What animals can teach us about stress

Aliza le Roux, University of the Free State

Humans, being essentially self-centred, want to know what makes them different from their wild relatives, as well as what similarities exist. But it’s not just a matter of curiosity. Other species can teach us a lot about the big issues that challenge us in modern society.

Stress is seen as a pervasive modern-day killer. It has an impact on everything from our intestinal processes to our cherished cognitive performance. But stress is not a modern thing. All animals stress about predators, hunger, and lack of sex. So, what can we learn from them?

If there were a sweet spot – the optimal stress level – at which most stressed animals show peak cognitive performance we could possibly use the information to modulate our own stress and mental feats. And it would be brilliant if we could develop a deep understanding of how wild animals perform under varying levels of risk, given that they have evolved to deal with these over millions of years.

Studying the link between stress and cognitive performance, however, is hampered by many challenges. Although our methods of measuring stress have improved dramatically in recent years, outside the lab it’s still very difficult to contrast chronic stress from, say, a long drought, versus acute stress, such as the presence of a predator. Or linking our measures of stress to wild animals’ learning and memory skills.

We’re only just scratching at the surface of this problem.

Not stressing the animals

The study of stress itself is coming into its own. Traditionally, researchers actually increased their study subjects’ stress levels by the collection of blood used to measure circulating stress hormone (cortisol) levels. More recently, though, we have been given a barrage of less invasive tools with which to measure animals’ anxiety.

Perhaps the most widely used technique is to extract hormonal data from fecal samples. There is no need to catch or handle the animal. By happy coincidence stressed animals produce even more poo than their calm counterparts. Fecal hormones have certainly confirmed many of our suspicions. Animals become more stressed when they are handled and in captive conditions like zoos. They also find losing a friend very stressful.

There have also been some surprise findings. It may seem obvious that being a subordinate animal is stressful, but research on baboons shows that alpha males may actually be the ones heading for a stomach ulcer.

Another way of indirectly assessing anxiety is by measuring changes in how much food wild animals leave behind in experimental feeding patches. The idea is that a relaxed animal will eat more of the food than an anxious individual, leaving behind more food. This is called the giving up density. Experiments such as these allow us to clearly see how wild animals perceive variation in risk in their natural landscapes.

We know from Giving Up Density experiments that Nubian ibex perceive increased tourism as risky, while samango monkeys use human observers as potential shields against predators, eating much more food when their human “guards” are nearby. These same monkeys also feel much more threatened near the ground, compared to positions higher up under the tree canopies.

An even more exciting recent development is the measure of stress through thermal imagery. Researchers are knee-deep in the development of reliable techniques using thermal cameras to detect rapid changes in body surface temperatures.

A spike in stress levels causes blood to shunt away from an animal’s body surface (may this be what gives us the chills when we panic?). Suddenly, and quite literally, the animal appears to be cooler. Armed with this knowledge, we may be able to monitor fluctuation in stress levels in real time.

With all of these tools at our disposal, you may imagine that we know everything there is to know about wild animals’ performance under pressure. Unfortunately we don’t.

There is still a lot to learn

Our knowledge of cognitive performance and stress is heavily skewed towards lab rats. A great deal has been learnt from them.

For example, experiments have shown some positive effects of stress on lab rats. Brief, acute stress can actually lead to an increase in neurons in rats’ brains. And rats who were stressed out as teenagers become more impulsive as adults, which can make them more effective foragers, especially under high risk conditions.

In some ways, these findings sound like great news. We can perhaps all relate to the idea that we perform rather well when the stressful situation is short-lived, but flunk out when the pressure is either non-existent or overwhelming. But what we can say about these very rodent-focused studies is that it’s time to move beyond rodents and beyond the lab.

Moving past rodents

Data are slowly trickling in.

Studies on wild animals appear to confirm the idea that long-term, chronic stressors can truly decrease your mental acuity. For example, a recent study on wild-caught guppies showed that those used to stress make a lot more mistakes in cognitive challenges compared to the relatively relaxed fish.

Left-handed marmosets, which are the target of more social attacks and are therefore perhaps more chronically stressed, also show negative cognitive biases compared to their right-handed group members.

Marmosets don’t function well cognitively in stressful situations.
Reuters

In my own lab we are trying to assess various ways in which varying risk can affect learning abilities. We are using Giving Up Density experiments to determine how well wild bat-eared foxes may perform in low-risk and high-risk situations.

The key to unlocking how animals deal with stress requires that we step off our pedestal and acknowledge that other animals may outdo us in some cognitive tasks. If we do this we may learn how to truly cope in our own rapidly changing landscape.

The Conversation

Aliza le Roux, Senior Lecturer , University of the Free State

This article was originally published on The Conversation. Read the original article.

How the zebra got its stripes: to ward off flies

Akshat Rathi, The Conversation and Angela White, The Conversation

Zebras’ stripes have baffled biologists since Charles Darwin. Many hypotheses have been proposed regarding their purpose but, despite hundreds of years of study, there remains disagreement.

