The Monarch Monitoring Project is a long-term study on monarch migration through Cape May, NJ. It is a part of the New Jersey Audubon Research Department, and closely affiliated with the Cape May Bird Observatory.

Friday, September 7, 2012

Monarchs and Unusual Coupling

Hello! There was a small group of Monarchs out flying today in the sunny weather but I don't believe a  large influx of new migrants has arrived yet. The distribution of wing wear seem fairly evenly distributed between older, more worn individuals and younger, fresher looking ones. However, females were finally out in larger numbers today, with approximately 1/3 of the local population being female, going by my tagging results. As we all know, if there are males and females around, then there's going to be mating.

Scene 1a: Clearly a male on top
Scene 1b: RNX022 on bottom, also clearly male
Scene 2: RNX022 pinned to ground by another male
Enter poor male RNX022. When I tagged RNX022 this morning, he wasn't doing so hot. Perhaps this was literally true, as I held him in the shade for a little bit before tagging him, but over all he was doing poorly, with tattered wings, sluggish flight, and difficulty holding on to the Joe Pye Weed. When I came back to the same yard in the afternoon, I found RNX022 clinging to a plant as another male Monarch seemingly tested Mr. RNX022 receptivity to mating. This was obviously an unsuccessful endeavor!

A little bit later, I found RNX022 pinned on the grass by another butterfly, which could be another male. Male monarchs will force females who are not receptive to their courtship displays into mating by sitting on them! Certainly this male seemed to be performing the "take-down" maneuver. So why was RNX022 being targeted by other males as a potential mate? What cues was RNX022 sending out or failing to send out that made others mistake him for a female?

For more information on mating, see the paper
"How Often Do Males and Females Mate, and What Affects the Timing of Mating?"

Edit 09/08/12: I've been reading "The Last Monarch Butterfly" by Phil Schappert, which says that larger male may attack smaller males and that male-male interactions are common. However, these interactions are not described in the book so I still don't know if this was simply one of those interactions or if it was truly a case of mistaken identity.

1 comment:

  1. There's a great paper by the late Miriam Rothschild, I think published in Antennae, about the take-down behavior. One can't keep male monarchs in the same greenhouse as tropical longwings; the monarchs will kill the longwings in attempts to mate with them.

    Carol Boggs