Tag Archives: animal behavior

Sleeping bear.

Wildlife is shifting activity to nighttime because they don’t want to run into humans

Humans are bugging wild animals — so the critters are staying hidden during the day.

Sleeping bear.

Image via Pixabay.

Animals are finding that the best way to deal with those pesky humans isn’t to go live someplace else, but to start living during the night. The findings, published by researchers from the University of California–Berkeley and Boise State University, show that previously-diurnal animals are shifting activity during night hours to avoid humans.

Under the cover of darkness

The team analyzed 76 studies involving 62 species of mammals on six continents, from opossums to elephants. These studies looked at how individual species changed their behavioral patterns in response to human activity such as hunting, farming, or development. Each study used some sort of technique to follow animals, from GPS trackers to motion-activated cameras.

The team then compared how much time those creatures spent actively at night under different types of human disturbance. One common feature all the surveyed animals shared was that they became far more active at night after humans arrived, the team reports. On average, they found that human presence triggered an increase of about 20 percent in nighttime activity, even in animals that aren’t normally night owls. Strikingly, the animals even delegated critical tasks such as hunting and foraging for nighttime activity. The team further reports that mammals which used to split activity roughly even between the day and night also shift more strongly towards darker hours — on average, these species increased nighttime activity to 68%.

It also became apparent that human activity doesn’t need to directly impact these species to determine a change in behavior. The team notes that all species responded similarly to human encroachment in their habitats. A deer, for example, will shift activity towards nighttime regardless if the humans it sees are hunters or hikers.

“It suggests that animals might be playing it safe around people,” Kaitlyn Gaynor, an ecologist at the University of California, Berkeley, who led the study, told PBS. “We may think that we leave no trace when we’re just hiking in the woods, but our mere presence can have lasting consequences.”

This shift in activity does help humans and animals coexist with less friction, the team notes. The findings might also help us design better conservation strategies that take into account species’ patterns of activity.

However, there’s also cause for concern. A nocturnal lifestyle can impact an animal’s ability to get food or mate, impacting the short- and long-term stability of whole species. This, ironically, also defeats the purpose of shifting activity in the first place. If animals are becoming more active at night to avoid us, but that only makes life harder for them, have they really escaped the impact of human activity?

The paper “The influence of human disturbance on wildlife nocturnality” has been published in the journal Science.

longhorn crazy ants

How crazy ants carry dinner 100 times their size: coordination and individual leadership

Different ant species employ various tactics to forage food and keep the colony in tip top shape. Most often scouts will scour for food, and when a source is deemed fit a trail of pheromones guide worker ants to pick up the crumbs, leftover pizza or cheerios. Ants aren’t very picky, you know. What they are is very strong. It’s common knowledge that ants carry loads multiple times heavier than their own weight. Some species, like longhorn crazy ants are able to carry some of the biggest loads among ants by working together, joining in a band to perform the lifting. It’s a curios matter, one you might have often noticed in your very own backyard.

longhorn crazy ants

Longhorn crazy ants work together to move great loads.

Simply by watching the longhorn ants, assisted of course by the latest motion tracking technology, a team of researchers at  the Weizmann Institute of Science in Israel documented this collaborative effort, which is quite rare in the animal kingdom. The ants in question are labeled as crazy because of the erratic paths they make to and fro foraging sites, often moving in zig-zag. It didn’t register at the beginning, but soon enough Ofer Feinerman of Weizmann found the ant brigade’s chaotic behavior made sense and in doing so found that ants – individual ants – are a lot smarter and independent than we might think.

Imaging having to move a couch down stairs or past a block with your friends. If each would pull and tug in his own direction, then the couch won’t go anywhere and all of your collective efforts would have been spent for nothing. By carefully coordinating yourselves, you and your friends can move that couch. For this to happen, there needs to be a leader: “be careful, there’s a turn there”, “slug it this way” and so on. The leader of the couch-moving maneuver can, of course, be anyone in the group, taking turns. The crazy ants work in a similar way, the researchers found.

Fresh help arrives to help the movers.

Fresh help arrives to help the movers.

The researchers placed longhorn crazy ants in a dotted arena littered with obstacles, but also food. By carefully analyzing their movements, the team built a model that revealed the band of ants move food by keeping their brigade fluid. When the ant brigade teams up to carry a load, after a while they lose sense of the track they need to take. So a leader scouts a bit ahead, returns to the pack a pulls the weight towards the right direction. The ants take turns as a the leader, with each ant taking on the role for as little as 10 to 15 seconds. This explains the zig-zag.

