Our newest open access paper on repeatability of avian signalling (song) traits just came online in the journal Frontiers in Zoology.
Repeatability, consistent individual differences, in signalling behaviour is interesting because it means that those receiving the signal (i.e. listening to the song) could reliably learn something about how the individual singer compares to other singers/competitors.
We repeatedly recorded the dawn song of great tit males throughout the breeding season and show that start time of dawn song and repertoire size are individually repeatable both before and during the egg-laying stage of the mate (when she is fertile). Surprisingly the time a male started singing appeared to be more repeatable (consistent) than repertoire size, despite that the start time was also influenced by variable overnight temperatures. Start time was also more repeatable before than during egg-laying and we suggest that this is related to the behaviour of the (assumingly) intended receivers of the song, the females.
For a subset of the singers, we also explored a potential link between the absolute song trait values, the repeatability of these values and personality. We did not find a link but follow-up studies with a larger sample size, and including additional song traits, will be needed to confirm the true absence of such a link.
Would you consider yourself to be social? More or less social than average? And try to think back, were you always like this or did you become more or less social later in life?
I think it is safe to say that humans are a social species. In Germany, people live with 120 people per one square kilometre, in Berlin with over 4000! That we still sort of like each other tells us we have a high social tolerance. Indeed, we humans even tend to be attracted to places with other people present.
But, as you may have realized, from one person to the next, we also differ in how social we are. Ranging from loners to people with 20.000 Facebook friends. There is plenty of variation. Partly because of how we were born, our genes, and partly because of our experiences.
This is true, not only for humans, but for many animal species as well. Individuals of one species can differ in how social they are. But there is one important thing to note here, something which we ‘social’ humans can easily forget, and that is that some species cannot stand each other! Take the giant panda. Males and females live by themselves. They guard their own area and chase out everyone who dares to enter. Even females chase away other females. Only for a short moment a male is allowed, but after he has done his thing, he has to go.
We have also animal species that are part time social, like the blue tit. In spring and summer, when the weather is nice and there is enough food around, these blue tits prefer to keep other birds at a distance. Only a partner is welcome. But in winter, when it is cold and food is difficult to find, they join flocks. Groups of other birds. Together they search for food. If you have a garden and leave some food for the birds in winter, you will probably have seen them.
Finally, there are animals that are social just all the time. Many bat species, for example. They often eat together, sleep together and even take care of their babies together in so-called ‘nurseries’.
So why do we see these differences in social behaviour between and within animal species? And what are the consequences of being social or asocial? These are the kind of questions I try to answer with my research.
Why is this relevant?
Finding the answers to such questions can be important for several reasons. (1) To increase our basic knowledge of nature. For the sake of knowledge itself, but also to inform other scientific fields, such as applied animal science, psychology, behavioural economics and sociology. (2) To help better manage and protect species and (3) to increase the welfare of the animals we live with.
In our homes, we have a variety of pets that also differ in how social they are. Dogs are classic group living animals, just think about the wolves living in packs. Also, rabbits are very social and prefer to be with other rabbits. Cats, however, are actually asocial (not a big surprise). The wild cat lives by itself. Most hamsters also don’t like others around, but certain hamster species, such as the Russian hamster, do like to have a companion from the opposite sex. They form pairs for live and can become depressed when they are not together.
In general, you can say that asocial species which are housed together become stressed. Imagine that you have to spent your whole life living with someone you really dislike. Yet social species, when housed alone, can become fearful and depressed. For dogs, humans can become their companions, but for most other animals this doesn’t work like that. When it comes to animals in captivity it is thus important to know whether they are social, live in pairs or are asocial.
Tracking the social live of a small songbird
In my studies, I focus on animals in the wild. How are their social lives structured and what benefits does it bring them? Since I was a little girl I have been fascinated with how and why animals behave the way they do. So it was not difficult for me to decide what I wanted to become: a biologist. I studied biology and did a PhD studying the daily social behaviour of a songbird: the great tit, a small bird you can often find in your garden and in the forest.
