Killer Guides

[This was written by Fran Siebrits and published online by Wild Magazine http://www.wildcard.co.za/, 2011]
 
It's not all milk and honey when it comes to sharing a nest with a honeyguide, especially if you happen to be the foster sibling. These brood parasites have a deadly way of dealing with any eggs left in the nest.

Honeyguides are brood parasites, just like the cuckoo, laying their eggs in a number of other birds' nests while the hosts are out. The female punctures the host eggs to prevent them from hatching and lays four to seven of her own eggs at a time. In doing so the honeyguide tricks the residents into caring for the foreign eggs as their own. 

But honeyguide behaviour is more brutal than just nest-stealing and manipulating. Hatchlings are equipped with extremely sharp hook-beaks. Chicks of the host nest that happen to survive and hatch are brutally pecked to death by the parasitic chicks. By killing off the competition, the honeyguides monopolise the nest and their host parents’ care.

Honeyguide birds internally incubate their eggs for an extra day so that they are the first to hatch in the host nest, ahead of the other species. In this way the parasite hatchlings have the advantage in a very unfair fight to the death.

Dr Claire Spottiswoode, lead author of the paper A stab in the dark: chick killing by brood parasitic honeyguides, says: "The killing behaviour is actually the culmination of a sequence of specialised adaptations that ensure that the young honeyguide has sole access to the food the host parents bring to the nest." The oblivious hosts rear the honeyguide chicks as their own, feeding and protecting them.

Egg puncturing by honeyguide parents, extra internal incubation and killing-off of host hatchlings ensure the survival of the parasitic brood chicks. Even though it may seem brutal, the African large honeyguide has developed successful ways of ensuring continuation of its species.

Did you know?
The scientific name of the African large honeyguide, Indicator indicator, is quite apt. These birds are known for guiding humans to beehives. These clever little birds have come to realise that once man opens up the hive and takes his share, there is easy access for them to go in and fill their bellies with nutritious bees wax.

Sources:
Biodiversity Explorer online [http://www.biodiversityexplorer.org/birds/indicatoridae/indicator_indicator.htm]
University of Cambridge (2011, September 13). Newly hatched chicks of African honeyguide birds bite to death their foster siblings to eliminate competition. ScienceDaily. [http://www.sciencedaily.com /releases/2011/09/110908210115.htm]