Sena pointed out a swallowtail butterfly fluttering around the lantana in our backyard garden yesterday. The lantana is great for attracting butterflies and hummingbirds because it has bright flowers and sweet nectar.
At first, I didn’t think it was unusual but I got video anyway. When I looked at it, I eventually noticed that the butterfly (which admittedly might be a different species) was lacking either one or both of the tips on its hindwings. For comparison, I checked a video clip of a swallowtail Sena shot when we were out on the Terry Trueblood walking trail a couple of weeks ago. The videos are obviously not the same quality. I shot the one yesterday through a window.
Sure enough, that swallowtail on the Terry Trueblood trail had impressive hindwing tips. I wondered what was so different about the tips on the one we saw yesterday. Not all swallowtails have tips and maybe the tips are smaller or only faintly visible on some species.
It turns out that the wing tips are probably a piece of butterfly anatomy that can be easily sacrificed when bird predators try to eat the butterflies. This is similar to some lizards whose tails can be sacrificed to predators for the same reason. Maybe the wing tips distract birds from attacking the central body parts. Anyway, I found an article about it on the web.
The article cites a study published in the May 2022 issue of the Proceedings of the Royal Society B that seemed to back up the idea that the tips might be an escape tactic. In the article, you can even see a video of bird preferentially targeting the sacrificial tips.
In our video, you can just barely make out either a transparent vestige of one of the tips or maybe there are two barely visible tips on the swallowtail in our garden. I saw a Facebook entry photo showing that females tend to be larger and have more prominent bluish coloring and males tend to be smaller and have more yellowish markings (interestingly, the male in that photo seems to be missing the right hindwing tip). Maybe we’re seeing a female in the video from 2 weeks ago and a male in yesterday’s video, only the male in that picture seems to have obvious hindwing tips, though they are smaller. I don’t know if anyone could help us sort this out.
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