Female birds that used to be silent are now singing like males

27 October 2017

By Andy Coghlan

For the first time, female dark-eyed juncos have been found to burst into song in the wild. Although many female tropical birds sing, singing females are rare among northern, temperate songbirds. However, the behaviour is now becoming more common, and climate change may mean it becomes even more widespread.

Dustin Reichard of Ohio Wesleyan University knew that female dark-eyed juncos (Junco hyemalis) sometimes sang in captivity, but only after being injected with testosterone. To find out if they sang in the wild, he and his colleagues goaded them by placing a live, caged female in their territories. The researchers also played recordings of a soft trill that females make when they are receptive to mating.

In all, 17 females, along with 25 males, interacted with the caged females. Half the females dived and lunged at them, and a minority also performed aggressive tail-spreads not normally seen in females. Three of the females sang songs similar to those of males.

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When it comes to evolution, testes may play a key role, studies find

Genomic differences in two bird subspecies shed new light on mechanics of testosterone-mediated evolution

Date: June 15, 2016

Source: Indiana University

A pair of studies led by Indiana University researchers provide new evidence that when it comes to evolution, the testes may play a key role.

The research, led by Kimberly Rosvall, assistant professor in the IU College of Arts and Sciences' Department of Biology, finds that the testes -- or gonads -- have a greater impact than previously thought in evolution. The research was conducted in two subspecies of dark-eyed junco, a type of American sparrow.

The white-winged junco, or Junco hyemalis aikeni, is found in the Black Hills of South Dakota. The slate-colored junco, or Junco hyemalis carolinensis, is from the Appalachian Mountains in Virginia. The first is larger and more aggressive; the other is smaller and more docile.

The studies are published in the journals of Hormones and Behavior and of Integrative and Comparative Biology.

The first paper compares the subspecies in their expression of enzymes that make testosterone within the gonad. The second paper investigates how the subspecies' gonads differ in the expression of stress hormone receptor genes, which are known to lower testosterone.

Continued … https://www.sciencedaily.com/releases/2016/06/160615111746.htm

Enormous array of bacteria discovered on common bird; could have agricultural implications

Date:

June 3, 2015

Source:

Wichita State University

Summary:

A microbiology professor and an ornithology professor have discovered that one of North America's most common migratory birds – the Dark-eyed Junco – carries on its feathers a remarkable diversity of plant bacteria, the greatest ever found on wild birds. And while many of these bacteria may be harmful to plants, the bacteria could also be of great benefit.

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