has led the International Union for Conservation of Nature (IUCN) to consider this species as critically endangered. The range of Hogna ingens is currently covered to a large extent by invasive alien plants: canary grass (Phalaris spp.). The colonisation of these grasses in the Vale da Castanheira had been obscured for some years due to the presence of rabbits that grazed and controlled the spread of the plants. With the eradication of rabbits from the valley in 1996, the canary grass lost their main predator and are now proliferating. They are displacing various native plants, but also many native animals, covering the soil and rock surfaces and making the microhabitats underneath the rocks more difficult for spiders to access. Lizards, birds and rodents are actually the main predators of the wolf spider, mainly during its juvenile stage. This is when the spider is most vulnerable to predators because, apart from its small size, it tends to disperse to find new places to shelter, thus maximising the probability of encounters with potential predators. As the spiders grow and find suitable shelter, mainly underneath rocks but also in crevices in the ground, their tendency to disperse is gradually decreasing. Conscious that the species would be likely to soon go extinct if nothing was done, the European Association of Zoos and Aquariums (E.A.Z.A.) launched an international conservation programme (Eaza-Ex-situ Program) in 2016 coordinated by Bristol Zoo. This programme aims to combine actions in the field (in situ conservation) and actions in captivity outside the species’ range (ex situ conservation). For example, the programme aims to ensure long-term monitoring of populations by assisting field rangers to restore the habitat in the valley by working with rangers and to coordinate a captive breeding programme to advance knowledge of the life cycle and create a reintroduction population. European zoos are demonstrating by example that arthropod conservation is a realistic and effective tool for safeguarding wild species and are sharing best practice by encouraging other zoos to undertake similar projects, while raising public awareness of the importance and uniqueness of the spider. The Natural History Museum and Vivarium in Tournai is participating in this Eaza-Ex-situ Program. The specimens that are presented in the exhibition have been entrusted to us by Cologne Zoo.