Personality
We should take care not to make the intellect our god; it has, of course, powerful muscles, but no personality. ~ German physicist Albert Einstein
Animals possess individual personalities, as do plants. Though it is hard to tell, microbes do as well. Personality is a basic facet of life, along with consciousness, mind, and body.
In promoting diversity and unpredictability, personality is a basic evolutionary stratagem. Variations in personality persist in populations because it improves survival odds under a range of conditions as well as making life more interesting.
Sharks were long thought to lead solitary lives, albeit occasionally coming together for feeding or breeding. Instead, sharks are social; or at least some are – it depends upon personality. Some sharks gregariously enjoy the company of others and share strong social connections. Others prefer solitude and to remain inconspicuous.
Flocks of birds navigate well in close quarters partly because of personality. Individuals may be biased to wing their way to the left or right. Having found their desired positions, personal inclinations let a flock fly past an obstacle quickly by splitting up without crowding or slowing down.
Shy brown trout do better in the wild than bolder ones, but not nearly as well in aquariums as more assertive trout, who grab most of the food. Trout learn and change behaviors to fit circumstance, but their underlying personality remains.
While personality has a biological basis, its development and maintenance depend upon long-term memory.
Personality most clearly shows in willingness to take risks. The best bee foragers are those with a sense of adventure.
Fish can learn to follow, but struggle to learn to lead. ~ Japanese biologist Shinnosuke Nakayama
Easy leadership of a fish school is innate. Leaders are born bold.
When swimming together, conformity is essential to efficient formation. Fish subdue their personalities when in a shoal or school.
The behaviour of the fish seems to be ‘plastic’ to the social situation. They show personality but are happy to suppress this if there are others around. ~ English zoologist Christos Ioannou
In protecting their nests against intruders, the most aggressive fish are the small ones, who psychologically compensate for their size. This is commonly referred to as the Napoléon complex, after the chronic aggressiveness displayed by French military and political leader Napoléon Bonaparte, a man of oversized ambition. (Some short men are known to compensate for the social disadvantage of low height with aggressiveness. Bonaparte’s chronic aggressiveness was attributed by his enemies to his being short. But Bonaparte was average height for his time (1.57 m).)
Relative boldness and assertiveness are personality traits in all animals. These attributes vary for an individual at different times. Any animal can have an especially grouchy or contented day.
Some birds are inclined to exaggerate their aggressiveness whereas others underplay it. What might be considered an honest signal may be a bluff. Depending upon personality, certain song sparrows may threaten attack but not follow through.
Other birds may have the confidence to keep relatively quiet but successfully stand their ground if attacked. Such under-signaling is hard to explain by itself. It may serve well in saving energy, and in earning a reputation as one tough bird who keeps his beak to himself.
Proactivity can be counterproductive. Red squirrel mothers that are more passive do better rearing pups when food is scarce than proactive ones, who waste energy when it cannot be afforded. When food is more plentiful, a go-getter mom has a healthier litter.
Sometimes living large has little to do with risk and more with robustness. Male crickets with a higher metabolism call to attract mates more often than those with less get up and go. Animals that keep themselves in shape lead healthier lives.
Fear is the major source of stress for animals. Fish with less fear are more aware and fare better. The same applies to other animals.
Timid birds are more stressed and less healthy those with courage and curiosity. Nestlings that feel stressed are less assertive about demanding food from their parents. It affects their long-term health.
Dunnocks at the Botanical Garden
Animals choose the habitat that best fits their personality. Personality plays a role in shaping population structure. ~ German zoologist Benedikt Holtmann
People choose to live in certain places based upon personality. Birds too.
Dunnocks (aka hedge sparrows) are a small perching bird found in temperate Eurasia. Dunnocks were introduced into New Zealand in the 19th century, and now happily reside throughout.
Benedikt Holtmann and colleagues researched the dunnocks residing at Botanic Garden in Dunedin, New Zealand. The Garden is open to the public, but certain areas are more frequently visited by people than others. Hedge sparrows have small territories, so a measure of human disturbance in a territory may be made with some precision.
99 dunnocks were surveyed. Threat tolerance was estimated by walking toward a bird and measuring how close one could get before the hedge sparrow flew away. This proximity tolerance proved consistent over several seasons, except that birds got a bit bolder with age: knowing more about the world and adjusting perceived margins of safety accordingly. Such worldly wisdom was minor compared with the intrinsic differences in boldness or timidity that individual dunnocks had. Whereas shy hedge sparrows wanted territories uninfringed by human presence, braver birds contentedly settled in spots where hairless apes might occasionally appear.
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Personality is attenuated by experience. Animals learn and alter their behavioral responses.
