Entries in animal behaviour (13)
A recent publication in the journal Animal Behaviour has found that the western scrub jay holds “funerals” for their dead.
Millions of bats have been affected by white-nose syndrome (WNS); a fungus that grows specifically on the bats’ nose, wings, ears and tail and eats through the skin, thus destroying the membrane. It has been the cause of approximately 5.5 million bat deaths.
Thanks to a revised photograph identification technique, developed originally for tigers, researchers from the Wildlife Conservation Society (WSC) are able to better recognise individual jaguars in Bolivia than previously possible.
Coat patterns are as unique as our fingerprints, allowing researchers to accurately log data about individuals. The technique involves creating a digital map of an individual’s coat pattern by stitching a series of photographs together which have been taken by camera traps or even tourist photographs. The use of this method has spread throughout the animal kingdom to include species such as grey seals, cheetahs, whale sharks and now, jaguars.
The technique is also proving to be useful for persecuting those involved in the illegal fur trade. Animals can now be traced back to their natural habitat through the development of ‘maps’ created by digital imaging. This drives the direction of investigative enquiries by establishing the location of the population in the wild.
WSC researchers using the photograph identification technique have been able to recognise 19 individual jaguars from a total of 975 photographs taken by only one camera. The number of photos taken during this study is at record high due to digital cameras being used rather than the normal traps that use film. The practice of using spot patterns to identify individual jaguars has been made possible due to the high resolution offered by digital cameras.
The ability to accurately identify individuals at such a high resolution will allow researchers to gain an intimate insight into the lives of these secretive animals and how best to protect them against the dangers of poaching.
You would probably recognise them by their distinctive appearance, but how much do you know about the toothed whale, the narwhal? It turns out researchers are also vague about the specifics of a narwhal’s life and how it may change as a result of global warming.
The WWF are trying to establish how Arctic melting is affecting ice – associated species such as the narwhal. Dr. Peter Ewins of WWF-Canada and his team tagged nine individuals in August of this year to try and establish how the elusive narwhal would cope with shrinking sea ice. Dr. Ewins is waiting on the results of their movement patterns to compare with anecdotal evidence of local Inuit’s to try and initiate a successful conservation plan. This is because narwhals are classed as near threatened by the IUCN, with their population at only approximately 50,000 - 80,000 individuals due to hunting practices for their meat and tusk.
Their long, helical tusk was thought to have initiated the fairytales of unicorns and who could blame anyone for being inspired by this mysterious species! The tusks originate from their left canine tooth and males can have tusks that reach up to 3m in length and in 1 out of 500 males, two are produced! Females also possess a tusk, but it is shorter and is not helical in shape. It is thought the tusk has evolved via sexual selection in a similar process to that of the peacock and its feathers. In addition to this, you may have thought the tusk could be used to break through ice patches enabling the narwhal to migrate with ease. However, it is thought the tusk is only used as a visual display to others as they are very rarely observed using their tusk in aggressive behavior.
They are the preyed upon by polar bears, orca and of course, humans, which further depletes their population. In addition to this, narwhals have a highly specialized diet (and therefore restricted) possibly hampering the recovery of their population in the future. When the results from this study are published it will provide greater knowledge to the scientific community when the time comes for a conservation plan for this unique species.
Scientists have recently discovered that the widely feared piranha, use sounds to communicate with one another in an attempt to intimidate rivals, instead of attacking them.
Dr Eric Parmentier, from the University of Liege, Belgium, previously studied sound production and communication in a variety of fish species including piranhas. This research discovered that piranhas made sounds, however was inconclusive as to why. Studies in this area suggest that a wide variety of fish use noises to attract potential mates, therefore the sounds made by piranhas could possibly indicate a reproduction process.
Through the use of hydrophones (underwater microphones), Dr Parmentier and his colleagues undertook a laboratory experiment that recorded the sounds piranhas made when they confronted each other, while also filming their interactions.
The recordings picked up three distinct sounds from the piranhas. The first was a bark that the fish produced when they “displayed” or confronted one another without engaging in fighting behaviour. The other two were a drum – like beat which they used when chasing one another and a softer croak made when biting other individuals. These physical confrontations tended to be made over food.
For much of the study the fish made no noise and did not engage in any passive or physical confrontations. It was only after hours of observations that researchers managed to capture this illusive behaviour.
The production of sound in piranhas is made by vibrating their swim bladders, a gas filled chamber that helps regulate their buoyancy. The vibration of the swim bladder is driven by high speed muscles that contract and relax 150 times every second.
Dr Parmentier suggests piranhas use noises to communicate as it uses less energy than physical conflicts. As a result, energy expenditure can be directed into other important biological activities such as reproduction and feeding.
Dr Parmentier and his team are aiming to conduct further studies on piranhas in the Amazon to find out more about the acoustic repertoire of this fascinating creature.