In an attempt to end the debate, researchers have pitted various models against each other and systematically analysed data from past studies. Their results reveal the one reason zebras have stripes: to ward off flies.

A handful of ideas regarding zebras’ stripes have found some support among biologists. One proposed that the dark and light bands change how air flows around a zebra’s body and helps in heat management, which could go a long way in the hot tropical areas that zebras live in.

Another proposed the stripes were used by zebras as a way of social interaction. They may use them to identify other zebras and for bonding as a group in the wild.

A third proposal suggested zebras used the stripes as camouflage. While stripes are clearly visible in the day, there some thought that it helped at dawn, dusk, and in the night.

All these ideas were shot down when tested rigorously. Two others, however, remained intriguing.

Now, how do I get rid of these ants?
dkeats, CC BY

The first was that the stripes were used to dodge predators. It is called the “motion dazzle hypothesis”, and it suggests predators are confused by zebras’ stripes and cannot understand their movement. Research published in the journal Zoology in 2013 used a simulated visual system to show that zebra stripes do interfere with visual perception. But this is a difficult hypothesis to test in the field.

Martin Stevens at the University of Exeter has researched the motion dazzle hypothesis by getting human subjects to catch moving stripy objects on a computer. “It’s an artificial experimental system,” he admitted.

The second proposal was that stripes helped keep flies at bay. Zebras are especially susceptible to biting flies due to their geographic spread. These flies, which include the tsetse fly, stomoxys stable flies, and tabanid biting flies, are particularly prevalent in areas with high temperature and humidity – exactly the areas where zebras are normally found.

Bites from these flies can be nasty and, quite literally, draining. About thirty flies feeding for six hours on just one horse can draw as much as 100mL of blood. Usually the flies can number in the hundreds around one animal.

Zebras have shorter hair than other equids – the family that includes horses, donkeys and zebras – which may also increase their susceptibility to attack. Also, four diseases which are fatal to equids have been found in Africa. This could mean that investing in anti-biting defenses such as stripes is especially important for zebras compared to non-African equids.

It is possible that the dazzle effect acts on flies, rather than larger predators, and deter them from biting. “Stripes clearly have a number of functions,” Stevens said, “and these could be interacting in zebras.”

Revealing maps

In the new research, just published in Nature Communications, Tim Caro and his colleagues at the University of California in Davis, didn’t perform experiments. Instead they used ecological and observational data on zebras’ geographical locations and related factors. It is the first time that a comparative approach has been applied to find the reasons for zebras’ characteristic colouration. Caro thinks his findings may have nailed the answer at last.

Caro looked at seven species of equids and scored them for number and intensity of stripes. Just to be sure, they tested all five hypotheses regarding zebra stripes’ use: camouflage, predator avoidance, heat management, social interaction, and warding off flies. The extent of overlap between the geographic distribution of striped equids with each of these five measures was calculated.

E. greyvi, E. burchelli and E. zebra have stripes on all their bodies. Other equids don’t.
Caro, Izzo, Reiner, Walker and Stankowich

“The results were a shock to me,” said Caro. Of these five proposals, only warding off flies had statistical support. He had not expected such a clear-cut answer to the question. As the map shows, the only places where flies and equids live together are areas that are populated by striped equids.

The exact mechanism by which stripes deter flies remains unknown, but experimental studies performed by researchers at Lund University in 2012 have found support for this proposal. They created striped surfaces and stuck glue on them. Based on the number of flies on the surfaces with different thicknesses of stripes, they concluded that these flies stayed away from stripes as thin as those found on zebras.

“As is normal in science you get a solution that asks more questions,” Caro said. It is time to hand the problem over to vector biologists, who can understand the susceptibility of horses to biting flies.

In Darwin’s days, people didn’t consider animal colouration with respect to fitness advantages. “People thought that animal colouration existed simply to please humans or was caused directly by the environment,” Caro said.

Darwin “would be delighted” that researchers are now considering animal colouration as a functional trait, he said. We might not have all the answers regarding zebra stripes – but it seems we may be looking through the right lens.

The Conversation

Akshat Rathi, Science and Data Editor, The Conversation and Angela White, Commissioning Editor, The Conversation

This article was originally published on The Conversation. Read the original article.

Baboons don’t play follow the leader – they’re democratic travellers

Robert John Young, University of Salford

Baboons in the wild are known for their highly strategic and hierarchical societies. So when it comes to decisions about where to go, one might expect that some bolshie individuals will direct the group through its habitat. However, a new study of the collective movements of wild olive baboons in Kenya suggests that there are more democratic processes at play.

For wild animals location is everything. The decision to head north instead of south may lead you to a fruiting tree, a pool with water or a place of shelter: all of these things could be the difference between life and death. For that reason, animal movements are never random. Even when searching for things, animals will use specific patterns of movements to sweep their environment. Social animal species like monkeys may not sit down and have a confab over a map, but they still need to make a decision about where the group should be heading.

