LSM1303 Animal Behaviour

There have been findings which have discovered that repeated and very loud blasts of sonar is able to cause dolphins to lose their hearing. Dolphins rely heavily upon sound for navigation purposes and because of ongoing naval campaigns and the sonar they give out, they become confused. In the past few years, there have been numerous incidents of dolphins and whales beaching and many have attributed the cause to naval campaigns.

Dead, beached dolphin in Ellisville (Plymouth), Massachusetts

Photo: Tasmanian Parks and Wildlife Service, Liz Wren, HO

It is suggested that their hearing becomes damaged due to powerful mid-range frequencies of the warship sonars. Sea mammals like dolphins and whales are heavily dependent on sounds for direction. The effects can be disastrous as dolphins and whales travel in herds. In the article by Michael Graham, the incident was already the 5th mass beaching and nearly 500 whales have died during that time.

In an interesting marine experiment led by Aran Mooney at University of Hawaii, a captive-born, trained Atlantic bottle-nosed dolphin was exposed to progressive louder pings of mid-frequency sonar. It appears that when it reached a certain limit, the dolphin was no longer responding to sound – it had gone deaf. It had gone deaf when “it had been exposed to constant barrages of the sonar.” In addition to that, there was significant increase in the dolphin’s breathing rate when the sonar was turned on as well. Clearly, the sonar was a disturbance.

It was also pointed out that there may not an easy way out of persistent and loud sonars. Mooney explained that sound doesn’t attentuate in the normal fashion in the ocean. They sometimes may get trapped at the surface of the ocean and this could have been a possible reason for confusion. In any case, it has clearly proven that sonar could be a possible likely primary cause for beaching is by far bizzare and unusual display of animal behaviour.

Citations

“Strong sonar causes deafness in dolphins” by AFP. Discovery Channel, 7/4/2009

“80+ Whales and Dolphin Beached In Australia” by Michael Graham Richard. Treehugger, 25/03/09

Camera?

What does this sound like to you?

Yes, it sounds like a camera taking pictures. 

How about this?

chainsaw?

If you hear these noises while walking in the forest of southeastern Australia, you might think that someone is out there stalking you with a camera and chainsaw. But don’t panic, as most likely what you heard has nothing to do with psychotic stalkers. 

If you think that the above 2 sound clips are sounds of camera and chainsaw, then you have just been fooled by the most amazing songbirds on the planet – the Superb Lyrebird (Menura novaehollandiae). 

Here is what it looks like.

The Superb Lyrebird can produce and mimic diverse and complicated sounds due to its syrinx, which is the vocal organ of songbirds.  The syrinx of the Lyrebird is the most complexly-muscled of the songbirds. It gives them the amazing ability of mimic sounds like camera shutters, chainsaws, car alarms and even crying babies. 

In order to attract females, the male Superb Lyrebird tries singing complex songs. The songs are complex as the Superd Lyrebird will copy the singing of other species of birds. Sometimes the mimicry is so good and accurate that even the original is fooled by it.

For those who have a hard time believing that a bird is capable of mimicking the sounds of camera shutters and chainsaws, below are clips of the birds performing.

 camera

chainsaw

Lyre Bird – Imitating Sounds

References

Richard Zann and Emily Dunstan (2008) Mimetic song in superb lyrebirds: species mimicked and mimetic accuracy in different populations and age classes

An exotic bird was seen wandering around Singapore’s Seletar hills during the month of Janaury 2009.  It was sighted at HDB void decks, on top of TV antennas and scavenging around houses for food. One of the houses it paid a visit to captured a video of it eating a papaya and posted it on Singapore’s Straits Times’ STOMP.

