There has been some serious forgery going on in the world of evolution!
And, despite any hopes the thought of that might raise in the deluded minds of creationists, I'm not talking about human forgeries such as the famous Piltdown skull hoax, but natural forgeries produced by the natural force of evolution by natural selection.
The forgeries in question are the way brood parasite birds' eggs mimic those of the hosts.
I wrote about this very phenomenon in my popular, illustrated book, The Malevolent Designer: Why Nature's God is not Good, in which I said:
Cuckoo Finches and Arms Races.Now one of the zoologists I cited in that section of my book, Professor Claire Spottiswoode from the Department of Zoology, Cambridge University, England, UK and the FitzPatrick Institute of African Ornithology, University of Cape Town, South Africa, along with Professor Michael Sorenson of the Department of Biology, Boston University, Boston, MA, USA, and others, has published an open access paper in PNAS which addresses the following questions:
The cuckoo finch or parasitic weaver, Anomalospiza imberbis of East Africa is an obligate brood parasite on other birds of the Cisticolas and Prinias families. As we have seen with the earlier brood parasites, this has resulted in the inevitable evolutionary arms race as the parasitized hosts evolve strategies to reduce the depredation and the cuckoo finch evolves ways to circumvent the defence strategies of its intended hosts.
The strategy adopted by the tawny-flanked prinia, Prinia subflava, is to change the colours of its eggs more quickly than the cuckoo finch can and to produce eggs in an array of colours with markings that the prinia recognises as its own, almost like a signature.
The red-faced cisticola, Cisticola erythrops, on the other hand, while not varying the colour of its eggs has evolved to be better at spotting the cuckoo finch’s eggs and removing them. Another species, the rattling cisticola, Cisticola chiniana which might be expected to be an ideal host for the cuckoo finch appears to have won the arms race and is not parasitized at all (89).