A long overdue update

This site has been quiet since early 2020 (and there’s probably a pretty good reason for that…), but despite our silence online we’ve still been hard at work with our kākā and toutouwai research. Since our last update we have published a couple of papers, one showcasing the toutouwai’s prodigious long-term memory and another highlighting the difficulties of replicating cognition research in endangered species, as well as a short opinion piece on some cool parrot tool use research. If you check out the newly updated Student page, you can also see the range of cool projects that our group is currently working on! Finally, we have some exciting new projects on the horizon for 2021, including getting the first experiments for the ManyIndividuals network up and running, developing AI based methods to recognise individual kākā and developing fear based strategies for reducing cat predation (an MBIE Smart Ideas project).


A small New Zealand songbird that hides food for later use provides insights into cognitive evolution

When we think about animals storing food, the image that usually comes to mind is a squirrel busily hiding nuts for the winter.

We don’t usually think of a small songbird taking down an enormous invertebrate, tearing it into pieces and hiding these titbits in the branches of trees to snack on later in the day. But this is also a form of caching behaviour, where food is handled and stored for later consumption.

For caching animals, the ability to recall where food is hidden is crucial for survival. My research into the spatial memory performance of a caching songbird, the New Zealand robin (Petroica longipes), shows male birds with superior memory abilities also have better breeding success.

Why memory matters

There’s no argument that New Zealand is home to a host of unusual birds, including the nocturnal, flightless parrot kākāpō (Strigops habroptila), or the hihi (Notiomystis cincta), the only bird in the world known to mate face to face.

By outward appearances, the small, grey toutouwai (Māori name for P. longipes) is not particularly remarkable. But its noteworthy behaviour includes feasting on some of the world’s largest invertebrates. There is only so much of a 30cm earthworm a 30g bird can eat, and rather than waste the leftovers, toutouwai will cache any surplus prey they don’t want to eat immediately.

An accurate spatial memory is therefore crucial for recovering caches and it has long been assumed that spatial memory is under strong selection pressure in caching species.

For selection to act on a trait, there must be individual variation that is passed onto offspring and that influences survival and reproduction. While researchers had looked at how spatial memory influences winter survival in caching mountain chickadees, no one had examined whether memory performance influences reproductive success in any caching species. Our research tackles this issue.

Measuring memory in the wild

We measured the spatial memory performance of 63 wild toutouwai during winter. We gave the birds a circular puzzle that had a mealworm treat hidden inside one of eight compartments. For each bird, we put the puzzle at the same location in their territory several times in a single day, with the food always hidden in the same spot.


The spatial memory test

Pepper searches for a mealworm treat


Over time, toutouwai learned the location of the hidden treat and began opening fewer compartments to find the mealworm. We then followed these same birds through the next breeding season and looked at whether their spatial memory performance (measured as the number of compartments they had to open to find the mealworm) was linked to their ability to feed chicks, and whether it influenced the survival of their offspring.

Our results suggested that spatial memory performance influences reproductive success in toutouwai. Males with more accurate memory performance successfully raised more offspring per nest and fed larger prey to chicks.

By contrast, we did not find the same patterns for females. This is the first evidence that spatial memory is linked to reproductive fitness in a food caching species.

Evolving intelligence

If there is such a great benefit for males in having an accurate recall of locations, why aren’t all males the best they can possibly be in terms of spatial memory performance? In other words, why didn’t all the male toutouwai we tested ace our memory task?

Intriguingly, our results suggest a role for conflict between the sexes in maintaining variation in cognitive ability. We found no effect of memory performance on female reproductive success, suggesting that the cognitive abilities that influence reproductive behaviour may well differ for females.

Such a difference between the sexes would ultimately constrain the effect of selection on male spatial memory, preventing strong directional selection from giving rise to uniformly exceptional memory in our toutouwai population.

Our work produced some tantalising evidence for both the causes and consequences of variation in cognitive ability, but it also raises several more questions. For example, while we’ve shown that memory performance matters for males, we still need to examine how it influences caching behaviour.

Another mystery that remains is why spatial memory ability may have less of an influence on female toutouwai fitness.  One possibility is that longer-term spatial memory for specific locations (rather than the short-term memory we measured) may matter more for female reproduction, because females do all of the nest building and incubation.

So far, we’ve only provided one piece of the puzzle. To get the full picture of how cognition evolves, we have many more avenues left to explore.The Conversation

Read the original article on The Conversation.

Evaluating whether song can signal an individual’s cognitive ability 

Post by Regan MacKinlay & Rachael Shaw

Can a songbird’s song act as a signal of their cognitive ability for listeners? Individual birds produce slight variations on their species’ specific song.  Previous research reveals that individuals’ song repertoires are learnt, and that song learning is influenced both by genetics and events during early development. Both genetics and developmental effects have also been shown to influence other cognitive processes. Importantly there is substantial evidence that both complex bird song and cognitive ability are the subjects of sexual selection. Given these links, it has been hypothesised that song complexity may be used by listeners to gauge the general cognitive ability of singers.