So what is the name of this species bird anyway? Well, it is none-other than the Ramphastos Toco Toucan, which is native to South America’s tropical rainforests. It looks vastly similar to, and should not be confused the Rhinoceros Hornbill which a bird native to our sunny, tropical island Singapore. Most toucans grow to a height of 63.5cm, and weigh between 700-780g. They are also are omnivorous and they feed on a diet of fruits, insects, frogs, lizards and bird eggs

Coming back to the STOMP entry, what I found intriguing about the Ramphastos Toco Toucan’s was its feeding behaviour.  If you paid close attention to the manner it ate its papaya in, you would notice something very interesting. The toucan would tear out a tiny piece of papaya, hold it at the tip of its beak, toss it up in the air and tilt its beak such that it was at a 45 degree angle to allow the papaya to land inside in a precise position such that it can slide down its really huge and long beak. I was mystified on why the toucan went to such pains to eat such a tiny piece of fruit! Surely it would be much simpler to just tilt its beak up so that the fruit could slide down its throat.

Of course I did my homework and found out the scientific reason for this. The article “Feeding mechanism in fruit-eating bird Toucan, Ramphastos toco” described my above mentioned behaviour as “Toucan took and positioned the food always at the same place by small beak opening and closing before to tilt rapidly the head backwards to impose a ballistic curve to the food. At about 140°, the upper beak was suddenly opened and the food continued freely its ballistic curve inside the beak. As the food reached the level of attachment of the beak on the skull, the tip of the tongue moved upward from its resting position on the lower jaw to open the pharyngeal cavity by depression of the hyoid apparatus. The ballistic projected food entered directly into the pharynx”

This meant that the toucan actually engaged in this complicated movement whenever it consumed food such that it could have “intra-oral food transport” without the food coming into contact with the tongue. As a result, toco toucans have really long and thin tongues! Isn’t it marvellous that we now know that toucans use their beak, not only for feeding, attracting mates, intimidating competition and predators, but also for storing and transporting food?

So what was he doing wandering around seletar hills? Apparently he’s someone’s lost pet. Isn’t he absolutely adorable?

click here for the video! :)

Toucan eats papaya on STOMPer’s house wall

References:

i. “Exotic bird pays surprise visit to my house” by STOMPer Cheryl, The Straits Times, STOMP, 19 Jan, 2009

ii. “Mystery of the lost toucan solved” by Ivan Kwan & Ashley Ng, BESGroup website, 25 Feb 09

iii. “Toucan sighting” by Summerian Turks & Michelle Ooi, BESGroup website, 5 Feb 09

iv. “Toucan tongue” by ninjavshippo, Youtube, 03 Aug 2007

V. “Toucan” by Austin, Animal Everyday, 20 Oct 2007

Vi. “Hornbills can thrive in urban Singapore” by The Singapore Hornbill Project, The Straits Times Forum, 6 Apr 2009

Vii. “Feeding mechanism in fruit-eating bird Toucan, Ramphastos toco” by S. Baussart, Museum National d Histoire Naturelle — MNHN, France, L. Korsun, Academy Moscow, Russia and V. Bels, Museum National d Histoire Naturelle — MNHN, France, science direct, 13 Apr 2007 http://www.sciencedirect.com.libproxy1.nus.edu.sg/science?_ob=ArticleURL&_udi=B6VNH-4NGKDXR-3P&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=203a2571afbd6424176242a6061179d2

Sea Monkeys Ad

You may have come across ads for these ‘instant pets’ years ago. You might even have gotten your own Sea Monkey starter kit out of curiousity. You’ve seen them miraculously ‘appear’ in your tank, swam around, and multiplied. And you wondered, “Are they really monkeys that live in water?”
 

Sea Monkeys are actually a hybrid of brine shrimp and are known as Artemia Salina. Brine shrimp were cross-bred to form a hybrid that can grow larger and live longer. This became known as Sea Monkeys.
 

Ever wondered how Sea Monkeys look under the microscope?

You’re probably feeling cheated at this point: “So you mean I’ve been growing shrimp instead of underwater monkeys?? Why call it ‘Sea Monkeys’ then?” The name was based on the Artemia Salina’s similarity in playful behaviour and long tail to the monkey.

“So how do the Sea Monkeys ‘appear’ out of nowhere??”
If environmental conditions are not suitable for live birth, Artemia Salina creates a sugar called trehalose to coat their eggs and protect them from extreme temperatures and dehydration. These eggs (or cysts) can live for many years in dry conditions. Sachets in Sea Monkeys kits contain crystallised cysts of Artemia Salina, which hatch in the presence of water. Hence, they seem to appear ‘miraculously’.

