iii) Discovery of some cuckoo eggs by the host birds and replacement based on the quality of local random walks .
a], which resembles the discovery of the cuckoo eggs by the host birds.
They have found that cuckoo eggs are internally incubated by the female bird for up to 24 hours before birth.
After this time, the zebra finch eggs were at the same stage as the cuckoo eggs at the time they were laid.
These observations strongly suggest that cuckoos punish hosts that remove cuckoo eggs from their nests, Soler wrote in a subsequent paper co-authored by University of Granada ecologists Juan Soler and Juan Martinez, and Anders Mol- ler, an evolutionary biologist at Pierre and Marie Curie University in Paris.
The study was done over three nesting seasons (1990-92), during which Soler and his colleagues removed cuckoo eggs from a total of 29 parasitized magpie nests, and left them untouched in 28 others.
Of the host birds that accept cuckoo eggs, some are apparently fooled by the cuckoo's mimicry skills.
Nests were randomly assigned to two groups: (1) experimental nests (N = 29), from which the cuckoo egg was artificially removed 0-3 d after laying; and (2) control nests (N = 28), visited in the same manner as experimental nests.
Only two of the seven magpies that ejected the cuckoo egg laid a replacement clutch; both of these were parasitized again by the cuckoo.
The Mafia hypothesis assumes that the reproductive success is higher for magpie hosts that accept a parasite egg than for those that eject the cuckoo egg.
First, we have information on the reproductive success of magpie acceptors that raised the cuckoo, ejectors that ejected the cuckoo egg, and abandoners that abandoned their nest after being parasitized.
Now an increasing proportion of cuckoo eggs
end up in the nests of long-distance migrants, Moller and his colleagues report online September 15 in Proceedings of the Royal Society B.
have a very short incubation period - 10 or 12 days, compared to 13 - 15 days for the host species - so invariably the young cuckoo hatches first,and though blind,naked and looking so helpless,it then proceeds to eject all the other eggs from the nest.
In a rare test of the idea, cuckoos retaliated against magpies in Spain that rejected cuckoo eggs
, scientists reported in 1995.
The robins' eggs didn't look at all to human volunteers like cuckoo eggs