To the casual observer of nature, you may not notice some strange things going on in the natural world at this time of year. For example, the other day I was passing by a large pond and noticed a small flock of Hooded Mergansers. These are small duck-like diving birds. The males have a set of black and white feathers on their head that they can raise and lower, like a hood, hence their common name, to flash a bright white patch of feathers to the females during the mating season. What I observed was that the males were actively raising and lowering their hoods, trying to impress the females. Normally, this wouldn’t be notable, but this is happening in late November. Definitely NOT the breeding season.
As you can imagine, I like to attract different species of birds to my yard, so it should come as no surprise that I scatter some whole and cracked corn occasionally on the ground to feed my local flock of Eastern Wild Turkey. A small group of adult male turkeys, called a Tom, stops by every couple of days, and a slightly larger group of females also stops by. One day, I looked out my office window, and I could see one of the male turkeys in full display, with his tail fanned, his wings drooping to the ground. He was working very hard to impress the females. Of course, the females were not impressed and completely ignored him. Once again, normally this wouldn’t be very notable, but it’s the time of year that makes it stand out and unusual. Turkeys breed in spring, not fall.
I could add to this list of interesting nature oddities, but I think you got the idea. So, what’s up with this out-of-season behavior? This is a well-known biological condition that happens each autumn or early winter. Technically, it is called gonadal recrudescence. Yep, if you read that correctly, you might understand that it is a condition where the gonads in males wake up and start to produce testosterone and push the male back into breeding condition.
So, let’s back up a minute and take a look at what goes on during the “normal” breeding season. Each spring, the amount of daylight increases each day. The time from sunrise to sunset is called the photoperiod. Each day, the photo period grows longer and longer. It’s the duration of daylight that kicks off the breeding season in birds, reptiles, and more.
In the fall, the photo period is getting shorter each day, but at some point, the total amount of daylight in the fall will match the photo period that occurred in the spring breeding season. So, when this happens, the males perceive the daylight as the same as spring and are tricked. The reproductive organs are also tricked and start to recrudescence or become active.
When this happens, the male starts to move into breeding condition. For the amphibians like frogs, the male will start to call. For turkeys, the males start to display for the females. If you are a Hooded Merganser, you swim in front of females and display your bright white hood, and so on and so on.
But as the days become shorter and shorter, the recrudescence subsides, and the male moves away from the false breeding conditions. All of the males’ displaying and calling fades away. He won’t return to these conditions until the length of daylight increases again in spring.
To the keen nature observer, these kinds of unusual behaviors are interesting and notable. I, for one, love to see these kinds of behaviors because it helps me to more fully understand what is happening in the natural world. Until next time…
Stan Tekiela is an author, naturalist, and wildlife photographer who travels extensively to study and photograph wildlife. He can be followed on Instagram and Facebook. He can be contacted via his website at naturesmart.com.
