Hihi Rose Thorogood Hihi Rose Thorogood

Our first "informed bird" has fledged!

At the end of November, Victoria Franks passed her viva with examiners Joah Madden (Exeter) and Bill Sutherland (Cambridge). We’re very proud of our first “fledgling”! Here Vix describes her main findings:

At the end of November, Victoria Franks passed her viva with examiners Joah Madden (Exeter) and Bill Sutherland (Cambridge). We’re very proud of our first “fledgling”! Here Vix describes her main findings:

My PhD at the University of Cambridge (supervised by Rose Thorogood, and John Ewen from ZSL) investigated how early-life social experiences affect foraging behaviour in naïve juvenile songbirds. I addressed this topic in wild hihi (Notiomystis cincta), a threatened New Zealand passerine - juveniles form groups after fledging which could be important for their learning and survival, but conservation efforts focus on moving individuals (not groups) to seed new populations.

The very talented Vix Franks, adding the finishing touches to her PhD thesis

The very talented Vix Franks, adding the finishing touches to her PhD thesis

I first explored how juveniles learn about food in comparison to adults, what social experiences they encounter early in life, and how these experiences influence their foraging decisions. My results showed that fledgling hihi learned about novel foraging opportunities (i.e. feeding stations) from their parents (available from BioRxiv), but did not learn as efficiently as more experienced adults when they were independent (see the published results). However, juvenile hihi formed ‘gangs’ during early independence which might provide new sources of social information from peers and other adults (BioRxiv). My experiments showed that social information from the gang allowed juvenile hihi to update their foraging behaviour, rather than maintaining behaviours learned earlier with parents (BioRxiv). As a consequence, group members conformed to the collective behaviour of peers in the same time and place as themselves, even when they moved among gangs (BioRxiv). Together my findings demonstrate that juvenile social experiences have implications for learning and can help young animals overcome the challenges of naïvety during early life.

How does this knowledge affect conservation management? A major tool for hihi is to seed new populations with reintroductions of juveniles, but these translocations of individuals disrupt both the physical and social environment. My results suggested that there is potential for downstream consequences on foraging and survival. During a planned translocation, I used social network analysis to explore whether juveniles maintained group associations once reintroduced, and considered the impacts of removal of group members on the birds left behind at the source site. While group identities largely remained intact for birds that were not moved, juveniles moved to a new site formed new social bonds. Most importantly in terms of their conservation, individuals that lost more associates were less likely to survive the first few months post-release (BioRxiv). Our plan is to explore this relationship further and investigate whether we can mitigate this cost of social disruption for improved conservation outcomes.

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Hihi, Papers Rose Thorogood Hihi, Papers Rose Thorogood

Older and wiser? What we now know about age & learning in hihi

One big problem young animals face is finding food, particularly when they 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.  Read about her latest results here on age differences in learning strategies by adult and juvenile hihi.

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.

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Two papers in one week: how birds learn (and why it matters!)

Highlights! A quick summary of our two papers out this week on associative learning by hihi, and the coevolutionary consequences of social transmission among predators.

Week 51 turned out to be a big week for our group: two papers out to finish the year! 

The first paper from Victoria Franks' PhD was accepted by Behavioural Processes: "Older and wiser? Age differences in foraging and learning by an endangered passerine." This was the culmination of hard work in the field and behind a computer, to understand what and how hihi juveniles learn.  The study forms an important part of Vix's thesis because it reminds us that adults and juveniles do not necessarily learn about food in the same way - and it dispels any rumours that hihi can't learn! 

A male hihi learns to associate the while circle with a food reward. From Franks & Thorogood Behavioural Processes 2017.

A male hihi learns to associate the while circle with a food reward. From Franks & Thorogood Behavioural Processes 2017.

Secondly, we had a big paper come out from our work on the co-evolutionary consequences of  social interactions among predators in Nature Ecology & Evolution: "Social transmission of avoidance among predators facilitates the spread of novel prey".  This was the experiment that started our core research project, but it needed some nice modelling by Hanna Kokko to finish it off.  There's more in a "Behind the Paper" blog post on Nature Ecology & Evolution Community, and Science News produced a fantastic video about it:

Finally, Liisa Hamalainen and her assistant Marianne Teichmann have now finished a gruelling set of experiments in Konnevesi continuing this research project.  The take home message: Blue tits never do what you expect them to! 

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Hihi translocation in progress

Translocations are an exciting time for hihi conservation - we're starting a new population, and also learning how the birds' social environment influences success.  

In 2005, we reached a milestone with hihi on Tiritiri Matangi Island with the first translocation of birds to seed a new population (Zealandia, in Wellington).  Thirteen years (and many translocations) later, Vix and Caitlin are now experiencing their first hihi translocation.  

The translocation in 2005 was also an experiment: the hihi recovery group tried something new - most of the birds moved were juveniles.  Tiri was producing lots of young each year, but it was suspected that there were not many opportunities for them to recruit to the breeding population.

Since the first Tiri translocation, we've been looking more closely at juvenile behaviour.  First, Kate Richardson's research with hihi moved to Maungatautari suggested that dispersal and choice of breeding location might be influenced by broad-scale familiarity among birds. Now, Vix's PhD research is showing us that juvenile hihi spend lots of time together, and some individuals have stronger social bonds than others.  How will translocation alter these bonds? Will moving "friends" together make it easier for them to adapt to their new location after translocation? How will they respond to the changes in resources? And, what happens to the birds left behind on Tiritiri?  This translocation to Rotokare - the first to investigate the role of social behaviour in this context - should give us some answers.  But, given what we know about hihi already, it's sure to also throw up lots of surprises!  Stay tuned...

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