A baboon in sheep’s clothing?

Numerous theoretical studies show the more you use collective information, the better the decision making process turns out. So it actually makes sense for clever animals like baboons to ignore a dominant individual no matter how much of a despot they are, but instead use a democratic process.

Oliver might be resourceful but look at that silly stroll. He clearly has no idea where he’s going.
Andicat/wikipedia

So far, there has been a limited amount of knowledge about how baboons make decisions about movements. The problem is how to study simultaneous and collective decision making in animals that live in large groups. Baboons typically live in groups of around 100. High accuracy GPS devices mounted on the majority of group members is the answer: this will reveal how animals coordinate their movements relative to one another. I have used this technique in the past on a much smaller scale to investigate the secretive lives of mated pairs of maned wolves in Brazil.

The researchers monitoring baboons in Kenya did just this. When an animal moved off, its influence on the other members of the group was observed. Did the other members follow (that is, did it “pull” them along)? Or did the other members resist the initiative to move off (that is, “anchor” the group). And what happened when several individuals moved off at the same time in different directions?

The researchers found that there was no relationship between position in the hierarchy and pulling the crowd along. In other words, top baboons were as likely to be followers as being followed. This illustrates that leadership and social roles within a social group can be distinct roles. Just because you are the leader does not mean that everyone else in the group treats you like you are infallible in your decision making.

In general individuals were followed when they moved purposefully off in a set direction and were able to rapidly recruit or “pull” other individuals in that direction. This makes sense in that it suggests to other group members that the moving individual’s behaviour is goal driven, for example by looking for food. Perhaps the individual has suddenly remembered the location of a fruiting tree. It would therefore appear that baboons like to follow the crowd – this is similar to quorum sensing behaviour in bees and ants when they are choosing a new nest. The option with the most votes wins.

The 90-degree rule

A big problem of group movement is how to resolve disagreement about the direction to be taken. It is rather like being lost in a strange city on a night out with a group of friends with widely differing opinions about where to go. One effect of this for both humans and baboons is that it delays any decision being made as the conflict is being resolved.

So what’s the solution? It turns out that baboons have a special rule. When the difference between two individuals trying to initiate movements in different directions is less than 90 degrees from one another, then it is resolved by splitting the difference and taking a middle path. However, if the difference of opinion about directions is greater than 90 degrees then individuals accept the choice of one individual over the other. Initiators of movement in a certain direction build up followers, and the individual that has accumulated most followers will end up determining the group’s direction.

You are wrong – the difference is 91 degrees, not 88. Let’s follow Jack.
Rod Waddington/wikimedia, CC BY-SA

It is surprising that something as important as group movement in baboons can be determined by a few simple rules, which are based on the idea that it is better to use the group’s collective knowledge than trust in the opinion of their leader. And perhaps even more so the fact that a dominant individual accepts that it is better to be a sheep than a shepherd in certain situations.

The Conversation

Robert John Young is Professor of Wildlife Conservation at University of Salford

This article was originally published on The Conversation. Read the original article.

The riddle behind zebra stripes

Brenda Larison, University of California, Berkeley

How the zebra got its stripes might at first seem like an esoteric question. But it has fascinated many generations and is embedded in the lore of Africa. It is also a question that offers a great educational tool by helping the general public understand how evolution shapes the variation we see in nature.

I began studying the question out of pure curiosity. But could it be more? Could the answer to why zebras are striped provide any benefits to society? There are many ideas about the advantages that stripes might confer on zebras.

Three ideas have some support: that stripes help zebra escape predation, avoid biting flies, and keeping cool. I’ll take up each of these ideas in turn, while speculating about the societal benefits that could obtain if they were proven to be true.

Predation and the dazzle effect

The most well-known idea about why zebras are striped is that they help them escape predation. The thought is that the dazzle effect of their stripes confuses the predator about either distance, speed, direction of movement, or where one zebra ends and the other begins.

The dazzle effect has already been put to use. In the first world war, ships were painted with bold black and white patterns in the hopes of making them less vulnerable to attack.

Research is mixed as to whether stripes actually lend such an advantage to zebras or might instead make them easier to catch. Once we understand whether stripes make something harder or easier to capture, rest assured that technology will make use of the fact.

Stripes as insect repellent

It has also been suggested that zebra stripes keep disease-carrying flies, such as tsetses and horseflies, from biting. Nagana, a form of sleeping sickness carried by tsetse flies, is a serious deterrent to livestock rearing in parts of Africa. Much research has gone into trying to mitigate this problem.

Researchers are working on not only why zebras are striped, but how. By trying to work out the genetic basis, we might one day be able to breed zebra-striped livestock. I can just see a herd of zebra striped cows contentedly munching away in a swarm of confused tsetse flies.

This solution for livestock would be a double-edged sword, though. The inability to rear livestock is one reason some areas of Africa are safe from human encroachment and are left for wildlife.

