Egg Mimicry of Cuckoos

Pattern mimicry through a birds eye

The Cuckoo bird is a brood parasite, this means that it lays its eggs inside the nest of another bird, the other bird then feeds and nurtures the eggs of the Cuckoos. 

This parasitism has caused both of the species involved to evolve further. The birds have evolved to notice when their nest has been parasitised. However the cuckoo has evolved to have egg mimicry. This study I am blogging about is going to explore this(Stoddard and Stevens, 2010). 

Previous studies have used the human eye to measure the pattern similarities, however this study used UV, Infrared and luminous analysis in order to detect mimicry as how a bird would see the eggs, instead of human vision(Stoddard and Stevens, 2010). 

The study found that the cuckoos eggs were evolved to mimic in the species which rejected the eggs the most. They are in an evolutionary arms race always changing to beat each others defenses. The study found that there was no pattern on the egg which has no rejection. One of the main issues is the markings sizes. The host is less likely to reject the egg if the marking sizes are the same. Some host species such as the Australian bronze-cuckoo do not reject the eggs even though they are darker. This could be due to the eggs being camouflaged in the nest(Stoddard and Stevens, 2010). 

Figure 1: Cuckoo eggs on top mimicing the Reed warbler eggs bottom (Chap, 2012).

References

Chap, C. (2012). [image] Available at: http://en.wikipedia.org/wiki/Common_cuckoo#/media/File:Cuckoo_Eggs_Mimicking_Reed_Warbler_Eggs.JPG [Accessed 9 May 2015].

Stoddard, M. and Stevens, M. (2010). Pattern mimicry of host eggs by the common cuckoo, as seen through a bird's eye. Proceedings of the Royal Society B: Biological Sciences, 277(1686), pp.1387-1393.

Deception of Primates

Using Social skills to deceive 

The primates as well as us humans have undergone natural selection in order to deceive others in order to gain something.

In baboons it was noticed that when another baboon was chasing them, they stood up in the alert position in order to seem like they had noticed a predator. The chasing baboon didn't resume the chase in order to look for the predator, even though there was no predator present. This is called tactical distraction deception (Byrne and Whiten, 1992).

Another type of deception would be concealment. This is when the individual hides something from the other individual. For example if a Chimp has found food, it will attempt to keep it behind his back and out of view of other chimps(Byrne and Whiten, 1992) .

This behaviour could be due to operent conditioning which is when an individual receives reinforcement for their behavior (McLeod, 2015) . Therefore the Chimpanzee may have discovered that by putting the food behind his back stops other chimps from taking the food from them.
A different learning method could have been more cognitive and this could be that be behaviour was observed and learnt from older primates (Byrne and Whiten, 1992) .

References

Byrne, R. and Whiten, A. (1992). Cognitive Evolution in Primates: Evidence from Tactical Deception. Man, 27(3), p.609.

McLeod, S. (2015). B.F. Skinner | Operant Conditioning | Simply Psychology. [online] Simplypsychology.org. Available at: http://www.simplypsychology.org/operant-conditioning.html [Accessed 8 May 2015].

Sexual/Female deception

Deception of plumage colours in Pied Flycatcher birds

This blog is on the topic of sexual mimicry and in particular for this species it is female mimicry. This is when a male mimics a female in order to deceive other males. They mimic their behavior, morphology or chemical signals. (Wikipedia, 2015)

During mating season the male Pied Flycatcher bird Ficedula hypoleuca is extremely aggressive towards other males with brightly coloured plumage. They are aggressive towards the males however they act sexually towards the less brightly coloured females. It has been found that these birds can also use deception when they intrude on a claimed area of the male bird. They use appearance deception and the male F.hypoleuca is deceived by another male with less brightly coloured plumage. The male acts sexually towards this male intruder(Slagsvold and Saetre, 1991).

There are a number of proposed causes for this deception. These include a delay in the sexual maturation, status signalling and spring molt constraints.

One reason for these delays of plumage colour could be to allow the younger bird to get a place in a previously occupied space in an older males territory. 

The molt hypothesis would be evolutionary not beneficial because this would prevent the younger birds from being able to mate for that year, therefore preventing the passing on of their genes.(Slagsvold and Saetre, 1991) 

The status signalling hypothesis suggests that the plumage colouration shows a female how useful the male is, in terms of reproductive quality. The plumage colour also could suggest the health of the genetics of the male. (Siitari, 2002)

Figure 1: Brown colour of young males or females (Wood, 2015)

Figure 2: Black and white colour of males / elder males. (Jonczyk, 2008)

References 

Jonczyk, P. (2008). [image] Available at: http://ibc.lynxeds.com/photo/european-pied-flycatcher-ficedula-hypoleuca/male [Accessed 8 May 2015].

Siitari, H. (2002). Individual color variation and male quality in pied flycatchers (Ficedula hypoleuca): a role of ultraviolet reflectance. Behavioral Ecology, 13(6), pp.737-741.

Slagsvold, T. and Saetre, G. (1991). Evolution of Plumage Color in Male Pied Flycatchers (Ficedula hypoleuca): Evidence for Female Mimicry. Evolution, 45(4), p.910.

Wikipedia, (2015). Sexual mimicry. [online] Available at: http://en.wikipedia.org/wiki/Sexual_mimicry [Accessed 8 May 2015].

Wood, J. (2015). [image] Available at: http://www.pbase.com/wildbirdimages/image/128748337 [Accessed 8 May 2015].