Trapdoor spiders have been suffering a decline across southern Australia as revealed by a recent survey. The findings, where scientists were able to compare numbers of trapdoors at various locations across Australia's southern agricultural and arid zones with survey data from the 1950s to the present, have been published in the journal Austral Entomology.
"We have good historical records of trapdoor spiders going back 60 years which showed population numbers were reasonably good, but recent surveys of the same areas show numbers are extremely low, and in some cases spiders are completely absent," shared Professor Andrew Austin from the University of Adelaide's Australian Centre for Evolution Biology and Biodiversity and the leader of the project.
Researchers from the University of Adelaide, in tandem with the Western Australian Museum, the Queensland Museum, the Department of Parks and Wildlife and The University of Western Australia, have found that trapdoor spiders are being threatened. Well-known for their camouflaged burrows, trapdoor spiders were prevalent in domestic gardens in towns and cities around Australia. Some females were recorded to have lived in the same burrow for over 25 years.
"The problem in some areas looks to be that the few spiders surviving are old females, and an absence of males means there is no capacity to reproduce, and they eventually die and the population disappears," explained Dr. Mark Harvey, a national expert on spiders based at the Western Australian Museum and a member of the research team. "The reasons for this decline are probably complex but are undoubtedly linked to a century of intensive land clearing and the fact that trapdoor spiders are susceptible to soil disturbance around their burrows."
Dr. Mike Rix from the University of Adelaide and the Queensland Museum, the lead author of the research, believes the results of the study are alarming on their own but could also be a sign of a decline in the population of invertebrate animals. "To get a better handle on the extent of the problem, there is a real need for more detailed follow up surveys, including to assess where remnant populations still exist," he concluded.