At any rate, the waterbuck may have already stolen the zebra’s thunder. Researchers have discovered that waterbuck give off an odour that deters tsetse flies. Collars exuding this smell are now being developed for livestock to wear. This is very much like your dog or cat wearing a flea collar.

Stripes to stay cool

There is another idea about the function of zebra stripes that could have an impact on their survival, and could possibly benefit humans and the rest of the planet. Collaborators and I recently discovered that the strength of striping in one species of zebra, the widespread plains zebra, varies with temperature.

The more stripy zebra are found in hot, tropical climates. Preliminary experiments also suggest that strong black and white stripes may help keep zebras cool under the tropical sun.

Zebra stripes differ.
Brenda Larison

If the biting fly hypothesis is true, temperature may also influence how many parasites they carry. Clearly this matters for zebra in the face of climate change. Zebra in regions of Africa that have seasonally cooler temperatures have subtler striping and often lack stripes on the legs.

Should climate change render these regions hotter, these less stripy zebras may have insufficient ability to thermoregulate and they may be subject to bites by flies that now harbour more parasites. Either of these could pose serious problems for zebras if their populations cannot evolve stronger striping quickly enough.

On a more positive note, if zebra stripes can truly create cooling, imagine an inexpensive cooling system for buildings that requires no energy input once in place. Instead of turning on the air conditioning, just roll out a black and white striped cover onto your roof during hot spells. This could significantly reduce energy usage and help mitigate climate change.

Only time will tell whether any of these ideas pan out. Meanwhile, I work simply to satisfy my curiosity, and hopefully yours.

The Conversation

Brenda Larison is Assistant Adjunct Professor, Department of Ecology and Evolutionary Biology at University of California, Berkeley

This article was originally published on The Conversation. Read the original article.

No wonder we are so fascinated by chimps – they remind us of ourselves

Robert John Young, University of Salford

I can quite happily go to a zoo just to watch the chimpanzees. It is not that the other animals are boring, but that chimps are so fascinating. In recent days the media has reported their drinking of alcohol, their ability to vary smiles and a US move to designate them as endangered. So, what makes chimps so attractive to scientists and the general public alike?

From a scientific point of view they are our closest
genetic relative. We share more than 98% of the same DNA and had a common evolutionary ancestor only 5-7m years ago. So chimpanzee biology and behaviour can tell us much about ourselves. And of course chimps look like us (as do most primate species). Due to these similarities, chimps are one of the most studied primate species of all time.

Head scratcher
International Fund for Animal Welfare Animal Rescue/flickr, CC BY-NC

Chimps were first described approximately 300 years ago and ever since they have appeared in books, films, TV adverts and have even flown in space ships. Their importance in understanding human evolution cannot be denied and this further adds to their high profile within human societies. But during my childhood, chimps were portrayed on the TV as loveable clowns: just think of the Tarzan films or adverts for PG Tips.

However, in my opinion there is something else in the human condition that leads us to be infatuated with chimps. And it is not that they are the most cute and cuddly looking animal. That title goes to the giant panda. Instead it is to do with our human propensity to be voyeurs: we love to watch other people.

Interesting people are those who put on public display their loves, hates and passions. The problem is there is only so much staring and gawping that interesting people (celebrities aside) will tolerate. Chimps provide an alternative outlet for our fascination with others.

What’s the gossip?
Nataša Stuper/flickr, CC BY

Chimps are passionate, scheming, aggressive animals. In many ways they seem to represent the human condition in its most elemental state. When we observe them we are looking at ourselves. But they act without the restrictions that polite society puts on us. And in zoos on wildlife documentaries, groups that are used to being watched by humans are not shy about expressing their desires, be they sexual or otherwise. In other words they are a voyeur’s dream.

To watch a group of chimpanzees is to watch a soap opera unfold before your eyes, but without the pretence of time passing quickly. They live life in the fast lane. Just as one example, chimpanzees are 100 to 1,000 times more aggressive than humans. Even TV soap operas do not show this much action happening in short spaces of time.

Not-so human drama
Tambako The Jaguar/flickr, CC BY-ND

If a male chimp is angry with someone or something then he lets them know in no uncertain terms. This happens not just in terms of bashing things, but also through pronounced facial expressions such as bearing teeth. I think we humans are jealous of chimps because they can vent their aggressive feelings without societal disapproval.

A friend of mine use to work on a project observing captive giant pandas, the world’s most marketed animal. But despite their cuteness they were boring to watch, just eating bamboo, sleeping, defecating every half hour and mating once a year. I challenge anyone to spend a whole day observing them. They just have too little behavioural diversity, expressing interesting behaviours such as aggression or sex at very low frequencies.

Chimps also have a caring side. Once they have attacked and beaten another individual, they will soon go over and give them a hug to prevent this negative interaction spiralling out of control. They show empathy towards sick members of their group. Older individuals are tolerant of the capers of the younger individuals. They live in a loving society where individuals hold hands, hug and kiss in the manner of people from Latin countries. And their partiality to a spot of alcohol has now generated much excitement.