But how do you study a bird that is hiding in the trees most of the time? I did this by putting small transmitters on their back (Figure 2). In this way, I could track where the birds were going and who was meeting whom. More than 150 receivers (small boxes with an antenna) recorded where the birds were going in the forest.
I was especially interested in knowing whether the social behaviour of the birds was related to their personality. Because also animals have personality, they differ in how they handle new or risky situations. Something that is well established now in science. If you have had several pets you will probably have noticed that one is not like the other. This is also true for wild animals.
So, basically, I wanted to know if bold birds were more social than shy birds. Bold birds are birds that take more risks and approach novel object quicker than shy birds. We tested the personality traits of wild birds in the lab before we spatially tracked them in the wild.
Are bold birds more social? This would make sense, right? Also in humans, bolder individuals usually seem the most popular. To answer this question, I analysed the spatial tracking data to find out who was hanging out with whom. In this way, I could construct a social network. A sort of Facebook for birds. And what did I find? Bolder birds (Bigger dots in Figure 3), were more central in the network, they spent relatively the most time close to other birds. While shy birds (Smaller dots in Figure 3), were on the edge of the network. They spent less time with other birds .
Playback experiments with songbirds
Still, being popular (i.e. having many social connections), like having 10000 Twitter followers, does not necessarily mean that you are also a more social individual. Even Donald Trump has more than 30 million twitter followers.
Being more ‘popular’ could be caused by other factors than being social. For example, these birds could be hanging out on spots that happen to attract a lot of other birds, like places where there is plenty of food. Also, other birds might be socially attracted to bolder individuals without these popular birds actively socializing themselves. So, Donald Trump has over 30 million followers on Twitter, but can anyone guess how many people he follows himself? Last time I checked: 45, including his own family, his business, his golf course and his campaign team. A little side note just to illustrate that you don’t have to be a social individual to be popular.
Thus, to find out if bolder birds are actually actively approaching other birds. I performed two different experiments
The first experiment involved pretending to be another bird. So how do you pretend to be another songbird…? By singing! Via a speaker I broadcasted the song of an unfamiliar great tit in the territory of another great tit, which goes a bit like this and I observed how the bird responded. Such an experiment is called a playback experiment. As expected, the bolder birds tried to get really close to the speaker, which they thought was another bird, while the shyer birds kept more of a distance .
However, this behaviour is of course also not really ‘social’. It is aggressive. Bolder birds are more aggressive than shy birds. Maybe also not a big surprise when you think of humans.
Thus secondly, I designed another test in which the birds got to meet an unfamiliar great tit, but without this great tit posing a threat. I did this by showing the birds a High Definition life-size video of a great tit in a neutral lab environment (Figure 4). This kind of experiment is called a video playback experiment. It maybe sounds a bit strange, but the birds respond to this as if there is another bird in the room. Here the birds could choose if they wanted to approach the video great tit or rather stay near a video showing an empty cage. Both videos were played on screens in a small cage so that the birds could not look behind the screen and see that there was not an actual bird there. Surprisingly, in this test, bolder birds did not spent more time with another great tit. Actually, if anything, the shy birds showed more social attraction. They spent most time near the video great tit .
What have I learned from my PhD studies? (1) Individuals of the same species can differ in their personality traits and the time they spent close to others and (2) being bold and popular does not per definition make you a social individual.
If you are interested in finding out more about my studies and animal behaviour in general, please follow me on Twitter. And, unlike Trump, I will follow you back.
Snijders, L.et al. (2014) Social networking in territorial great tits: slow explorers have the least central social network positions.Animal Behaviour98: 95-102.
[2} Snijders, L. et al. (2015) Dawn song predicts behaviour during territory conflicts in personality-typed great tits. Animal Behaviour109: 45-52.
 Snijders, L.et al. (2017) Dominance rank and boldness predict social attraction in great tits. Behavioral Ecology28: 398-406.