The learning abilities of non-human animals often pale in comparison to the impressiveness of human intelligence. Though often overlooked, we encounter animal learning frequently. Dog training is a common example: basic tricks like sit, stay, and shake work because the dog learns to associate the specified action with a food reward. Further from home, many people have heard about how New Caledonian crows learn to use primitive “tools” to dig for food and solve complex puzzles.
Another common example that might not be so obvious is how songbirds acquire their distinct tunes. Birdsongs are not innate; in other words, birds aren’t born with the ability to sing. Instead, young birds often learn their songs from tutors during a short period of time in their development. In this time, the birds learn to copy the song of their tutor until they become independent and add their own variation before their songs crystallize.
Because of the short timeframe and critical nature of song learning for fitness, song learning is a delicate process that can be easily interrupted by external factors. A recent study conducted on zebra finches, songbirds that exhibit song learning behavior, examined the potential effects of ambient temperature variability during the development of young birds on their learning ability and the quality of the songs they produce1. Assuming that more temperature variability would increase stress levels in developing birds, the researchers hypothesized that song learning ability would be impaired in more variable environments.
To test their theory, they raised several clutches of zebra finches in temperature-controlled indoor aviaries. Half the clutches were allowed to develop under stable temperature conditions while the other half was exposed to conditions that varied at random each day. After hatching, half of the offspring in each group were swapped to examine the effects of each treatment on song learning at different times during development (pre- vs. post-hatching). The courting songs of male tutors were recorded and analyzed for comparison with the songs of their tutees, which were recorded once fully mature.
Researchers were surprised to find that temperature variability did not impair learning ability or song quality. In fact, temperature variability appeared to enhance song learning accuracy (how well the tutee copied the tutor’s song). What’s more is that variability post-hatching also increased young birds’ motivation to sing, estimated from the number of singing bouts per 5-minute recording and the number of attempts before a recording was successful.
These results were perplexing considering the researchers’ hypothesis. Under their assumptions, developing birds would be forced to allocate more resources and energy to basic survival under variable temperature conditions, thereby giving brain development and learning capacity the short end of the stick. Previous research on the effects of cold stress on zebra finch song learning led the researchers to conclude that temperature variability is not “a stressor severe enough to impair song complexity,” implying no harmful effects of variability on the learning process. Several factors might account for the observed results: young birds exposed to pre-hatching variability might rely more on social cues than those that experienced stable conditions, and the role of various parental effects remains unknown. In either case, the study implies that variable conditions might actually enrich learning ability in zebra finches rather than harm it.
Other results reveal that song quality itself, though not affected by temperature variability, was positively affected by tutee motivation to sing—practice makes perfect, after all. Additionally, higher tutor motivation and larger song repertoires encouraged higher learning quality and smaller proportions of song syllables copied by tutees, respectively, illustrating the complexity of tutor effects on song learning and quality. Researchers were also surprised that the birds that were swapped between the treatments faired no worse in their musical education than birds who received the same treatment consistently, which they attribute to the nature of quality birdsong as a universal fitness advantage.
These unexpected findings provide interesting insights into the development of birdsong and animal learning in general. It goes to show that many common assumptions we accept as truth are not really so certain. In this case, the idea that increased environmental variability puts animals at an unequivocal disadvantage breaks down. In an increasingly ecologically unstable world, perhaps findings like these can act as a reminder of how complicated the living world is.
References
- Lefeuvre, M., Lu, C., Botero, C., & Rutkowska, J. 2023. Variable ambient temperature promotes song learning and production in zebra finches. Behavioral Ecology, 34(3), pp 408–417. https://doi.org/10.1093/beheco/arad014
