The other day I saw a small flock of starlings perched along a telephone wire. A magpie flew down and perched on the wire about twenty feet away. The starlings didn’t seem to take much notice of it, until it shuffled towards them. Then half a dozen or so of the birds closest to the magpie flew up and landed on the wire a few feet behind it. The magpie then shuffled back towards the smaller group, which flew up and re-joined their fellows. The magpie waited a little then shuffled towards the main group again, this time a little faster. Again a small group of the birds flew up and landed just behind the magpie. Again it shuffled back towards them, and again they flew back to join the main group. This happened twice more, each time the group that hopped over the magpie got slightly larger. Finally, after a few minutes all the starlings flew off, leaving the magpie alone on the wire. Then it too flew away.
I couldn’t see any obvious reason for this behaviour. The leisurely pace at which they took part did not suggest a serious threat, and neither side sought to attack the other. There seemed something playful about it. I wondered if the birds might be engaging in some kind of teasing game.
Birds and animals do of course engage in kinds of play, but usually this is part of growing up, when they learn vital skills that will keep them alive. Play tends to be associated with animals that take longer to develop to maturity and are more dependent in their infancy. The antics so beloved of pet owners are often relics of these kinds of behaviours, a kind of perpetual juvenilia induced by their dependency on humans and the time and security provided by domesticity. But sometimes wild creatures do seem to do things that can’t be explained in developmental terms. Is that really the case, or is it just a matter of perception?
Now, some might say that if something looks like it is having fun then it probably is. End of story. But as ‘fun’ is an emotional state then to make such an assumption is to attribute thoughts and feelings to a creature – human or otherwise – whose mind we can only know from external signs, and these are ambiguous at best.
In thinking about this I came across an article in the journal Current Biology, which is worth reporting as it picks this issue apart quite neatly. The authors argue that if an action is to be classed as ‘fun’ it needs to have a reward, and for that reward to induce a hedonistic response (pleasure) and be sought more than once. The reward has to be independent of nutrition, reproduction, social status and so on (these things can be pleasurable, of course, but they carry rewards other than pleasure).
To be able to have fun, a creature has to have the capacity in the brain to experience pleasure. Such things can be observed and measured. It seems that dopamine is a key ingredient: tests in rodents and primates have shown that parts of their brain are susceptible to the effects of dopamine and other chemicals that are associated with pleasure. Birds have brains that are in some ways similar in structure to these animals: thus is follows that birds are likely to have at least the neurological capacity for pleasure.
Only a few birds are observed to have behaviours that could be called ‘fun’, and these tend to be amongst the crow and parrot families, each of which has a longer period of development than most other birds. Ravens and other crows are well known for their aerial acrobatics, a kind of locomotor play. Crows and Parrots are known, sometimes notoriously, for their curiosity, which could be described as a kind of object play. Then there is social play, which can often involve objects, and can mimic courtship or fighting behaviour. In each case there may be subtle signals that distinguish the play behaviour from the real thing.
Play takes time and energy, of which adult animals and birds usually have little to spare. If play is have a function it needs to be worth the effort. Perhaps bonding and stress reduction are among the rewards that come from play, apart from pleasure itself?
The action among birds that is most often associated with pleasure is singing, perhaps because we humans like to sing for pleasure, though our own attempts are not often (or at least not openly) associated with the acquisition of territory or a mate. It seems that dopamine is involved in the process of singing in birds too, perhaps producing the drive to sing. But while some birds do sometimes appear to sing without the objective of territory or a mate, this is hard to confirm. It seems that bird song, which we find beautiful and thus pleasurable, is to the birds a strictly utilitarian pastime, while to us it seems sublime.
So how can we tell if a bird might be experiencing pleasure? They don’t have the muscles that allow emotions to be expressed in their faces, though they can alter the way they display their feathers and affect certain movements of the body. Beyond that, what else can we know?
The short answer is not much, not very reliably anyway. Measures such as temperature and heart rate are unreliable when taken as measures of specific emotions. Observations, unless rigorously done, are equally unreliable.
So it seems that we are still a long way from finding an explanation for pleasure in birds. Does it matter? Well, if we want to claim that animals have emotions and thus have a right to happiness beyond the absence of pain and the maintenance of life we need more than anthropomorphism and introspection to do so.
Which is not to say these things have no value. They’re part of our understanding, ways to express a mystery, perhaps.