“The individual ant has the idea of how to pass an obstacle but lacks the muscle power to move the load. The group is there to amplify the leader’s strength so that she can actually implement her idea”

The ants eventually managed to tug this huge load for 16 centimeters. They were unable, however, to navigate it past obstacles.

The ants eventually managed to tug this huge load for 16 centimeters. They were unable, however, to navigate it past obstacles.

When the load is too great or when there are too many obstacles, the ants can’t seem to carry the load. They have the muscle power to do it, though. Just bring in more ants. The larger the group, the harder it is to coordinate the whole movement, though. So, there’s a certain sweet spot, the researchers say.  “Too many cooks spoil the broth,” says Vijay Kumar, a mechanical engineer at the University of Pennsylvania who studies collective animal behavior who wasn’t part of the study.

“Usually when people talk of ants they have this very romantic view that one ant is really stupid, but if you take many ants you get something very smart—an emergence of intelligence or something like that,” says Feinerman. “If you look at this system it looks like the intelligence of knowing where to go and how to pass obstacles does not come from the big group. The big group just gets stuck at the big obstacle and they never pass it. The problem-solving abilities come from the single ant who knows which way to go to pass the obstacle.”

This male mouse has left brownish scent marks by depositing pheromone-rich urine on a fence separating his territory from those of other mice. (c) Doug Cornwall, University of Utah

Promiscuous female mice breed sexier male offspring. Research may help conservation efforts

University of Utah researchers found that female mice that live in a competitive social environment and choose to mate casually with multiple partners give birth to males who are much more attractive to female mice, at the cost of a dramatic cut in life expectancy however. You only have one life, says the sexy male mouse.

The research is a fantastic example of epigenitics at work –  how parents’ environment modifies their offspring’s genes; in other words, not only do parents’ gene count, but also a great contribution in the overall offspring genetic mark-up depends on the environment.

“If your sons are particularly sexy, and mate more than they would otherwise, it’s helping get your genes more efficiently into the next generation,” says biology professor Wayne Potts, senior author of the new study.

“Only recently have we started to understand that environmental conditions experienced by parents can influence the characteristics of their offspring. This study is one of the first to show this kind of ‘epigenetic’ process working in a way that increases the mating success of sons.”

A promiscuous family

Typically, lab mice breeding is skewed from the animals’ natural conditions. Domesticated mice are generally monogamous and hardly touch each other in the cage – go figure.   “In nature, mice must seek out and choose their own mates – a process that is eliminated in standard lab breeding conditions,” says   University of Utah doctoral student Adam C. Nelson.

This male mouse has left brownish scent marks by depositing pheromone-rich urine on a fence separating his territory from those of other mice. (c) Doug Cornwall, University of Utah

This male mouse has left brownish scent marks by depositing pheromone-rich urine on a fence separating his territory from those of other mice. (c) Doug Cornwall, University of Utah

To simulate seminatural conditions, the researchers bred mice in a  22-foot-by-13.5-foot enclosure (mice barn),  divided by wire mesh fencing into six sections or territories which were easy to cross in and out by the mice. However, some of these territories were made more appealing than others, as they had more food, water or a more spacious nest box. So, the mice had to compete with each other – almost like in natural conditions. As a measure of control, the mice which were introduced descended from wild mice and were bred for 10 consecutive generations  in domesticated conditions: in cages with assigned mates.

Prospective parents first lived in one of two environments: the promiscuous mouse barn or monogamous cages. They were removed after eight weeks and bred in cages in four combinations: mother and father from promiscuous environment; both from monogamous environment; mother from promiscuous environment and father from monogamous environment; and vice versa.

Regardless of the father’s origin, the researchers found that females which came from promiscuous environments gave birth to sons which  produced more pheromones than sons of monogamous, domesticated moms.  More than just a classy perfume, mice pheromones are a sex magnet and the stronger the scent, the harder it is for females to resist the call. Hey, guys, stop looking for deodorants online now – it doesn’t work for humans that way.

