Older and wiser? Foraging in adult and juvenile hihi
Research by PhD Student Vix Franks
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. During my PhD, I’m investigating how juvenile birds overcome this challenge.
Foraging in young hihi is particularly important to think about. While 6 of the 7 hihi populations in New Zealand (including ZEALANDIA) are provided with supplementary sugar water for conservation management, not much is known on how they learn to find food. Understanding if juveniles are poorer 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). I set out to ask: how do hihi learn about food sources, and do adults and juveniles learn differently?
Over a couple of weeks in May 2015, I gave hihi in the Discovery Area at ZEALANDIA 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: I predicted that hihi would learn through trial and error which hole provided food. After a few days I changed the position of the food hole with the white marker and recorded which holes hihi now tried. This meant I 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, I changed the task again, but now switched the marker of the food hole from white to black. Again, I looked at which holes hihi tried, even when white no longer marked food. It was really interesting watching the birds figuring out what they needed to do, even if I did get rained on a few times!
I 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? My 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 me with this study. If you’d like to read more, the paper is freely available here.
Article and photo by Vix Frank