Even when chimps are sitting around doing nothing, as a human observer you sense that something interesting could happen at any second. They never seem to have vacant expressions even when they are resting. They appear to be scheming away, working out how to manipulate other members of their group for food, friendship or sex. Chimps give the impression of being intelligent without the need to be making and using tools to procure food – just sitting down will do.

Cuddle time
Carlos López Molina/flickr, CC BY-NC-ND

Finally, chimps display remarkably strong personalities. Just one day of watching a group in a zoo is enough for you to determine their characters. Some are bold, others timid. Some are very agitated, whereas others seem serene. It is this blend of personalities that creates interesting group dynamics and the script for their soap operatic lives.

We are addicted to chimps because they let us spy on their lives, lives that are so rich and amazing that one, whose name was Flo, even had her obituary published in the Sunday Times newspaper.

The Conversation

Robert John Young is Professor of Wildlife Conservation at University of Salford

This article was originally published on The Conversation. Read the original article.

Tornquist feral horses WE

Atlas entry registered by Dr. Alberto Scorolli, based on work and research carried out with the feral horses at  Ernesto Tornquist Provincial Park (website).


Country: Argentina                                                                                                          Region/Province/Range: Ernesto Tornquist Provincial Park (ETPP) – Buenos Aires

Species: Equus caballus             Subspecies/Breed/Type: Feral Creole

Estimated Population size: +/- 400 horses (2014)

Management Authority:  Ernesto Tornquist Provincial Park (ETPP)

Management Practices: Population Management Strategy is urgently needed

 

Ernesto Tornquist Provincial Park (ETPP) is located in the south of the Province of Buenos Aires, Argentina, between 38 º 00’- 38º 07’S and 61º 52’- 62º 03’W.  This natural reserve was established in 1938 and covers 67 Km2 of hilly grassland with heights ranging between 450 and 1175 m above sea level. The climate is temperate and humid (Burgos 1968) with a mean annual rainfall of 800 mm. Rains fall mainly in spring with a second peak in autumn. Snowfalls are occasional and, in general, light. The typical vegetation is grassland steppe dominated by species of the genera Stipa and Piptochaetium (Cabrera 1976; Frangi and Bottino 1995).
This Natural Protected Area is very important for biodiversity conservation as it includes many endemic plant and animal species (Kristensen and Frangi 1995). In 1942 a small group between 5-10 horses, which became feral, were introduced to ETPP. In 1995, their descendants, 450 horses, occupied a fenced-off sector of approximately 20 Km2 (Scorolli 2007). These horses were of Creole breed, like all other feral horse populations in Argentina. This breed has originated from Spanish and Andalusian horses, of essentially African barb ancestry, brought to South America by the colonizers during the XVI century (Cabrera, 1945).

Structure and demographics

Currently approximately 40 harem-bands, most single stallion H-Bands. Population size in year 2014 400 feral horses, sex ratio 1:1. adult+sub-adult+yearling: foals (7:1).

Issues worth noting and needed actions

Current density 20 horses/km2, in year 2001-2002 population was food-limited, approaching carrying capacity and reaching 35 horses/km2 (annual mortality more than 80 horses/year).
In 2014 after a massive fire in January and a exceptionally rainy year (highest in decades) the body condition is good and the demographic potential to increase is also high!!
A Population Management Strategy is urgently needed in order to reduce current population size to appropriate levels that preclude high mortality by starvation and environmental impact in a natural protected area created by its grassland biodiversity unusual value.
There is a conflict between government authorities and some horse protection groups that see management as unacceptable.


Bibliography and Further reading

Scorolli, A.L., A.C. Lopez Cazorla and L.A. Tejera. 2006. Unusual mass mortality of feral horses during a violent rainstorm in Parque Provincial Tornquist, Argentina. Mastozoología Neotropical 13: 255-258.
Scorolli, A.L. 2009. Feral horse management in Argentina. In 10th. International Mammalogical Congress. Mendoza, Argentina.
Scorolli A.L. y López Cazorla. 2010a. Demography of feral horses (Equus caballus): a long-term study in Tornquist Park, Argentina. Wildlife Research 37: 207-214.
Scorolli, A. and A. Lopez Cazorla. 2010b. Feral horse social stability in Tornquist Park, Argentina. Mastozoología Neotropical 17 (2): 391-396.
Scorolli, A.L. 2012. Feral horse demography and management in Tornquist Park, Argentina.  International Wild Equid Conference. VetMedUni, Viena.
Scorolli, A.L. 2012. Feral horse body condition: a useful tool for population management?. International Wild Equid Conference. VetMedUni, Viena.
About potential environmental impact
de Villalobos, A.E. and S.M. Zalba. 2010. Continuous feral horses grazing and grazing exclusion in mountain pampean grasslands in Argentina. Acta Oecologica 36: 514-519.
de Villalobos, A.E., S.M. Zalba and D.V. Peláez. 2011. Pinus halepensis invasion in mountain pampean grassland: Effects of feral horses grazing on seedling establishment. Environmental Research 111: 953-959.
Loydi, A. and S.M. Zalba. 2009. Feral horses dung piles as invasion windows in natural grasslands. Plant Ecology 201: 471-480.
Loidy, A. and R.A. Distel. 2010. Diversidad florística bajo diferentes intensidades de pastoreo por grandes herbívoros en pastizales serranos del Sistema de Ventania, Buenos Aires. Ecología Austral 20: 281-291.
Loidy, A., R.A. Distel and S.M. Zalba. 2010. Large herbivore grazing and non-native plant invasions in montane grasslands of central Argentina. Natural Areas Journal, 30(2): 148-155.
Zalba S.M. and N. Cozzani. 2004. The impact of feral horses on grassland bird communities in Argentina. Animal Conservation 7: 35-44.

