Nav: Home

Lack of opportunities promotes brood care

October 11, 2016

Male black coucals who care for their broods alone are just as successful as pairs of the closely related white-browed coucal, where partners share parental duties. Researchers from the Max Planck Institute for Ornithology in Seewiesen discovered that a single white-browed coucal parent would be sufficient to raise the brood; they believe that females share the job primarily because they are unlikely to find another mate. In white-browed coucals the sex-ratio is relatively balanced, whereas in black coucals there are more than twice as many males than females.

In most animals, females take a larger share in caring for their young than males - but there are exceptions: For example in about one percent of all bird species females compete for access to males, and the males rear the young without help from the female. Exceptions like these help biologists study the evolutionary processes that have shaped sex roles in nature.

One of these exceptions is the black coucal, a species in which a female mates with up to five different males during each season. Once the eggs have been laid, each of her mates takes care of his brood alone, while the female continues to defend her large territory and lays eggs for the next male in line. A closely related species, the white-browed coucal, displays a radically different behaviour. Even though both species occur in the same habitat and occupy a similar ecological niche, white-browed coucals form monogamous pairs and males and females share parental duties.

Researchers from the Max Planck Institute for Ornithology in Seewiesen have now examined the differences in parental effort between the two species and found that male black coucals invest far more into parental care than pairs of white-browed coucals. Black coucal fathers feed their young four to five times more often than either white-browed coucal parent. Even when the efforts of both partners are combined, a black coucal father still flies to the nest two to three times more frequently than a pair of white-browed coucals together - probably because white-browed coucals feed their young a higher proportion of frogs than insects. Unlike the black coucal, white-browed coucals also spend long periods just "hanging around" in bushes, even during the period when they are tending a nest. The parental effort required to raise their brood seems to be relatively low.

"A single white-browed coucal parent would probably be enough to successfully raise a brood, as is the case for black coucals", concludes Wolfgang Goymann, who headed the study. The scientists believe that white-browed coucals only form pairs and share parental duties because the females lack the opportunity to find additional male partners. The sex-ratio of black coucals is strongly biased towards males probably because females are more likely to die during adolescence. As a consequence there are about two and a half males for every female in the adult population. This means a female can easily find several partners, to whom she can then leave the parenting. In contrast, the sex-ratio is relatively even among white-browed coucals. Therefore, a female is unlikely to find additional partners and is better off investing in the brood together with her current mate.
Original publication:

Wolfgang Goymann, Ignas Safari, Christina Muck, Ingrid Schwabl
Sex roles, parental care and offspring growth in two contrasting coucal species.
Royal Society Open Science; 5 October, 2016


Related Species Articles:

Two new species of orchids discovered in Okinawa
Two new species of parasitic plants have been discovered on the main island of Okinawa, Japan, and named Gastrodia nipponicoides and Gastrodia okinawensis.
Cornering endangered species
Geographic areas occupied by certain species shrink as they decline in abundance, leaving them more vulnerable to extinction by harvest.
New species of Brazilian copepod suggests ancient species diversification and distribution
A new species and genus of a tiny freshwater copepod has been found in the Brazilian rocky savannas, an ecosystem under heavy anthropogenic pressure.
Redefining 'species'
What is a species? Biologists -- and ornithologists in particular -- have been debating the best definition for a very long time.
New species discovered in Antarctica
A team of Japanese scientists has discovered a new species of polychaete, a type of marine annelid worm, 9-meters deep underwater near Japan's Syowa Station in Antarctica, providing a good opportunity to study how animals adapt to extreme environments.
Genomic tools for species discovery inflate estimates of species numbers, U-Michigan biologists contend
Increasingly popular techniques that infer species boundaries in animals and plants solely by analyzing genetic differences are flawed and can lead to inflated diversity estimates, according to a new study from two University of Michigan evolutionary biologists.
Common US snake actually 3 different species
New research reveals that a snake found across a huge swath of the Eastern United States is actually three different species.
The origins of Cuban species
An international research team suggests the endangered Cuban solenodon evolved after the extinction of dinosaurs.
New rare species of whale identified
Researchers have identified a new rare species of beaked whale with a range in the remote North Pacific Ocean.
Unusual new zoantharian species is the first described solitary species in over 100 years
A very unusual new species of zoantharian was discovered by two researchers in Okinawa.

Related Species Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".