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
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.