Joro spider: Study documents spider web so sturdy even birds can perch on them


The first documented observation of a bird perching on a spider web has been made by an amateur scientist in the US, revealing the extent of the sturdiness of an arachnid’s weave.

The study, published recently in the journal Insects, describes an observation of a northern cardinal that foraged for food from a jorō spider’s web while perching on it.

Previous research using a force gauge in lab settings has shown that typical webs can support masses up to 70 grams before collapsing.

However, the new study is the first one in the wild to confirm that the spider’s web can support a perching bird that weighs about 42-48g, according to amateur scientist Arty Schronce.

“This appears to be the first documented case of a spider web supporting a perching bird,” researchers wrote in the study.

Jorō spiders are an orb-weaving species native to Japan and eastern Asia, but have been recently documented as an invasive species in southeast US.

These big spiders can grow to 3in (7.6cm) in size and can be identified by their colorful blue and yellow markings on their bulbous bodies, with red markings on their undersides.

Since their first discovery in 2013 in a few locations in northern Georgia, studies have found that the spider is rapidly expanding its range across the US.

Research has also shown that these spiders weave thick, golden webs and sometimes use their silk as a kind of parachute to float through the air to new locations.

“They are expected to continue spreading beyond the southeast, since their physiology appears suited for surviving the colder climates of the north of the US,” researchers write in the study.

In the latest study, Mr Schronce observed a web built by a jorō spider next to the side of his house facing the neighboring house.

The spider had used stalks of wintersweet as support on one side, and the neighboring house on the other.

Scientists documented a female cardinal (Cardinalis cardinalis) perched on the top support strands of the web.

The study noted that the cardinal lunged toward the spider while perched, though the arachnid moved away from the bird.

Researchers said the cardinal proceeded to glean from the web, pecking at discarded insect carcasses while still perched on the top strands – a behavior that lasted for about two minutes.

“The fact that a full-sized northern cardinal could perch on this spider’s web without it breaking appears to be a scientific first,” scientists wrote.

They said the findings, “to our knowledge”, represent the first documented case of a spider web supporting a perching bird, underscoring the studiness of the webs of this particular species.



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