I swear that there were more dock spiders at my cottage this summer (as compared to last summer). Is that true? Did we have more dock spiders this year?—Phoebe Will, via email
The short answer? Maybe. “In the absence of a bona fide regular population monitoring program—such as there are for birds or pest insects, for example—spider population fluctuations over time are difficult to determine,” says Robb Bennett, a spider biologist with the Royal BC Museum (and a fan of Cottage Life—he was wearing our dock spider sweatshirt when he addressed your question!). But it’s possible. “Various factors, weather especially, can cause major changes in population numbers. Here on the left coast, unseasonably cool, damp weather has apparently negatively affected population levels of many insects, spiders, and plants this year,” says Bennett.
If the weather in your neck of the woods has been warm and humid, and the temperature and relative humidity were “markedly different than last year” dock spider populations may also have changed, says Bennett. “There are also cascading effects, for example, if prey species are on the rise, then their predators may benefit.”
Brad Hubley, the entomology collection manager at the Royal Ontario Museum, agrees. A milder winter, followed by a warmer spring and summer, “could provide favourable conditions for the development of prey that dock spiders feed upon, such as flies and mayflies.” More spider prey, more spiders.
Of course, the experts can’t rule out that your perception may have played a role in this reported dock spider increase. It’s possible that you were simply paying more attention to the presence of dock spiders this year, says Hubley. “Once you saw one of them, you may have then been noticing more of them without even realizing it.”
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