In the human world, females often dress down to avoid sexual harassment. In the hummingbird world, females may actually be dressing up to keep the boys away. It’s a story that just might ruffle a few feathers — if the males figured it out. Male birds are usually the more colourful of the species, dazzling the not-so-flashy females with their vibrant plumage. But in the case of hummingbirds, females sometimes imitate the look of their suitors in a natural display of cross-dressing. It’s called plumage transvestism (the technical term is female-limited polymorphism), and a recent paper in Current Biology suggests the females are disguising themselves to avoid being harassed while feeding. The strategy: confuse the amorous males long enough to finish a leisurely liquid lunch — sugar water in this case — before they figure it out! Hummingbirds have one of the highest metabolic demands per gram of body weight of any animal on Earth, so it makes sense that anything that detracts from feeding is a bad thing. What’s not clear yet is why some of the females keep the disguise, while others go on to abandon it and take on the drab plumage that drives the men wild. 

Tracking “transgenes” 

Scientists from McGill University have discovered a novel method of tracking genetically modified animals that’s seemingly straight out of sci-fi. As a genetically modified animal makes its way through an environment, it leaves behind artificial transgenes in soil and water, or in the form of saliva, urine and feces. In a new study, published in the journal PLOS ONE, the researchers show that the DNA left behind in the soil can be sequenced and traced back to the genetically engineered animal that left it behind. The scientists claim that tracking via environmental DNA, or eDNA, is both more accurate and more efficient than traditional tracking methods, saving money and time. 

Thanks to technological advances in genome-editing, such as CRISPR, creating genetically modified animals is far simpler than ever before. However, this comes with ecological, evolutionary, and bioethical concerns. If genetically engineered animals escape from labs or farms, they could move into places they do not belong, crossbreed with natural animals and negatively impact the ecosystem. This new tracking technique can be used to detect the transgenes of a variety of genetically modified animals. One example is tracking genetically modified mosquitoes from pools of standing water in areas where they were recently released — as well as other animals such as fruit flies, mice, and tetra fish.

Incredible shrinking prey