Episode 218 – Gouldian Finch: The Golden Mouth

“…and today we’re talking about a Gouldian bird with a golden mouth. But more on that later…”

Nature has all kinds of odd developments where several species are in close competition. When resources are limited, it takes some stand out skills to survive and grow. For a species of finch, the stand out performance starts when they are hatched. But you would want your parents to notice you too, if there were an imposter in your nest, eating all of your food. But a bright smile can get you pretty far in Life, Death, and Taxonomy. 

Description of the Gouldian Finch

  • Small, very colorful birds.
  • Standard finch shape with a short, sharp beak, rounded head, and puffed chest.
  • In the wild, males have white and red beaks, black heads, bright blue edges around the face, green backs, purple chests, and yellow bellies. However, there are some variants that have bright red faces.
  • Females have similar coloration but they’re not as vibrant.
  • Juveniles start out as a drab brown and green and gradually develop their colors as they reach sexual maturity.
  • In captivity, people have been able to breed certain color variations for the face and chest.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro! 

  1. Boston Terrier
  2. Barking owl
  3. Gray Fox
  4. Cockatoo


  • 125–140 mm (5.5 inches)
  • How many gouldian finches go into the thickness of Saturn’s rings?
  • Hint: The rings, in total, are about 175,000 miles (282,000 km) in diameter and 35,628.75 miles wide.
  • 69,818 finches. Their thickness is about 1 kilometer (32,000 feet).


  • 0.42 ounces
  • How many Gouldian Finches go into the lightest chair?
  • Hint: The chair was designed by Massimiliano Della Monaca in Italy, and it went through several durability tests and passed. This is a real chair an adult can sit in, not a dollhouse chair.
  • 51.8 finches. The chair is 0.617 kg (1.36 lbs).

Fast Facts about the Gouldian Finch

  • Range: Lives in sporadic regions in northern Australia
  • Diet: Mainly seeds. They have to eat over a third of their body weight in seeds every day. They eat grass seeds that they find on the ground.

Major Fact

The hatchlings of Gouldian finches have bright, shiny markings on the sides of their mouths that make them look strangely alien. 

The open mouth of the finch hatchlings are bespeckled with white, black, blue, and yellow dots. Bright blue and yellow dots are on the sides of their mouths. These are particularly bright and even highly reflective phosphorescent beads.

But why do they have these strange markings? We aren’t totally sure!

The prevailing theory is that they developed these markings to compete with brood parasites. Brood parasites are birds that lay eggs in the nests of other birds so that they become a drain on another bird’s resources. 

Many finches in the Estrildidae have similar mouth markings, so developing a unique pattern and reflective quality makes the imposter stand out. It may be an arms race where parasites are adapting to be more like the host species but the host species is getting weirder and more intense. 

However, another theory is that the Gouldian finches started with these markings before brood parasitism, and parasites had to adapt to look like them. Still, that leaves the question of why they developed phosphorescent markings to begin with. 

According to the second theory, the birds may have developed these markings to tell the development and health of the chicks. Young chicks have pale markings that grow brighter with age. 

A 2005 study found out what happened when the markings were painted over. The chicks that had their markings covered were fed less and grew smaller. Though it didn’t seem to affect their survivability. Maybe it would if resources were scarce.

Ending: So stay colorful, feed your young, and be sure to maintain the opalescent luster of your tubercles like the Gouldian finch here in LDT.