Early research indicated the existence of associations between song complexity (typically measured as repertoire size) and cognitive ability in song sparrows (Melospiza melodia). One study found a positive correlation with detour reaching performance (a measure of inhibitory control), and another found a negative correlation with performance on a spatial learning task (a measure of spatial memory). However, a recent attempt to replicate these two studies failed, and in fact found opposing patterns. Re-examining these relationships in a species with a differing ecology to the song sparrow, namely a caching species, may offer a different perspective on the relationship between song complexity and cognitive ability. In a special issue of Intelligence we report that, despite adopting similar testing methodology and sample sizes as previous studies, song repertoire size was not correlated with cognitive performance in spatial memory or inhibitory control tasks in toutouwai (Petroica longipes).


For male toutouwai like Bruiser, song repertoire size does not correlate with spatial memory or detour reaching performance

It remains possible that other song features (i.e. besides repertoire size) are correlated with cognitive ability in other domains, but evaluating this will require further research into biologically relevant markers of birdsong complexity. For now at least, it appears that song repertoire is unlikely to be a useful indicator of cognitive ability for song listeners. We therefore recommend that song repertoire sizeshould not be considered a proxy for cognitive ability in song birds.

The development of robin caching behaviour

Toutouwai can take down some of the world’s largest invertebrates, but if you’ve caught a 50 cm long earthworm, what do you do with it all? One answer is to shake it to pieces and hide it around your territory to snack on over the next day or so. This ‘caching’ strategy lets toutouwai make the most of temporarily abundant food by saving some for later.

Caching is widespread in the animal kingdom, yet there have been very few studies looking at how individuals develop caching behaviour. For her MSc thesis, Latu Clark investigated how juvenile toutouwai learn to make their caches. The results of her work have just been published in Behavioural Processes.

After young birds left the nest, Latu visited them a couple of times a week for up to 12 weeks. Each visit, she fed the birds several mealworms and documented their behaviour. If a bird cached, Latu monitored what happened to their cache (check out the image below of one of her juveniles inspecting the camera – if you look closely you might spot a cached mealworm in the log in the background). Her work demonstrated that it takes several weeks for juveniles to develop some aspects of adult-like caching behaviour, but that other components of caching appear spontaneously and do not change during development.

These results suggest that learning how to handle prey and hide it for later comes naturally to young toutouwai, but that they also require extensive experience to do it well. Interestingly, it also seems that toutouwai caching behaviour follows similar developmental trajectories to other, distantly related Northern hemisphere bird species.

Robin selfie

A juvenile robins gets up close and personal with a camera. Photo courtesy of Latu Clark.

Cognitive test batteries, where to from here?

It’s been a while since the last update, but that’s not to say that we haven’t been hard at work! The robin/toutouwai breeding season is well underway and this year we’ve also begun to look beyond the sanctuary fence, to try and understand what might be limiting the toutouwai’s survival. Meanwhile, we’ve been developing a new research project with kākā (watch this space…).

However, this year I also took time to reflect and focus on writing a review together with Martin Schmelz. Our paper, ‘Cognitive test batteries in animal cognition research: evaluating the past, present and future of comparative psychometrics’, was recently published in Animal Cognition. In it, we examine the various pitfalls and possibilities that lie ahead for non-human cognitive test battery research. (As an added bonus, it also includes discussion of the relationship between reproductive success and cognitive test battery performance in wild male North Island robins)

There’s already some exciting things happening in this rapidly growing field, but there is still a lot of room for improving how we design, implement and analyse non-human test batteries. We hope that our review will be a useful resource for anyone who is undertaking non-human cognitive test battery research.

Talking about bird brains

The updates have been a little slow while my students and I have been wrapping up the latest round of breeding season monitoring and crunching numbers…

However, I did manage to make time this week to chat about our research to Sciblogs and Radio New Zealand.

To read about why I think it is important to study bird brains, check out this interview with Sciblogs.

To listen to me discuss how to attract an enraged researcher in the forest, among other, more scientific things, have a listen listen to this interview with Radio New Zealand.

Designing smart tests for bird brains


Bruiser participated in my first North Island robin cognition study in 2014 and is no stranger to cognitive tests. In my latest research, carried out in 2015 and recently published in Behavioural Processes, Bruiser quickly mastered opening swivel lids to grab a snack. By contrast, those robins that had never been tested were slow to catch on.

If prior experience affects performance in a cognitive task, how can we fairly compare naïve and experienced birds? Designing tests that can give us unbiased, accurate measures of cognitive ability in the wild gets even more complicated when we start to consider other factors, such as hunger or boldness.

As it turns out,  I also found that hungry robins performed worse than their well-fed counterparts in a test of inhibitory control. These birds were more likely to keep pecking at food through a transparent barrier, rather than reaching around the barrier to retrieve it.

Lid-opening and ‘detour-reaching’ tasks are commonly used cognitive tests for birds. However, the robins’ performance reveals some pitfalls in relying on these tasks to measure individual cognitive ability. It hardly seems fair to compare a spoilt little Bruiser with a hungry bird who has never been to robin school…

Robin selfies

Over the past few weeks Latu has been hard at work documenting the caching behaviour of the youngest birds in our study population. Judging from the footage, it looks like her efforts to film cache sites haven’t gone unnoticed by all of the juveniles…

Robin selfie