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, this 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!!!


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: (accessed: 9 Apr. 2010).

Baloo, the baby killer?

sloth bear with cub

Baloo, the Baby Killer?

I recently chanced upon an article from the Asian Geographic magazine which suggested the possibility of the adult male of the sloth bear, Melursus ursinus, to be a threat to the cubs of its own species. (Baloo from the Jungle Book, 2010) Now this is surprising revelation, as anyone who has seen the classic Disney film animation, The Jungle Book, would know that Baloo, the sloth bear in the movie, is portrayed as the alternative “mentor” to Mowgli, the man-cub, teaching him how to lead a carefree “slacker” lifestyle by living off the jungle. (The Jungle Book [1967 film]) The incongruity of Disney choosing an animal that could possibly have infanticidal tendencies as Mowgli’s mentor was apparent to me. I was intrigued to find out why animals, in particular the sloth bear, would kill their offspring.

Research shows that infanticide is common in the animal kingdom, and there are varying explanations for its occurrence. One main explanation is that the individuals responsible for infanticide benefit by gaining fitness through several sources that include: “(1) exploitation of the infant as a resource, (2) elimination of a competitor for resources, (3) increased maternal survival or lifetime reproductive success for either mother or father by elimination of an ill-timed, handicapped, or supernumerary infant, and, finally, (4) increased access for individuals of one sex for reproductive investment by the other sex at the expense of same-sex competitors.” The last source of benefit mentioned is used to explain sexually-selected infanticide (SSI), which is a common practice with bears. (Hrdy, 1979) There is little research available on SSI occurring amongst sloth bears, although it is well documented amongst other species such as brown bears (Ursus arctos) and polar bears (Ursus maritimus). (Stirling and Derocher, 1990)

In the magazine article, the female sloth bear tending to her cubs that the writer observed became very nervous upon the appearance of a male (which is typically 50 percent heavier than a female). She proceeded by rushing towards the male accompanied by “impressive roars”, a typical mock-charge to deter potential aggression. Considering that the female would probably be severely injured in a confrontation with the male, her counterstrategy to SSI might not be the best. Females of other bear species have been observed to counter male SSI behaviour by becoming sexually promiscuous, effectively mating with every male they chance upon, which would allow the males to mate with the females in the hope that the cubs would be spared. (Bellemain, Swenson and Taberlet, 2006)


“Baloo from the Jungle Book” by Axel Gomille. Asian Geographic , Vol. 72, 3/2010, pp. 32-35.

“The Jungle Book (1967 film)” in Wikipedia. URL: (Accessed on: 09 Mar 2010)

Hrdy, Sarah Blaffer, 1979. Infanticide among animals: A review, classification, and examination of the implications for the reproductive strategies of females. Ethology and Sociobiology, Vol. 1, Issue 1 (October 1979), pp. 13-40.

Ian Stirling and Andrew E. Derocher, 1990. Factors Affecting the Evolution and Behavioral Ecology of the Modern Bears. Bears: Their Biology and Management, Vol. 8 (1990), pp. 189-204.

Eva Bellemain, Jon E. Swenson and Pierre Taberlet, 2006. Mating Strategies in Relation to Sexually Selected Infanticide in a Non-Social Carnivore: the Brown Bear. Ethology,  Vol . 112, No. 3 (2006), pp. 238-246.