2017

Male robins fighting over territory

Robins and Evolution for Kids

[This post was posted in March of 2017, before John & Colleen Marzluff and I created Crow Scientist, the free app that teaches kids how to observe real-life crow behavior.]

Now that spring has come to the northern latitudes, here in Seattle the robins are back in the parks. Robins are easy to observe so they provide a good opportunity to talk to kids about how behavior and natural selection play out. Here are science notes for kids, worded simply and arranged roughly from the most basic for the younger kids to the more advanced for older kids. These notes teach a core evolutionary concept, that individuals within a species compete with each other to have healthier and more numerous offspring.

Brighter Robins Are Male, Plainer Robins Are Female

The robins you see easily are males. They have bright red feathers on their chests, and they spend a lot of time out in the wide open. You can sometimes spot females, too, but they have duller breast feathers, and they don’t put themselves on display the way males do. Males also tend to be somewhat larger than females. Male robins are like roosters, and female robins are like hens. 

Male Robins Fight for Land

Robins need to gather food for their children, so each male fights to have a bigger plot of land. You often see two male robins out on a field or big yard, each keeping his distance from the other. When two robins face off and neither one backs down, they fly at each other and turn around each other in a sort of whirlwind. It’s easy to spot male robins facing off against each other because they stand out in the open. If they notice that you’re watching them, however, they might stop fighting, so be sneaky.  

Female Robins Choose Males with Good Land, Good Feathers, and Good Songs

When a female chooses a male with brighter feathers and a stronger song, that male is probably healthier than average. When she picks a male with a larger area of land, she probably gets more food for her chicks. If her mate is healthier and her chicks have more food, then her chicks are more likely to be strong and to survive. 

Most Chicks Die

A robin mother might hatch a dozen hatchlings in one summer, and most of them die before winter.   

Robins Fight Because They Can’t Cooperate

Robins don’t have language, laws, money, or other tools that humans use to divide up resources. That’s why robins are stuck fighting. Fighting takes lots of time and energy, and it’s dangerous, but it’s the only way a male robin can claim enough land to get a mate. Male robins don’t help each other, work together, or make friends with each other. 

Robins Don’t Know What They’re Doing

Male robins don’t know why they’re fighting. When they see another male’s red chest, they just feel like fighting. Female robins don’t know why they choose males with lots of land, bright feathers, or strong voices. They just feel like making that choice. Humans are driven by feelings, too, but we can reflect on our own behavior and even make explicit agreements with others about what we will do or won’t.  

This lesson is a big one because it’s easy for humans to project human-like thinking onto animals, or even machines.  

Testosterone Drives Male Competition

Hormones are chemicals that animals’ bodies make that affect how they grow, feel, or act. Testosterone is a hormone that affects how robin chicks develop in the egg. One effect of testosterone is to organize the male chick’s brain for fighting. When the chick grows into an adult and the breeding season starts, the male chick’s body creates more testosterone, driving it to fight the other males. Testosterone is a type of hormone called a steroid.

“Testosterone for Amateurs”, the basics about this much-talked-about hormone.

Cock robins at peace, a 10-second video of newly returned male robins hanging out peacefully. 

Bonus Science Humor

Robins are a type of thrush, and the genus name for thrushes is Turdus (Latin for thrush).

Crows in the Park
Once you learn the call of a hungry juvenile crow, it’s easy to spot crows families. With any luck, you'll see the the juvenile beating its wings and the parents feeding it.