BBC - Earth News - Cuckoos are no match for local reed warblers
Research into the relationship between cuckoos and reed warblers has to date concentrated on the behaviour of individual birds and their. The cuckoo is a brood parasite, which means it lays its eggs in the nests of other birds, thus forcing the unwitting "foster parents" to hatch and raise the cuckoo's. With their landmark publication 'Cuckoos versus reed warblers: adaptations and but when the young bird is born it casts out of the nest those with whom it has A. Lotem, H. Nakamura, A. ZahaviRejection of cuckoo eggs in relation to host .
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Egg marking contrast showed a decreasing trend, with species differences also decreasing, suggesting better mimicry. Our results suggest multidirectional evolution of eggshell components in this system, with potential implications for mimicry and rejection over time. During long-term coevolutionary arms races among brood parasites and their hosts, selection pressures drive adaptations of the brood parasites and counter-adaptations of hosts Davies, Many hosts have evolved the ability to recognize alien eggs and eject them from their nests, or desert their clutch entirely, and so many female cuckoos deceive host parents through laying eggs that mimic those of their host, making recognition of foreign eggs more difficult.
Even when studies are based on eggs stored in museum collections e. As such, there is a pressing need for long-term studies on the coevolution of egg colour e. Previous modelling has predicted that cuckoos should over time benefit from increasing the resemblance of their own eggs to those of the host and that hosts should be under selection to escape parasitism Takasu, Therefore, the selection pressure derived from brood parasitism may promote host eggs in a given population to change phenotypes over time Takasu et al.
As sole occupant, it tricks its warbler 'parents' into supplying its voracious appetite until it fledges.
Cuckoos are expert tricksters: If the reed warbler detects an alien egg in its nest, or spots a cuckoo nearby, it may eject the odd-looking egg. But cuckoos are so swift in laying their eggs only one is laid per nest and the process is over in as little as 10 secondsand so clever at disguising their eggs, that warblers are often uncertain whether an odd egg in the clutch is a cuckoo egg or one of their own.
Research into the relationship between cuckoos and reed warblers has to date concentrated on the behaviour of individual birds and their interactions with cuckoos, described as parasites. A new study published today 22 January in Scientific Reports looks at wider interactions between neighbouring communities of reed warblers, their strategies for coping with cuckoos, and, in particular, how warblers assess levels of risk by gathering information from a variety of sources. After two years of observation of warblers that spend the breeding season at Wicken Fen in Cambridgeshire, authors Rose Thorogood and Nicholas Davies Department of Zoology reveal that a kind of "neighbourhood watch" exists out in the reed beds, keeping birds up-to-date with the latest threats.
Using a series of controlled experiments, involving model cuckoos and broadcasts of reed warbler alarm calls, the researchers revealed that reed warblers factored information gathered from close surveillance of the neighbourhood into their decision-making when assessing whether or not to eject an egg.
When reed warblers spot a cuckoo, they may mob it and emit alarm calls that carry up to 40 metres. Nick Davies Reed warblers are a little smaller than sparrows and each one weighs no more than a large envelope. As autumn begins they migrate some 5, km from Britain to West Africa, a journey they might make just two or three times in their short lives.
In April they fly north to breed in the watery landscapes of northern Europe where they raise their young in nests suspended from reeds.
Cuckoo and Warbler Symbiotic Relationship by Kelsie Reid on Prezi
Sometimes they are tricked into raising cuckoo chicks which grow to four times their size. He carefully parts the reeds until he can see a pair of warblers feeding their young in a nest. When several hours later he stands up, the intimate world of the warbler disappears into the great expanse of fenland and the wide East Anglian skies.
Observation remains vital to learning more about the world, believes Davies.Common Cuckoo Chick Ejects Eggs Of Reed Warbler Out Of The Nest