Young animals face many challenges when they become independent from their parents. One problem is they need to find food, but have little experience to help them. Even human teenagers can struggle when there’s no one else around to do the shopping, and for wild animals, making the best foraging decisions is even more crucial for their survival. Victoria Franks is investigating how juvenile birds overcome this challenge during her PhD.
Foraging in young hihi is particularly important to think about. While we provide 6 of the 7 hihi populations with supplementary sugar water for conservation management, not much is known about how they learn to find food. Understanding if juveniles are poorer trial-and-error learners could help inform how we provide food, or explain why young hihi seem to be more social than adults (perhaps they need to use a “wisdom of the crowd” strategy). In her recent paper published in Behavioural Processes, Victoria set out to ask: how do hihi learn about food sources, and do adults and juveniles learn differently?
A male hihi trying out the feeder task. He figures out that white marks the correct hole and receives a sugar water reward. Photo credit: Victoria Franks.
Over a couple of weeks in May 2015, Victoria gave hihi at Zealandia Eco-Sanctuary (Wellington, New Zealand) a small feeding challenge. When they entered their normal feeding station, they now encountered a feeder with three access holes, but only one contained food. This hole was marked white, while the other two holes were marked black: we predicted that hihi would learn through trial and error which hole provided food. After a few days Victoria changed the position of the food hole with the white marker and recorded which holes hihi now tried. This meant we could detect how many mistakes adults and juveniles made: did they follow the white marker (the “right” hole), or did they go back to the old location (now a “wrong” hole)?
Finally, Victoria changed the task again, but now switched the marker of the food hole from white to black. Now white no longer marked food, and it was fascinating to watch the birds figure out what they needed to do after each switch.
The feeder task was presented in three different ways - letters denote the holes with capitals indicating which provided food. In Stages 1 & 2 the white circle marked a food reward, but the location changed, whereas in Stage 3 the location remained the same but the colour changed. The figure is taken from the paper.
We found juveniles continued visiting more non-food holes than adults, although both age groups did learn about which hole meant food. Adults seemed to pay better attention to both colour and location to help them find food, whereas juveniles used location only. This meant adults generally re-located the food more quickly than juveniles. Ultimately, juveniles had to spend longer in the feeder station to get the same amount of food as adults.
What strategies could juveniles use to help them avoid the risk of wasting time and energy when foraging? Victoria's next step is to determine if being social helps: perhaps they can use the experience of others to help their own learning. This “social learning” can help animals avoid mistakes they make when learning alone, but it also comes with its own downsides if everyone copies a wrong decision. Time will tell if young hihi have a solution…
Thank you to everyone at Zealandia who helped us with this study. If you’d like to read more, the paper is freely available.
Franks, V. R., & Thorogood, R. (2017). Older and wiser? Age differences in foraging and learning by an endangered passerine. Behavioural processes.