Back to pheromones. Yes, lady mice love these, understandably: the more the male’s scent is saturated with  pheromones produced in mouse urine and other glands the more the said male with mate. Apparently, male mice who came from promiscuous parents produced 31 percent more major urinary proteins or “sexy” pheromones  than male mice from caged monogamous parents. Previous research established that male mice with promiscuous parents actually produce about one-third more progeny than sons of monogamous parents.

It’s clear that the social life of female mice has a great impact on their male offspring, something that is described through epigenetic inheritance. In epigenetic inheritance, however, genes aren’t mutated, instead genes are either activated or expressed. So, epigenetics deals with gene modification and a common mechanism is methylation , a change that reduces a gene’s production of a protein.  In the new study, Nelson and co-authors looked at a pheromone gene named Mup11. They found that methylation of the gene was twice as high in sons of monogamous, domesticated mice than it was in sons of promiscuous, social mice. So the sons of the promiscuous mice were able to produce more pheromone.

Sexy to die for

This illustration depicts how the researchers liken the way mouse pheromones act much like a male peacock’s tail to attract mates. Illustration by Sarah Bush, University of Utah

This illustration depicts how the researchers liken the way mouse pheromones act much like a male peacock’s tail to attract mates. Illustration by Sarah Bush, University of Utah

You win some, you lose some. Apparently, those enhanced pheromones come at a huge price tag, though. n. Only 48 percent of them lived to the end of the experiment, compared with 80 percent of the male mice whose parents lived monogamously in cages.

“Production of pheromones is outrageously expensive,” says biology professor Wayne Potts, senior author of the new study.  “A single mouse’s investment in pheromone production compares with the investment that 10 male peacocks make in the production of their tails, which also are used to attract females.”

Besides gaining insights in mice sex habits and practices, the University of Utah preset research has some important practical applications. Through a better understanding of how pheromones work and how these influence mating, scientists, workers or volunteers associated with conservation efforts may improve their success with captive-breeding programs. It might be better, for instance, than forcing pandas to watch panda porn in hope they might get aroused and actually get off their lazy butts to mate.

“It’s amazing how often reintroduction of captive-breed endangered species fails – it’s estimated to be as high as 89 percent,” says Potts. “Domestication stimulates epigenetic mechanisms that make animals less fit for nature.”

 

dog_tail_wag

Reading a dog’s mood by studying its tail wag

dog_wagging_TailAny dog lover will tell you if you see a dog wagging its tail it’s a sign that the dog is happy. Apparently, there are subtle signals given off by variations in tail wagging and these are used to communicate with other dogs what their stance is. Researchers at University of Trento, Italy found that happy dogs wag their tails more to the right (from the dog’s point of view), while nervous dogs more to the left. Findings also show that dogs recognize and respond to these distinct patterns.

Though structurally symmetric, the brain is asymmetrical in function  hence the right and left hemisphere of brain each with distinct functions (i.e. the left hemisphere controls speech, the right hemisphere controls spatial coordination). The wiring is reversed however in terms of body coordination; the left hand is controlled by the right hemisphere of the brain and right hand is controlled by the left hemisphere of the brain for instance. This is true for all vertebrates, including dogs.

“It is very well known in humans that the left and right side of the brain are differently involved in stimuli that invokes positive or negative emotions,” says Prof Georgio Vallortigara, a neuroscientist from the University of Trento.

[RELATED] After studying dog emotions with MRI: “Dogs are people, too

“Here we attempted to look at it in other species.”

Researchers monitored dogs as they watched recordings on a TV screens of other dogs who were wagging their tails either more to the right or the left. The dogs were presented in two versions: a naturalistic version or a silhouette to get rid of any other confounding issues. Meanwhile the heart rate and behavior of the animals were monitored.

dog_tail_wag

(c) Current Biology

When the animals saw an otherwise expressionless dog move its tail to the right (from the tail-wagging dog’s point of view), they stayed perfectly relaxed. After if the wag strayed to the left, the dogs’ heart rate increased and they also looked anxious. Just like body language in humans conveys certain feelings and messages unconsciously which other people also unconsciously pick up and respond to, so dogs have their own behavioral patterns which aren’t made intentionally but which nevertheless get recognized.

 “If you have several meetings with other dogs, and frequently their tail wagging one way is associated with a more friendly behaviour, and the right side is producing a less friendly behaviour, you respond on the basis of that experience,” says Vallortigara.

The researchers claim the findings could help vets, dog owners and animal behaviorists gain better insight into dogs’ emotions. A paper was published in the journal Current Biology.