FLYING BUTTER?

Although wide spreading with woods and bushes, but is really hard to see much more insects around my place, I believe that should impute to birds. There are a lot of birds, on sky, on garden, on tree, on bush, you can see them anywhere and anytime. Once I saw three blackbirds preying on catch a poor moth on my way, and know how dangerous to most insects is birds.

But for Monarch butterfly, something seemed very different. It is really strange, you could often see they leisurely flew in sky without any scaring. One time, I saw a blackbird fly to a Monarch, but just 50 cm near, it suddenly turn away with an odd curve. So I speculate the Monarch butterfly is venomous to birds, that is a only reasonable explanation.

I checked my speculation via internet yesterday, the result is as following:

Monarchs have an effective chemical defense. When they eat milkweed, they sequester the poisonous cardenolides in the milkweed. Cardenolides are poisonous to vertebrates, and most Monarchs face little predation from frogs, lizards, mice, birds, and other species with backbones. (http://www.monarchwatch.org/biology/pred1.htm)

That is true, Monarch is poisonous to birds, and other vertebrates. How interesting that is, flying butter is not a morsel.