Echolocation in Bats

We hear animals communicate vocally throughout our day to day lives; birds singing, crickets chirping, and frogs croaking are only a few examples. Yet not a lot of people take the time to wonder, how and why are these sounds traveling and evoking a response from the receiver? Bats for example, produce calls that travel through the air in a unique way. They use echolocation to locate objects and search for prey. What’s even more fascinating is that bats actually construct unique signals by changing the frequencies, intensities, and harmonics. They also have different patterns in signaling, as the duration and intervals between calls also vary.

Even the environment around echolocating bats can influence their calls, as it can obstruct as well as aid these mammals in their endeavors. Echoes of certain leaves can serve as a disturbance to the bats search for food, but the echoes of other leaves can do the opposite. Other leaves in specific plants act as a sort of radar for the bats, as the echoes produced lead them to flowers that contain both pollen and nectar. It has been discovered that these ultrasonic guides are not always located on the flower itself, but often on the dish-shaped leave above it. This is true in the vine Marcgravia evenia, as the leaves above its flowers serve as a beacon for bats echoes and lead them to the nectar.

Although this echoing method of communication can be very helpful, it can also disclose information much more easily to potential predators or prey. To help diminish the risk of exposing information to possible prey, the bats manipulate the intensity of their calls by altering the frequency. For example the species Barbastella barbastellus can produce echolocating calls that are undetectable to moths while Eptesicus fuscus use harmonics to lessen interference.

Yet bat communication is not restricted only to vocal signals; it also extends to the olfactory system as well. In the species Saccopteryx bilineata, males use odors that are produced by composites stored in their wing sacs for mating. Vampire bats, belonging to the species Desmodus rotundus, are equipped with infrared detectors on their noseleaf, the same structures that are found in various snakes. These structures detect the heat from the blood just below the skin, and use this to locate their prey.

There are still so many unanswered questions about echolocation in bats like how it evolved and the functional roles of physical structure and ear movement. What we do know that this adaption benefited bats inside the realm of communication, as their signals can travel much longer distances as well as allow them to locate objects and prey. Through further research, we can gain more insight into the daily lives of these flying mammals and be able to really view the world through a bats ear.

http://www.sciencemag.org/content/333/6042/528.full?sid=763c97e8-6771-49c6-a2ad-9064db86ae55

Posted by Sara Corey(1)

From Animal Gestures and Songs to the Roots of Language

From Animal Gestures and Songs to the Roots of Language

Animals are constantly communicating with each other. Just walking around campus one may notice birds chirping at each other or squirrels moving their tail to signal another squirrel nearby. I believe that the origins of our modern language can be traced back to the simplest animal gesture or song. The basic structure for efficient communication was set up long before human origins. Natalie Uomini (archaeologist at the University of Liverpool) says “The more we study animals, the more we realize that they have abilities similar to ours. “ It is likely that the first human language contained gestures, similar to those seen in many animals.

In the 1950’s scientists closely studied the communication methods of a chimpanzee named Viki. Scientists raised Viki in a human home and tried to teach her how to speak. Viki proved to be very poor at vocalizing, managing to roughly make out four words (mama, papa, cup, and up). Decades later, scientists found much more success in teaching a chimp sign language. The fact that chimps had much stronger gestures as a communication method than vocalizations probably means that the first human language was based on different forms of gestures. Vocalizations in primates are believed to be more innate than learned. For example the vervet monkey gives out a specific alarm call if a leopard is around.

Both apes and humans rely on language-related centers in the left brain when pointing with their right hand. The left hemisphere of the brain contains specialized regions for language and controls movements of the right side of the body. Researchers found in baboons that during a gesture such as begging for food, they have a strong tendency to move their right hand in making a gesture. A similarity is found in infants using their right hand to point. I believe these resemblances are evidence that human gesture and speech are linked, and are localized in the left part of the brain.

The vocalization aspect of language is likely to be closely related to bird songs. Although primates are our closest relatives they do not seem to have a strong ability for vocal learning. However the ability of infants to mimic the sounds of adults is strongly seen in birds. A researcher found that for vocalization to develop in both humans and birds the infant must be exposed to an adult tutor and be allowed to babble (called subsong in birds) to develop mature vocalizations. Another researcher proved that birds can process human vocalizations. A zebra finch was taught to peck a certain button after hearing the words “white” or “law”. I believe this research is strong proof that there is relatedness between human and bird vocalizations.

The research made in the article I read reveals a lot about the origins of language. I believe the roots of language are in part from developing vocalizations for basic gestures seen in primates. Primates have proved that the use of language is strongly influenced by the left part of the brain. Also in part, language has developed because of the inherited ability found in birds to mimic sounds made by an adult.

