While most birds are loving parents that invest great efforts to raise their chicks, some use a more hands-off approach. Instead of finding a safe nesting spot, spending weeks building a nest, and raising their offspring, so-called brood parasites outsource parenting by laying their eggs in the nests of other birds. There, they are raised like the host bird’s own.
The cuckoo is the most famous example. But how does the cuckoo do this without being noticed? The answer lies in the cuckoo’s genes. Because bird’s eggs vary in pattern and colour, ornithologists can often identify bird species by looking at their nests – and birds can easily identify which eggs are their own. These colours are created with two kinds of pigment, both of which the cuckoo has evolved to produce. Therefore, cuckoos can emulate the look of the eggs of other birds. Currently, 3D printing technology is being used to create fake eggs of varying sizes, shapes, and colours in order to study what the most recognisable features are to bird parents – or if they will incubate eggs that look completely different.
Egg mimicry is not the only survival tactic that cuckoos have developed. They have learned not to put all their eggs in one basket. Ornithologists found that when brood conditions are rough, the birds will spread their eggs among several nests and even different species. Distributing the eggs means that if one host bird parent abandons its nest, only part of the cuckoo’s brood is lost. Evidence suggests that high stress hormone levels can lead to eggs being rejected. Behavioural ecologist Prof. Dr. Mark Hauber (University of Illinois) and his team are investigating this phenomenon.
Raising brood parasites puts a big strain on the host bird parents, and many cuckoo chicks reduce competition by pushing eggs and hatchlings out of the nest. And yet, some highly intelligent birds like crows happily accept cuckoos in their nests. This is because having a cuckoo chick among their own can actually be beneficial to them. The chicks secrete a smelly, acidic fluid that makes predators like cats and hawks avoid the nest entirely.
So could some brood parasites not be as parasitic as their name suggests? These and many other questions remain to be answered – with the help of modern technology, researchers and lots of birdwatching.
Did you know?
• Over 75 billion IoT (Internet of Things) connected devices will be in use by 2025, a three-fold increase over 2019.
• Malta has its own unique endemic honey bee that is darker, easy-going and resilient to the local climate.
• An Analytics Insight survey forecasts that data science will create 3,037,809 new job openings worldwide by the end of 2021.
• One of the 60 moons orbiting Saturn, called Enceladus, is entirely covered in ice.
• Children have more bones than adults, 94 more!
For more trivia see: www.um.edu.mt/think
Sound bites
• New research from University of Arkansas scientists suggests that tyrannosaur dinosaurs that ruled the world between 66-100 million years ago may not have been solitary predators but social carnivores with complex hunting strategies like wolves. The finding is based on a unique fossil bone site inside Utah’s Grand Staircase-Escalante National Monument, with large amount of tyrannosaur bones all found together.
www.sciencedaily.com/releases/2021/04/210420121419.htm
• University of Southern California researchers examined the shoulder assembly of Little Foot, a modern human ancestor (an Australopithecus) that lived more than three million years ago, and may have confirmed how our ancestors used their arms. These ancestral shoulders suggests a creature that could have swung from trees, an ability that was later lost.
www.sciencedaily.com/releases/2021/03/210315132143.htm
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