Fantastic Feigners of Injury and Death

The critically endangered St. Helenian Plover

(Charadrius sanctaehelenae) feigning injury 

(Source: Flickr. Image by Burns)

Two weeks ago my boyfriend’s parents came back from a trip away to the remote island of St. Helena Island off the coast of South Africa where they stumbled upon a bird called the wirebird or St. Helenian plover (Charadrius sanctaehelenae) and came back telling me stories of their find. They were able to watch how a nesting pair they found tried to protect their eggs. I was told that one (they were unsure whether it was the male or the female) sat on the nest and refused to budge while the other moved about around the nest and pretended to be injured in the hope that the predator (in this case my boyfriend’s parents) would get distracted by this display and not go after the eggs anymore but instead go after the ‘injured’ parent.

This in known as ‘injury-feigning’ and is relatively common among birds. Many species of doves and plovers have been observed feigning injury (Swrath, 1935) as well as the Florida nighthawk (Ckhordeiles minor chapmani) (Tompkins, 1942) among others. I have even been lucky enough to witness this in a family of Willy Wagtails (Rhipidura leucophrys) in my back yard back in Innisfail. 

Initially, the reason behind this display was thought to be the birds mixed emotions between wanting to flee the nest to get away from a predator and its attachment to its young causing a muscular inhibition and an inability to fly (Friedmann 1934; Tompkins, 1934). Further observations have lead scientists to believe that this behaviour is in fact a device used voluntarily to lure predators away from young. This would prove to be an advantageous behaviour to adopt because the parent is obviously better able to escape the predator than the chicks in the nest (and definitely the eggs if they are unhatched). By acting injured, the predator is alerted of the existence of a larger and more filling meal being available for only a little more work than it would take to get the chicks or eggs. Weighing the cost over the benefits, the predator is then more likely to attempt to attack the ‘injured’ parent. Hopefully, the injured parent will be able to get away at the last moment and the predator will give up on this meal.

Animals are also known to go one step further. Many animals are able to feign death in order to trick their predators into discarding them. This is called letisimilation or thanatosis (Gregory, et al., 2007) and is widespread among the animal kingdom from insects, amphibians and reptiles to birds and mammals (Gregory, et al., 2007). Some examples of the animals that demonstrate this behaviour are the red flour beetle (Tribolium castaneum) (Miyatake, et al., 2008), ant-lions (of the family Myrmeleontidae) (Turner, 1915), some crickets (eg Gryllus bimaculatus), grass snakes (Natrix natrix) (Gregory, et al., 2007) and rough earth snakes (Virginia striatula) among others (Thomas & Hendricks, 1976) to name a few. 

Western hog-nosed snake (Heterodon nasicus) 

feigning death to escape predation

(Source: Arkive. Image by Visuals Unlimited)

The strategy of feigning death is usually used as a last resort when an animal has been captured by a predator and all its other attempts to avoid predation (eg. toxicity, crypsis, group living, predator confusion, pursuit deterrent signals etc.) have failed. Simulated death may be achieved by rolling over onto their back and opening their mouth like the Western hog-nosed snake (Heterodon nasicus), or by releasing chemicals through their skin threat smell as tough they have been dead for a while and slowing their heart rate. By acting as if they are dead they will either confuse the predator for a split second allowing it to escape or the predator will believe the deception and moves on. Either way, feigning death makes them less likely to be eaten by the predator and more likely to reach their goal of passing their genes onto the next generation (Gregory, et al., 2007).

References

Friedmann, H., 1934. The Instinctive Emotional Life of Birds. The Psychoanalytic Review, 21(3 - 4), pp. 1-57.

Gregory, P. T., Isaac, L. A. & Griffiths, R. A., 2007. Death feigning by grass snakes (Natrix natrix) in response to handling by human "predators.". Journal of Comparative Psychology, 121(2), pp. 123-129..

Miyatake, T. et al., 2008. Pleiotropic antipredator strategies, fleeing and feigning death, correlated with dopamine levels in Tribolium castaneum. Animal Behaviour, 75(1), pp. 113 - 121.

Swrath, H. S., 1935. Injury-Feigning in Nesting Birds. The Auk, 52(3), pp. 352 - 354.

Thomas , R. A. & Hendricks, F. S., 1976. Letisimulation in Virginia striatula (Linnaeus). The Southwestern Naturalist , 21(1), pp. 123-124.

Tompkins, I. R., 1942. The "Injury-Feigning" Behavior of the Florida Nighthawk. The Wilson Bulletin, 54(1), pp. 43 - 49.

Turner, C. H., 1915. Notes on the Behavior of the Ant-Lion with Emphasis on the Feeding Activities and Letisimulation. Biological Bulletin, 29(5), pp. 277 - 307.

University of Bath, 2010. The critically endangered St. Helenian Plover feigning injury, photograph, viewed 27 May 2014

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Visuals Unlimited, n.d., Western hog-nosed snake (Heterodon nasicus) feigning death to escape predation, photograph, viewed 27 May 2014

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