Agressive Behaviour

[pianopete]

At first I hesitated to mention this... but here goes. This summer I have witnessed several incidences of agressive behaviour in the monarchs. (1) A monarch had a grip atop a dusky wing as they both struggled on the ground. The dusky wing kept trying to get free, but the monarch maintained a grip for 10 minutes or so. (2) On two occasions I've witnessed a monarch carrying another butterfly in-flight like a hawk carries a rabbit. (3) I maintain a platform bird feeder so I have many birds in the yard. On a couple of occasions I've witnessed a monarch dive and whack a bird (dove) on the head causing the bird to fly away. (4) This morning as I was walking thru our butterfly garden I saw what I thought were two monarchs mating. However, upon closer inspection I noticed that it was two large males and that were going at it like two cocks at a cock fight. First on a flowering plant, then continuing on the ground once they fell off the flower. Don't know what they accomplished. Anyone seen anything similar? I've only noticed this behaviour with the monarchs. We raise and release many monarchs in our area.

[psi_chemie]

Wow that's cool. I can't imagine why a monarch would interact with a dusky wing like that. How big was the dusky wing?

Once I saw two monarchs swoop down on another monarch in mid-air, and all three hit the ground. When I found them, it was two males and a female. One of the males had attached to the female, and was trying to fly away with her. The second male had a grip on the female too and was trying to displace the other male. Then the first one took off, carrying both! I was shocked, but now I know one monarch can lift two other monarchs.. just barely, in short hops.

Eventally the second male gave up and fell off, but continued to dive bomb as the freed pair made for a tree top.

As for interaction across species, I've seen monarchs in fields go after birds like they would if they were going after another monarch to check out. The birds usually ignore, as far as I can tell.

I've also seen a painted lady trying to mate with a (male) monarch, following it from flower to flower for like 10 minutes and being completely ignored. I actually have video of this. Hmmm.. maybe I should get some human friends :)

[pianopete]

Seems we have both witnessed similar behaviour.

The Dusky Wing was about 1 to 1.5 inch wing tip to wing tip.

The butterflies that I saw the monarchs carrying in mid-flight were not other monarchs. I could not identify, but one appeared to be yellow (giant sulphur?) and the other appeared to be more of a tan color.

I always keep my camera ready, but I've never had it in-hand when I witnessed these events.... so far.

You can see some of my photos at:

http://pianopete.blogspot.com/

[Sarah]

Most of the behavior you've described is the result of the way monarchs mate. Two males wrestling on the ground isn't really all that uncommon. While it may seem like they are fighting, they are both trying to mate. Unfortunately, they just don't realize that it isn't going to work! Most of the butterflies in the same scientific family as monarchs (milkweed butterflies) use pheremones to attract mates. However, monarchs do not use these pheremones. Instead, the male will fly at the female and knock her to the ground. Once he has her on the ground, he will attempt to couple with her. The males are successful most of the time, but ocassionally she will escape. If a male knocks down another male or another type of butterfly, he will try to couple for several minutes and will then give up and fly off to look for a female. We aren't quite sure why mating monarchs seem to attract some males, but we've seen quite a few males trying to disrupt mating pairs.