The first rule of fight club is…well…I have an issue with following rules sometimes, so I’m going to go ahead and talk about it. Maybe I’m just a gossip. Anyway, I was running around Freedom Park the other day and came to a dead stop on the East Blvd. bridge across Little Sugar Creek because of a big commotion in the water. I looked down into the creek to see a group of male Mallards fighting it out. Well, not all of them, actually. There were four males and only two were fighting at any given time. The others were just sort of watching. It was either a big battle or they were doing a pro-wrestling tag-team match. Off to the side (and not particularly interested) was a lone female Mallard.
For those of you that regularly watch birds, I’ll wager that a post about Mallards is already losing your interest. Hold on, though! It gets more interesting (and a bit wacky, too!). I watched these birds go at it for about 5 or so minutes and one male seemed to be doing most of the fighting. He would chase, bite, mount and submerge one male at a time. When that submerged male moved away, he’d switch to another one. There was never a free-for-all and one male was always involved in the interactions. One male, actually, mostly retreated from the fights. He got bit a couple times, but swam away before things escalated. The other two got bitten and submerged multiple times. Over and over, one male was clearly the victor in these altercations.
As the fights wore on, the female actually climbed out of the stream and moved into the tall grasses on the side of the creek. One of the males (the one who wouldn’t fight) also climbed out and moved towards her, but stopped about 5 feet away from the grass where she sat. Eventually, the other two challenging males drifted far enough away that the main male stopped attacking. What happened next, I don’t know. It’s not that it happened so quickly or anything. It’s that I went back to my run.
Now I know that ducks are very aggressive when they mate. In fact, the term “forced copulation” really began to get used regularly in reference to the kind of mating that people see in ducks all the time.
The situation that I observed was different, though. It was not a copulatory event. It looked much more like fighting for access to a mate in the first place. Ducks, though, don’t build their pair bonds in the spring. They get together in the previous fall and winter so that when spring rolls around, they’re all ready to go. So what kind of interaction was it?
Well, it may still have been a competitive sort of interaction. Given that there was only one female in that stretch of stream with four different males, I’m guessing there was a group of single guys roaming around. The sex ratio of wild populations is not always one-to-one, which means that there are more males around than females, in which case, you end up with competition for mates. One more thing to add to the mix is the fact that forced copulations are more likely to place in the morning.
Now, before I go on about the ducks, let’s talk about hormones for a second. Actually, let’s talk about one hormone in particular: testosterone. Testosterone is a hormone associated with many things (most of which I won’t mention here!). In birds, testosterone has been associated with both mating behaviors and with aggressive behaviors. As a result, many of the people who have studied duck behaviors and forced copulation behaviors have looked for correlates with testosterone. Several studies have compared the testosterone levels of male Mallards that had been paired to a female to males who were unpaired. One study found a correlation between testosterone levels and the frequency of forced copulation, but showed that there was no difference in the likelihood of either unpaired or paired males attempting the copulation.
In a follow-up to that article, the same researcher (with the same birds, very likely) built off that idea and noted that paired males actually tended to have higher levels of testosterone than unpaired males during the breeding season. What if testosterone is not about aggression to compete for mates or to force copulation, but it is about protecting the female involved in the pair bond from the ravages of other males. The researcher from this paper also noted that females that were paired to males with high levels of testosterone had less feather damage than other females.
Maybe females like males who are good fighters! Oh! It’s like the avian version of Rocky (the original one, not the sequels). Adrian liked Rocky, but she didn’t like to watch him fight, either.