Posted by Nick Gast (1)

Source: http://www.radicalanthropologygroup.org/old/class_text_119.pdf

Juvenile Northern Gannet, Possibly Injured or Sick

While interning on White Island in the Isles of Shoals, NH, this summer (2011), I encountered a juvenile Northern Gannet (NOGA). White Island and Seavey Island, which are connected at low tide, are extremely small islands that are primarily occupied by three species of Terns during the summer months. However, there are also many other species of birds that live in the area or that fly by during the course of the summer. One of these species, Northern Gannets, rarely land on White and Seavey islands; rather, they can often be seen offshore, diving and catching fish. However, at one point this summer, a juvenile Northern Gannet appeared and remained on the islands for a few days. It seemed like it might be injured; it was capable of flight but one of it's wings looked funky while it was flying, and it primarily just sat on the outer, rocky edge of one of the islands. If it got too close to the Terns, they dive-bombed it and chased it out of their breeding area like they do to all other interlopers in their territory.

Once, when I was walking around the outer edge of Seavey Island doing gull control, I was forced to walk near it on my way, and I recorded a video of its reaction to my approach. It was very clearly upset at my proximity, and squawked at me. I walked by it as quickly as I could to avoid disturbing it too much.



Posted By Johanna Brophy (1)

ANIMALS AND EMOTIONS

Humans often believe that we are the only species capable of complex thought and emotions. One such emotion is that of grief. It is a well known fact that humans grieve over the death of other humans, especially those they are close to, but are animals aware of death? For a long time people did not consider the ways animals deal with death. Recently there has been more of an interest since observation of chimpanzees and other primates have shown that some animals may confront death in human-like ways.

Interest was sparked back in 2008 when an 11-year-old gorilla at the German Münster Zoo refused to give up her dead baby. He died at the age of three months from a heart defect. It took days before she stopped holding him and allowed zookeepers to remove his body. It had previously been observed that many primate mothers show this type of behavior upon the death of their child; they will hold on to their infants and treat them as though they were still alive.

It was also observed at Blair Drummond Safari Park in Scotland that chimpanzees will react to the death of an elder in their group. A 50-year-old chimpanzee named Pansy started to become slower as she neared death. The other chimpanzees appeared to be aware and started to sleep by her and would even stroke and groom her. After her death one chimpanzee studied her face and moved her arms, as if to check if she were still alive. Contact with her stopped after that, except for one chimpanzee that pounded on her torso that night, as if in an attempt to make her wake up.

Research doesn’t stop with primates. It has been observed that elephants also react in a particular way to death. Elephants presented with a number of species of bones will spend the most time observing those of other elephants. When one elephant dies they will often all stand nearby and touch their tusks to that elephant’s tusks before leaving. Elephants will also return to the place a loved one has died and stand there for a long period of time in silence. Behavior has also been studied in lions, mole rats, and honeybees. Recently a video has emerged of a squirrel protecting another squirrel’s body from a pack of crows.

Then the question is: are these animals morning death just as humans do or are they just not aware of what is happening?

Video of squirrel protecting another dead squirrel:

http://news.discovery.com/animals/video-shows-squirrel-reacting-to-death.html

Posted by Caitlin Descovich O’Hare (1)

For additional Reading:

http://news.discovery.com/animals/chimpanzee-death-dying-behavior.html

http://www.nytimes.com/2008/09/02/science/02angi.html

Unique Form of Mammal Communication Found in Madagascar

Unique Form of Mammal Communication Found in Madagascar

I was actually watching a documentary on Animal Planet the other day about Madagascar, and the tenrec struck me as a great animal to blog about. Tenrecs are small mammals, sometimes described as appearing to be a cross between a shrew and a hedgehog. They are covered with protective quills, and are endemic to Madagascar, where there are about 30 known species. I was particularly intrigued by the Lowland Streaked (or Striped) Tenrec, (Hemicentetes semispinosus), a largely nocturnal insectivore that lives in family groups of up to 20 individuals, usually living together in the same burrow. What is unique about these tenrecs is their ability to use a strange form of communication known as stridulating in a number of different scenarios (such as foraging), although much about this is still not understood.

Stridulation is accomplished by vibrating specialized quills on their back, making a unique high-frequency grinding sound that they can easily differentiate from the sounds of other animals foraging at night, likely so they can keep track of their family group. This behavior is also said to be more commonly observed between mother and offspring, likely so they can communicate information about their location to each other without attracting the attention of potential predators. What is particularly interesting about this is that the streaked tenrec is the only known mammal to communicate using stridulation, something that is most commonly seen in insects, fish, snakes, and arachnids.

Something else that struck me while I was doing background research was the general lack of information on these curious mammals. Many of the sources I came across had conflicting information about their foraging habits (some said they were entirely nocturnal, others said they forage during the day as well), as well as basic information about when they breed, when young mature, etc. This was really surprising to me because I think an understanding of a species’ life history traits is essential for understanding possible reasons for various adaptations. Also, I think there is a lot to be learned from these tenrecs, such as how long ago did they develop these specialized quills? Did something happen during this time period that may have caused them to develop this adaptation (such as the introduction of a new predator)? Do any of their close relatives have similar adaptations? Or, when comparing their stridulations with those of insects, are there any similarities between them that may suggest context or meaning? I think there is a lot to be learned from the Lowland Streaked Tenrec, especially on the communication front, so I was surprised when I had so much difficulty finding reliable information.

