Verbal Deception

Verbal deception

Much like the previous forms of deceptions and mimicry in animals; the use of sound and verbal signals can be exploited in order to deceive possible predators, prey or even members of the same (or different) species. Remember in my second blog? Batesian mimicry; where a harmless animals mimics the appearance of harmful one? Well, certain animals have evolved to utilise sound and verbal signals in the same way, to mimic the sounds of a harmful animal in order to avoid predation. Syntomrida epilais(Polka-Dot Wasp Moth) is an animal that utilises this method. It copies a clicking sound that the distasteful Cycnia tenera (Delicate Cycnia Moth), that predators have some learn, has signalled to predators. However, The Polka-Dot Wasp Moth is an incredible evolutionary example that utilises multiple deceptions and will be explored in great detail later in the future.

Dicrurus adsimilis (Fork-tailed Drongo) is a small passerine bird that has the ability to mimic false alarm calls of not only their on species but other species as well. The Drongo would make these alarm calls when watching a target handling there food, in response to which the target would abandon their food for the safety of cover. They then utilise this opportunity to steal the abandoned food. Flower (2011) has described that the Fork-tailed Drongo has even shown the ability to mimic the alarm calls of Suricata suricatta (Meercats). Further examples of verbal deception and mimicry will be explored next week.

Figure 1: Dicrurus adsimilis watching over a hunting ground. Photographer: Rust de winter (2004)

References

Flower, T. (2011). Fork-tailed drongos use deceptive mimicked alarm calls to steal food. Proceedings. Biological Sciences / The Royal Society. 278, 1548-55.

Rust de winter, L. (2004). Dicrurus adsimilis watching over a hunting ground. http://www.birdforum.net/opus/Fork-tailed_Drongo. Retrieved: 24/04/2015

Feigned Injury and Automimicry

This week we will examine another example of feigned injury deception as well as further explain what automimicry is as requested. The following week we will continue to define the different levels of deception and mimicry and in the future really explore the biology behind how species have developed these fascinating traits.

Feigning death is the level of feigned injury; to be able to deceive possible predators (or prey) into believing that they no longer are alive is incredible. The classic case of feigned death can be seen portrayed by Didelphimorphia (the opossums). Ever heard the expression playing dead or playing possum? When Didelphimorphia are threatened or harmed, they will display the appearance and smell as if they are dead. When they are feigning death, the animals lips are drawn back, revealing bared teeth, saliva foams around the mouth and they secrete foul-smelling fluid from their anal glands. This deters possible predators that prefer to take live prey. Thompson et al (1981) describes that the lack of movement in the prey species confers selection benefits by depriving predators of the necessary movement stimulus to launch a final attack. In this case the Opossum utilises feigned death as a defensive mimicry. Next week we will explore the use of feigned death as an aggressive mimicry.

Figure 1: Didelphimorphia playing dead. Photographer: T.Alter (2011).

 Now to take a step back and further explore Automimicry. As stated in my last post, automimicry is where one part of an organism’s body resembles another part. This only occurs within a single species. Chaetodon capistratus (the four-eyed butterfly fish) is such a species that utilises automimicry. It gets its common name from the large dark spots found on the rear portion of both sides of its body. These spots are lined with a bright white colouration creating the illusion that these are its eyes. A vertical bar on its true head runs through its eyes, making it harder to distinguish. Neudecker (1989) states that false eyespots are located in these areas of the body to allow escape and survival following an attack. When threatened they will flee by putting the false eyes in the direction of the predator. Most predators aim for the eyes of their prey, and by placing the false eyes towards the predator, the predator is clueless to the apparent escape attempt that follows.

Figure 2: Chaetodon capistratus displaying its false eyes. Photographer: J.Lyle (2012).

References

Lyle, J. (2012). Chaetodon capistratus displaying its false eyes. http://diver.net/bbs/posts003/87969.shtml; retrieved 19/04/2015

Neudecker, S. (1989). Eye camouflage and false eyespots: chaetodontid responses to predators. Environmental Biology of Fishes. 25, 143-157.

Thompson, R. K. R., Foltin, R. W., Boylan, R. J., Sweet, A., Graves, C. A., & Lowitz, C. E. (1981). Tonic immobility in Japanese quail can reduce the probability of sustained attack by cats. Animal Learning & Behavior. 9, 145-149.

Tony, A. (2011). Didelphimorphia playing dead. http://www.flickr.com/photos/ 78428166@Noo/6289417559/; retrieved 19/04/2015.

