Tag Archives: behavior

Cockatoo Can Play At That Game

Australia is once again at war with the birds – but instead of trying to fight off emus in the outback, this time it’s a bit closer to home(s). The cockatoos of Sydney have taken the saying ‘one man’s trash is another man’s treasure’ to heart, and have taken to ‘dumpster diving’ in search of food. Although the challenge of keeping urban wildlife out of rubbish bins is not a uniquely ‘Australia problem’, finding a solution to thwart the brainy cockatoos is proving difficult. For every deterrent that humans come up with, the cockatoos seem to find a work-around – similar to the evolutionary arms race that we might expect between a predator and prey.

Read more: Is bin-opening in cockatoos leading to an innovation arms race with humans?

What makes this really cool is that it is essentially an ‘evolution in action’ scenario happening right in the backyards of Sydney residents! There are different strategies being deployed by both the humans (to deter the the cockatoos) and the cockatoos (to open the rubbish bins). These strategies have costs for both parties as well (how long it takes to secure the rubbish bin vs how long it takes to open) and we expect these strategies to experience different selection pressures that might lead to the selection of an optimal rubbish bin securing strategy (that is until the cockatoos work out how to thwart the humans once again).

I for one am rooting for the birds – if at minimum so that they can claim having defeated humans not once but twice!

Tanya Strydom is a PhD candidate at the Université de Montréal, mostly focusing on how we can use machine learning and artificial intelligence in ecology. Current research interests include (but are not limited to) predicting ecological networks, the role species traits and scale in ecological networks, general computer (and maths) geekiness, and a (seemingly) ever growing list of side projects. Tweets (sometimes related to actual science) can be found @TanyaS_08.

Form Versus Function

Image Credit: Graham Wise, CC BY 2.0, Image Cropped

Sexual differences in weaponry and defensive behavior in a neotropical harvestman (2018) Segovia et al., Current Zoology, https://doi.org/10.1093/cz/zoy073

QUICK NOTE: Harvestmen (aka Daddy Long Legs in North America) are NOT spiders! Despite the false myth that they can’t bite you due to short fangs, harvestmen aren’t even venomous. They can’t hurt you! There, now that I got that off my chest…

The Crux

Sexual dimorphism is a common phenomenon in nature whereby male and female members of a given species differ from one another physically. Think of the large bull moose or elk with its antlers, peacocks and their colorful tails, or the larger horns of male stag beetles. Because of these differences, natural selection is able to act on both their behavioral and functional differences. That is to say, differences in performance and morphology mean that males and females of the same species may experience differential selection pressures. As a result, males and females could be expected to react differently to the same challenge, such as a predator.

Harvestmen (known in North America as Daddy-Long-Legs) are a group of arachnids that, although bearing a resemblance to and being commonly mistaken for spiders, are not actually spiders. They belong to a group called Opiliones. Some males of this group have thicker legs with pronounced spines, used in male-to-male competition and anti-predator defenses. In addition to using these spines against predators, these arachnids also engage in thanatosis (“playing dead”, see Did You Know?) and use chemical defenses. Due to these morphological differences, the authors hypothesized that males and females would differ in their response to predators.

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