In conclusion, while little is known for sure about the Lowland Streaked (or Striped) Tenrec, it is undoubtedly a great example of how Madagascar's geographic isolation has promoted the divergence of many unique animal adaptations not found anywhere else on Earth.

http://www.youtube.com/watch?v=W9kJKu4cpXM

Posted by Brianna Eddy (1)

(additional sources of background info: http://www.arkive.org/lowland-streaked-tenrec/hemicentetes-semispinosus/ & http://www.tsaracamp-madagascar.com/mammals.html)

Week 1: A Pack of Commuincation

Wolves (Canis lupus) are extremely intelligent organisms that communicate through body language, scent, and vocals. They live across the globe, but are most heavily concentrated in North America, including many Canadian and Alaskan territories.

The pack is a social hierarchy beginning with the leaders, also known as the alphas. The alphas are usually the oldest, largest, strongest, and most intelligent male and female wolves in the pack. However, any wolf can become an alpha, but they need to find an unoccupied territory and a member of the opposite sex. To communicate dominance in the pack the alphas stand tall and hold their tails high. Less dominate wolves hold their bodies low to the ground and hold their tails down while pawing at the higher ranking wolves.

There are two kinds of submissive behavior: active and passive. Active submission is a contact activity in which signs of lower ranking are evident such as crouching, muzzle licking, and tail tucking. These behaviors are first seen in pups to "elicit" regurgitation in adults. These behaviors are retained into adulthood by lower ranking wolves, where they function as ways to show the alphas they know they are lower in rank. Passive submission is when a subordinate wolf is on its side and shows its underside to the alpha. Sometimes the subordinate wolf will allow the alpha to sniff its genitalia, but if the alpha disagrees with the subordinate, teeth may be shown between the two. Most of the time the lower wolf will back down to avoid a fight.

Wolves have a sense of smell 100 times greater than humans. They use this sense of communication to do a behavior called scent-marking. Using scat and urine wolves mark the perimeters are their territories. When a passing wolf comes into contact with these scents they know that this territory is off limits. Wolves also use chemical messages to communicate. They have an array of pheromones that are released from their toes, tail, eyes, anus, genitalia, and skin. Males can tell when a female is going into estrus by the scent of her pheromones. Their sense of smell also lets them know when enemies and food is near.

Vocals are a huge part of wolves and they way they live. Howling, barking, whimpering, and growling are the main types of vocalizations. Howling can happen all day, but is most likely to be heard in the evenings when wolves are most active. It is used to communicate over large distances to either gather the pack or keep the pack together and invaders away. Growling and barking are used for warnings. Whimpering is used by a mother wanting her pups to nurse or by a subordinate to communicate "I give up" if in a confrontation with a dominate wolf.

Wolves are very beautiful and intelligent creatures and should be treasured. Humans should learn about social structures and ways of communicating signals through body language. A lot can be learned from the pack and it's only a howl away.

Sources:

http://www.wolf.org/wolves/learn/basic/biology/communication.asp
http://www.bio.davidson.edu/people/vecase/behavior/Spring2003/Bergeron/habitat.htm



Posted by Em Arsenault

Early Peanut Exposure

It’s hard to imagine that a hint of any type of food that a person may be allergic to can kill them in an instant. In present day there are all sorts of medications that prevent fatal injury when people consume foods that they are allergic to. I guess the question really arises when we want to know when you know when you are allergic. How can we prevent someone from finding out without a tragic experience? Well The beginning of all humans comes from birth, so this is must be where it all begins.

An allergic reaction to peanut butter in infancy is one of the many significant public health issues today. It is common to see someone over the age of six having an allergic reaction to peanut butter and have to take out an epipen or something like it to cure them of getting an instantaneous reaction like anaphylaxis or from dying. So when a baby is still in the mother’s womb how we know what that baby is allergic too. Must we wait until there is an incident?

When the body is allergic to something it reacts. Usually what makes an allergen what it is, is that when it enters the body it is seen as a foreign body itself. So the body uses a specific protein to create a specific protein for that allergen. This way when the allergy enters the body again you will have an allergic reaction. Of course this takes time and depends on how much exposure is received in order for the body to have had time to create this specific protein. This is the process a baby must go through except it takes them much longer because they probably wont have all that exposure and because their bodies and immune system are not developed enough.

Researchers suggested that perhaps it be a good idea that pregnant woman hold out on consuming peanut butter during pregnancy. Yet they saw that the rates for this incident were low but what about the few that it happens to? This of course seems like the best idea as a solution to this public health problem because there is no way of telling what allergies a baby might come out having. Sometimes these allergies are learnt by the body and sometimes hereditary. If there is no way of telling its better not to take such a risk as it is better to be safe than sorry.


Cambridge Journals Online. Version doi:10.1017/S0007114509993813. British Journal of Nutrition, n.d. Web. 9 Feb. 2010 .


Posted by Jean Fedna