False Behaviour and Feigned Injury

False behavior and feigned injury

As a continuation of false behavior and an introduction to feigned injury, we will be exploring how birds in particular exploit these forms of deception. The techniques explored below are often called distraction displays as they function as anti-predator behaviours, utilised in order to attract the attention of the predator away from an object such as the nest.

Charadrius volciferus (killdeer) is a medium-sized plover that displays false behavior as a distraction display. When a predator begins to approach, the killdeer will move to several places, squatting as if incubating eggs. This is called false brooding and confuses the predator to the actual location of its nest. This was the most frequent female response of killdeer during early incubation when a predator approaches (Brunton, 1990). This is the response of a female, however, the male will display behavior very different to their partners. This is known as the broken-wing act and is a form of feigning injury.

Figure 1. Charadrius volciferus performing a broken-wing act. Photographer: Anonymous (2010)

This distraction display involves the bird walking away from the nesting area, with its wings held in a position that simulates injury. It then flaps helplessly emitting a distress signal. Thinking that they are easy prey, the predators will follow the killdeer away from the nest. This is done until the predator is well away from the nest and then the killdeer will simply fly away. Should the predator show no interest initially to the “injured” killdeer, they will move closer to the predator themselves and call out louder to grab their attention. Note that both techniques can be employed by both sexes. Brunton (1990) continues to state that males took greater risks when performing distraction displays and this may lead to unintentionally getting caught by the predator; a disadvantage to the evolved trait.

We will continue to explore feigned injuries next week.

References

1.  Anonymous. (2010). Charadrius volciferus performing a broken-wing act. http://www.anthive.com/killdeer/killdeer.html; retrieved 07/04/2015.

1.     2. Brunton, D. H. (1990). The effects of nesting stage, sex, and type of predator on parental defense by killdeer (<i>Charadrius vociferous</i>): testing models of avian parental defense. Behavioral Ecology and Sociobiology. 26, 181-190.

False Behaviour

False Behaviour

The next level of deception in animals concerns the utilisation of false behaviour. Behaviour that conceals the true nature of the animals’ intentions. Such a predator acting in such a way that it hides it predatory nature around possible prey. These behaviours are more examples of aggressive mimicry as seen in the last blog.

Stenolemus bituberus (assassin bug) deceive spiders into thinking they are the prey rather than the predator. They hunt web-building spiders by plucking the silk of the web, generating vibrations that lure the spider into striking range. Wignall & Taylor (2010) describe that the assassin bugs mimic enough vibrations within the range of vibrations that are classified as ‘prey’ to the spiders.

Figure 1. Stenolemus bituberus exploring a spider web. Photographer: Anonymous (2005).

False behaviour techniques can also be utilised through the use of automimicry. Automimicry is when animals have one body part that mimics another in order to increase survival during an attack or to hide a predators intentions. Laticuda colubrine (yellow-lipped sea krait) appears to have two heads, however, it has evolved through successful use of automimicry to have a tail that looks and behaves like its head. This species of sea snake will intrude into nests looking for a meal exposing the behind unprotected to the environment. However, its tail looks and behaves like it venomous head deterring any would be predators. This species has combined false behaviour and automimicry in order to greatly increase its chances of survival. However, there are fitness trade-offs for such an advantages trait. Rasmussen & Elmberg (2009) describe that the tail needs to be flattened in order to move through the water but this would lead to the tail looking different to the head. We must remember that evolved traits may prove to be advantageous in one aspect but may hinder a species in another, and this will be explored in the future on this blog.

Figure 2. Laticauda colubrina displaying “both” heads. Photographer: Anonymous (2009).

References

1.     1. Anonymous. (2005). Stenolemus bituberus exploring a spider web. http://bio.mq.edu.au/research/groups/behavbiol/Assassins.html ; retrieved 05/04/2015.

2.     2. Anonymous. (2009). Laticauda colubrina displaying “both” heads. http://www.sciencedaily.com/releases/2009/08/090805201539.htm; retrieved 05/04/2015

1.     3. Rasmussen, A. R., & Elmberg, J. (2009). ‘Head for my tail’: a new hypothesis to explain how venomous sea snakes avoid becoming prey. Marine Ecology. 30, 385-390.

2.     4. Wignall, A. E., & Taylor, P. W. (2010). Assassin bug uses aggressive mimicry to lure spider prey. The Royal Society. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3061146.