Problem-Solving Budgies Make More Attractive Mates - Forbes
- 11 January 2019
Direct observation of problem-solving skills in male budgerigars increases their attractiveness to females and this mate preference may contribute to the evolution of enhanced cognitive abilities underlying such skills
Recently, I shared a study that uncovered hundreds of genes, many new to scientists, that appear to be involved in ageing and cognition in parrots (more here). Although that research did not address how enhanced cognitive abilities actually evolved in parrots, most scientists think that females may be the driving force behind enhanced intelligence (ref), as well as a variety of other traits. Basically, mate choice may push the evolution of cognitive skills by females preferentially choosing partners that are more “clever”.
But how to test this idea? Today, an elegant study was published in Science by an international collaboration of scientists from China and the Netherlands demonstrating that female budgerigars who chose a particular male will change their minds after observing their less-preferred male successfully solving a foraging puzzle toy. This study also found that these females’ preferences were not affected by food in control experiments where they were allowed to observe males with free access to food nor were they affected by social preferences after observing “demonstrator” females who successfully solved the same foraging puzzle toy. This thought-provoking study suggests that direct observation of problem-solving skills increases male attractiveness and may contribute to the evolution of the cognitive abilities underlying such skills.
How did the researchers figure this out?
The researchers, led by Jiani Chen, at the Key Laboratory of Animal Ecology and Conservation Biology at the Chinese Academy of Sciences, designed a simple but elegant series of experiments where they provided test females with a choice between two males, identified which she preferred, then showed that the test females changed which male she preferred after observing her less-preferred male demonstrating superior problem-solving abilities.
Thirty-four males (17 pairs) and 17 females participated in the first experiment. The parrots were divided into a problem-solving group (18 males and 9 females) and a control group (16 males and 8 females). Females in both groups were first given a series of preference tests where each test female was allowed to choose between two male budgerigars placed in a two-choice cage. Each female’s preferred mate was identified as the male whom she spent most of her time perched close to (Figure 2A).
Did the presence of food affect the test females’ preferences? To test whether a male who was eating was preferable to one who was not, each test female budgerigar was again allowed to observe both males -- but only her less-preferred male enjoyed free access to food provided in their normal food container, whilst her preferred male had none. Despite this, the test females still spent more time perched close to their preferred male (Figure 2A).
Here’s the sneaky part of this study. Each female’s less-preferred male was then trained (out of the test female’s sight) to open two different puzzle toys containing food. One puzzle toy was a petri dish and the other was a three-step box (Figure 1A). The preferred males did not receive such training.
Each test female was once again allowed to observe and choose between her less-preferred male, who now was a skilled problem-solver that was able to open two puzzle boxes to obtain food (Figure 1B), and her preferred male, who was unable to open these boxes (Figure 1C).
After watching her less-preferred (but now problem-solving) male access food whilst her preferred male could not, most test females changed their minds and spent more time perched near the problem-solving male (Figure 2A).
To test whether the test female’s preference for problem-solving individuals reflected an increased social, rather than sexual, preference to hang around with clever problem-solving individuals, a second experiment was performed. This experiment was identical to the first, except that the test females were exposed to two females -- one a skilled problem-solver and the other not -- rather than two males, and the test female’s preference for either type of female was assessed (Figure 2B). In this situation, almost none of the test females changed their minds about who they wished to socialize with.
Why do female budgerigars prefer clever males?
“Very interesting study,” said Alex Kacelnik, a professor of behavioral ecology at the University of Oxford, who was not involved with the study.
“As the authors say, the link between sexual selection and cognitive evolution is a well-established hypothesis (for instance, siskin males with more prominent sexually-selected characters are better at sorting novel foraging tasks [ref]),” Professor Kacelnik pointed out in email. “[B]ut here they show that females increase preferences for males that show good foraging performance, but not for females that do the same.”
But this study raises some interesting points. First, the females did not observe the problem-solving males actively learning how to solve the puzzle toys to obtain food: they only saw the problem-solving males performing competently.
“It would be interesting to test if females are sensitive to the ability to discover new solutions, namely, the transition from incompetent to competent,” Professor Kacelnik pointed out in email.
At this time, scientists don’t know if it’s possible to rank males in terms of their overall problem-solving abilities, so researchers aren’t able to determine whether problem-solving males are generally more clever. Further, there are different sorts of cleverness.
“Some males may be better at tasks requiring haptic exploration [active exploration of the puzzle toys] and others [may excel] at tasks requiring visual discriminations,” Professor Kacelnik elaborated in email. “Some may be good at controlling impulsiveness and others at rapidly discovering new solutions.”
“The theoretical implications of this study are rich, and worth tackling in depth.”
But why would a female favor a clever male, even if he originally was not her preferred choice? Two predominant scientific explanations may be operating here.
“The females may prefer competent males because they will provide direct benefits (i.e., better males increase the female’s access to food) or because they have heritable traits that are passed to the offspring,” Professor Kacelnik replied in email.
“The first alternative does not require males to be genetically better: any developmental factor that led to them being good today will do for the female,” Professor Kacelnik said in email. “But if males do not differ genetically, female selectivity will not drive cognitive evolution.”
The second alternative, known as the good genes hypothesis, suggests that the traits that females choose when selecting a mate are honest indicators of the male’s ability to pass on genes that will increase the survival or reproductive success of her offspring. But this explanation reveals a dilemma in sexual selection, known as the lek paradox. In a lek mating system, nearly all females in the population choose to mate with the same or just a very few males, which could be a problem, especially over thousands of generations: despite strong female choice for certain traits, how do males maintain their genetic variation?
“If the genetic variance is evolutionarily stable, the cognitive benefit must be compensated by some other cost, thus making clever males not worth choosing because in the end they have the same fitness as thick [stupid] ones that avoid paying the cost of being clever,” Professor Kacelnik explained in email. “If intelligence variance is not stable, and clever males are both better at getting food and getting mates, then we must be observing an evolutionarily ephemeral phase, leading soon to everybody being clever, with no between-male differences [in cognitive abilities] and no benefit of selectivity for females.”
Jiani Chen, Yuqi Zou, Yue-Hua Sun, and Carel ten Cate (2019). Problem-solving males become more attractive to female budgerigars, Science, published online on 10 January 2019 ahead of print | doi:10.1126/science.aau8181
Read more about the science of parrot intelligence on Forbes:
GrrlScientist. “Parrot Genomes Provide Insights Into Evolution Of Longevity And Cognition”, Forbes, 21 December 2018. (Link.)
GrrlScientist. “‘Walnut Test’ Reveals Parrots Are Shrewd Investors”, Forbes, 27 August 2018. (Link.)
GrrlScientist. “Brainier Birds Live On Islands” Forbes, 31 July 2018. (Link.)
GrrlScientist. “What Makes Parrots So Intelligent?” Forbes, 12 July 2018. (Link.)
GrrlScientist. “Cockatoos Are As Crafty As Crows”, Forbes, 13 September 2017. (Link.)
GrrlScientist. “Cockatoos Might Make Better Economic Decisions Than You Do”, Forbes, 12 July 2016. (Link.)
GrrlScientist. “Can An Old Parrot Learn New Tricks?”, Forbes, 2 January 2016. (Link.)