Each mouse lemur has its own personality. Males tend to be shy when young, becoming more audacious as they grow up. Bold males have more mating success.
Appetite for risk can be part of diet. Blue tits like to feed their chicks spiders. Spiders are rich in taurine, an amino acid found in mammal breast milk, known to help premature babies develop. Tit chicks fed spiders were bolder and better learners than those not on an abundant arachnid diet.
In predator-prey interactions, the personalities of the individuals involved weigh heavily in the outcome. A persistent predator spells bad luck for those hunted. A bold prey facing a hesitant predator stands a better chance of surviving than the reverse situation.
Personality affects mating prospects. In species where a female selects her mate, favor goes to males with pronounced personalities. A bold young bighorn sheep ram can seduce an ewe away from an older dominant male.
Flycatcher males that take a more exposed stage and sing like they mean it have a better chance of taking a mate than birds more safely perched. Adventurous zebra finch females prefer a dashing male regardless of his other assets.
Zebra finch couples with similar personalities make better parents, as the inevitable conflicts in couples with opposite personalities affects the prospects for their offspring. Especially in species with shared parenting, females are receptive to predictable males.
Well-matched mates can make a considerable difference in parenting quality. Blue tit males that don’t find their partner attractive are likely to be less attentive providers. But then, drab blue tit females are not particularly good mothers; an illustration of how looks and personality may go together.
The matching of personalities is a factor in the mating of many species, including vinegar flies, guppies, and side-blotched lizards. Bold is not always best.
An overly aggressive male water strider may spoil the mating prospects for his fellows. Female water striders avoid groups of males when even 1 in the group is hyperaggressive.
The personality of a small number of individuals in a group can have considerable effect on the whole group’s fortunes. A barnacle goose, shy or bold, fares better foraging in the company of a goose with gumption.
Personality can permit greater exploitation of available resources. When stickleback fish are feeding in densely populated waters, they tend to specialize on specific food sources depending upon personality, particularly willingness to contend with others. Some go for critters in the rocks, while others are pacified feeding on plankton.
All but a few of the 90,000+ species of spiders are peevish loners, each making its own way with silk and cunning. 25 spider species are social: pooling their powers to exploit resources that elude sole practitioners.
Stegodyphus mimosarum is a small social spider that lives in colonies of 20–300 individuals, weaving huge communal webs over the bushes and trees of the Kalahari in southern Africa. Spider communities gain their strength through division of labor determined by personality. Industrious members specialize in web repair and caring for the young, while the brazen ones relish capturing prey and defending the colony. Spider personalities develop gradually via social interactions.
The longer the spiders were with the same individuals, the stronger their personalities became, and the more different they became from each other. ~ American ethologist Jonathan Pruitt
Comb-Foot Spiders
They’re great thieves. ~ Johnathan Pruitt
Shy and sly can go well together. Female comb-footed spiders may live alone or share web weaving and hunting duties with roommates. A colony of these tiny spiders may number up to a dozen.
As a keystone species, a colonial comb-footed web can attract other spider species to weave their webs nearby, forming a web network. In these multispecies webs, the personalities of even 1 individual in the comb-foot group can make a difference.
An aggressive comb-foot may be so bold as to pick a fight with another spider 20 times her size. A brawl may ensue, with her roommates are drawn into the conflict. Such scrappy females don’t fare well: producing fewer offspring and facing the prospect of dwindling away.
More sociable spiders share space contentedly and stealthily, if at least 1 of the comb-foots in the group is shifty enough to steal food from the neighbors. Such illicit windfalls allow the comb-foots to thrive and reproduce abundantly. The downside to being docile is that the spiders may not be as adept at defense if attacked.
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Animal personality can play a powerful organizational role in a social system. ~ Jonathan Pruitt
Anelosimus studiosus is a comb-foot spider that can be either asocial or gregarious. A. studiosus increasingly become colonial in habitats with harsher winters, where cooperation pays especial dividends.
A. studiosus spiders have distinct personalities: some are assertive, others more docile. They naturally take to doing tasks befitting their character. Assertive females tend toward capturing prey, building webs, and defending the colony, whereas meeker spiders mother: caring for offspring in the colony crèche. Food is shared among all.
Docile spiders are much better parents than aggressive spiders. ~ American ethologist Colin Wright
Colonial A. studiosus tend to be more closely related than their solitary sisters, as well as being typically less aggressive, and thereby more sociable.
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Social animals fare better in groups with a mixture of personalities. Ant colonies are more successful when workers have considerable variation in their aggressive tendencies.
Fish with loner tendencies school but never build to large populations, as they keep moving on to avoid the crowd. A mixed school of social and asocial fish have the most success in population growth.
