Improving Our Knowledge of Island Spiders
This week, we hear from retired wildlife biologist and President of Nature PEI, Rosemary Curley, on a project she worked on in 2015 to improve our knowledge of Island spiders.
From the Nature PEI website, “Shaking the Bushes for PEI Spiders” published July 29, 2015:
“Few share a fascination for spiders, but this summer in Prince Edward Island, the few that do are shaking the bushes in an effort to learn more about these creatures in the provincial context. It is known that 437 species of spider have been recorded in Nova Scotia and 382 species tallied in New Brunswick, but the Island list is a scant 38 species, with a few additional species located recently. Museums usually sponsor and house biological collections but the PEI Museum and Heritage Foundation has only rarely made such collections; outside institutions have not filled the gap and thus spiders (and many insect and other invertebrate wildlife species) exist here in a “black hole” of ignorance.
It is easy to explain the difference in species lists but harder to obtain a remedy. However, Nature PEI is recruiting “citizen scientists” with a passion for collecting and carefully recording data on each successful expedition. The aim is to assemble at least 1,000 specimens, have them sorted by student Caleb Harding at the University of Prince Edward Island, and then identified by a spider specialist. Unfortunately, spiders are not easily identified by amateurs, and photographs are generally insufficient to allow identification for most species.
“The landscape of species distributions is altering rapidly with climate change and it will be valuable to have a baseline of spider information against which future change can be measured” says Rosemary Curley, President of Nature PEI. “As well, we know the number and variety of alien species entering Canada is skyrocketing with global trade, and the effects of introduced spiders cannot begin to be assessed without a baseline of native species. Species of European origin were recently collected on the Island and all alien species are of concern as they may negatively affect native species”. Nature PEI has been fortunate to receive funding from the PEI Wildlife Conservation Fund to enable this work.”
And from Rosemary - February, 2016:
Almost 10% of our 171 known spider species are exotic spiders. Exotic spiders can outcompete native spiders, so that is a concern. These spiders can arrive with ships and transfer trucks, and in their cargo. Young spiderlings from further south may float in on suspended silken threads and survive in our warming climate. Imported ornamental plants are a major source of new arrivals, as are imported vegetable displays at the supermarket. Some, like the European House spider, like to live in our houses.
It appears that the rate of arrivals to Canada may be accelerating.
Currently there are only 74 exotic spiders known in Canada but provinces like NL and BC that have very recent spider studies are showing greater numbers of exotic spiders. British Columbia has 50 of the 74 due to much higher shipping traffic, but they also have had a much larger number of people (3) than in other provinces studying spiders since 2008 (Robb Bennett personal communication). Newfoundland and Labrador have studies in this century. On the island of NL there are 21 exotics in a list of 363 spiders (5.8%) (Pickavance and Dondale 2005). Meanwhile Labrador has 213 spiders but no known alien species (Perry et al. 2014). Currently, PEI has 16 exotics in a list of 171, almost 10%. In NS and NB, where there are no recent studies, only 10 and 19 are known out of lists of over 400 and 300 species, respectively.