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Across the animal kingdom, many animals build structures. One especially diverse example is that of nest building by birds. It remains unclear, however, what birds know or whether they learn about the structural aspects of the material with which they build a nest. Here we tested whether nest-building male zebra finches would choose the appropriate type of material when building in a novel situation. They did do this: males provided with a nestbox with either a small or a large entrance hole and with nest material of two types (‘long’ and ‘short’) chose the type of material that was appropriate for the box in which they built. Additionally, the birds' material use improved with experience: males building in nestboxes with small entrances became less choosy in their material choice as they became more skilled at inserting material of either length into their nestbox. The birds, therefore, first chose the appropriate materials for the nestbox in which they were building but then modified their handling skills so as to make use of all of the available material. How the cognitive abilities used in this nest-building context compare with those used in solving other physical problems such as tool use tasks is not yet clear. [Copyright &y& Elsevier]

Whether learning plays a role in nest building in birds is largely unknown. Here we investigated whether the colour of nest materials used to build a first nest affected the subsequent nest material choices made by male zebra finches when building a second nest. Males were tested for their preference for green or brown nest material and then were provided with either their preferred or nonpreferred colour with which to build their first nest. The success of this nesting attempt was manipulated such that half of the breeding pairs had their eggs removed, while the other half were allowed to keep their eggs and fledge chicks. Males were then retested to determine which colour of nest material they now preferred. Males had strong initial preferences for one or other of the two colours of nest material. Males that built a nest with their preferred colour of nest material continued to prefer that colour after nesting, regardless of their breeding success in that nest. However, of the males that built a nest with material of their nonpreferred colour, those that raised and fledged chicks from it subsequently preferred that colour of material for their second nest, while males that suffered a failed breeding attempt did not. Thus breeding experience can influence decisions relating to nest material choice in nest construction in the zebra finch. [Copyright &y& Elsevier]