Affiliative (af)

A review of literature on the social behaviour of horses is likely to lead many to think equine society is governed solely by the establishment of social hierarchies, usually based on the outcomes of social conflict or competition, commonly referred to as agonistic behaviour.

The description of animal societies is mainly based on agonistic classifications, in which cooperation and affiliative behaviour were overshadowed by the competition-aggression-reconciliation paradigm generally emphasized by many writers.

Affiliative interactions [af] refer to the activities between two or more (dyadic, triadic, poliadic) individuals within a social group with the function of developing, maintaining or enhancing social bonds. {Equus Ethogram Project}

Affiliative is from Medieval Latin; affiliatus, past participle of affiliare to adopt as a son, from Latin ad- + filius son

konik stallions mutual grooming

Indeed, agonistic and affiliative behaviour are inextricably intertwined (Price & Sloman, 1993) in the complexity of social interactions, making it a laborious task to filter away the units of behaviour neatly into separate compartments for either one type of interaction, or the other.

Social interactions lay on a behavioural continuum, a continuous stream of movements  (Fentress, 1990; MacNulty et al, 2007) or spectrums of behavior (Abrantes, 2011):

“The distinction between any two behaviour is a matter of function; the borderline separating one category from the other is a matter of observational skill, contextual parameters and convention; the way we understand it all is a matter of definition.” (Abrantes, 2011)

For instance, in the ‘Agonistic ethogram of the equid bachelor band’ published by McDonnell & Haviland (1994), agonistic encounters were considered based on their intensity, running or flowing across a spectrum from “very quiet affiliative behaviour to serious aggression” (McDonnell & Haviland, 1994).

In this Equus Ethogram Project, affiliative interactions will be classified separately from agonistic ones, at least when at all possible. A host of authors have extracted units of agonistic behaviours from the interwoven fabric of equine social interactions, so it should be likewise possible to extract those other units of behaviour which promote group cohesion: affiliative behaviours.

DSC03382

The results of a growing body of research on free-living mammals suggests that affiliative social interactions, those enhancing social bonds, have important fitness consequences for individuals ( Swedell, 2002; Weidt et al, 2007; Silk et al. 2003, 2010; Cameron et al. 2009; Frere et al. 2010; Wey & Blumstein 2012) engaged in them.

In horses as in most social mammals, affiliative interactions are usually described by mutual grooming, play and group resting. This ethogram considers including more subtle forms of affiliative behaviour, such as the frequency or duration one individual is found sharing close proximity with others as an indication of their level of bonding (Hinde 1976; Garai 1992; Kleindorfer &Wasser 2004).

This Equus Ethogram Project is an on-going work, and the general framework, or particular sections and pages will be updated as new light is shed or brought to our knowledge.

Caging horses

Versión Español

Standard practice in the horse world dictates that horses be stabled, and provided with food, water and a place to rest. This minimalistic requirement for keeping horses in stables is a clear limiting factor for the horse’s expression of normal behavioral repertoires which undoubtedly compromises well-being and welfare.

A stall, whether you are selling vegetables in a local market, or using the same for confining your horse, usually refers to a small compartment. Small compartments for confining animals are referred to as cages.

Even the best of stalls are just glorified animal compartments, barren environments where horses are incapable of, or not allowed to, interact naturally with conspecifics or carry out the daily activities they would engage in, in free living or even enriched conditions.

This may be quite hard to digest for the majority of “naked apes”, as our life history is quite different to theirs.  With best intentions in mind, we confine them from extreme weather, keep them away from other horses that could potentially injure them, and lock them up for their own well-being, and of course our own peace of mind. We strive to feed them the best quality feed, usually the expensive stuff, based on counsel from professionals or even just because that is what has always been done.

Confinement in cages, stalls or even aquariums in most cases prevents animals from engaging in behaviors exhibited when living in free conditions and this in turn is well known to cause suffering and distress.

