Screamers: Reproduction

Summary: How do Screamers make more Screamers? Join Kiersten to find out about Screamer reproduction. 

 

For my hearing impaired followers, a complete transcript of this podcast follows the show notes on Podbean

 

Show Notes: 

Screamers: https://animaldiversity.org

Ornithology 3rd Edition by Frank B. Gill

The Most Perfect Thing: Inside (and Outside) a Bird’s Egg by Tim Birkhead

Music written and performed by Katherine Camp

 

Transcript

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Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating. 

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

Welcome to the third episode of Screamers. The third thing I like about Screamers is how they make new Screamers. Let’s talk about reproduction.

Since this is the first bird we’ve discussed, I’m going to start off with a very basic introduction to bird egg anatomy and overall bird reproduction. Then we’ll look at individual Screamers. 

Basic egg anatomy explains how chicks can actually survive inside what looks like a solid capsule. I know I used to wonder how baby birds could live and grow inside a hard shelled egg. What I’m going to walk you through next is a basic egg anatomy lesson. To learn more in depth, I recommend Tim Birkhead’s book The Most Perfect Thing. He describes the avian egg masterfully and it is an enjoyable read. 

The avian egg consists of three main layers, the hard outer shell, the albumen (egg whites), and the yolk (the yellow center). In a fertilized egg, not the ones we eat for breakfast, the embryo will start off in a pocket in the yolk. As the embryo grows the yolk decreases. There are other layers, capillaries, and veins throughout the the egg connecting the chick to food (the yolk), removing its waste, and exchanging gases such as oxygen and carbon dioxide. 

The albumen is the chick’s water supply and consists of water and proteins. It also acts as a shock absorber protecting the embryo from movement aa well as protecting it from drastic temperature changes. Sounds cozy! Sounds like nature at its most amazing. 

The outer shell protects the chick from getting squished when mom and dad incubate, it is permeable to allow exchange of gases. There are teeny-tiny holes that allow oxygen in and carbon dioxide out. That is the key to a chicks survival, a sturdy out protective shell that is flexible enough to let thing in and out. Seriously, bird eggs really are the most perfect thing nature has ever created.

Where do bird eggs come from? Well, from inside the female. It begins in the ovary where a ovum waits to be released into the oviduct. As it travels through this structure, it gathers all the layers it needs around the ovum or fertilized embryo to result in a successfully laid egg. There are ‘pitstops’ along the journey through the oviduct where the egg gathers each layer, approximately three until the eggs arrives at the cloaca ready to be laid. This process can take as little as 24 hours or up to a week. Birds lay only one egg at a time. They can lay one to several eggs in a clutch and this depends on the species of bird and the resources available to them during breeding season. 

Now that we have a very rudimentary understanding of egg production let’s take a trip out to the field and find out how Screamers reproduce.

Horned Screamers, Anhima cornuta, pair for life or at least for several years. The male gets the female’s attention with a variety of courtship behaviors. Now, males will fight each other for the right to court a female and they use the spurs on their wings as weapons. Once the males has won the right to court the female, one courtship behavior consists of head-bobbing. Both partners will participate in this activity. One partner will approach the other and they will both stretch their necks out and bob their heads up and down one to three times. To confirm their pair bond, preening of each other’s head and neck feathers will commence and this behavior will continue throughout the year and throughout their relationship. 

Before copulation, the male walks around the female with his beak pressed down against his inflated crop. His neck is retracted and his dorsal feathers are standing up. After he circles her, he will bow his head 1 to 3 times in front of the female. If she accepts copulation will occur and take only about ten seconds. Seems like a lot of work for just te