This behaviour also occurs in their natural habitat. Artemis Salina is found in saltwater lakes with high alkalinity. These lakes dry up periodically due to changes in seasons. Hence, the ability of Artemis Salina’s eggs to survive extreme temperatures and lack of water is essential for their survival. In fact, their eggs do not hatch unless they experience a dry spell! This is to ensure that they do not hatch prematurely, before the lakes dry up.

So now you know.. Sea Monkeys are not water monkeys. They’re brine shrimp!

Top: Advertised Sea-monkey, Bottom: Real Sea-monkey

References:

Sea Monkeys Official Website (2009). The Amazing Live Sea-Monkeys® 2009. Accessed 5 April 09.

Captain’s Universe (2007). Captain@captain.at. Accessed 5 April 09.

News in Science (2000). Abbie Thomas – The Lab. Accessed 5 April 09.

The flocking behavior of thousands of starlings, flying in incredible aerial formations, to their roosting sites before settling into trees for the night never fail to amaze by-standers. Collective animal behavior of large groups of animals, such as bird flocks, fish school and mammal herds, is a fascinating natural phenomenon. The main goal of collective behavior among individuals is to maintain cohesion of the group. This cohesion is an important requirement for survival: small groups and individuals are significantly more susceptible to predation than animals belonging to large and highly cohesive aggregations. For example, when a flock of starlings is under attack by a falcon, the flock contracts, expands, and even splits. Despite continuously changing its structure and density, no bird remains isolated, and soon, the flock reforms as a whole.

A common starling, sturnus vulgaris

A group of starling in 'aerial display'

The question to answer is: what kind of interaction enables the birds to maintain cohesion in such a robust way? One proposed theory is that individuals align and attract each other base on metric distance [Couzin et al (2002)] which they can estimate by stereovision, retinal image size and optic flow [Goodale et al (1990)]. This means that such interaction would decay when distance between individuals is increased. For example, 2 birds 5metres apart would attract each other less than 2 birds separated by 1metre in between them. However, if such interaction is based on metric distance, changes observed during predator attack cannot be explained. This is because one would expect the loss of cohesiveness of the flock when metric distances between individuals become larger than the interaction range.

An alternative hypothesis has been proposed [Ballerini et al (2008)] regarding collective behavior: individuals attract each other based on topological interactions. This means that each individual interacts and tracks a fixed number of neighbors despite their metric distance. In this case, 2 birds in a sparse flock and separated by 5metres would attract each other as much as 2 birds in a denser flock and separated by 1metre in between them, provided the number of individuals between the 2 birds is the same. The strength of interaction would thus remain the same for flocks at different densities, enabling the flock to stay together during strong density fluctuations (for example in predator attacks).

To test this hypothesis, Ballerini et al (2008) observed and reconstructed the 3D positions of individual birds in flocks of a few thousand members using stereo-metric and computer vision techniques. Computational numeric simulations were also conducted to test the topological hypothesis with the metric distance hypothesis. The research group concluded that cohesion in flocks, interacting based on topological cues, are much more robust under perturbations than metric ones, and that topologically, each bird interacts on average with six to seven neighbors.

In conclusion, collective animal behavior is an interesting phenomenon which allows large groups of animals to maintain cohesion that is necessary for survival. However, the underlying principles of interaction between the animals are still not fully elucidated, and might be attributed to topological cues between individuals.

References:

ID Couzin, J Krause, R James, GD Ruxton and NR Franks. (2002). Collective memory and spatial sorting in animal groups. Journal of Theoretical Biology 218: 1–11.

MA Goodale, CG Ellard and L Booth. (1990). The role of image size and retinal motion in the computation of absolute distance by the Mongolian gerbil (Meriones unguiculatus). Vision Res 30:399–413.

M Ballerini, N Cabibbo, R Candelier, A Cavagna, E Cisbani, I Giardina, V Lecomte, A Orlandi, G Parisi, A Procaccini, M Viale and V Zdravkovic. (2008). Interaction ruling animal collective behavior depends on topological rather than metric distance: evidence from a field study. Proceedings of the National Academy of Sciences, U.S.A. 105: 1232–1237.