Band stallion mounting mare

Lately there has been a huge interest in improving the quality of life of captive and domestic animals which have led to the development of environmental enrichment, which in turn offer stimulation and opportunities to express species-specific behaviors.

An example from the father of Zoo Biology, Heini Hediger (1955), was an enrichment he provided in the Zurich Zoo to captive zebras.  During one of his trips to Africa, he noticed that many termite mound tops had been polished or rubbed away. Zebras would come along and rub themselves on these mounds as part of their grooming activities. In the zebra enclosure back in the Zurich Zoo, a cement make-believe termite mound was placed and the zebra were reported to be so excited by this enrichment that they rushed to it with such enthusiasm as to topple them over. Once these makeshift mounds were reinforced, Hediger reported that the mound “has been in daily use ever since” (Hediger, 1955).

On another note, Ernst Inhelder, a Swiss zoologist, studied species kept in impoverished or barren enclosures. He noted that animals kept in these conditions carried out repetitive stereotyped meaningless activities, such as walking back and forth a short distance, literally treading on their own footsteps.

Similar studies were carried out on laboratory animals and for example; rabbits were found to head sway, bite bars or walk in circles. (Morton et al., 1993). The same was true for birds (Morris,1966), carnivores (Fox, 1986), rodents (Baenninger, 1967; Wiedenmayer, 1987; Würbel et al., 1998; Callard et al., 2000; Reinhardt and Reinhardt, 2001a) and primates (Erwin and Deni, 1979; Poole, 1988; Harris, 1989).

In an attempt to improve conditions through cage size, Galef and Durlach (1993) as well as Bayne and McCully (1989), found that cage size does not necessarily reduce stereotypy. This is to be expected as it is the impoverished environment that is likely to be causing the stereotypies and not only the size of the cage.

Open stalls, or mini paddocks have been recently provisioned in many riding centers, precisely in an attempt to enrich the life of their horses. These open compartments are still barren and lack enrichment, especially of the social kind. But they are better than a kick in the bum!

A stereotypy is a ritualistic and repetitive type of behavior that serves no apparent function.  Here a quote from Katherine Houpt:

“For years, we’ve called behaviors like these stall or stable “vices.” The first part of the name is right—with the exception of fence-walking, a horse doesn’t do these things unless he’s in a stall. But the “vice” part isn’t correct, according to modern research, which indicates these actually aren’t bad habits per se, but simply the reactions of horses that aren’t getting what they need.” Katherine Houpt, from Stable Vice or Stereotypie?

Despite domestication, animals largely retain the basic behavioral repertoire of their wild counterparts. There is little evidence suggesting that the process of domestication has resulted in the loss of behaviors from the species specific repertoire (Price, 1999), or that basic motor patterns associated with the species repertoire have changed (Scott & Fuller, 1965; Hale, 1969; Miller, 1977).

“Domestic animals are sometimes provided with an environment that is physically similar to the habitat of their wild ancestors. Behavioral and physiological adaptations to such an environment will be readily achieved. Very often, however, the captive environment does not match the ancestral environment and adaptation is challenged. “ (Price,  1999)

It is no surprise that when these animals are taken out of their “boring”, isolated and rather barren confines most will react to novel stimuli with fearful or even aggressive behavior. It seems that horses “(…) show a compensatory increase in activity when released from their stalls (Houpt et al., 2001).

Social isolation is a disturbing experience for horses, and isolated subjects show behavioral and physiological stress reactions (Mal et al., 1991).

It is in the light of all exposed above that we must consider that horses confined or isolated in barren environments such as those of conventional battery stalls, or cages are insufficient in providing desirable behavioral well-being, as they cannot perform the majority of their species specific behavior, fleeing, engaging in normal social behavior, explore the environment, exercise or even graze or walk.

In the end, it is really up to you whether you decide to cage your horse or not.

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Affiliative behavior in Equus caballus

Introduction

A review of literature on the social behavior of horses is likely to lead many to think equine society is governed solely by the establishment of social hierarchies, usually based on the outcomes of social conflict or competition, commonly referred to as agonistic behavior.

Agonistic interactions are social activities “related to fighting, whether aggression or conciliation and retreat.” (Wilson, 1975)

“Behavior patterns associated with fighting and retreat, such as attack, escape, threat, defense and appeasement.” (Slater, 1999)

The description of animal societies is mainly based on agonistic classifications, in which cooperation and affiliative behaviors were overshadowed by the competition-aggression-reconciliation paradigm generally emphasized by many writers.

Affiliative interactions refer to the activities between two or more (dyadic, triadic and so on) individuals within a social group with the function of developing, maintaining or enhancing social bonds. {Equus Ethogram Project}

konik stallions mutual grooming

Indeed, agonistic and affiliative behavior are inextricably intertwined (Price & Sloman, 1993) in the complexity of social interactions, making it a laborious task to filter away the units of behavior neatly into separate compartments for either one type of interaction, or the other.