By Anthony Kubale
“Alan! Alan! Alan!” Not only can small mammals respond to their name, but it has now been established that they are able to recognise calls specific to other individuals. Research has been conducted by Dr Simon Townsend on meerkats inhabiting the Kalahari Desert, South Africa. Dr. Townsend and his research team are the first scientists to discover that voice recognition occurs in other species apart from primates and also suggests the possibility of it being more wide spread in the animal kingdom than previously thought.
Although the research has produced interesting results, Dr. Townsend and his team had to overcome the problem of the meerkat’s reaction to an individual’s call. Although it is widely known that meerkats are social animals, it is much harder to distinguish the relationships to one another in a clan. Consequently, it is difficult to observe which individual will respond to whom. To solve this problem, audio playback was used to gauge the individual’s reaction to a call.
Recordings of staccato "close calls" (noises made to reassure other members of the clan they are there and as territory warnings) were played to an individual from one location and their response recorded. A call from the opposite orientation from which the original call came from was then played to the same meerkat and the response was once again recorded. In the final stages of the experiment, recordings from the same meerkat were played to one individual from conflicting directions.
Dr. Townsend commented this process as being a "violation of the animal's expectation" as the meerkat making the call could not physically be in two places at the same time. Also, during these periods of “violation” the meerkats became more vigilant to their surroundings. It is possible the ability to recognise individual voices has evolved to make communication between members of the same clan more efficient due to meerkats having complex social groups.
It is hoped this research will inspire others to investigate whether other animals can also recognise individual calls and whether we have underestimated other mammals’ communication methods.
Have you ever wondered what noise a koala makes? A roar? A squeak? Or a g'day? Well researchers and many other people that live in, or have visited the wonderful land of Oz, know that they make a low grumbling noise. Intriguingly, the mechanism of how they create this sound has not been understood until now.
The low, grumbling, dulcet tones normally occur during mating season, perhaps recreating some Barry White magic for female koalas? Dr. Benjamin Charlton and his team from the University of Queensland, Australia have discovered how koalas produce an astonishingly ear deafening noise and a very low frequency for such a small marsupial. The loud noise has probably evolved during the process of sexual selection. This is because typically, the louder the noise generated by a male, the larger and fitter the male is.
The instrument from which koalas make this noise has been deciphered by using MRI scans and post mortem studies on the larynx (which houses the vocal chords). It was found that the larynx, which is normally located near the throat, has descended all the way to the 3rd and 4th cervical vertebrae. In addition to this, the muscle anchoring the larynx to the sternum was found to reach much deeper in the chest cavity than previously thought. This allows the larynx to be pulled down even further in the chest when making mating calls.
This anatomy has never been seen in marsupials before and causes loud, rumbling sounds to enter the voice box, which act like a large empty room, amplifying the call further. In fact, the noise they make is so deafening it is even louder then a bison! This makes any male koalas sound larger than they actually are, intimidating other males nearby and impressing female koalas and hence increasing their chances to mate.
The female koalas really can’t get enough of their love, babe.
Some of the more obvious and even famous examples of predator and prey relationships include the lion and wildebeest in Africa, the bear and salmon in Canada and of course the farmers arch enemy; the rabbit that eats the lettuce. However, there is one particularly unprecedented predator-prey relationship that has caught the attention of researchers at the Department of Zoology at Tel-Aviv University in Israel.
In a study published in the online journal PLoS ONE, hungry larvae of two recently discovered beetles of the genus Epomis have been found to have reversed their predator-prey relationship with amphibians, thus becoming the predator themselves. Usually it is amphibians that catch unsuspecting bugs for a tasty snack, but it appears that this particular type of larvae has evolved to take advantage of their would-be predators with an almost 100 per cent success rate.
Laboratory research has shown that the larvae combine a sit-and-wait strategy while enticing the amphibians with a ‘dance’ of their mouths and antennae. The study shows that when the amphibian ‘goes in for the kill’ of what it expects to be a relatively easy meal, the larva dodges the predator's tongue and uses its unique double-hooked mouthparts to attach itself to the amphibian's body. From the safety of its host, the larvae will feed on the defenceless and duped amphibian, ultimately resulting in death.
“Normally amphibians eat small larvae, so the larvae seem to be taking their revenge here,” said entomologist and leader of the study, Gil Wizen.
According to the report about 10 per cent of predator-prey relationships in the animal kingdom result in a smaller animal eating a bigger one, but they are all active attacks — not a small creature luring its prey and outwitting them in a magnificent feat of evolution.
These novel findings extend the perspective of co-evolution between predator and prey and suggest that this counterattack, defense behavior has evolved into predator-prey role reversal; the hunter has become the hunted.
Is this just a unique and one-off accident of nature or is it an extremely rare glimpse of what is to come in the next steps of evolution? Will it be the wildebeest that turns on the lion in a glorious battle of revenge, or a school of salmon taking on a bear in a Canadian waterfall?
Who knows what will become of the notorious relationship between the rabbit and the lettuce.
By Nicki Hollamby