Parental Infanticide: Children for Breakfast?

Eclectus parrots, Eclectus roratus, exhibit reverse sexual dichromatism which means that males and females differ in terms of colouration (see fig.1). In eclectus parrots, stark differences in colour of the beak and plumage are evident from as early as when they are nestlings. In fact it is interesting to note that till a few decades ago scientists believed that the two were different species altogether!

Male (left) and female (right) eclectus parrots perched on branch.

Fig 1: Male (left) and female (right) eclectus parrots perched on branch.

However, this reverse sexual dichromatism is not merely of aesthetic significance. The eclectus parrot is reknowned for being able to exercise extreme bias in sexual allocation. Hence,┬áthis is the reason why: “one eclectus in Chester Zoo produced 30 sons before the first daughter was produced” (Heinsohn et al., p. 1325). So what is the secret behind being able to maintain such a remarkable bias in sexual allocation?

Fig. 2: on day 3 this check is already clearly a male due to its yellow beak.

Heinsohn recognises the likelihood, yet until further study merely specualtion, of bias to occur at fertilization and probably, during ovulation (ibid., p. 1328). However, scientists also recognise that infanticide and cannibalism is likely because nestlings go missing and no remains are found. In addition, since eclectus parrots can be easily sexed after hatching, the parents job of sexing their children is made appraent at first sight. Therefore, eclectus parrots it is either ‘death or love at first sight’. Siblicide is common amongst birds when the youngest nestlings are pushed off the nest. However, parental infanticide is a less well known area of study which Heinsohn promises to look at in closer in detail in his studies to come.

Closer to home, more substantial evidence of parental infanticide and cannibalism can be found in the case of the Oriental Pied Hornbill, Anthracoceros albirostris, in Singapore (photgrpahic evidence is included). Afterall, one may have to conlcude that parental supervision may not always be the best thing for children!!!

References

R. Heinsohn, S. Legge & S. Barry, 1997. Extreme bias in sex allocation in Eclectus parrots. Proceedings of the Royal Society, Biological Sciences, 264: 1325-1329.

Ellegren H, Gustaffson L & Sheldon BC, 1996. Sex ratio adjustment in relation to paternal attractiveness in a wild bird population. Proceedings of National Academy of Science USA, 93(21):11723-11728.

Kevin J McGraw & Mary C Nogare, 2005. Distribution of unique red feather pigments in parrots. Biology Letters, 1, 38-43.

“Infanticide-cannibalismm in Oriental Pied Hornbill,” Prof Ng Soon Chye et al. Bird Ecology Study Group, 09 Apr. 2009. URL: http://besgroup.talfrynature,com/2009/04/09/infanticide-cannibalism-in- oriental-pied-hornbill/ (accessed: 9 Apr. 2010).

“Oriental Pied Hornbill: Parental infanticide,” Marc Cremades & Prof Ng Soon Chye. Bird Ecology Study Group, 07 Jun. 2007. URL: http://besgroup.talfrynature.com/2007/06/07/oriental-pied-hornbill-parental-infanticide/ (accessed: 9 Apr. 2010).