Social interactions lay on a behavioral continuum, a continuous stream of movements  (Fentress, 1990; MacNulty et al, 2007) or spectrums of behavior (Abrantes, 2011):

“The distinction between any two behaviors is a matter of function; the borderline separating one category from the other is a matter of observational skill, contextual parameters and convention; the way we understand it all is a matter of definition.” (Abrantes, 2011)

For instance, in the ‘Agonistic ethogram of the equid bachelor band’ published by McDonnell & Haviland (1994), agonistic encounters were considered based on their intensity, running or flowing across a spectrum from “very quiet affiliative behavior to serious aggression” (McDonnell & Haviland, 1994).

In this Equus Ethogram Project, affiliative interactions will be classified separately from agonistic ones, at least when at all possible. A host of authors have extracted units of agonistic behaviors from the interwoven fabric of equine social interactions, so it should be likewise possible to extract those other units of behavior which promote group cohesion: affiliative behaviors.

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The results of a growing body of research on free-living mammals suggests that affiliative social interactions, those enhancing social bonds, have important fitness consequences for individuals ( Swedell, 2002; Weidt et al, 2007; Silk et al. 2003, 2010; Cameron et al. 2009; Frere et al. 2010; Wey & Blumstein 2012) engaged in them.

In horses as in most social mammals, affiliative interactions are usually described by mutual grooming, play and group resting. This ethogram considers including more subtle forms of affiliative behavior, such as the frequency or duration one individual is found sharing close proximity with others as an indication of their level of bonding (Hinde 1976; Garai 1992; Kleindorfer &Wasser 2004).

This Equus Ethogram Project is an on-going work, and the general framework, or particular sections and pages will be updated as new light is shed or brought to our knowledge.

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Herding behavior

Similar to  herdsmen or shepherd dogs herding their flocks of sheep, stallions herd or drive conspecifics  controlling their direction and speed, and this is usually referred to as herding or driving behavior (Tyler, 1972; Feist & McCullough, 1976; Lucy Rees, 1986; McDonnell, 2003).

Stallions have been observed to adopt a species specific herding posture (Berger, 1986) characterized by lowering their heads, stretching out their necks, pinning back their ears, and moving forward toward the targeted conspecifics. If we breakdown the herding posture to its component parts we would find a conglomerate of behaviors which may be interesting to consider on their own. The pinning in a backward direction of the ears, or Ears Laid Back (McDonnell, 2003), or Ears Retracted (Berger, 1986), is typical of a threat posture or expression (Tyler, 1972) as is the Head Threat (McDonnell, 2003) in which the head is pointed forward with neck extended and it is usually associated with agonistic encounters.

The targeted individuals typically responded by moving in the opposite direction from which the stallion was approaching. According to Tyler (1972), ocassionally the stallion would have to gallop in front of the group to ensure that mares did not straggle from the rest of the group in higher intensity movements.

The vigour or intensity of this behavior is assumed to correspond to how low the head is dropped and the general speed and gait adopted by the stallion. Not only that but how far ears are pinned in a backward position may also be indicative of intensity.

Additionally stallions may move the head from side to side in a snake-like fashion usually referred to as snaking movement, or head tossing (Berger, 1986). So, if a stallion approached with the herding posture at a walk, it was most common that the targeted conspecific/s would respond in a similar pace.

Stallions usually approached from the rear pushing the individuals forward, but they also approach from slightly to one side in order to direct movement.

Feist & McCullough (1976) observed this behavior in their study of the Pryor Mountain  feral horses of Montana. From a total of 139 instances wherein stallions were recorded to perfom this behavior, they noted that 42% (n=55) of these corresponded to stallions herding or driving their band away from other bands or stallions, in 30% (n=39) stallions where guiding the direction of movement of their bands while on the move, 12% (n=15) of the time stallions singled out a mare for courting, in 12% (n=15) stallions drove  non-band members away from theirs, and in the remaining 4% (n=6) stallions herded-in new members.

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If you are a photographer or happen to have images related to this topic, and wish to share them, please do contact us. We could surely use them, and would appreciate it greatly!

This is a work in progress under our ongoing Equus Ethogram Project, further information and suggestions are welcome and will contribute to further updates.

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Reference list

Berger, J. (1986) Wild Horses of the Great Basin The University of Chicago Press, Chicago, IL

Feist, J.D. and D.R. McCullough (1975) Reproduction in feral horses. J. Reprod. Fert., Suppl. 23:13–18.

Keiper, R. (1985) The Assateague Ponies. Tidewater Press, Cambridge, MD.

McDonnell, S.M. (2003). A practical field guide to horse behavior: The Equine Ethogram. Lanham,US.: The Blood-Horse, Inc.

Rees, L. (1984). The Horse’s Mind. London: Stanley Paul.

Tyler, S. .J (1972) The behaviour and social organization of the New Forest ponies. Anim. Behaviour Monographs 5 (2): 85-196.