Far away in the middle of the Atlantic Ocean there is a tiny island off the coast of Madeira; a barren stretch of land only 10 km2 in size known as Desertas Grande. There are no permanent inhabitants, there is no drinkable fresh water. This is a remote and alien place, what little vegetation there is grows barely a meter in height and all of the large animals are restricted to the coasts which also offer sanctuary to oceanic birds and Mediterranean monk seals. Inland the ecosystem consists of small native lizards and several species of invertebrate; at the top of this food chain sits a magnificent spider - Hogna ingens, the Desertas Grande wolf spider. This is one of the largest wolf spiders in the world.
Although arguably one of the most famous residents of the Desertas Islands, not much is known about these spiders. Their life-cycle, breeding, hunting habits and even their taxonomy all remain largely a mystery. What is known however is that they are in grave danger of extinction.
Despite the islands remoteness, man has made some damaging changes to the environment. A native plant called Phalaris aquatica has taken over the majority of the spider’s valley thanks to its competition being reduced by goats and previously by rabbits. It is a type of tough, drought resistant grass and it is making the spiders die out. Why is this the case? The plant covers everything, filling the gaps under and between rocks thus preventing the spiders from building nests. According to the IUCN:
"This plant covers the entire surface of the soil and crevices, preventing the accessibility to shelters that are usually occupied by the spider as well as other endemic fauna."
This has had a dramatic affect on the spiders. When they were last surveyed in 2012 it was found that their area of occupancy had decreased by 81% since 2005,less than a decade earlier.
The species was granted Critically Endangered status by the IUCN in 2014 and a group of stalwart conservationists set out to save the species from extinction, meeting in Madeira in May 2016 to create a strategy for saving the spiders from extinction. As part of this, a team from the Bristol Zoological Society led by Mark Bushell has started an ex-situ conservation programme to save the spiders. The plan is simple; set up a captive breeding population of the spiders in a number of zoos in Europe, and also engage in field-work to try and restore the habitat on Desertas alongside colleagues from Madeira. Carefully managed captive breeding and release programmes can be very successful with invertebrates as long as they are done well. As we know, Helen Smith managed the fen raft spider conservation programme from her kitchen in Norfolk and now fen raft spider numbers are increasing in their few remaining habitats. A quote from Helen's website www.dolomedes.org.uk:
"Summer 2014 saw record breeding numbers in all three of the fen raft spider populations established in the Norfolk and Suffolk Broads since 2010."
My first film
the Desertas wolf spider programme structure has its roots in the initial work carried out by Helen and it has already started. As of writing this a number of Desertas wolf spiders are already living in Bristol Zoo (do go and see them if you can!) where they will hopefully serve to start up a successful captive programme.
Where do I fit in? I am a wildlife documentary filmmaker with a good track record of filming endangered spiders. I worked with Helen Smith several years ago to make my first film about fen raft spiders and now I'm turning my attention to these lovely creatures, as well as the people working to save them. Through this film we hope to learn as much as we can about their behavior, providing insights to scientists and conservationists alike and producing a beautiful film in the process. If you are interested, please have a look at my previous films by visiting www.youtube.com/teamcandiru! And follow us on facebook and twitter for more updates.